iccprofile: Refactoring

[deark.git] / modules / psd.c

// This file is part of Deark.
// Copyright (C) 2016 Jason Summers
// See the file COPYING for terms of use.

// * Photoshop PSD and PSB format
//  * PSD "image resources"
//  * PSD "series of tagged blocks"
// * Photoshop Action file format (.atn)
// * Photoshop Gradient file format (.grd)
// * Photoshop Styles (.asl)
// * Photoshop Brush (.abr)
// * Photoshop Custom Shape (.csh)
// * Photoshop Pattern file (.pat)

#include <deark-config.h>
#include <deark-private.h>
#include <deark-fmtutil.h>
DE_DECLARE_MODULE(de_module_psd);
DE_DECLARE_MODULE(de_module_ps_action);
DE_DECLARE_MODULE(de_module_ps_gradient);
DE_DECLARE_MODULE(de_module_ps_styles);
DE_DECLARE_MODULE(de_module_ps_brush);
DE_DECLARE_MODULE(de_module_ps_csh);
DE_DECLARE_MODULE(de_module_ps_pattern);

#define CODE_8B64 0x38423634U
#define CODE_8BIM 0x3842494dU
#define CODE_AgHg 0x41674867U
#define CODE_Alph 0x416c7068U
#define CODE_AnDs 0x416e4473U
#define CODE_CgEd 0x43674564U
#define CODE_Clss 0x436c7373U
#define CODE_DCSR 0x44435352U
#define CODE_Enmr 0x456e6d72U
#define CODE_FEid 0x46456964U
#define CODE_FMsk 0x464d736bU
#define CODE_FXid 0x46586964U
#define CODE_GdFl 0x4764466cU
#define CODE_GlbC 0x476c6243U
#define CODE_GlbO 0x476c624fU
#define CODE_IRFR 0x49524652U
#define CODE_LMsk 0x4c4d736bU
#define CODE_Layr 0x4c617972U
#define CODE_Lr16 0x4c723136U
#define CODE_Lr32 0x4c723332U
#define CODE_MeSa 0x4d655361U
#define CODE_Mt16 0x4d743136U
#define CODE_Mt32 0x4d743332U
#define CODE_Mtrn 0x4d74726eU
#define CODE_ObAr 0x4f624172U
#define CODE_Objc 0x4f626a63U
#define CODE_PHUT 0x50485554U
#define CODE_Pat2 0x50617432U
#define CODE_Pat3 0x50617433U
#define CODE_Patt 0x50617474U
#define CODE_PtFl 0x5074466cU
#define CODE_PxSD 0x50785344U
#define CODE_PxSc 0x50785363U
#define CODE_SoCo 0x536f436fU
#define CODE_SoLd 0x536f4c64U
#define CODE_TEXT 0x54455854U
#define CODE_Txt2 0x54787432U
#define CODE_TySh 0x54795368U
#define CODE_UnFl 0x556e466cU
#define CODE_UntF 0x556e7446U
#define CODE_VlLs 0x566c4c73U
#define CODE_abdd 0x61626464U
#define CODE_alis 0x616c6973U
#define CODE_anFX 0x616e4658U
#define CODE_artb 0x61727462U
#define CODE_artd 0x61727464U
#define CODE_blwh 0x626c7768U
#define CODE_bool 0x626f6f6cU
#define CODE_clbl 0x636c626cU
#define CODE_comp 0x636f6d70U
#define CODE_cust 0x63757374U
#define CODE_desc 0x64657363U
#define CODE_doub 0x646f7562U
#define CODE_enum 0x656e756dU
#define CODE_fxrp 0x66787270U
#define CODE_indx 0x696e6478U
#define CODE_infx 0x696e6678U
#define CODE_knko 0x6b6e6b6fU
#define CODE_lfx2 0x6c667832U
#define CODE_liFD 0x6c694644U
#define CODE_lnk2 0x6c6e6b32U
#define CODE_lnk3 0x6c6e6b33U
#define CODE_lnkD 0x6c6e6b44U
#define CODE_lnsr 0x6c6e7372U
#define CODE_long 0x6c6f6e67U
#define CODE_lrFX 0x6c724658U
#define CODE_lsct 0x6c736374U
#define CODE_lspf 0x6c737066U
#define CODE_luni 0x6c756e69U
#define CODE_lyid 0x6c796964U
#define CODE_mani 0x6d616e69U
#define CODE_mlst 0x6d6c7374U
#define CODE_mopt 0x6d6f7074U
#define CODE_mset 0x6d736574U
#define CODE_name 0x6e616d65U
#define CODE_obj  0x6f626a20U
#define CODE_patt 0x70617474U
#define CODE_prop 0x70726f70U
#define CODE_pths 0x70746873U
#define CODE_rele 0x72656c65U
#define CODE_samp 0x73616d70U
#define CODE_shmd 0x73686d64U
#define CODE_tdta 0x74647461U
#define CODE_tySh 0x74795368U
#define CODE_type 0x74797065U
#define CODE_vibA 0x76696241U
#define CODE_vmsk 0x766d736bU
#define CODE_vogk 0x766f676bU
#define CODE_vscg 0x76736367U
#define CODE_vsms 0x76736d73U
#define CODE_vstk 0x7673746bU

#define PSD_CM_BITMAP   0
#define PSD_CM_GRAY     1
#define PSD_CM_PALETTE  2
#define PSD_CM_RGB      3

// (I can't think of a good name for this struct, and the corresponding variables.
// It's used so much that the name needs to be short, distinct, and easy to type.)
// PSD format involves so many nested data elements with implicit lengths that
// it's worth developing a way to handle this with a maximum of convenience.
// This struct helps to do that.
// A function that processes an element has an instance of it (named zz) that it
// got from its parent (caller). It often creates new zz structs to pass to its
// children.
// The struct is used for both input and output.
// A function updates the 'pos' field as it consumes the data, but 'startpos' and
// 'endpos' never change.
//
// Some functions assume that the zz passed to them was created just for them, and
// thus .pos should be equal to .startpos, and .endpos should be exactly the size of
// that data element, if known. The code is more robust if a function can't directly
// modify its parent's zz, and this lets the child use the .startpos field.
// However, for convenience, some functions are designed such that they can use
// their parent's zz.
//
// Note that the struct has no way to indicate an error. It is expected that the
// functions' return values will be used, when error handling is necessary.
typedef struct zz_struct {
        // Represents a segment of the input file, and a position within that segment.
        // All fields are byte offsets from the beginning of c->infile.
        i64 pos; // The "current position". Also used to calculate the number of bytes consumed.
        i64 startpos; // Offset of the first byte in the segment.
        i64 endpos; // Offset of first byte *after* the segment.
} zztype;

// The PSD spec calls this data structure a
// "4 bytes (length), followed either by string or (if length is zero) 4-byte ID",
// but that's too unwieldy for me, so I'll call it a "flexible_id".
struct flexible_id {
        int is_fourcc;
        struct de_fourcc fourcc;
        char *sz; // Present if !is_fourcc. Raw bytes (+NUL), used for matching.
        de_ucstring *s; // Present if !is_fourcc. Text form of sz.
        i64 bytes_consumed;
};

struct image_info {
        i64 width, height;
        i64 color_mode;
        i64 num_channels;
        i64 bits_per_channel;
        struct de_density_info density;

        i64 pal_entries;
        u32 pal[256];
};

typedef struct localctx_struct {
        int version; // 1=PSD, 2=PSB
        int is_le;
        int input_encoding;
        int tagged_blocks_only;
#define MAX_NESTING_LEVEL 50
        int nesting_level;
        u8 jpeg_rbswap_mode;
        i64 intsize_2or4;
        i64 intsize_4or8;

        int abr_major_ver, abr_minor_ver;
        u8 has_iptc;
        struct de_density_info density;

        struct image_info *main_iinfo;
} lctx;

struct rsrc_info;

typedef void (*rsrc_handler_fn)(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri);

struct rsrc_info {
        u16 id;

        // 0x0004 = Item consists of a version number, followed by a "Descriptor structure".
        // 0x0010 = Do not include ASCII in hexdumps.
        u32 flags;

        const char *idname;
        rsrc_handler_fn hfn;
};

#define DECLARE_HRSRC(x) static void x(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)

DECLARE_HRSRC(hrsrc_resolutioninfo);
DECLARE_HRSRC(hrsrc_namesofalphachannels);
DECLARE_HRSRC(hrsrc_printflags);
DECLARE_HRSRC(hrsrc_iptc);
DECLARE_HRSRC(hrsrc_exif);
DECLARE_HRSRC(hrsrc_xmp);
DECLARE_HRSRC(hrsrc_iccprofile);
DECLARE_HRSRC(hrsrc_slices);
DECLARE_HRSRC(hrsrc_thumbnail);
DECLARE_HRSRC(hrsrc_byte);
DECLARE_HRSRC(hrsrc_uint16);
DECLARE_HRSRC(hrsrc_uint32);
DECLARE_HRSRC(hrsrc_unicodestring);
DECLARE_HRSRC(hrsrc_unicodestring_multi);
DECLARE_HRSRC(hrsrc_pascalstring);
DECLARE_HRSRC(hrsrc_plaintext);
DECLARE_HRSRC(hrsrc_urllist);
DECLARE_HRSRC(hrsrc_versioninfo);
DECLARE_HRSRC(hrsrc_printscale);
DECLARE_HRSRC(hrsrc_pixelaspectratio);
DECLARE_HRSRC(hrsrc_layerselectionids);
DECLARE_HRSRC(hrsrc_pathinfo);
DECLARE_HRSRC(hrsrc_printflagsinfo);
DECLARE_HRSRC(hrsrc_pluginresource);

static const struct rsrc_info rsrc_info_arr[] = {
        { 0x03e8, 0, "channels/rows/columns/depth/mode", NULL },
        { 0x03e9, 0, "Macintosh print manager print info", NULL },
        { 0x03ea, 0, "Macintosh page format information", NULL },
        { 0x03eb, 0, "Indexed color table", NULL },
        { 0x03ed, 0, "Resolution info", hrsrc_resolutioninfo },
        { 0x03ee, 0, "Names of the alpha channels", hrsrc_namesofalphachannels },
        { 0x03ef, 0, "Display information", NULL },
        { 0x03f0, 0, "Caption", NULL },
        { 0x03f1, 0, "Border information", NULL },
        { 0x03f2, 0, "Background color", NULL },
        { 0x03f3, 0, "Print flags", hrsrc_printflags },
        { 0x03f4, 0, "Grayscale and multichannel halftoning information", NULL },
        { 0x03f5, 0, "Color halftoning info", NULL },
        { 0x03f6, 0, "Duotone halftoning information", NULL },
        { 0x03f7, 0, "Grayscale and multichannel transfer function", NULL },
        { 0x03f8, 0x0010, "Color transfer functions", NULL },
        { 0x03f9, 0, "Duotone transfer functions", NULL },
        { 0x03fa, 0, "Duotone image information", NULL },
        { 0x03fb, 0, "Effective black and white values", NULL },
        //{ 0x03fc, 0, "(Obsolete)", NULL },
        { 0x03fd, 0, "EPS options", NULL },
        { 0x03fe, 0, "Quick Mask information", NULL },
        //{ 0x03ff, 0, "(Obsolete)", NULL },
        { 0x0400, 0, "Layer state information", hrsrc_uint16 },
        { 0x0401, 0, "Working path", hrsrc_pathinfo },
        { 0x0402, 0x0010, "Layers group information", NULL },
        //{ 0x0403, 0, "(Obsolete)", NULL },
        { 0x0404, 0, "IPTC-NAA", hrsrc_iptc },
        { 0x0405, 0, "Image mode for raw format files", NULL },
        { 0x0406, 0x0010, "JPEG quality", NULL },
        { 0x0408, 0x0010, "Grid and guides info", NULL },
        { 0x0409, 0, "Thumbnail - Photoshop 4.0", hrsrc_thumbnail },
        { 0x040a, 0, "Copyright flag", hrsrc_byte },
        { 0x040b, 0, "URL", hrsrc_plaintext },
        { 0x040c, 0, "Thumbnail", hrsrc_thumbnail },
        { 0x040d, 0, "Global Angle", hrsrc_uint32 },
        { 0x040e, 0, "Color samplers resource (Photoshop 5.0)", NULL },
        { 0x040f, 0, "ICC Profile", hrsrc_iccprofile },
        { 0x0410, 0, "Watermark", hrsrc_byte },
        { 0x0411, 0, "ICC Untagged Profile", hrsrc_byte },
        { 0x0412, 0, "Effects visible", hrsrc_byte },
        { 0x0413, 0, "Spot Halftone", NULL },
        { 0x0414, 0, "Document-specific IDs seed number", hrsrc_uint32 },
        { 0x0415, 0, "Unicode Alpha Names", hrsrc_unicodestring_multi },
        { 0x0416, 0, "Indexed Color Table Count", NULL },
        { 0x0417, 0, "Transparency Index", NULL },
        { 0x0419, 0, "Global Altitude", hrsrc_uint32 },
        { 0x041a, 0, "Slices", hrsrc_slices },
        { 0x041b, 0, "Workflow URL", hrsrc_unicodestring },
        { 0x041c, 0, "Jump To XPEP", NULL },
        { 0x041d, 0, "Alpha Identifiers", NULL },
        { 0x041e, 0, "URL List", hrsrc_urllist },
        { 0x0421, 0, "Version Info", hrsrc_versioninfo },
        { 0x0422, 0, "EXIF data 1", hrsrc_exif },
        { 0x0423, 0, "EXIF data 3", NULL },
        { 0x0424, 0, "XMP metadata", hrsrc_xmp },
        { 0x0425, 0x0010, "Caption digest", NULL },
        { 0x0426, 0, "Print scale", hrsrc_printscale },
        { 0x0428, 0, "Pixel Aspect Ratio", hrsrc_pixelaspectratio },
        { 0x0429, 0x0004, "Layer Comps", NULL },
        { 0x042a, 0, "Alternate Duotone Colors", NULL },
        { 0x042b, 0, "Alternate Spot Colors", NULL },
        { 0x042d, 0, "Layer Selection ID(s)", hrsrc_layerselectionids },
        { 0x042e, 0, "HDR Toning information", NULL },
        { 0x042f, 0, "Auto Save Format", NULL },
        { 0x0430, 0x0010, "Layer Group(s) Enabled ID", NULL },
        { 0x0431, 0, "Color samplers resource (Photoshop CS3)", NULL },
        { 0x0432, 0x0004, "Measurement Scale", NULL },
        { 0x0433, 0x0004, "Timeline Information", NULL },
        { 0x0434, 0x0004, "Sheet Disclosure", NULL },
        { 0x0435, 0, "DisplayInfo", NULL },
        { 0x0436, 0x0004, "Onion Skins", NULL },
        { 0x0438, 0x0004, "Count Information", NULL },
        { 0x043a, 0x0004, "Print Information", NULL },
        { 0x043b, 0x0004, "Print Style", NULL },
        { 0x043c, 0, "Macintosh NSPrintInfo", NULL },
        { 0x043d, 0, "Windows DEVMODE", NULL },
        { 0x043e, 0, "Auto Save File Path", hrsrc_unicodestring },
        { 0x043f, 0, "Auto Save Format", hrsrc_unicodestring },
        { 0x0440, 0x0004, "Path Selection State", NULL },
        // 0x07d0 to 0x0bb6: See lookup_rsrc() below
        { 0x0bb7, 0, "Name of clipping path", hrsrc_pascalstring },
        { 0x0bb8, 0x0004, "Origin Path Info", NULL },
        // 0x0fa0 to 0x1387: See lookup_rsrc() below
        { 0x1b58, 0, "Image Ready variables", NULL },
        { 0x1b59, 0, "Image Ready data sets", NULL },
        { 0x1b5a, 0x0004, "Image Ready default selected state", NULL },
        { 0x1b5b, 0, "Image Ready 7 rollover expanded state", NULL },
        { 0x1b5c, 0, "Image Ready rollover expanded state", NULL },
        { 0x1b5d, 0x0004, "Image Ready save layer settings", NULL },
        { 0x1b5e, 0, "Image Ready version", NULL },
        { 0x1f40, 0, "Lightroom workflow", NULL },
        { 0x2710, 0, "Print flags info", hrsrc_printflagsinfo }
};

// Forward declarations
static int read_descriptor(deark *c, lctx *d, zztype *zz, int has_version, const char *dscrname);
static void do_tagged_blocks(deark *c, lctx *d, zztype *zz, int tbnamespace);
static int do_descriptor_item_ostype_and_data(deark *c, lctx *d,
        const struct flexible_id *key_flid, zztype *zz, i64 itempos);

#define psd_getu16(p) dbuf_getu16x(c->infile,p,d->is_le)
#define psd_geti16(p) dbuf_geti16x(c->infile,p,d->is_le)
#define psd_getu32(p) dbuf_getu32x(c->infile,p,d->is_le)
#define psd_geti32(p) dbuf_geti32x(c->infile,p,d->is_le)
#define psd_geti64(p) dbuf_geti64x(c->infile,p,d->is_le)

// Initialize a zz, from known start and end positions.
static void zz_init_absolute(zztype *zz, i64 startpos, i64 endpos)
{
        zz->startpos = startpos;
        zz->pos = startpos;
        zz->endpos = endpos;
}

// Initialize zz such that its startpos is parentzz's *current* pos,
// and its endpos is the same as parentzz's.
static void zz_init(zztype *zz, const zztype *parentzz)
{
        zz_init_absolute(zz, parentzz->pos, parentzz->endpos);
}

// Initialize zz such that its startpos is parentzz's *current* pos.
static void zz_init_with_len(zztype *zz, const zztype *parentzz, i64 len)
{
        i64 startpos, endpos;

        if(len<0) len=0;
        startpos = parentzz->pos;
        endpos = startpos + len;
        if(endpos > parentzz->endpos) endpos = parentzz->endpos;

        zz_init_absolute(zz, startpos, endpos);
}

// Number of bytes consumed so far.
// I.e. number of bytes from startpos to the current position.
static i64 zz_used(zztype *zz)
{
        if(zz->endpos <= zz->startpos) return 0;
        if(zz->pos <= zz->endpos) return zz->pos - zz->startpos;
        return zz->endpos - zz->startpos;
}

// Number of bytes remaining / still available.
// I.e. number of bytes from the current position to endpos.
static i64 zz_avail(zztype *zz)
{
        if(zz->pos >= zz->endpos) return 0;
        if(zz->pos >= zz->startpos) return zz->endpos - zz->pos;
        return zz->endpos - zz->startpos;
}

// Functions that modify a shared "current file position" variable are
// discouraged in Deark, but PSD format practically forces us to use them
// in many cases.
// May as well go all the way, and even do it for simple get_int functions.

static u8 psd_dbuf_getbyte_zz(dbuf *f, zztype *zz)
{
        u8 val = dbuf_getbyte(f, zz->pos);
        zz->pos++;
        return val;
}

static i64 psd_dbuf_getu16_zz(dbuf *f, zztype *zz, int is_le)
{
        i64 val = dbuf_getu16x(f, zz->pos, is_le);
        zz->pos += 2;
        return val;
}

static i64 psd_dbuf_geti16_zz(dbuf *f, zztype *zz, int is_le)
{
        i64 val = dbuf_geti16x(f, zz->pos, is_le);
        zz->pos += 2;
        return val;
}

static i64 psd_dbuf_getu32_zz(dbuf *f, zztype *zz, int is_le)
{
        i64 val = dbuf_getu32x(f, zz->pos, is_le);
        zz->pos += 4;
        return val;
}

static i64 psd_dbuf_geti32_zz(dbuf *f, zztype *zz, int is_le)
{
        i64 val = dbuf_geti32x(f, zz->pos, is_le);
        zz->pos += 4;
        return val;
}

static i64 psd_dbuf_geti64_zz(dbuf *f, zztype *zz, int is_le)
{
        i64 val = dbuf_geti64x(f, zz->pos, is_le);
        zz->pos += 8;
        return val;
}

#define psd_getbytezz(z) psd_dbuf_getbyte_zz(c->infile,z)
#define psd_getu16zz(z) psd_dbuf_getu16_zz(c->infile,z,d->is_le)
#define psd_geti16zz(z) psd_dbuf_geti16_zz(c->infile,z,d->is_le)
#define psd_getu32zz(z) psd_dbuf_getu32_zz(c->infile,z,d->is_le)
#define psd_geti32zz(z) psd_dbuf_geti32_zz(c->infile,z,d->is_le)
#define psd_geti64zz(z) psd_dbuf_geti64_zz(c->infile,z,d->is_le)

// Read a 32-bit (if d->intsize_4or8==4) or 64-bit int from c->infile.
// This function is used to help support PSB format.
static i64 psd_getu32or64zz(deark *c, lctx *d, zztype *zz)
{
        if(d->intsize_4or8>4)
                return psd_geti64zz(zz);
        return psd_getu32zz(zz);
}

static const char *get_colormode_name(i64 n)
{
        const char *name = "?";
        switch(n) {
        case PSD_CM_BITMAP: name="bitmap"; break;
        case PSD_CM_GRAY: name="grayscale"; break;
        case PSD_CM_PALETTE: name="indexed"; break;
        case PSD_CM_RGB: name="RGB"; break;
        case 4: name="CMYK"; break;
        case 7: name="multichannel"; break;
        case 8: name="duotone"; break;
        case 9: name="Lab"; break;
        }
        return name;
}

static void dbg_print_compression_method(deark *c, lctx *d, i64 cmpr)
{
        const char *name = "?";

        switch(cmpr) {
        case 0: name="uncompressed"; break;
                // (At one point the PSD spec says that "1 is zip", but I think that's a
                // clerical error. My best guess is that all the compression fields use
                // the same compression codes.)
        case 1: name="PackBits"; break;
        case 2: name="ZIP without prediction"; break;
        case 3: name="ZIP with prediction"; break;
        }
        de_dbg(c, "compression method: %d (%s)", (int)cmpr, name);
}

// The PSD module's version of dbuf_read_fourcc()
static void psd_read_fourcc_zz(deark *c, lctx *d, zztype *zz, struct de_fourcc *fourcc)
{
        dbuf_read_fourcc(c->infile, zz->pos, fourcc, 4, d->is_le ? DE_4CCFLAG_REVERSED : 0);
        zz->pos += 4;
}

// For rectangles in top-left-bottom-right order
static void read_rectangle_tlbr(deark *c, lctx *d, zztype *zz, const char *name)
{
        i64 n[4];
        i64 k;
        for(k=0; k<4; k++) {
                n[k] = psd_geti32zz(zz);
        }
        de_dbg(c, "%s: (%d,%d)-(%d,%d)", name, (int)n[1], (int)n[0], (int)n[3], (int)n[2]);
}

// For rectangles in left-top-right-bottom order
static void read_rectangle_ltrb(deark *c, lctx *d, zztype *zz, const char *name)
{
        i64 n[4];
        i64 k;
        for(k=0; k<4; k++) {
                n[k] = psd_geti32zz(zz);
        }
        de_dbg(c, "%s: (%d,%d)-(%d,%d)", name, (int)n[0], (int)n[1], (int)n[2], (int)n[3]);
}

// (Okay to use a shared zz.)
static void read_pascal_string_to_ucstring(deark *c, lctx *d, de_ucstring *s, zztype *zz)
{
        i64 dlen;

        if(zz_avail(zz)<1) return;

        // First byte is the string length
        dlen = (i64)psd_getbytezz(zz);

        if(zz->pos + dlen > zz->endpos) { // error
                zz->pos = zz->endpos;
                return;
        }

        dbuf_read_to_ucstring(c->infile, zz->pos, dlen, s, 0, d->input_encoding);
        zz->pos += dlen;
}

// Like a Pascal string, but with a 4-byte prefix
// (Okay to use a shared zz.)
static void read_prefixed_string_to_ucstring(deark *c, lctx *d, de_ucstring *s, zztype *zz)
{
        i64 dlen;

        if(zz_avail(zz)<4) {
                zz->pos = zz->endpos;
                return;
        }

        dlen = psd_getu32zz(zz);

        if(zz->pos + dlen > zz->endpos) { // error
                zz->pos = zz->endpos;
                return;
        }

        dbuf_read_to_ucstring(c->infile, zz->pos, dlen, s, 0, d->input_encoding);
        zz->pos += dlen;
}

// Caller supplies ri_dst. This function will set its fields.
static int lookup_rsrc(u32 sig_id, u16 n, struct rsrc_info *ri_dst)
{
        i64 i;
        int found = 0;

        de_zeromem(ri_dst, sizeof(struct rsrc_info));

        if(sig_id==CODE_PHUT) { // PhotoDeluxe resources seem to use incompatible formats.
                ri_dst->id = n;
                ri_dst->idname = "?";
                return 0;
        }

        for(i=0; i<(i64)DE_ARRAYCOUNT(rsrc_info_arr); i++) {
                if(rsrc_info_arr[i].id == n) {
                        *ri_dst = rsrc_info_arr[i]; // struct copy
                        if(!ri_dst->idname) ri_dst->idname = "?";
                        return 1;
                }
        }

        ri_dst->id = n;
        ri_dst->idname = "?";

        // Handle pattern-based resources that don't fit nicely in our table.

        if(n>=0x07d0 && n<=0x0bb6) {
                found = 1;
                ri_dst->idname = "Path Information";
                ri_dst->hfn = hrsrc_pathinfo;
        }
        else if(n>=0x0fa0 && n<=0x1387) {
                found = 1;
                ri_dst->idname = "Plug-In resource";
                ri_dst->hfn = hrsrc_pluginresource;
        }

        return found;
}

static const char* units_name(i64 u)
{
        switch(u) {
        case 1: return "pixels/inch";
        case 2: return "pixels/cm";
        }
        return "?";
}

static void hrsrc_resolutioninfo(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        i64 xres_int, yres_int;
        double xres, yres;
        i64 xres_unit, yres_unit;

        if(zz_avail(zz)!=16) return;
        xres_int = psd_getu32(zz->pos);
        xres = ((double)xres_int)/65536.0;
        de_dbg(c, "xres=%.2f dpi", xres);
        xres_unit = psd_getu16(zz->pos+4);
        de_dbg(c, "xres display unit: %d (%s)", (int)xres_unit, units_name(xres_unit));
        //width_unit = psd_getu16(pos+6);

        yres_int = psd_getu32(zz->pos+8);
        yres = ((double)yres_int)/65536.0;
        de_dbg(c, "yres=%.2f dpi", yres);
        yres_unit = psd_getu16(zz->pos+12);
        de_dbg(c, "yres display unit: %d (%s)", (int)yres_unit, units_name(yres_unit));
        //height_unit = psd_getu16(pos+14);

        d->density.code = DE_DENSITY_DPI;
        d->density.xdens = xres;
        d->density.ydens = yres;
}

static void hrsrc_namesofalphachannels(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        de_ucstring *s = NULL;
        int idx = 0;

        // This is a "series of Pascal strings", whatever that is.

        s = ucstring_create(c);
        while(zz->pos < (zz->endpos-1)) {
                ucstring_empty(s);
                read_pascal_string_to_ucstring(c, d, s, zz);
                de_dbg(c, "%s[%d]: \"%s\"", ri->idname, idx, ucstring_getpsz_d(s));
                idx++;
        }
        ucstring_destroy(s);
}

static void hrsrc_printflags(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        u8 fl[9];
        if(zz_avail(zz)!=9) return;
        de_read(fl, zz->pos, 9);
        de_dbg(c, "%s: labels=%d, crop marks=%d, color bars=%d, registration marks=%d, "
                "negative=%d, flip=%d, interpolate=%d, caption=%d, print flags=%d",
                ri->idname, (int)fl[0], (int)fl[1], (int)fl[2], (int)fl[3],
                (int)fl[4], (int)fl[5], (int)fl[6], (int)fl[7], (int)fl[8]);
}

static void do_pathinfo(deark *c, lctx *d, zztype *zz)
{
        i64 num_records;
        i64 i;

        num_records = zz_avail(zz) / 26;
        de_dbg(c, "calculated number of records: %d", (int)num_records);
        for(i=0; i<num_records; i++) {
                zztype czz;
                i64 t;
                i64 x;
                const char *name;

                de_dbg(c, "path data record[%d] at %d", (int)i, (int)zz->pos);
                zz_init_with_len(&czz, zz, 26);
                de_dbg_indent(c, 1);

                t = psd_getu16zz(&czz);
                switch(t) {
                case 0: name="Closed subpath length"; break;
                case 1: name="Closed subpath Bezier knot, linked"; break;
                case 2: name="Closed subpath Bezier knot, unlinked"; break;
                case 3: name="Open subpath length"; break;
                case 4: name="Open subpath Bezier knot, linked"; break;
                case 5: name="Open subpath Bezier knot, unlinked"; break;
                case 6: name="Path fill rule"; break;
                case 7: name="Clipboard"; break;
                case 8: name="Initial fill rule"; break;
                default: name="?"; break;
                }
                de_dbg(c, "path record type: %d (%s)", (int)t, name);

                switch(t) {
                case 0: case 3:
                        x = psd_getu16zz(&czz);
                        de_dbg(c, "number of Bezier knot records: %d", (int)x);
                        break;
                case 8:
                        x = psd_getu16zz(&czz);
                        de_dbg(c, "value: %d", (int)x);
                        break;
                }

                zz->pos += 26;
                de_dbg_indent(c, -1);
        }
}

static void hrsrc_pathinfo(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        do_pathinfo(c, d, zz);
}

static void hrsrc_printflagsinfo(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        i64 version, bleed_width_value, bleed_width_scale;
        u8 crop_marks;

        if(zz_avail(zz)!=10) return;
        version = psd_getu16zz(zz);
        crop_marks = psd_getbytezz(zz);
        zz->pos++;
        bleed_width_value = psd_getu32zz(zz);
        bleed_width_scale = psd_getu16zz(zz);
        de_dbg(c, "%s: version=%d, crop marks=%d, bleed width value=%d, bleed width scale=%d",
                ri->idname, (int)version, (int)crop_marks,
                (int)bleed_width_value, (int)bleed_width_scale);
}

static void hrsrc_exif(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        fmtutil_handle_exif(c, zz->pos, zz_avail(zz));
}

static void hrsrc_iptc(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        d->has_iptc = 1;
        fmtutil_handle_iptc(c, c->infile, zz->pos, zz_avail(zz), 0x0);
}

static void hrsrc_xmp(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        dbuf_create_file_from_slice(c->infile, zz->pos, zz_avail(zz), "xmp", NULL, DE_CREATEFLAG_IS_AUX);
}

static void hrsrc_iccprofile(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        dbuf_create_file_from_slice(c->infile, zz->pos, zz_avail(zz), "icc", NULL, DE_CREATEFLAG_IS_AUX);
}

static void do_pluginrsrc_mani(deark *c, lctx *d, zztype *zz)
{
        struct de_fourcc fourcc;
        i64 len;
        zztype czz;

        // This function is based on reverse engineering, and may not be correct.

        if(zz_avail(zz)<4) goto done;
        psd_read_fourcc_zz(c, d, zz, &fourcc);
        de_dbg(c, "id: '%s'", fourcc.id_dbgstr);

        if(fourcc.id==CODE_IRFR) { // Most likely related to Image Ready
                if(zz_avail(zz)<4) goto done;
                len = psd_getu32zz(zz);
                de_dbg(c, "length: %d", (int)len);
                if(zz_avail(zz)<12) goto done;
                zz_init_with_len(&czz, zz, len);
                // This data seems to have the same structure as a "series of tagged
                // blocks", but with different "keys". I don't know whether the keys are
                // in a different namespace, or what.
                do_tagged_blocks(c, d, zz, 1);
        }

done:
        ;
}

static void do_pluginrsrc_mopt(deark *c, lctx *d, zztype *zz)
{
        i64 x;
        i64 num_items;
        i64 i;
        int saved_indent_level;
        zztype czz;

        // This function is based on reverse engineering, and may not be correct.

        de_dbg_indent_save(c, &saved_indent_level);

        x = psd_getu32zz(zz);
        de_dbg(c, "unknown int: %d", (int)x);
        num_items = psd_getu32zz(zz);
        de_dbg(c, "number of mopt items: %d", (int)num_items);

        for(i=0; i<num_items; i++) {
                i64 dlen;
                i64 something_len;

                something_len = 1138;
                if(zz_avail(zz)<something_len) break;
                de_dbg(c, "mopt item[%d] at %d", (int)i, (int)zz->pos);
                de_dbg_indent(c, 1);

                de_dbg(c, "[%d bytes of data at %d]", (int)something_len, (int)zz->pos);
                if(c->debug_level>=2) {
                        de_dbg_indent(c, 1);
                        de_dbg_hexdump(c, c->infile, zz->pos, something_len, 256, NULL, 0x1);
                        de_dbg_indent(c, -1);
                }
                zz->pos += something_len;

                if(zz_avail(zz)<4) break;

                dlen = psd_getu32zz(zz);
                de_dbg(c, "descriptor length: %d", (int)dlen);

                if(dlen>0 && zz_avail(zz)>0) {
                        zz_init_with_len(&czz, zz, dlen);
                        read_descriptor(c, d, &czz, 1, "");
                        zz->pos += dlen;
                }

                de_dbg_indent(c, -1);
        }

        de_dbg_indent_restore(c, saved_indent_level);
}

// Any plugin resource containing just a descriptor (after the ID code)
static void do_pluginrsrc_descriptor(deark *c, lctx *d, zztype *zz)
{
        zztype czz;
        zz_init(&czz, zz);
        read_descriptor(c, d, &czz, 1, "");
}

static void hrsrc_pluginresource(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        struct de_fourcc fourcc;
        zztype czz;

        // Plug-in resources seem to start with a fourcc.
        if(zz_avail(zz)<4) return;
        psd_read_fourcc_zz(c, d, zz, &fourcc);
        de_dbg(c, "id: '%s'", fourcc.id_dbgstr);
        zz_init(&czz, zz);
        switch(fourcc.id) {
        case CODE_mani:
                do_pluginrsrc_mani(c, d, &czz);
                break;
        case CODE_mopt:
                do_pluginrsrc_mopt(c, d, &czz);
                break;
        case CODE_mset:
                do_pluginrsrc_descriptor(c, d, &czz);
                break;
        default:
                if(zz_avail(&czz)>0) {
                        de_dbg(c, "[%d more bytes of plug-in resource data at %d]",
                                (int)zz_avail(&czz), (int)czz.startpos);
                        if(c->debug_level>=2) {
                                de_dbg_indent(c, 1);
                                de_dbg_hexdump(c, c->infile, czz.startpos, zz_avail(&czz), 256, NULL, 0x1);
                                de_dbg_indent(c, -1);
                        }
                }
        }
}

// Read a Photoshop-style "Unicode string" structure, and append it to s.
// (Okay to use a shared zz.)
static void read_unicode_string(deark *c, lctx *d, de_ucstring *s, zztype *zz)
{
        i64 num_code_units;

        if(zz_avail(zz)<4) { // error
                zz->pos = zz->endpos;
                return;
        }

        num_code_units = psd_getu32zz(zz);
        if(zz->pos + num_code_units*2 > zz->endpos) { // error
                zz->pos = zz->endpos;
                return;
        }

        // Use DE_DBG_MAX_STRLEN, because we assume the string is being read for
        // the purposes of printing it in the debug info.
        dbuf_read_to_ucstring_n(c->infile, zz->pos, num_code_units*2, DE_DBG_MAX_STRLEN*2, s, 0,
                d->is_le ? DE_ENCODING_UTF16LE : DE_ENCODING_UTF16BE);
        zz->pos += num_code_units*2;

        // For no apparent reason, a fair number of these strings have been observed
        // to end with an extraneous U+0000 character.
        ucstring_strip_trailing_NUL(s);
}

static void flexible_id_free_contents(deark *c, struct flexible_id *flid)
{
        if(flid->s) {
                ucstring_destroy(flid->s);
                flid->s = NULL;
        }
        if(flid->sz) {
                de_free(c, flid->sz);
                flid->sz = NULL;
        }
}

// Caller allocates flid, and must free flid->s
static void read_flexible_id(deark *c, lctx *d, i64 pos,
        struct flexible_id *flid)
{
        i64 length;

        de_zeromem(flid, sizeof(struct flexible_id));

        length = psd_getu32(pos);
        if(length==0) {
                flid->is_fourcc = 1;
                dbuf_read_fourcc(c->infile, pos+4, &flid->fourcc, 4, d->is_le ? DE_4CCFLAG_REVERSED : 0);
                flid->bytes_consumed = 4 + 4;
        }
        else {
                i64 adjusted_length;

                // I don't know what the maximum length of an identifier is.
                // I'll pretend it's 100 bytes.
                adjusted_length = length;
                if(adjusted_length>100) adjusted_length=100;
                flid->sz = de_malloc(c, adjusted_length+1);
                dbuf_read(c->infile, (unsigned char*)flid->sz, pos+4, adjusted_length);
                flid->sz[adjusted_length] = '\0';

                flid->s = ucstring_create(c);
                ucstring_append_bytes(flid->s, (unsigned char*)flid->sz, adjusted_length, 0, DE_ENCODING_ASCII);

                flid->bytes_consumed = 4 + length;
        }
}

static void read_flexible_id_zz(deark *c, lctx *d, zztype *zz, struct flexible_id *flid)
{
        read_flexible_id(c, d, zz->pos, flid);
        zz->pos += flid->bytes_consumed;
}

static void dbg_print_flexible_id(deark *c, lctx *d,
        const struct flexible_id *flid, const char *name)
{
        if(flid->is_fourcc) {
                de_dbg(c, "%s: fourcc('%s')", name, flid->fourcc.id_dbgstr);
        }
        else {
                de_dbg(c, "%s: string(\"%s\")", name, ucstring_getpsz(flid->s));
        }
}
// The PSD spec calls this type "Boolean" (or "Boolean structure").
static void do_item_type_bool(deark *c, lctx *d, zztype *zz)
{
        u8 b;
        b = psd_getbytezz(zz);
        de_dbg(c, "value: %d", (int)b);
}

// The PSD spec calls this type "Integer".
static void do_item_type_long(deark *c, lctx *d, zztype *zz)
{
        i64 n;
        // No idea if this is signed or unsigned.
        n = psd_geti32zz(zz);
        de_dbg(c, "value: %d", (int)n);
}

// "Double"
static void do_item_type_doub(deark *c, lctx *d, zztype *zz)
{
        double v;
        v = dbuf_getfloat64x(c->infile, zz->pos, d->is_le);
        de_dbg(c, "value: %f", v);
        zz->pos += 8;
}

// "Unit float"
static void do_item_type_UntF(deark *c, lctx *d, zztype *zz)
{
        double v;
        struct de_fourcc unit4cc;

        psd_read_fourcc_zz(c, d, zz, &unit4cc);
        de_dbg(c, "units code: '%s'", unit4cc.id_dbgstr);

        v = dbuf_getfloat64x(c->infile, zz->pos, d->is_le);
        de_dbg(c, "value: %f", v);
        zz->pos += 8;
}

static int do_item_type_class(deark *c, lctx *d, zztype *zz)
{
        de_ucstring *tmps = NULL;
        struct flexible_id flid;

        tmps = ucstring_create(c);
        read_unicode_string(c, d, tmps, zz);
        de_dbg(c, "name from classID: \"%s\"", ucstring_getpsz_d(tmps));

        read_flexible_id_zz(c, d, zz, &flid);
        dbg_print_flexible_id(c, d, &flid, "classID");
        flexible_id_free_contents(c, &flid);

        ucstring_destroy(tmps);
        return 1;
}

static int do_item_type_alis(deark *c, lctx *d, zztype *zz)
{
        i64 x;

        x = psd_getu32zz(zz);
        de_dbg(c, "alias length: %d", (int)x);
        zz->pos += x;
        return 1;
}

// Undocumented UnFl descriptor item type
static void do_item_type_UnFl(deark *c, lctx *d, zztype *zz)
{
        i64 count;
        struct de_fourcc unit4cc;

        psd_read_fourcc_zz(c, d, zz, &unit4cc);
        de_dbg(c, "units code: '%s'", unit4cc.id_dbgstr);

        count = psd_getu32zz(zz);
        de_dbg(c, "count: %d", (int)count);

        zz->pos += count*8; // TODO: [what we assume is a] float array
}

static void do_text_engine_data(deark *c, lctx *d, i64 pos, i64 len)
{
        if(len<1) return;
        de_dbg(c, "text engine data at %d, len=%d", (int)pos, (int)len);
        if(c->extract_level<2) return;
        dbuf_create_file_from_slice(c->infile, pos, len, "enginedata", NULL, DE_CREATEFLAG_IS_AUX);
}

// The PSD spec calls this type "String" (or "String structure").
static void do_item_type_TEXT(deark *c, lctx *d, zztype *zz)
{
        de_ucstring *s = NULL;

        s = ucstring_create(c);
        read_unicode_string(c, d, s, zz);
        de_dbg(c, "value: \"%s\"", ucstring_getpsz_d(s));
        ucstring_destroy(s);
}

// "tdta" / "Raw Data"
static int do_item_type_tdta(deark *c, lctx *d,
        const struct flexible_id *key_flid, zztype *zz)
{
        i64 dlen;

        // The public PSD spec does not reveal how to calculate the length of a 'tdata'
        // item. Evidence suggests it starts with a 4-byte length field.
        dlen = psd_getu32zz(zz);
        de_dbg(c, "raw data at %d, dlen=%d", (int)zz->pos, (int)dlen);
        if(zz->pos+dlen > zz->endpos) {
                return 0;
        }

        if(key_flid->sz) {
                if(!de_strcmp(key_flid->sz, "EngineData")) {
                        do_text_engine_data(c, d, zz->pos, dlen);
                }
        }

        zz->pos += dlen;
        return 1;
}

// The PSD spec calls this type "Enumerated", and also "Enumerated descriptor"
// (but not "Enumerated reference"!)
static void do_item_type_enum(deark *c, lctx *d, zztype *zz)
{
        struct flexible_id flid;

        read_flexible_id_zz(c, d, zz, &flid); // "type"
        dbg_print_flexible_id(c, d, &flid, "enum type");
        flexible_id_free_contents(c, &flid);

        read_flexible_id_zz(c, d, zz, &flid); // "enum"
        dbg_print_flexible_id(c, d, &flid, "enum value");
        flexible_id_free_contents(c, &flid);
}

// "List"
static int do_item_type_VlLs(deark *c, lctx *d,
        const struct flexible_id *key_flid, zztype *zz, i64 outer_itempos)
{
        i64 num_items;
        i64 i;
        int ret;
        int retval = 0;
        zztype czz;

        num_items = psd_getu32zz(zz);
        de_dbg(c, "number of items in list: %d", (int)num_items);
        if(num_items>5000) {
                de_warn(c, "Excessively large VlLs item (%d)", (int)num_items);
                goto done;
        }

        if(d->nesting_level>MAX_NESTING_LEVEL) goto done;

        for(i=0; i<num_items; i++) {
                i64 inner_itempos;
                inner_itempos = zz->pos;
                de_dbg(c, "item[%d] at %d (for list@%d)", (int)i,
                        (int)inner_itempos, (int)outer_itempos);
                de_dbg_indent(c, 1);
                d->nesting_level++;
                zz_init(&czz, zz);
                ret = do_descriptor_item_ostype_and_data(c, d, key_flid, &czz, inner_itempos);
                d->nesting_level--;
                de_dbg_indent(c, -1);
                if(!ret) goto done;
                zz->pos += zz_used(&czz);
        }

        retval = 1;
done:
        return retval;
}

static int do_item_type_descriptor(deark *c, lctx *d, zztype *zz, int has_version)
{
        int retval = 0;

        d->nesting_level++;
        if(d->nesting_level>MAX_NESTING_LEVEL) goto done;

        // This descriptor contains a descriptor. We have to go deeper.
        retval = read_descriptor(c, d, zz, has_version, "");

done:
        d->nesting_level--;
        return retval;
}

static int do_Enmr_reference(deark *c, lctx *d, zztype *zz)
{
        de_ucstring *tmps = NULL;
        struct flexible_id flid;

        tmps = ucstring_create(c);
        read_unicode_string(c, d, tmps, zz);
        de_dbg(c, "name from classID: \"%s\"", ucstring_getpsz_d(tmps));

        read_flexible_id_zz(c, d, zz, &flid);
        dbg_print_flexible_id(c, d, &flid, "classID");
        flexible_id_free_contents(c, &flid);

        read_flexible_id_zz(c, d, zz, &flid);
        dbg_print_flexible_id(c, d, &flid, "typeID");
        flexible_id_free_contents(c, &flid);

        read_flexible_id_zz(c, d, zz, &flid);
        dbg_print_flexible_id(c, d, &flid, "enum");
        flexible_id_free_contents(c, &flid);

        ucstring_destroy(tmps);
        return 1;
}

static int do_prop_reference(deark *c, lctx *d, zztype *zz)
{
        de_ucstring *tmps = NULL;
        struct flexible_id flid;

        tmps = ucstring_create(c);
        read_unicode_string(c, d, tmps, zz);
        de_dbg(c, "name from classID: \"%s\"", ucstring_getpsz_d(tmps));

        read_flexible_id_zz(c, d, zz, &flid);
        dbg_print_flexible_id(c, d, &flid, "classID");
        flexible_id_free_contents(c, &flid);

        read_flexible_id_zz(c, d, zz, &flid);
        dbg_print_flexible_id(c, d, &flid, "keyID");
        flexible_id_free_contents(c, &flid);

        ucstring_destroy(tmps);
        return 1;
}

static int do_Clss_reference(deark *c, lctx *d, zztype *zz)
{
        return do_item_type_class(c, d, zz);
}

static int do_name_reference(deark *c, lctx *d, zztype *zz)
{
        de_ucstring *tmps = NULL;
        struct flexible_id flid;

        // I can't find any credible documentation of the 'name' reference format.
        // This code is based on reverse engineering, and may not be correct.

        tmps = ucstring_create(c);

        read_unicode_string(c, d, tmps, zz);
        de_dbg(c, "name from classID: \"%s\"", ucstring_getpsz_d(tmps));
        ucstring_empty(tmps);

        read_flexible_id_zz(c, d, zz, &flid);
        dbg_print_flexible_id(c, d, &flid, "undocumented id");
        flexible_id_free_contents(c, &flid);

        read_unicode_string(c, d, tmps, zz);
        de_dbg(c, "undocumented unicode string: \"%s\"", ucstring_getpsz_d(tmps));

        ucstring_destroy(tmps);
        return 1;
}

static int do_rele_reference(deark *c, lctx *d, zztype *zz)
{
        de_ucstring *tmps = NULL;
        struct flexible_id flid;
        i64 offs;

        tmps = ucstring_create(c);

        read_unicode_string(c, d, tmps, zz);
        de_dbg(c, "name from classID: \"%s\"", ucstring_getpsz_d(tmps));
        ucstring_empty(tmps);

        read_flexible_id_zz(c, d, zz, &flid);
        dbg_print_flexible_id(c, d, &flid, "classID");
        flexible_id_free_contents(c, &flid);

        offs = psd_geti32zz(zz);
        de_dbg(c, "offset: %d", (int)offs);

        ucstring_destroy(tmps);
        return 1;
}

static int do_indx_reference(deark *c, lctx *d, zztype *zz)
{
        de_ucstring *tmps = NULL;
        struct flexible_id flid;
        i64 x;

        // I can't find any official documentation of the 'indx' reference format.
        // This code may not be correct.

        tmps = ucstring_create(c);

        read_unicode_string(c, d, tmps, zz);
        de_dbg(c, "name from classID: \"%s\"", ucstring_getpsz_d(tmps));
        ucstring_empty(tmps);

        read_flexible_id_zz(c, d, zz, &flid);
        dbg_print_flexible_id(c, d, &flid, "undocumented id");
        flexible_id_free_contents(c, &flid);

        x = psd_geti32zz(zz);
        de_dbg(c, "undocumented int: %d", (int)x);

        ucstring_destroy(tmps);
        return 1;
}

// "Reference structure"
static int do_item_type_obj(deark *c, lctx *d, zztype *zz)
{
        i64 num_items;
        i64 i;
        int retval = 0;
        int saved_indent_level;
        zztype czz;

        de_dbg_indent_save(c, &saved_indent_level);

        num_items = psd_getu32zz(zz);
        de_dbg(c, "number of items in reference: %d", (int)num_items);

        for(i=0; i<num_items; i++) {
                struct de_fourcc type4cc;
                i64 itempos;

                itempos = zz->pos;
                if(itempos >= zz->endpos) goto done;
                psd_read_fourcc_zz(c, d, zz, &type4cc);
                de_dbg(c, "reference item[%d] '%s' at %d", (int)i, type4cc.id_dbgstr, (int)itempos);

                de_dbg_indent(c, 1);

                zz_init(&czz, zz);
                switch(type4cc.id) {
                case CODE_Enmr:
                        if(!do_Enmr_reference(c, d, &czz)) goto done;
                        zz->pos += zz_used(&czz);
                        break;
                case CODE_prop:
                        if(!do_prop_reference(c, d, &czz)) goto done;
                        zz->pos += zz_used(&czz);
                        break;
                case CODE_name:
                        if(!do_name_reference(c, d, &czz)) goto done;
                        zz->pos += zz_used(&czz);
                        break;
                case CODE_Clss:
                        if(!do_Clss_reference(c, d, &czz)) goto done;
                        zz->pos += zz_used(&czz);
                        break;
                case CODE_rele:
                        if(!do_rele_reference(c, d, &czz)) goto done;
                        zz->pos += zz_used(&czz);
                        break;
                case CODE_indx:
                        if(!do_indx_reference(c, d, &czz)) goto done;
                        zz->pos += zz_used(&czz);
                        break;
                default:
                        // TODO: 'Idnt'
                        goto done;
                }

                de_dbg_indent(c, -1);
        }

        retval = 1;
done:
        de_dbg_indent_restore(c, saved_indent_level);
        return retval;
}

// key_flid is relevant "key" identifier.
static int do_descriptor_item_ostype_and_data(deark *c, lctx *d,
        const struct flexible_id *key_flid, zztype *zz, i64 itempos)
{
        int ret;
        int retval = 0;
        struct de_fourcc type4cc;
        zztype czz;

        psd_read_fourcc_zz(c, d, zz, &type4cc);
        de_dbg(c, "item OSType: '%s'", type4cc.id_dbgstr);

        zz_init(&czz, zz);

        switch(type4cc.id) {
        case CODE_bool:
                do_item_type_bool(c, d, &czz);
                zz->pos += zz_used(&czz);
                break;
        case CODE_long:
                do_item_type_long(c, d, &czz);
                zz->pos += zz_used(&czz);
                break;
        case CODE_doub:
                do_item_type_doub(c, d, &czz);
                zz->pos += zz_used(&czz);
                break;
        case CODE_comp:
                // TODO
                zz->pos += 8;
                break;
        case CODE_UntF:
                do_item_type_UntF(c, d, &czz);
                zz->pos += zz_used(&czz);
                break;
        case CODE_UnFl:
                do_item_type_UnFl(c, d, &czz);
                zz->pos += zz_used(&czz);
                break;
        case CODE_TEXT:
                do_item_type_TEXT(c, d, &czz);
                zz->pos += zz_used(&czz);
                break;
        case CODE_enum:
                do_item_type_enum(c, d, &czz);
                zz->pos += zz_used(&czz);
                break;
        case CODE_VlLs:
                ret = do_item_type_VlLs(c, d, key_flid, &czz, itempos);
                zz->pos += zz_used(&czz);
                if(!ret) goto done;
                break;
        case CODE_Objc:
        case CODE_GlbO:
                ret = do_item_type_descriptor(c, d, &czz, 0);
                zz->pos += zz_used(&czz);
                if(!ret) goto done;
                break;
        case CODE_ObAr:
                // Undocumented type. Appears to contain a versioned descriptor.
                ret = do_item_type_descriptor(c, d, zz, 1);
                zz->pos += zz_used(&czz);
                if(!ret) goto done;
                break;
        case CODE_obj:
                ret = do_item_type_obj(c, d, &czz);
                zz->pos += zz_used(&czz);
                if(!ret) goto done;
                break;
        case CODE_tdta:
                ret = do_item_type_tdta(c, d, key_flid, &czz);
                zz->pos += zz_used(&czz);
                if(!ret) goto done;
                break;
        case CODE_type:
        case CODE_GlbC:
                ret = do_item_type_class(c, d, &czz);
                zz->pos += zz_used(&czz);
                if(!ret) goto done;
                break;
        case CODE_alis:
                ret = do_item_type_alis(c, d, &czz);
                zz->pos += zz_used(&czz);
                if(!ret) goto done;
                break;
                // TODO: 'Pth ' (undocumented type)
        default:
                goto done;
        }

        retval = 1;
done:
        return retval;
}

static int do_descriptor_item(deark *c, lctx *d, zztype *zz)
{
        struct flexible_id key;
        zztype czz;
        i64 itempos;
        int ret;

        itempos = zz->pos;

        read_flexible_id_zz(c, d, zz, &key);
        dbg_print_flexible_id(c, d, &key, "key");

        zz_init(&czz, zz);
        ret = do_descriptor_item_ostype_and_data(c, d, &key, &czz, itempos);
        flexible_id_free_contents(c, &key);
        if(!ret) return 0;
        zz->pos += zz_used(&czz);

        return 1;
}

// Read a "Descriptor" structure.
// If has_version==1, the data begins with a 4-byte Descriptor Version field.
// dscrname is extra debug text that will appear after the word "descriptor".
// (Okay to use a shared zz, but use caution.)
static int read_descriptor(deark *c, lctx *d, zztype *zz, int has_version, const char *dscrname)
{
        de_ucstring *name_from_classid = NULL;
        struct flexible_id classid;
        i64 ver_pos = 0;
        i64 dscr_pos;
        i64 num_items;
        i64 i;
        int ret;
        int retval = 0;
        i64 dv = 16;
        zztype czz;
        int saved_indent_level;

        de_dbg_indent_save(c, &saved_indent_level);

        if(has_version) {
                ver_pos = zz->pos;
                dv = psd_getu32zz(zz);
        }

        dscr_pos = zz->pos;

        if(has_version) {
                de_dbg(c, "descriptor%s at %d (version# at %d)", dscrname, (int)dscr_pos, (int)ver_pos);
        }
        else {
                de_dbg(c, "descriptor%s at %d", dscrname, (int)dscr_pos);
        }

        if(dv!=16) {
                de_warn(c, "Unsupported descriptor version: %d", (int)dv);
                goto done;
        }

        de_dbg_indent(c, 1);

        name_from_classid = ucstring_create(c);
        read_unicode_string(c, d, name_from_classid, zz);
        if(name_from_classid->len > 0) {
                de_dbg(c, "name from classID: \"%s\"", ucstring_getpsz_d(name_from_classid));
        }

        read_flexible_id_zz(c, d, zz, &classid);
        dbg_print_flexible_id(c, d, &classid, "classID");
        flexible_id_free_contents(c, &classid);

        num_items = psd_getu32zz(zz);
        de_dbg(c, "number of items in descriptor: %d", (int)num_items);

        // Descriptor items
        for(i=0; i<num_items; i++) {
                if(zz->pos >= zz->endpos) {
                        de_dbg(c, "[Expected %d descriptor items, only found %d.]", (int)num_items, (int)i);
                        goto done;
                }
                de_dbg(c, "item[%d] at %d (for descriptor@%d)", (int)i, (int)zz->pos, (int)dscr_pos);
                de_dbg_indent(c, 1);
                zz_init(&czz, zz);
                ret = do_descriptor_item(c, d, &czz);
                if(!ret) {
                        de_dbg(c, "[Failed to fully decode descriptor item.]");
                }
                de_dbg_indent(c, -1);
                if(!ret) goto done;
                zz->pos += zz_used(&czz);
        }

        retval = 1;

done:
        de_dbg_indent_restore(c, saved_indent_level);
        ucstring_destroy(name_from_classid);
        return retval;
}

static void hrsrc_descriptor_with_version(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        read_descriptor(c, d, zz, 1, "");
}

static int do_slices_resource_block(deark *c, lctx *d, i64 slice_idx, zztype *zz)
{
        de_ucstring *s = NULL;
        i64 id, group_id, origin, slice_type;
        int retval = 0;

        s = ucstring_create(c);

        id = psd_getu32zz(zz);
        de_dbg(c, "id: %d", (int)id);

        group_id = psd_getu32zz(zz);
        de_dbg(c, "group id: %d", (int)group_id);

        origin = psd_getu32zz(zz);
        de_dbg(c, "origin: %d", (int)origin);

        if(origin==1) {
                i64 layer_id;
                layer_id = psd_getu32zz(zz);
                de_dbg(c, "associated layer id: %d", (int)layer_id);
        }

        read_unicode_string(c, d, s, zz); // Name
        if(s->len>0) {
                de_dbg(c, "name: \"%s\"", ucstring_getpsz(s));
        }
        ucstring_empty(s);

        slice_type = psd_getu32zz(zz);
        de_dbg(c, "type: %d", (int)slice_type);

        read_rectangle_ltrb(c, d, zz, "position");

        read_unicode_string(c, d, s, zz); // URL
        ucstring_empty(s);

        read_unicode_string(c, d, s, zz); // Target
        ucstring_empty(s);

        read_unicode_string(c, d, s, zz); // Message
        ucstring_empty(s);

        read_unicode_string(c, d, s, zz); // Alt Tag
        ucstring_empty(s);

        zz->pos += 1; // Flag: Cell text is HTML

        read_unicode_string(c, d, s, zz); // Cell text
        ucstring_empty(s);

        zz->pos += 4; // Horizontal alignment
        zz->pos += 4; // Horizontal alignment
        zz->pos += 4; // Alpha color, Red, Green, Blue

        if(zz->pos > zz->endpos) goto done;
        retval = 1;

done:
        ucstring_destroy(s);
        return retval;
}

static void do_slices_v6(deark *c, lctx *d, zztype *zz)
{
        i64 num_slices;
        i64 i;
        de_ucstring *name_of_group_of_slices = NULL;
        zztype czz;
        int ret;

        zz->pos += 4; // version (already read)
        read_rectangle_tlbr(c, d, zz, "bounding rectangle");
        if(zz->pos >= zz->endpos) goto done;

        name_of_group_of_slices = ucstring_create(c);
        read_unicode_string(c, d, name_of_group_of_slices, zz);
        de_dbg(c, "name of group of slices: \"%s\"",
                ucstring_getpsz_d(name_of_group_of_slices));
        if(zz->pos >= zz->endpos) goto done;

        num_slices = psd_getu32zz(zz);
        de_dbg(c, "number of slices: %d", (int)num_slices);

        for(i=0; i<num_slices; i++) {
                if(zz->pos >= zz->endpos) {
                        de_dbg(c, "[Expected %d slices, only found %d]", (int)num_slices, (int)i);
                        goto done;
                }
                de_dbg(c, "slice[%d] at %d", (int)i, (int)zz->pos);
                de_dbg_indent(c, 1);
                zz_init(&czz, zz);
                do_slices_resource_block(c, d, i, &czz);
                de_dbg_indent(c, -1);
                zz->pos += zz_used(&czz);
        }

        // The PSD spec seems to show that a Descriptor can (optionally) appear after
        // every slice resource block.
        // But if that were true, there would seem to be no way to tell whether a slice
        // is followed by a descriptor, or immediately by the next slice.
        // Fortunately, evidence suggests that a Descriptor can only appear after the
        // last slice in the array.

        if(zz->pos >= zz->endpos) goto done;

        ret = read_descriptor(c, d, zz, 1, " (for slices)");
        if(!ret) goto done;

done:
        ucstring_destroy(name_of_group_of_slices);
}

static void do_slices_v7_8(deark *c, lctx *d, zztype *zz)
{
        zz->pos += 4; // Skip version number (7 or 8), already read.
        read_descriptor(c, d, zz, 1, "");
}

static void hrsrc_slices(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        i64 sver;

        if(zz_avail(zz)<4) return;
        sver = psd_getu32(zz->pos);
        de_dbg(c, "slices resource format version: %d", (int)sver);

        if(sver==6) {
                do_slices_v6(c, d, zz);
        }
        else if(sver==7 || sver==8) {
                do_slices_v7_8(c, d, zz);
        }
}

static void hrsrc_thumbnail(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        i64 fmt;
        const char *ext;
        dbuf *outf = NULL;
        i64 dpos;
        i64 dlen;

        if(zz_avail(zz)<=28) goto done;

        fmt = psd_getu32(zz->pos);
        if(fmt != 1) {
                // fmt != kJpegRGB
                de_dbg(c, "thumbnail in unsupported format (%d) found", (int)fmt);
                goto done;
        }

        zz->pos += 28;
        dpos = zz->pos;
        dlen = zz_avail(zz);

        if(ri->id==0x0409) {
                ext = "psdthumb_rbswap.jpg";
                if(c->extract_policy!=DE_EXTRACTPOLICY_MAINONLY) {
                        de_info(c, "Note: This Photoshop thumbnail uses nonstandard colors, "
                                "and may not look right.");
                }
        }
        else {
                ext = "psdthumb.jpg";
        }

        outf = dbuf_create_output_file(c, ext, NULL, DE_CREATEFLAG_IS_AUX);

        if(ri->id==0x0409 && d->jpeg_rbswap_mode && dlen>=11 &&
                !dbuf_memcmp(c->infile, dpos, "\xff\xd8\xff\xe0\x00\x10" "JFIF" "\x00", 11))
        {
                // If we were to extract this image as-is, there will be no way to tell
                // later that the red/blue channels are swapped. So, we have this feature
                // to mark it by inserting a custom segment (after the JFIF segment).
                dbuf_copy(c->infile, dpos, 20, outf);
                dbuf_write(outf, (const u8*)"\xff\xe1\x00\x10" "Deark_RB_swap\0", 18);
                dbuf_copy(c->infile, dpos+20, dlen-20, outf);
        }
        else {
                dbuf_copy(c->infile, dpos, dlen, outf);
        }

done:
        dbuf_close(outf);
}

// Handler for any resource that consists of a 1-byte numeric value
static void hrsrc_byte(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        u8 b;
        if(zz_avail(zz)!=1) return;
        b = psd_getbytezz(zz);
        de_dbg(c, "%s: %d", ri->idname, (int)b);
}

static void hrsrc_uint16(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        i64 n;
        if(zz_avail(zz)!=2) return;
        n = psd_getu16zz(zz);
        de_dbg(c, "%s: %d", ri->idname, (int)n);
}

static void hrsrc_uint32(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        i64 n;
        if(zz_avail(zz)!=4) return;
        n = psd_getu32zz(zz);
        de_dbg(c, "%s: %d", ri->idname, (int)n);
}

// Handler for any resource that consists of a single "Unicode string".
static void hrsrc_unicodestring(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        de_ucstring *s = NULL;

        s = ucstring_create(c);
        read_unicode_string(c, d, s, zz);
        de_dbg(c, "%s: \"%s\"", ri->idname, ucstring_getpsz_d(s));
        ucstring_destroy(s);
}

// Handler for the "Unicode Alpha Names" resource, which the documentation
// incorrectly says is a single Unicode string.
static void hrsrc_unicodestring_multi(deark *c, lctx *d, zztype *zz,
        const struct rsrc_info *ri)
{
        de_ucstring *s = NULL;
        int idx = 0;

        s = ucstring_create(c);
        while(zz_avail(zz)>=4) {
                ucstring_empty(s);
                read_unicode_string(c, d, s, zz);
                de_dbg(c, "%s[%d]: \"%s\"", ri->idname, idx, ucstring_getpsz_d(s));
                idx++;
        }
        ucstring_destroy(s);
}

// Handler for any resource that consists of a single "Pascal string".
static void hrsrc_pascalstring(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        de_ucstring *s = NULL;

        s = ucstring_create(c);
        read_pascal_string_to_ucstring(c, d, s, zz);
        de_dbg(c, "%s: \"%s\"", ri->idname, ucstring_getpsz(s));
        ucstring_destroy(s);
}

// Raw byte-oriented text
static void hrsrc_plaintext(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        de_ucstring *s = NULL;

        s = ucstring_create(c);
        dbuf_read_to_ucstring_n(c->infile, zz->pos, zz_avail(zz), DE_DBG_MAX_STRLEN,
                s, 0, d->input_encoding);
        de_dbg(c, "%s: \"%s\"", ri->idname, ucstring_getpsz(s));
        ucstring_destroy(s);
}

static void hrsrc_urllist(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        de_ucstring *s = NULL;
        i64 count;
        i64 i;

        count = psd_getu32zz(zz);
        de_dbg(c, "URL count: %d", (int)count);

        s = ucstring_create(c);

        for(i=0; i<count; i++) {
                struct de_fourcc url4cc;
                i64 id;

                // undocumented field, seems to be a fourcc
                psd_read_fourcc_zz(c, d, zz, &url4cc);

                id = psd_getu32zz(zz);

                read_unicode_string(c, d, s, zz);
                de_dbg(c, "URL[%d]: '%s', id=%d, value=\"%s\"", (int)i,
                        url4cc.id_dbgstr, (int)id, ucstring_getpsz(s));
                ucstring_empty(s);
        }

        ucstring_destroy(s);
}

static void hrsrc_versioninfo(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        i64 ver, file_ver;
        u8 b;
        de_ucstring *s = NULL;

        ver = psd_getu32zz(zz);
        de_dbg(c, "version: %d", (int)ver);

        b = psd_getbytezz(zz);
        de_dbg(c, "hasRealMergedData: %d", (int)b);

        s = ucstring_create(c);
        read_unicode_string(c, d, s, zz);
        de_dbg(c, "writer name: \"%s\"", ucstring_getpsz(s));

        ucstring_empty(s);
        read_unicode_string(c, d, s, zz);
        de_dbg(c, "reader name: \"%s\"", ucstring_getpsz(s));

        file_ver = psd_getu32zz(zz);
        de_dbg(c, "file version: %d", (int)file_ver);

        ucstring_destroy(s);
}

static void hrsrc_printscale(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        i64 style;
        double xloc, yloc, scale;
        if(zz_avail(zz)!=14) return;
        style = psd_getu16zz(zz);
        de_dbg(c, "style: %d", (int)style);
        xloc = dbuf_getfloat32x(c->infile, zz->pos, d->is_le);
        zz->pos += 4;
        yloc = dbuf_getfloat32x(c->infile, zz->pos, d->is_le);
        zz->pos += 4;
        de_dbg(c, "location: (%f,%f)", xloc, yloc);
        scale = dbuf_getfloat32x(c->infile, zz->pos, d->is_le);
        zz->pos += 4;
        de_dbg(c, "scale: %f", scale);
}

static void hrsrc_pixelaspectratio(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        i64 version;
        double ratio;
        if(zz_avail(zz)!=12) return;
        version = psd_getu32zz(zz);
        de_dbg(c, "version: %d", (int)version);
        ratio = dbuf_getfloat64x(c->infile, zz->pos, d->is_le);
        zz->pos += 8;
        de_dbg(c, "x/y: %f", ratio);
}

static void hrsrc_layerselectionids(deark *c, lctx *d, zztype *zz, const struct rsrc_info *ri)
{
        i64 count;
        int i;

        if(zz_avail(zz)<2) return;
        count = psd_getu16zz(zz);
        de_dbg(c, "count: %d", (int)count);
        if(zz_avail(zz)<4*count) return;
        for(i=0; i<count; i++) {
                i64 lyid;
                lyid = psd_getu32zz(zz);
                de_dbg(c, "layer id[%d]: %u", (int)i, (unsigned int)lyid);
        }
}

static int do_image_resource(deark *c, lctx *d, zztype *zz)
{
        i64 resource_id;
        i64 block_data_len;
        struct rsrc_info ri;
        de_ucstring *blkname = NULL;
        struct de_fourcc sig4cc;
        const char *signame = "Photoshop";
        zztype czz;
        int retval = 0;

        // Check the "8BIM" (etc.) signature.
        // TODO: Maybe we should allow arbitrary signatures, but restricting it to
        // known signatures lets us know if the parser has gone off the rails.
        psd_read_fourcc_zz(c, d, zz, &sig4cc);
        if(sig4cc.id==CODE_8BIM) {
                ;
        }
        else if(sig4cc.id==CODE_AgHg) { // Seen in Photoshop Elements files
                signame = "AgHg";
        }
        else if(sig4cc.id==CODE_DCSR) { // ExifTool says this exists
                signame = "DCSR";
        }
        else if(sig4cc.id==CODE_MeSa) { // Image Ready resource?
                signame = "MeSa";
        }
        else if(sig4cc.id==CODE_PHUT) { // PhotoDeluxe resource?
                signame = "PHUT";
        }
        else {
                de_warn(c, "Bad Photoshop resource block signature '%s' at %d",
                        sig4cc.id_sanitized_sz, (int)zz->startpos);
                goto done;
        }

        resource_id = psd_getu16zz(zz);

        // Read resource block name. A "Pascal string" padded to an even number of bytes.
        blkname = ucstring_create(c);
        zz_init(&czz, zz);
        read_pascal_string_to_ucstring(c, d, blkname, &czz);
        zz->pos += de_pad_to_2(zz_used(&czz));

        block_data_len = psd_getu32zz(zz);

        // TODO: Are resource_ids "namespaced" based on the block signature?
        lookup_rsrc(sig4cc.id, (u16)resource_id, &ri);

        de_dbg(c, "%s rsrc 0x%04x (%s) pos=%d blkname=\"%s\" dpos=%d dlen=%d",
                signame, (int)resource_id, ri.idname, (int)zz->startpos,
                ucstring_getpsz(blkname), (int)zz->pos, (int)block_data_len);

        if(zz->pos+block_data_len > zz->endpos) {
                de_warn(c, "PSD rsrc exceeds its parent's bounds. Ends at %"I64_FMT
                        ", parent ends at %"I64_FMT".", zz->pos+block_data_len, zz->endpos);
        }

        de_dbg_indent(c, 1);
        if(ri.hfn) {
                zz_init_with_len(&czz, zz, block_data_len);
                ri.hfn(c, d, &czz, &ri);
        }
        else if(ri.flags&0x0004) {
                zz_init_with_len(&czz, zz, block_data_len);
                hrsrc_descriptor_with_version(c, d, &czz, &ri);
        }
        else if(c->debug_level>=2) {
                de_dbg_hexdump(c, c->infile, zz->pos, block_data_len, 256, NULL,
                        (ri.flags&0x0010)?0x0:0x1);
        }
        de_dbg_indent(c, -1);

        zz->pos += de_pad_to_2(block_data_len);

        retval = 1;

done:
        if(blkname) ucstring_destroy(blkname);
        return retval;
}

static void do_image_resource_blocks(deark *c, lctx *d, zztype *zz)
{
        zztype czz;

        while(1) {
                if(zz->pos>=zz->endpos) break;
                zz_init(&czz, zz);
                if(!do_image_resource(c, d, &czz)) break;
                zz->pos += zz_used(&czz);
        }
}

// Layer mask / adjustment layer data
static void do_layer_mask_data(deark *c, lctx *d, zztype *zz)
{
        i64 dlen;
        dlen = psd_getu32zz(zz);
        de_dbg(c, "layer mask data size: %d", (int)dlen);
        zz->pos += dlen;
}

static void do_layer_blending_ranges(deark *c, lctx *d, zztype *zz)
{
        i64 dlen;
        dlen = psd_getu32zz(zz);
        de_dbg(c, "layer blending ranges data size: %d", (int)dlen);
        zz->pos += dlen;
}

static void do_layer_name(deark *c, lctx *d, zztype *zz)
{
        de_ucstring *s = NULL;

        // "Pascal string, padded to a multiple of 4 bytes"
        s = ucstring_create(c);
        read_pascal_string_to_ucstring(c, d, s, zz);
        de_dbg(c, "layer name: \"%s\"", ucstring_getpsz(s));
        zz->pos = zz->startpos + de_pad_to_4(zz_used(zz));
        ucstring_destroy(s);
}

struct channel_data {
        i64 num_channels;
        i64 total_len;
};

static int do_layer_record(deark *c, lctx *d, zztype *zz, struct channel_data *cd)
{
        i64 nchannels;
        i64 extra_data_len;
        struct de_fourcc tmp4cc;
        i64 ch_id, ch_dlen;
        u8 b;
        int i;
        zztype czz;
        zztype extradatazz;
        int retval = 0;

        read_rectangle_tlbr(c, d, zz, "bounding rectangle");

        nchannels = psd_getu16zz(zz);
        de_dbg(c, "number of channels: %d", (int)nchannels);

        for(i=0; i<nchannels; i++) {
                ch_id = psd_geti16zz(zz);
                ch_dlen = psd_getu32or64zz(c, d, zz);
                de_dbg(c, "channel[%d] id=%d, data len=%"I64_FMT"", (int)i, (int)ch_id, ch_dlen);
                cd->num_channels++;
                cd->total_len += ch_dlen;
        }

        psd_read_fourcc_zz(c, d, zz, &tmp4cc);
        if(tmp4cc.id != CODE_8BIM) {
                de_warn(c, "Expected blend mode signature not found at %d", (int)(zz->pos-4));
                goto done;
        }

        psd_read_fourcc_zz(c, d, zz, &tmp4cc);
        de_dbg(c, "blend mode: '%s'", tmp4cc.id_dbgstr);

        b = psd_getbytezz(zz);
        de_dbg(c, "opacity: %d", (int)b);

        b = psd_getbytezz(zz);
        de_dbg(c, "clipping: %d", (int)b);

        b = psd_getbytezz(zz);
        de_dbg(c, "flags: 0x%02x", (unsigned int)b);

        zz->pos += 1; // filler

        extra_data_len = psd_getu32zz(zz);

        if(zz->pos + extra_data_len > zz->endpos) {
                de_warn(c, "Malformed layer record at %d", (int)zz->startpos);
                goto done;
        }

        zz_init_with_len(&extradatazz, zz, extra_data_len);
        zz->pos = extradatazz.endpos;

        zz_init(&czz, &extradatazz);
        do_layer_mask_data(c, d, &czz);
        extradatazz.pos += zz_used(&czz);

        zz_init(&czz, &extradatazz);
        do_layer_blending_ranges(c, d, &czz);
        extradatazz.pos += zz_used(&czz);

        zz_init(&czz, &extradatazz);
        do_layer_name(c, d, &czz);
        extradatazz.pos += zz_used(&czz);

        if(extradatazz.pos < extradatazz.endpos) {
                // The rest of the layer record data seems to be undocumented,
                // or unclearly documented.
                de_dbg(c, "layer record tagged blocks at %d, len=%d",
                        (int)extradatazz.pos, (int)(extradatazz.endpos-extradatazz.pos));
                de_dbg_indent(c, 1);
                zz_init(&czz, &extradatazz);
                do_tagged_blocks(c, d, &czz, 0);
                de_dbg_indent(c, -1);
        }

        retval = 1;
done:
        return retval;
}

static int do_layer_info_section(deark *c, lctx *d, zztype *zz, int has_len_field)
{
        int retval = 0;
        i64 layer_info_len;
        i64 layer_count_raw, layer_count;
        int saved_indent_level;
        int merged_result_flag;
        i64 layer_idx;
        zztype datazz;
        zztype czz;
        struct channel_data *cd = NULL;

        de_dbg_indent_save(c, &saved_indent_level);
        if(zz_avail(zz)<4) goto done;

        de_dbg(c, "layer info section at %d", (int)zz->pos);
        de_dbg_indent(c, 1);

        if(has_len_field) {
                layer_info_len = psd_getu32or64zz(c, d, zz);
                de_dbg(c, "length of layer info section: %d", (int)layer_info_len);
        }
        else {
                layer_info_len = zz_avail(zz);
        }
        zz_init_with_len(&datazz, zz, layer_info_len);
        zz->pos += layer_info_len;
        retval = 1;

        if(datazz.pos>=datazz.endpos) {
                // If the length field is 0, it's legal for this section to end here.
                goto done;
        }

        layer_count_raw = psd_geti16zz(&datazz);
        if(layer_count_raw<0) {
                merged_result_flag = 1;
                layer_count = -layer_count_raw;
        }
        else {
                merged_result_flag = 0;
                layer_count = layer_count_raw;
        }
        de_dbg(c, "layer count: %d", (int)layer_count);
        de_dbg(c, "merged result flag: %d", (int)merged_result_flag);

        // Due to the recursive possibilities of PSD format, it would probably
        // be a bad idea to store this channel information in the 'd' struct.
        // Instead, we'll use a local variable.
        cd = de_malloc(c, sizeof(struct channel_data));
        cd->num_channels = 0;
        cd->total_len = 0;

        for(layer_idx=0; layer_idx<layer_count; layer_idx++) {
                de_dbg(c, "layer record[%d] at %d", (int)layer_idx, (int)datazz.pos);
                de_dbg_indent(c, 1);
                zz_init(&czz, &datazz);
                if(!do_layer_record(c, d, &czz, cd))
                        goto done;
                datazz.pos += zz_used(&czz);
                de_dbg_indent(c, -1);
        }

        de_dbg(c, "channel image data records at %d, count=%d, total len=%"I64_FMT"",
                (int)datazz.pos, (int)cd->num_channels, cd->total_len);

done:
        de_dbg_indent_restore(c, saved_indent_level);
        de_free(c, cd);
        return retval;
}

static void do_uint32_block(deark *c, lctx *d, zztype *zz,
        const struct de_fourcc *blk4cc, const char *name)
{
        i64 value;

        if(zz_avail(zz)!=4) return;
        value = psd_getu32zz(zz);
        de_dbg(c, "%s: %d", name, (int)value);
}

static void do_boolean_block(deark *c, lctx *d, zztype *zz,
        const struct de_fourcc *blk4cc, const char *name)
{
        u8 value;
        i64 len;

        len = zz_avail(zz);
        if(len<1 || len>4) return;
        value = psd_getbytezz(zz);
        de_dbg(c, "%s: %d", name, (int)value);
}

static void do_fourcc_block(deark *c, lctx *d, zztype *zz,
        const struct de_fourcc *blk4cc, const char *name)
{
        struct de_fourcc fourcc;

        if(zz_avail(zz)!=4) return;
        psd_read_fourcc_zz(c, d, zz, &fourcc);
        de_dbg(c, "%s: '%s'", name, fourcc.id_dbgstr);
}

static void do_Layr_block(deark *c, lctx *d, zztype *zz, const struct de_fourcc *blk4cc)
{
        // "Layer info" section, but starting with the "Layer count" field
        do_layer_info_section(c, d, zz, 0);
}

static void extract_linked_layer_blob(deark *c, lctx *d, i64 pos, i64 len)
{
        const char *ext = "layer.bin";
        u8 buf[8];

        if(len<1) return;

        // Sniff the file type.
        // (The "File Type" FourCC is not reliable.)
        de_read(buf, pos, sizeof(buf));
        if(!de_memcmp(buf, "8BPS\x00\x01", 6)) {
                ext = "layer.psd";
        }
        else if(!de_memcmp(buf, "8BPS\x00\x02", 6)) {
                ext = "layer.psb";
        }
        else if(!de_memcmp(buf, "\x89\x50\x4e\x47", 4)) {
                ext = "layer.png";
        }
        else if(!de_memcmp(buf, "\xff\xd8\xff", 3)) {
                ext = "layer.jpg";
        }
        else if(!de_memcmp(buf, "%PDF", 4)) {
                ext = "layer.pdf";
        }

        // TODO: Maybe we should try to use the "original filename" field, somehow,
        // to construct our filename.
        dbuf_create_file_from_slice(c->infile, pos, len, ext,
                NULL, DE_CREATEFLAG_IS_AUX);
}

static int do_one_linked_layer(deark *c, lctx *d, zztype *zz, const struct de_fourcc *blk4cc)
{
        int retval = 0;
        i64 dlen, dlen2=0;
        i64 ver;
        u8 file_open_descr_flag;
        struct de_fourcc type4cc;
        struct de_fourcc tmp4cc;
        de_ucstring *s = NULL;
        zztype datazz;

        dlen = psd_geti64zz(zz);
        de_dbg(c, "length: %"I64_FMT"", dlen);
        if(dlen<8 || zz->pos+dlen>zz->endpos) {
                de_warn(c, "Bad linked layer size %"I64_FMT" at %"I64_FMT"", dlen, zz->startpos);
                goto done;
        }

        zz_init_with_len(&datazz, zz, dlen);

        // Seems to be padded to a multiple of 4 bytes. (The spec says nothing
        // about this.)
        zz->pos += de_pad_to_4(dlen);
        retval = 1;

        psd_read_fourcc_zz(c, d, &datazz, &type4cc);
        de_dbg(c, "type: '%s'", type4cc.id_dbgstr);

        ver = psd_getu32zz(&datazz);
        de_dbg(c, "version: %d", (int)ver);

        s = ucstring_create(c);
        read_pascal_string_to_ucstring(c, d, s, &datazz);
        de_dbg(c, "unique id: \"%s\"", ucstring_getpsz(s));

        ucstring_empty(s);
        read_unicode_string(c, d, s, &datazz);
        de_dbg(c, "original file name: \"%s\"", ucstring_getpsz(s));

        psd_read_fourcc_zz(c, d, &datazz, &tmp4cc);
        de_dbg(c, "file type: '%s'", tmp4cc.id_dbgstr);

        psd_read_fourcc_zz(c, d, &datazz, &tmp4cc);
        de_dbg(c, "file creator: '%s'", tmp4cc.id_dbgstr);

        dlen2 = psd_geti64zz(&datazz);
        de_dbg(c, "length2: %"I64_FMT"", dlen2);
        if(dlen2<0) goto done;

        file_open_descr_flag = psd_getbytezz(&datazz);
        de_dbg(c, "has file open descriptor: %d", (int)file_open_descr_flag);

        if(file_open_descr_flag) {
                if(!read_descriptor(c, d, &datazz, 1, " (of open parameters)")) {
                        goto done;
                }
        }

        if(type4cc.id!=CODE_liFD) {
                // TODO: liFA and liFE need special handling.
                de_dbg(c, "[this linked layer type is not supported]");
                goto done;
        }

        de_dbg(c, "raw file bytes at %"I64_FMT", len=%"I64_FMT"", datazz.pos, dlen2);
        extract_linked_layer_blob(c, d, datazz.pos, dlen2);

        // TODO: There may be more fields after this, depending on the version.

done:
        ucstring_destroy(s);
        return retval;
}

static void do_lnk2_block(deark *c, lctx *d, zztype *zz, const struct de_fourcc *blk4cc)
{
        int ret;
        zztype czz;

        while(zz->pos<zz->endpos) {
                de_dbg(c, "linked layer data at %"I64_FMT"", zz->pos);
                de_dbg_indent(c, 1);
                zz_init(&czz, zz);
                ret = do_one_linked_layer(c, d, &czz, blk4cc);
                de_dbg_indent(c, -1);
                if(!ret) break;
                zz->pos += zz_used(&czz);
        }
}

static void do_vm_array(deark *c, lctx *d, zztype *zz)
{
        i64 n;
        i64 dlen, idata_len;
        i64 saved_pos;

        zz->pos += 4; // Skip array-is-written flag (already processed)

        dlen = psd_getu32zz(zz);
        de_dbg(c, "length: %d", (int)dlen);
        if(dlen==0) goto done;

        saved_pos = zz->pos;

        n = psd_getu32zz(zz);
        de_dbg(c, "depth: %d", (int)n);

        read_rectangle_tlbr(c, d, zz, "rectangle");

        n = psd_getu16zz(zz);
        de_dbg(c, "depth: %d", (int)n);

        n = (i64)psd_getbytezz(zz);
        dbg_print_compression_method(c, d, n);

        idata_len = saved_pos + dlen - zz->pos;
        de_dbg(c, "[%d bytes of data at %d]", (int)idata_len, (int)zz->pos);

        zz->pos = saved_pos + dlen;
done:
        ;
}

static void do_vm_array_list(deark *c, lctx *d, zztype *zz)
{
        i64 ver;
        i64 dlen;
        i64 num_channels;
        zztype czz;
        i64 i;

        de_dbg(c, "virtual memory array list at %d, len=%"I64_FMT"", (int)zz->pos,
                zz_avail(zz));
        de_dbg_indent(c, 1);

        ver = psd_getu32zz(zz);
        de_dbg(c, "version: %d", (int)ver);

        dlen = psd_getu32zz(zz);
        de_dbg(c, "length: %d", (int)dlen);

        read_rectangle_tlbr(c, d, zz, "rectangle");

        num_channels = psd_getu32zz(zz);
        de_dbg(c, "number of channels: %d", (int)num_channels);

        for(i=0; i<num_channels+2; i++) {
                i64 is_written;

                // Look ahead at the array-is-written flag.
                is_written = psd_getu32(zz->pos);

                de_dbg(c, "virtual memory array[%d] at %d%s", (int)i, (int)zz->pos,
                        is_written?"":" (empty)");
                if(is_written) {
                        zz_init(&czz, zz);
                        de_dbg_indent(c, 1);
                        do_vm_array(c, d, &czz);
                        de_dbg_indent(c, -1);
                        zz->pos += zz_used(&czz);
                }
                else {
                        zz->pos += 4;
                }
        }

        de_dbg_indent(c, -1);
}

// The main part of a "pattern" object, starting with the version and
// color_mode[l] fields.
static int do_pattern_internal(deark *c, lctx *d, zztype *zz)
{
        i64 pat_color_mode;
        i64 ver;
        i64 w, h;
        de_ucstring *s = NULL;
        zztype vmalzz; // for virtual memory array list
        int retval = 0;

        ver = psd_getu32zz(zz);
        de_dbg(c, "version: %d", (int)ver);
        if(ver!=1) goto done;

        pat_color_mode = psd_getu32zz(zz);
        de_dbg(c, "color mode: %d (%s)", (int)pat_color_mode, get_colormode_name(pat_color_mode));

        h = psd_getu16zz(zz);
        w = psd_getu16zz(zz);
        de_dbg_dimensions(c, w, h);

        s = ucstring_create(c);
        read_unicode_string(c, d, s, zz);
        de_dbg(c, "name: \"%s\"", ucstring_getpsz_d(s));

        ucstring_empty(s);
        read_pascal_string_to_ucstring(c, d, s, zz);
        de_dbg(c, "id: \"%s\"", ucstring_getpsz_d(s));

        if(pat_color_mode==PSD_CM_PALETTE) {
                de_dbg(c, "palette at %d", (int)zz->pos);
                zz->pos += 3*256;
        }

        zz_init(&vmalzz, zz);
        do_vm_array_list(c, d, &vmalzz);
        zz->pos += zz_used(&vmalzz);
        retval = 1;
done:
        ucstring_destroy(s);
        return retval;
}

// Decode a single "pattern" object, starting with the "length" field for this
// pattern.
static int do_pattern(deark *c, lctx *d, zztype *zz, i64 pattern_idx)
{
        i64 pat_dlen;
        zztype datazz; // zz for the pattern data (minus the length field)
        int retval = 0;

        if(zz_avail(zz)<16) goto done;

        de_dbg(c, "pattern[%d] at %d", (int)pattern_idx, (int)zz->pos);
        de_dbg_indent(c, 1);

        pat_dlen = psd_getu32zz(zz);
        de_dbg(c, "length: %d", (int)pat_dlen);

        zz_init_with_len(&datazz, zz, pat_dlen);

        do_pattern_internal(c, d, &datazz);

        zz->pos += de_pad_to_4(pat_dlen);

        de_dbg_indent(c, -1);

        retval = 1;
done:
        return retval;
}

static void do_pattern_sequence(deark *c, lctx *d, zztype *zz)
{
        i64 pattern_idx;
        zztype czz;

        pattern_idx = 0;
        while(1) {
                if(zz_avail(zz)<16) break;
                zz_init(&czz, zz);
                if(!do_pattern(c, d, &czz, pattern_idx)) {
                        break;
                }
                zz->pos += zz_used(&czz);
                pattern_idx++;
        }
}

static void do_Patt_block(deark *c, lctx *d, zztype *zz, const struct de_fourcc *xblk4cc)
{
        do_pattern_sequence(c, d, zz);
}

// Process a v6.1 'samp' block, starting right after the ID.
static void do_samp_block_v61stuff(deark *c, lctx *d, zztype *zz)
{
        i64 n;
        i64 idata_len;

        // This code is based on guesswork, and may not be correct.

        zz->pos += 8; // 8 unknown bytes

        // Note the similarity to vm_array.

        n = psd_getu16zz(zz);
        de_dbg(c, "depth: %d", (int)n);

        read_rectangle_tlbr(c, d, zz, "rectangle");

        n = psd_getu16zz(zz);
        de_dbg(c, "depth: %d", (int)n);

        n = (i64)psd_getbytezz(zz);
        dbg_print_compression_method(c, d, n);

        idata_len = zz_avail(zz);
        de_dbg(c, "[%d bytes of data at %d]", (int)idata_len, (int)zz->pos);

}

// Process a v6.2 'samp' block, starting right after the ID.
static void do_samp_block_v62stuff(deark *c, lctx *d, zztype *zz)
{
        i64 x;
        zztype czz;

        // This code is based on guesswork, and may not be correct.

        // I don't know what the first 4 bytes are for. Observed to be 00 01 00 00.
        x = psd_getu32zz(zz);
        if(x != 0x00010000) {
                return;
        }

        zz_init(&czz, zz);
        do_vm_array_list(c, d, &czz);
}

static void do_samp_block(deark *c, lctx *d, zztype *zz)
{
        i64 item_idx;
        int saved_indent_level;
        de_ucstring *tmps = NULL;
        zztype czz;

        // Note: This code is based on guesswork, and may be incorrect.

        de_dbg_indent_save(c, &saved_indent_level);
        tmps = ucstring_create(c);

        item_idx = 0;
        while(1) {
                i64 item_data_len2;
                zztype datazz; // zz for the item data (minus the length field)

                if(zz->pos+16 > zz->endpos) break;

                de_dbg(c, "item[%d] at %d", (int)item_idx, (int)zz->pos);
                de_dbg_indent(c, 1);

                item_data_len2 = psd_getu32zz(zz);
                de_dbg(c, "length: %d", (int)item_data_len2);

                zz_init_with_len(&datazz, zz, item_data_len2);

                ucstring_empty(tmps);
                read_pascal_string_to_ucstring(c, d, tmps, &datazz);
                de_dbg(c, "id: \"%s\"", ucstring_getpsz_d(tmps));

                if(d->abr_major_ver==6 && d->abr_minor_ver<=1) {
                        zz_init(&czz, &datazz);
                        do_samp_block_v61stuff(c, d, &czz);
                }
                else if(d->abr_major_ver>6 || (d->abr_major_ver==6 && d->abr_minor_ver>=2)) {
                        zz_init(&czz, &datazz);
                        do_samp_block_v62stuff(c, d, &czz);
                }

                zz->pos += de_pad_to_4(item_data_len2);

                de_dbg_indent(c, -1);
                item_idx++;
        }

        ucstring_destroy(tmps);
        de_dbg_indent_restore(c, saved_indent_level);
}

static void do_lrFX_block(deark *c, lctx *d, zztype *zz, const struct de_fourcc *blk4cc)
{
        i64 ver;
        i64 count;
        i64 i;
        u32 sig;
        struct de_fourcc sig4cc;

        ver = psd_getu16zz(zz);
        if(ver!=0) goto done;

        count = psd_getu16zz(zz);
        de_dbg(c, "effects count: %d", (int)count);

        for(i=0; i<count; i++) {
                i64 epos;
                i64 dlen;

                if(zz->pos>=zz->endpos) goto done;
                epos = zz->pos;

                sig = (u32)psd_getu32zz(zz);
                if(sig!=CODE_8BIM) {
                        de_warn(c, "Bad 'effects' block signature at %d", (int)zz->pos);
                        goto done;
                }

                psd_read_fourcc_zz(c, d, zz, &sig4cc);

                dlen = psd_getu32zz(zz);

                de_dbg(c, "effects[%d] '%s' at %d, dpos=%d, dlen=%d", (int)i, sig4cc.id_dbgstr,
                        (int)epos, (int)zz->pos, (int)dlen);
                zz->pos += dlen;
        }

done:
        ;
}

static void do_fxrp_block(deark *c, lctx *d, zztype *zz)
{
        double v[2];

        if(zz_avail(zz)!=16) return;
        v[0] = dbuf_getfloat64x(c->infile, zz->pos, d->is_le);
        zz->pos += 8;
        v[1] = dbuf_getfloat64x(c->infile, zz->pos, d->is_le);
        zz->pos += 8;
        de_dbg(c, "reference point: %f, %f", v[0], v[1]);
}

static void do_lsct_block(deark *c, lctx *d, zztype *zz)
{
        i64 x;
        struct de_fourcc tmp4cc;

        if(zz_avail(zz)<4) return;
        x = psd_getu32zz(zz);
        de_dbg(c, "section divider setting type: %d", (int)x);

        zz->pos += 4; // skip '8BIM' signature

        if(zz_avail(zz)<4) return;
        psd_read_fourcc_zz(c, d, zz, &tmp4cc);
        de_dbg(c, "blend mode key: '%s'", tmp4cc.id_dbgstr);

        if(zz_avail(zz)<4) return;
        x = psd_getu32zz(zz);
        de_dbg(c, "sub type: %d", (int)x);
}

static void do_lspf_block(deark *c, lctx *d, zztype *zz)
{
        unsigned int x;
        if(zz_avail(zz)!=4) return;
        x = (unsigned int)psd_getu32zz(zz);
        de_dbg(c, "protection flags: transparency=%u, composite=%u, position=%u",
                (x&0x1), (x&0x2)>>1, (x&0x4)>>2);
}

static void do_vmsk_block(deark *c, lctx *d, zztype *zz)
{
        i64 ver;
        i64 flags;
        zztype czz;

        ver = psd_getu32zz(zz);
        if(ver!=3) return;
        flags = psd_getu32zz(zz);
        de_dbg(c, "flags: 0x%08x", (unsigned int)flags);

        de_dbg(c, "path components at %d", (int)zz->pos);
        de_dbg_indent(c, 1);
        zz_init(&czz, zz);
        do_pathinfo(c, d, &czz);
        de_dbg_indent(c, -1);
}

static void do_vscg_block(deark *c, lctx *d, zztype *zz)
{
        struct de_fourcc key4cc;

        psd_read_fourcc_zz(c, d, zz, &key4cc);
        de_dbg(c, "key: '%s'", key4cc.id_dbgstr);
        read_descriptor(c, d, zz, 1, " (for Vector Stroke Content Data)");
}

static void do_vogk_block(deark *c, lctx *d, zztype *zz)
{
        i64 ver;

        ver = psd_getu32zz(zz);
        if(ver!=1) return;
        read_descriptor(c, d, zz, 1, " (for Vector Origination Data)");
}

static void do_unicodestring_block(deark *c, lctx *d, zztype *zz, const struct de_fourcc *blk4cc,
        const char *name)
{
        de_ucstring *s = NULL;

        s = ucstring_create(c);
        read_unicode_string(c, d, s, zz);
        de_dbg(c, "%s: \"%s\"", name, ucstring_getpsz(s));
        ucstring_destroy(s);
}

static void do_descriptor_block(deark *c, lctx *d, zztype *zz,
        const struct de_fourcc *blk4cc, const char *name)
{
        char dscrname[100];

        if(name[0])
                de_snprintf(dscrname, sizeof(dscrname), " (for %s)", name);
        else
                de_strlcpy(dscrname, "", sizeof(dscrname));

        read_descriptor(c, d, zz, 1, dscrname);
}

static void do_lfx2_block(deark *c, lctx *d, zztype *zz, const struct de_fourcc *blk4cc)
{
        i64 oe_ver;
        zztype czz;

        if(zz_avail(zz)<8) return;
        oe_ver = psd_getu32zz(zz);
        de_dbg(c, "object effects version: %d", (int)oe_ver);
        if(oe_ver!=0) return;

        zz_init(&czz, zz);
        do_descriptor_block(c, d, &czz, blk4cc, "object-based effects layer info");
}

// Handles 'TySh' and 'tySh'
static void do_TySh_block(deark *c, lctx *d, zztype *zz, const struct de_fourcc *blk4cc)
{
        i64 ver, textver;

        ver = psd_getu16zz(zz);
        de_dbg(c, "version: %d", (int)ver);
        if(ver!=1) goto done;

        zz->pos += 6*8; // transform

        textver = psd_getu16zz(zz);
        de_dbg(c, "text version: %d", (int)textver);
        // For 'tySh', textver should be 6 -- TODO
        // For 'TySh', textver should be 50
        if(textver!=50) goto done;

        if(!read_descriptor(c, d, zz, 1, " (for type tool object setting - text)")) {
                goto done;
        }

        zz->pos += 2; // warp version
        if(!read_descriptor(c, d, zz, 1, " (for type tool object setting - warp)")) {
                goto done;
        }

        // TODO: "left, top, right, bottom" (field purpose and data type are undocumented)
        zz->pos += 4*8;

done:
        ;
}

static void do_SoLd_block(deark *c, lctx *d, zztype *zz)
{
        struct de_fourcc id4cc;
        i64 ver;

        psd_read_fourcc_zz(c, d, zz, &id4cc);
        de_dbg(c, "identifier: '%s'", id4cc.id_dbgstr);
        ver = psd_getu32zz(zz);
        de_dbg(c, "version: %d", (int)ver);

        read_descriptor(c, d, zz, 1, " (of placed layer information)");
}

static void do_filter_effect_channel(deark *c, lctx *d, zztype *zz)
{
        i64 dlen;
        i64 saved_pos;
        i64 cmpr_mode;

        zz->pos += 4; // Skip array-is-written flag (already processed)

        dlen = psd_geti64zz(zz);
        de_dbg(c, "length: %"I64_FMT"", dlen);
        saved_pos = zz->pos;
        if(dlen<=0) goto done;

        cmpr_mode = psd_getu16zz(zz);
        dbg_print_compression_method(c, d, cmpr_mode);

        de_dbg(c, "[%d bytes at %d]", (int)(saved_pos + dlen - zz->pos), (int)zz->pos);
        zz->pos = saved_pos + dlen;
done:
        ;
}

static void do_filter_effect(deark *c, lctx *d, zztype *zz)
{
        i64 ver2;
        i64 dlen2;
        de_ucstring *s = NULL;
        i64 x;
        i64 ch;
        i64 max_channels;
        u8 b;
        zztype czz;
        int saved_indent_level;
        i64 filter_effects_savedpos;

        de_dbg_indent_save(c, &saved_indent_level);

        s = ucstring_create(c);

        ucstring_empty(s);
        read_pascal_string_to_ucstring(c, d, s, zz);
        de_dbg(c, "identifier: \"%s\"", ucstring_getpsz(s));

        // Note the clear similarites to the "virtual memory array lists" used in
        // Pattern data. But it is not the same. Maybe some of the code should be
        // consolidated.

        ver2 = psd_getu32zz(zz);
        de_dbg(c, "version: %d", (int)ver2);
        if(ver2 != 1) goto done;

        dlen2 = psd_geti64zz(zz);
        de_dbg(c, "length: %"I64_FMT"", dlen2);
        filter_effects_savedpos = zz->pos;

        read_rectangle_tlbr(c, d, zz, "rectangle");

        x = psd_getu32zz(zz);
        de_dbg(c, "depth: %d", (int)x);

        max_channels = psd_getu32zz(zz);
        de_dbg(c, "max channels: %d", (int)max_channels);

        for(ch=0; ch<max_channels+2; ch++) {
                i64 is_written;

                if(zz->pos >= zz->endpos) goto done;

                // Look ahead at the array-is-written flag.
                is_written = psd_getu32(zz->pos);

                de_dbg(c, "channel[%d] at %d%s", (int)ch, (int)zz->pos,
                        is_written?"":" (empty)");

                if(is_written) {
                        zz_init(&czz, zz);
                        de_dbg_indent(c, 1);
                        do_filter_effect_channel(c, d, &czz);
                        de_dbg_indent(c, -1);
                        zz->pos += zz_used(&czz);
                }
                else {
                        zz->pos += 4;
                }
        }

        if(zz->pos < (filter_effects_savedpos + dlen2)) {
                de_dbg(c, "[%d unknown bytes at %d]", (int)(filter_effects_savedpos + dlen2 - zz->pos),
                        (int)zz->pos);
        }

        zz->pos = filter_effects_savedpos + dlen2;

        b = psd_getbytezz(zz);
        de_dbg(c, "next-items-present: %d", (int)b);

        if(b) {
                x = psd_getu16zz(zz);
                dbg_print_compression_method(c, d, x);
        }

        de_dbg(c, "[%d bytes at %d]", (int)zz_avail(zz), (int)zz->pos);
        zz->pos = zz->endpos;

done:
        ucstring_destroy(s);
        de_dbg_indent_restore(c, saved_indent_level);
}

static void do_FXid_block(deark *c, lctx *d, zztype *zz, const struct de_fourcc *blk4cc)
{
        i64 ver1;
        i64 dlen1;
        i64 idx;
        i64 main_endpos;
        zztype czz;

        ver1 = psd_getu32zz(zz);
        de_dbg(c, "version: %d", (int)ver1);
        if(ver1<1 || ver1>3) goto done;

        // TODO: I suspect that this next "length" field is actually part of each
        // individual filter effect, contrary to what the documentation says.
        // That way, there can be multiple "filter effects" in the same block.
        // Sample files needed.

        dlen1 = psd_geti64zz(zz);
        de_dbg(c, "length: %"I64_FMT"", dlen1);
        main_endpos = zz->pos + dlen1;

        idx = 0;

        {
                de_dbg(c, "filter effect[%d] at %d", (int)idx, (int)zz->pos);
                zz_init_with_len(&czz, zz, main_endpos-zz->pos);
                de_dbg_indent(c, 1);
                do_filter_effect(c, d, &czz);
                de_dbg_indent(c, -1);
                zz->pos += zz_used(&czz);
                idx++;
        }

        if(zz->pos < main_endpos) {
                de_dbg(c, "[%d bytes of data at %d]", (int)(main_endpos-zz->pos), (int)zz->pos);
        }

        zz->pos = main_endpos;
done:
        ;
}

static void do_shmd_block(deark *c, lctx *d, zztype *zz)
{
        i64 count;
        i64 i;
        zztype czz;

        if(zz_avail(zz)<4) return;

        count = psd_getu32zz(zz);
        de_dbg(c, "number of metadata items: %d", (int)count);

        for(i=0; i<count; i++) {
                i64 itempos, dpos, dlen;
                struct de_fourcc key4cc;

                if(zz->pos >= zz->endpos) break;
                itempos = zz->pos;

                zz->pos += 4; // signature ("8BIM", presumably)

                psd_read_fourcc_zz(c, d, zz, &key4cc);

                zz->pos += 1; // flag
                zz->pos += 3; // padding

                dlen = psd_getu32zz(zz);

                dpos = zz->pos;
                de_dbg(c, "metadata item[%d] '%s' at %d, dpos=%d, dlen=%d",
                        (int)i, key4cc.id_dbgstr, (int)itempos, (int)dpos, (int)dlen);

                de_dbg_indent(c, 1);

                switch(key4cc.id) {
                case CODE_cust: // Undocumented, but seems to be a versioned Descriptor
                case CODE_mlst: // Undocumented, but seems to be a versioned Descriptor
                        zz_init_with_len(&czz, zz, dlen);
                        read_descriptor(c, d, &czz, 1, "");
                        break;
                }

                de_dbg_indent(c, -1);

                zz->pos += dlen;
        }
}

static int do_tagged_block(deark *c, lctx *d, zztype *zz, int tbnamespace)
{
        i64 blklen;
        i64 blklen_len = 4; // Length of the block length field
        struct de_fourcc blk4cc;
        u32 sig;
        zztype czz;

        if(zz_avail(zz)<12) return 0;

        sig = (u32)psd_getu32zz(zz);
        if(sig!=CODE_8BIM && sig!=CODE_8B64) {
                de_warn(c, "Expected tagged block signature not found at %d", (int)zz->pos);
                return 0;
        }

        psd_read_fourcc_zz(c, d, zz, &blk4cc);

        // Some blocks types have an 8-byte length in PSD format
        if(d->intsize_4or8==8) {
                switch(blk4cc.id) {
                case CODE_LMsk: case CODE_Lr16: case CODE_Lr32: case CODE_Layr:
                case CODE_Mt16: case CODE_Mt32: case CODE_Mtrn: case CODE_Alph:
                case CODE_FMsk: case CODE_lnk2: case CODE_FEid: case CODE_FXid:
                case CODE_PxSD:
                        blklen_len = 8;
                }
        }

        if(blklen_len==8) {
                blklen = psd_geti64zz(zz);
        }
        else {
                blklen = psd_getu32zz(zz);
        }

        zz_init_with_len(&czz, zz, blklen);

        de_dbg(c, "tagged block '%s' at %d, dpos=%d, dlen=%d", blk4cc.id_dbgstr,
                (int)zz->startpos, (int)czz.startpos, (int)blklen);

        de_dbg_indent(c, 1);
        switch(blk4cc.id) {
        case CODE_clbl:
                do_boolean_block(c, d, &czz, &blk4cc, "blend clipped elements");
                break;
        case CODE_infx:
                do_boolean_block(c, d, &czz, &blk4cc, "blend interior elements");
                break;
        case CODE_knko:
                do_boolean_block(c, d, &czz, &blk4cc, "knockout");
                break;
        case CODE_lyid:
                do_uint32_block(c, d, &czz, &blk4cc, "layer ID");
                break;
        case CODE_lnsr:
                do_fourcc_block(c, d, &czz, &blk4cc, "layer name ID");
                break;
        case CODE_Layr:
        case CODE_Lr16:
                do_Layr_block(c, d, &czz, &blk4cc);
                break;
        case CODE_lnkD:
        case CODE_lnk2:
        case CODE_lnk3:
                do_lnk2_block(c, d, &czz, &blk4cc);
                break;
        case CODE_Patt:
        case CODE_Pat2:
        case CODE_Pat3:
                do_Patt_block(c, d, &czz, &blk4cc);
                break;
        case CODE_lrFX:
                do_lrFX_block(c, d, &czz, &blk4cc);
                break;
        case CODE_luni:
                do_unicodestring_block(c, d, &czz, &blk4cc, "Unicode layer name");
                break;
        case CODE_GdFl:
                do_descriptor_block(c, d, &czz, &blk4cc, "Gradient fill setting");
                break;
        case CODE_PtFl:
                do_descriptor_block(c, d, &czz, &blk4cc, "Pattern fill setting");
                break;
        case CODE_SoCo:
                do_descriptor_block(c, d, &czz, &blk4cc, "Solid color sheet setting");
                break;
        case CODE_vstk:
                do_descriptor_block(c, d, &czz, &blk4cc, "Vector Stroke Data");
                break;
        case CODE_blwh:
                do_descriptor_block(c, d, &czz, &blk4cc, "Black and White");
                break;
        case CODE_CgEd:
                do_descriptor_block(c, d, &czz, &blk4cc, "Content Generator Extra Data");
                break;
        case CODE_vibA:
                do_descriptor_block(c, d, &czz, &blk4cc, "Vibrance");
                break;
        case CODE_pths:
                do_descriptor_block(c, d, &czz, &blk4cc, "Unicode Path Name");
                break;
        case CODE_anFX:
                do_descriptor_block(c, d, &czz, &blk4cc, "Animation Effects");
                break;
        case CODE_PxSc:
                do_descriptor_block(c, d, &czz, &blk4cc, "Pixel Source Data");
                break;
        case CODE_artb:
        case CODE_artd:
        case CODE_abdd:
                do_descriptor_block(c, d, &czz, &blk4cc, "Artboard Data");
                break;
        case CODE_vmsk:
        case CODE_vsms:
                do_vmsk_block(c, d, &czz);
                break;
        case CODE_vscg:
                do_vscg_block(c, d, &czz);
                break;
        case CODE_vogk:
                do_vogk_block(c, d, &czz);
                break;
        case CODE_fxrp:
                do_fxrp_block(c, d, &czz);
                break;
        case CODE_lsct:
                do_lsct_block(c, d, &czz);
                break;
        case CODE_lspf:
                do_lspf_block(c, d, &czz);
                break;
        case CODE_lfx2:
                do_lfx2_block(c, d, &czz, &blk4cc);
                break;
        case CODE_Txt2:
                do_text_engine_data(c, d, czz.startpos, blklen);
                break;
        case CODE_TySh:
        case CODE_tySh:
                do_TySh_block(c, d, &czz, &blk4cc);
                break;
        case CODE_SoLd:
                do_SoLd_block(c, d, &czz);
                break;
        case CODE_FEid:
        case CODE_FXid:
                do_FXid_block(c, d, &czz, &blk4cc);
                break;
        case CODE_shmd:
                do_shmd_block(c, d, &czz);
                break;
        case CODE_AnDs: // Observed in Plug-in Resources/'mani'/'IRFR'
                if(tbnamespace==1) {
                        do_descriptor_block(c, d, &czz, &blk4cc, "");
                }
                break;
        case CODE_desc:
                if(tbnamespace==2) { // Observed in ABR (brush) files
                        do_descriptor_block(c, d, &czz, &blk4cc, "");
                }
                break;
        case CODE_patt:
                if(tbnamespace==2) {
                        do_Patt_block(c, d, &czz, &blk4cc);
                }
                break;
        case CODE_samp:
                if(tbnamespace==2) {
                        do_samp_block(c, d, &czz);
                }
                break;
        default:
                if(blklen>0) {
                        if(c->debug_level>=2) {
                                de_dbg_hexdump(c, c->infile, czz.startpos, blklen, 256, NULL, 0x1);
                        }
                        else {
                                de_dbg(c, "[%d bytes of tagged block data at %d]", (int)blklen, (int)czz.startpos);
                        }
                }
        }
        de_dbg_indent(c, -1);

        // Apparently, the data is padded to the next multiple of 4 bytes.
        // (This is not what the PSD spec says.)
        zz->pos += de_pad_to_4(blklen);
        return 1;
}

// A "Series of tagged blocks" - part of the "Layer and Mask Information" section.
// Or, the payload data from a TIFF "ImageSourceData" tag.
// Or, at the end of a "layer record".
static void do_tagged_blocks(deark *c, lctx *d, zztype *zz, int tbnamespace)
{
        zztype czz;

        d->nesting_level++;
        if(d->nesting_level>MAX_NESTING_LEVEL) goto done; // Defend against excessive recursion.

        if(d->tagged_blocks_only && d->nesting_level==1) {
                // If we're reading *only* this data structure (e.g. from a TIFF file), the
                // byte order may be of interest.
                de_dbg(c, "byte order: %s-endian", d->is_le?"little":"big");
        }

        while(1) {
                if(zz->pos+12 > zz->endpos) break;
                zz_init(&czz, zz);
                if(!do_tagged_block(c, d, &czz, tbnamespace)) break;
                zz->pos += zz_used(&czz);
        }

done:
        d->nesting_level--;
}

static int do_layer_and_mask_info_section(deark *c, lctx *d, zztype *zz)
{
        i64 layer_and_mask_info_section_len; // The "Length" field. Whole section is 4 bytes longer.
        i64 gl_layer_mask_info_len;
        zztype lmidataczz;
        zztype czz;
        int saved_indent_level;
        int retval = 0;

        de_dbg_indent_save(c, &saved_indent_level);

        // The "layer and mask section" contains up to 3 sub-sections:
        // 1. layer info
        // 2. global layer mask info
        // 3. tagged blocks

        de_dbg(c, "layer & mask info section at %d", (int)zz->pos);
        de_dbg_indent(c, 1);

        layer_and_mask_info_section_len = psd_getu32or64zz(c, d, zz);
        de_dbg(c, "layer & mask info section total data len: %d", (int)layer_and_mask_info_section_len);
        if(zz->pos + layer_and_mask_info_section_len > zz->endpos) {
                de_err(c, "Unexpected end of PSD file");
                goto done;
        }
        zz_init_with_len(&lmidataczz, zz, layer_and_mask_info_section_len);

        // We won't use zz again (we'll use lmidataczz instead), so we can go ahead and
        // advance its ->pos field.
        zz->pos += layer_and_mask_info_section_len;
        // Now that we know the size of this element, we can treat this function as "successful".
        retval = 1;

        ///// 1. layer info /////

        zz_init(&czz, &lmidataczz);
        if(!do_layer_info_section(c, d, &lmidataczz, 1)) {
                goto done;
        }
        if(czz.endpos > lmidataczz.endpos) {
                de_warn(c, "Oversized Layer Info section");
                goto done;
        }
        lmidataczz.pos += zz_used(&czz);

        /////

        if(lmidataczz.pos >= lmidataczz.endpos) {
                goto done;
        }

        ///// 2. global layer mask info /////

        de_dbg(c, "global layer mask info at %d", (int)lmidataczz.pos);
        de_dbg_indent(c, 1);
        gl_layer_mask_info_len = psd_getu32zz(&lmidataczz);
        de_dbg(c, "length of global layer mask info section: %"I64_FMT, gl_layer_mask_info_len);
        de_dbg_indent(c, -1);
        if(lmidataczz.pos+gl_layer_mask_info_len > lmidataczz.endpos) {
                de_warn(c, "Oversized Global Layer Mask Info section");
                goto done;
        }
        lmidataczz.pos += gl_layer_mask_info_len;

        /////

        if(lmidataczz.pos >= lmidataczz.endpos) {
                goto done;
        }

        ///// 3. tagged blocks /////

        de_dbg(c, "tagged blocks at %d", (int)lmidataczz.pos);
        de_dbg_indent(c, 1);
        de_dbg(c, "expected length of tagged blocks section: %d", (int)(lmidataczz.endpos-lmidataczz.pos));
        zz_init(&czz, &lmidataczz);
        do_tagged_blocks(c, d, &czz, 0);
        de_dbg_indent(c, -1);

done:
        de_dbg_indent_restore(c, saved_indent_level);
        return retval;
}

static int do_action_item(deark *c, lctx *d, zztype *zz)
{
        struct de_fourcc id4cc;
        de_ucstring *s = NULL;
        i64 dscr_flag;
        int retval = 0;

        zz->pos += 1; // action-is-expanded
        zz->pos += 1; // action-is-enabled
        zz->pos += 1; // dialogs-should-be-displayed
        zz->pos += 1; // options for displaying dialogs

        s = ucstring_create(c);

        psd_read_fourcc_zz(c, d, zz, &id4cc);
        de_dbg(c, "identifier type: '%s'", id4cc.id_dbgstr);
        if(id4cc.id==CODE_TEXT) {
                read_prefixed_string_to_ucstring(c, d, s, zz);
                de_dbg(c, "id: \"%s\"", ucstring_getpsz_d(s));
        }
        else if(id4cc.id==CODE_long) {
                i64 id_long;
                id_long = psd_getu32zz(zz);
                de_dbg(c, "itemID: %d", (int)id_long);
        }
        else {
                de_err(c, "Unsupported identifier type: '%s'", id4cc.id_sanitized_sz);
                goto done;
        }

        ucstring_empty(s);
        read_prefixed_string_to_ucstring(c, d, s, zz);
        de_dbg(c, "dictionary name: \"%s\"", ucstring_getpsz_d(s));

        dscr_flag = psd_geti32zz(zz);
        de_dbg(c, "descriptor flag: %d", (int)dscr_flag);

        if(dscr_flag == -1) {
                if(!read_descriptor(c, d, zz, 0, "")) goto done;
        }
        else if(dscr_flag==0) {
                ;
        }
        else {
                de_err(c, "Unsupported descriptor flag: %d", (int)dscr_flag);
                goto done;
        }

        retval = 1;

done:
        ucstring_destroy(s);
        return retval;
}

static int do_one_action(deark *c, lctx *d, zztype *zz)
{
        i64 action_pos;
        i64 idx;
        i64 num_items;
        i64 item_idx;
        de_ucstring *s = NULL;
        zztype czz;
        int saved_indent_level;
        int retval = 0;

        de_dbg_indent_save(c, &saved_indent_level);
        action_pos = zz->pos;
        idx = psd_getu16zz(zz);
        de_dbg(c, "index: %d", (int)idx);

        zz->pos += 1; // shift key flag
        zz->pos += 1; // command key flag
        zz->pos += 2; // color index info

        s = ucstring_create(c);
        read_unicode_string(c, d, s, zz);
        de_dbg(c, "action name: \"%s\"", ucstring_getpsz_d(s));

        zz->pos += 1; // action-is-expanded

        num_items = psd_getu32zz(zz);
        de_dbg(c, "number of items: %d", (int)num_items);

        for(item_idx=0; item_idx<num_items; item_idx++) {
                if(zz_avail(zz)<1) goto done;
                zz_init(&czz, zz);
                de_dbg(c, "item[%d] at %d (for action @%d)", (int)item_idx, (int)zz->pos, (int)action_pos);
                de_dbg_indent(c, 1);
                if(!do_action_item(c, d, &czz)) goto done;
                zz->pos += zz_used(&czz);
                de_dbg_indent(c, -1);
        }

        retval = 1;

done:
        de_dbg_indent_restore(c, saved_indent_level);
        ucstring_destroy(s);
        return retval;
}

static void do_action_set(deark *c, lctx *d, zztype *zz)
{
        i64 ver;
        i64 num_actions;
        i64 action_idx;
        de_ucstring *s = NULL;
        zztype czz;
        int saved_indent_level;
        u8 b;

        de_dbg_indent_save(c, &saved_indent_level);
        ver = psd_getu32zz(zz);
        de_dbg(c, "version: %d", (int)ver);
        if(ver!=16) {
                de_err(c, "Unsupported Action format version: %d", (int)ver);
                goto done;
        }

        s = ucstring_create(c);
        read_unicode_string(c, d, s, zz);
        de_dbg(c, "action set name: \"%s\"", ucstring_getpsz_d(s));

        b = psd_getbytezz(zz);
        de_dbg(c, "set-is-expanded: %d", (int)b);

        num_actions = psd_getu32zz(zz);
        de_dbg(c, "number of actions: %d", (int)num_actions);

        for(action_idx=0; action_idx<num_actions; action_idx++) {
                if(zz_avail(zz)<1) goto done;
                zz_init(&czz, zz);
                de_dbg(c, "action[%d] at %d", (int)action_idx, (int)zz->pos);
                de_dbg_indent(c, 1);
                if(!do_one_action(c, d, &czz)) goto done;
                zz->pos += zz_used(&czz);
                de_dbg_indent(c, -1);
        }

done:
        de_dbg_indent_restore(c, saved_indent_level);
        ucstring_destroy(s);
}

// Call this after setting d->version.
static void init_version_specific_info(deark *c, lctx *d)
{
        if(d->version==2) { // PSB format
                d->intsize_2or4 = 4;
                d->intsize_4or8 = 8;
        }
        else { // Regular PSD format
                d->intsize_2or4 = 2;
                d->intsize_4or8 = 4;
        }

        // The PSD spec does not say what encoding these strings use.
        // Some sources say they use MacRoman, and *some* PSD files do use MacRoman.
        // But other PSD files use other encodings, and I don't know how to know what
        // encoding they use.
        d->input_encoding = de_get_input_encoding(c, NULL, DE_ENCODING_MACROMAN);

        d->jpeg_rbswap_mode = 1;
}

static int do_psd_header(deark *c, lctx *d, i64 pos)
{
        int retval = 0;

        de_dbg(c, "header at %d", (int)pos);
        de_dbg_indent(c, 1);
        d->version = (int)psd_getu16(pos+4);
        de_dbg(c, "PSD version: %d", d->version);
        init_version_specific_info(c, d);

        if(d->version==1) {
                de_declare_fmt(c, "PSD");
        }
        else if(d->version==2) {
                de_declare_fmt(c, "PSB");
        }
        else {
                de_err(c, "Unsupported PSD version: %d", (int)d->version);
                goto done;
        }

        d->main_iinfo->num_channels = psd_getu16(pos+12);
        de_dbg(c, "number of channels: %d", (int)d->main_iinfo->num_channels);

        d->main_iinfo->height = psd_getu32(pos+14);
        d->main_iinfo->width = psd_getu32(pos+18);
        de_dbg_dimensions(c, d->main_iinfo->width, d->main_iinfo->height);

        d->main_iinfo->bits_per_channel = psd_getu16(pos+22);
        de_dbg(c, "bits/channel: %d", (int)d->main_iinfo->bits_per_channel);

        d->main_iinfo->color_mode = psd_getu16(pos+24);
        de_dbg(c, "color mode: %d (%s)", (int)d->main_iinfo->color_mode,
                get_colormode_name(d->main_iinfo->color_mode));

        retval = 1;

done:
        de_dbg_indent(c, -1);
        return retval;
}

static void do_external_tagged_blocks(deark *c, lctx *d, zztype *zz)
{
        u32 code;

        d->tagged_blocks_only = 1;
        if(zz_avail(zz)<4) return;

        // Evidently, it is possible for this to use little-endian byte order. Weird.

        // Peek at the first 4 bytes
        code = (u32)de_getu32le(0);
        if(code==CODE_8BIM || code==CODE_8B64) {
                d->is_le = 1;
        }

        do_tagged_blocks(c, d, zz, 0);
}

static void do_psd_color_mode_data(deark *c, lctx *d, zztype *zz)
{
        i64 len;
        i64 k;
        u8 r, g, b;
        struct image_info *iinfo = d->main_iinfo;

        len = zz_avail(zz);
        de_dbg(c, "color data at %d, len=%d", (int)zz->pos, (int)len);
        iinfo->pal_entries = len/3;
        if(iinfo->pal_entries<1) return;
        if(iinfo->pal_entries>256) iinfo->pal_entries=256;

        de_dbg_indent(c, 1);
        for(k=0; k<iinfo->pal_entries; k++) {
                r = de_getbyte(zz->pos + k);
                g = de_getbyte(zz->pos + iinfo->pal_entries + k);
                b = de_getbyte(zz->pos + 2*iinfo->pal_entries + k);
                iinfo->pal[k] = DE_MAKE_RGB(r, g, b);
                de_dbg_pal_entry(c, k, iinfo->pal[k]);
        }
        de_dbg_indent(c, -1);
}

static u8 scale_float_to_255(double x)
{
        if(x<=0.0) return 0;
        if(x>=1.0) return 255;
        return (u8)(0.5+x*255.0);
}

// Extract the primary image
static void do_bitmap(deark *c, lctx *d, const struct image_info *iinfo, dbuf *f,
        i64 pos, i64 len)
{
        de_bitmap *img = NULL;
        de_finfo *fi = NULL;
        i64 i, j, plane;
        i64 nplanes = 0; // Number of planes to read. May be less than d->num_channels.
        i64 planespan, rowspan, samplespan;
        u8 b;

        if(!de_good_image_dimensions(c, iinfo->width, iinfo->height)) goto done;

        if(iinfo->color_mode==PSD_CM_BITMAP && iinfo->bits_per_channel==1 &&
                iinfo->num_channels==1)
        {
                de_convert_and_write_image_bilevel2(f, 0, iinfo->width, iinfo->height,
                        (iinfo->width+7)/8, DE_CVTF_WHITEISZERO, NULL, 0);
                goto done;
        }

        if(iinfo->bits_per_channel!=8 && iinfo->bits_per_channel!=16 &&
                iinfo->bits_per_channel!=32)
        {
                de_err(c, "Unsupported bits/channel: %d", (int)iinfo->bits_per_channel);
                goto done;
        }

        if(iinfo->color_mode==PSD_CM_GRAY && iinfo->num_channels>=1) {
                nplanes = 1;
        }
        else if(iinfo->color_mode==PSD_CM_PALETTE && iinfo->num_channels>=1 && iinfo->bits_per_channel==8) {
                nplanes = 1;
        }
        else if(iinfo->color_mode==PSD_CM_RGB && iinfo->num_channels>=3) {
                nplanes = 3;
        }
        else {
                de_err(c, "This type of image is not supported (color=%d, "
                        "num channels=%d, bits/channel=%d)",
                        (int)iinfo->color_mode, (int)iinfo->num_channels, (int)iinfo->bits_per_channel);
                goto done;
        }

        img = de_bitmap_create(c, iinfo->width, iinfo->height,
                iinfo->color_mode==PSD_CM_GRAY ? 1 : 3);

        fi = de_finfo_create(c);

        if(iinfo->density.code!=DE_DENSITY_UNKNOWN) {
                fi->density = iinfo->density;
        }

        samplespan = iinfo->bits_per_channel/8;
        rowspan = iinfo->width * samplespan;
        planespan = iinfo->height * rowspan;

        for(plane=0; plane<nplanes; plane++) {
                for(j=0; j<iinfo->height; j++) {
                        for(i=0; i<iinfo->width; i++) {
                                if(iinfo->bits_per_channel==32) {
                                        // TODO: The format of 32-bit samples does not seem to be documented.
                                        // This is little more than a guess.
                                        double tmpd;
                                        tmpd = dbuf_getfloat32x(f, pos + plane*planespan + j*rowspan + i*samplespan, d->is_le);
                                        b = scale_float_to_255(tmpd);
                                }
                                else {
                                        b = dbuf_getbyte(f, pos + plane*planespan + j*rowspan + i*samplespan);
                                }
                                if(iinfo->color_mode==PSD_CM_RGB) {
                                        de_bitmap_setsample(img, i, j, plane, b);
                                }
                                else if(iinfo->color_mode==PSD_CM_GRAY) {
                                        de_bitmap_setpixel_gray(img, i, j, b);
                                }
                                else if(iinfo->color_mode==PSD_CM_PALETTE) {
                                        de_bitmap_setpixel_rgb(img, i, j, iinfo->pal[(unsigned int)b]);
                                }
                        }
                }
        }

        de_bitmap_write_to_file_finfo(img, fi, 0);
done:
        de_bitmap_destroy(img);
        de_finfo_destroy(c, fi);
}

static void do_bitmap_packbits(deark *c, lctx *d, zztype *zz, const struct image_info *iinfo)
{
        dbuf *unc_pixels = NULL;
        i64 cmpr_data_size = 0;
        i64 k;

        // Data begins with a table of row byte counts.
        de_dbg(c, "row sizes table at %"I64_FMT", len=%d", zz->pos,
                (int)(iinfo->num_channels * iinfo->height * d->intsize_2or4));

        for(k=0; k < iinfo->num_channels * iinfo->height; k++) {
                if(d->intsize_2or4==4) {
                        cmpr_data_size += psd_getu32zz(zz);
                }
                else {
                        cmpr_data_size += psd_getu16zz(zz);
                }
        }

        de_dbg(c, "compressed data at %"I64_FMT", len=%"I64_FMT"", zz->pos, cmpr_data_size);
        if(zz->pos + cmpr_data_size>c->infile->len) {
                de_err(c, "Unexpected end of file");
                goto done;
        }

        unc_pixels = dbuf_create_membuf(c, 1024, 0);
        fmtutil_decompress_packbits(c->infile, zz->pos, cmpr_data_size, unc_pixels, NULL);
        zz->pos += cmpr_data_size;
        de_dbg_indent(c, 1);
        de_dbg(c, "decompressed %"I64_FMT" bytes to %"I64_FMT"", cmpr_data_size, unc_pixels->len);
        de_dbg_indent(c, -1);
        do_bitmap(c, d, iinfo, unc_pixels, 0, unc_pixels->len);

done:
        dbuf_close(unc_pixels);
}

static void do_image_data(deark *c, lctx *d, zztype *zz)
{
        i64 cmpr;
        i64 len;
        i64 image_data_size;
        zztype czz;

        len = zz_avail(zz);
        if(len<2) return;
        de_dbg(c, "image data section at %d, expected len=%d", (int)zz->pos, (int)len);
        de_dbg_indent(c, 1);
        cmpr = psd_getu16zz(zz);
        dbg_print_compression_method(c, d, cmpr);

        image_data_size = zz_avail(zz);

        if(c->extract_policy == DE_EXTRACTPOLICY_AUXONLY) goto done;

        // Copy the global density info (from Resources section, presumably) to the image info
        d->main_iinfo->density = d->density;

        if(cmpr==0) { // Uncompressed
                do_bitmap(c, d, d->main_iinfo, c->infile, zz->pos, image_data_size);
        }
        else if(cmpr==1) { // PackBits
                zz_init(&czz, zz);
                do_bitmap_packbits(c, d, &czz, d->main_iinfo);
                zz->pos += zz_used(&czz);
        }
        else {
                de_err(c, "Compression method not supported: %d", (int)cmpr);
        }

done:
        de_dbg_indent(c, -1);
}

static void de_run_psd(deark *c, de_module_params *mparams)
{
        lctx *d = NULL;
        i64 x;
        zztype *zz = NULL;
        zztype czz;
        int whattodo = 0;

        d = de_malloc(c, sizeof(lctx));
        zz = de_malloc(c, sizeof(zztype));
        zz_init_absolute(zz, 0, c->infile->len);

        if(de_havemodcode(c, mparams, 'R')) {
                whattodo = 'R';
        }
        else if(de_havemodcode(c, mparams, 'T')) {
                whattodo = 'T';
        }
        else if(de_havemodcode(c, mparams, 'B')) {
                whattodo = 'B';
        }
        else if(!dbuf_memcmp(c->infile, 0, "8BIM", 4)) {
                // Assume this is a raw resources file (maybe extracted from an
                // .8bimtiff file)
                whattodo = 'R';
        }

        if(whattodo=='R') { // Image resources
                de_declare_fmt(c, "Photoshop resources");
                d->version = 1;
                init_version_specific_info(c, d);
                do_image_resource_blocks(c, d, zz);
                if(mparams) {
                        // .out_params.flags: 0x02: has_iptc
                        mparams->out_params.flags = 0;
                        if(d->has_iptc) mparams->out_params.flags |= 0x02;
                }
                goto done;
        }
        else if(whattodo=='T') { // Tagged blocks
                d->version = 1;
                init_version_specific_info(c, d);
                do_external_tagged_blocks(c, d, zz);
                goto done;
        }
        else if(whattodo=='B') { // Tagged blocks, PSB-format
                d->version = 2;
                init_version_specific_info(c, d);
                do_external_tagged_blocks(c, d, zz);
                goto done;
        }

        d->main_iinfo = de_malloc(c, sizeof(struct image_info));

        if(!do_psd_header(c, d, zz->pos)) goto done;
        zz->pos += 26;

        de_dbg(c, "color mode data section at %d", (int)zz->pos);
        de_dbg_indent(c, 1);
        x = psd_getu32zz(zz);
        zz_init_with_len(&czz, zz, x);
        do_psd_color_mode_data(c, d, &czz);
        zz->pos += x;
        de_dbg_indent(c, -1);

        de_dbg(c, "image resources section at %d", (int)zz->pos);
        de_dbg_indent(c, 1);
        x = psd_getu32zz(zz); // Length of Image Resources
        // The PSD spec is ambiguous, but in practice the "length" field's value
        // does not include the size of the "length" field itself.
        de_dbg(c, "image resources data at %d, len=%d", (int)zz->pos, (int)x);

        if(x>0) {
                if(de_get_ext_option_bool(c, "extract8bim", 0)) {
                        fmtutil_handle_photoshop_rsrc(c, c->infile, zz->pos, x, 0x1);
                }
                else {
                        de_dbg_indent(c, 1);
                        zz_init_with_len(&czz, zz, x);
                        do_image_resource_blocks(c, d, &czz);
                        de_dbg_indent(c, -1);
                }
        }
        zz->pos += x;
        de_dbg_indent(c, -1);

        zz_init(&czz, zz);
        if(!do_layer_and_mask_info_section(c, d, &czz)) goto done;
        zz->pos += zz_used(&czz);

        zz_init(&czz, zz);
        do_image_data(c, d, &czz);

done:
        de_free(c, zz);
        if(d) {
                de_free(c, d->main_iinfo);
                de_free(c, d);
        }
}

static void de_run_ps_action(deark *c, de_module_params *mparams)
{
        lctx *d = NULL;
        zztype *zz = NULL;

        de_declare_fmt(c, "Photoshop Action");

        d = de_malloc(c, sizeof(lctx));
        d->version = 1;
        init_version_specific_info(c, d);

        zz = de_malloc(c, sizeof(zztype));
        zz_init_absolute(zz, 0, c->infile->len);

        do_action_set(c, d, zz);

        de_free(c, zz);
        de_free(c, d);
}

static void de_run_ps_gradient(deark *c, de_module_params *mparams)
{
        lctx *d = NULL;
        zztype *zz = NULL;
        i64 grd_ver;

        de_declare_fmt(c, "Photoshop Gradient");

        d = de_malloc(c, sizeof(lctx));
        d->version = 1;
        init_version_specific_info(c, d);

        zz = de_malloc(c, sizeof(zztype));
        zz_init_absolute(zz, 0, c->infile->len);

        zz->pos += 4; // 8BGR signature
        grd_ver = psd_getu16zz(zz);
        de_dbg(c, "file version: %d", (int)grd_ver);

        if(grd_ver==5) {
                read_descriptor(c, d, zz, 1, "");
        }
        else {
                de_err(c, "Unsupported Photoshop Gradient file version: %d", (int)grd_ver);
        }

        de_free(c, zz);
        de_free(c, d);
}

// .asl format, "Patterns" object
static void do_asl_patterns(deark *c, lctx *d, zztype *zz)
{
        i64 pat_ver;
        i64 patseq_len;
        zztype czz_patseq;

        de_dbg(c, "patterns at %d", (int)zz->pos);
        de_dbg_indent(c, 1);
        pat_ver = psd_getu16zz(zz);
        de_dbg(c, "patterns version: %d", (int)pat_ver);
        patseq_len = psd_getu32zz(zz);
        de_dbg(c, "patterns total length: %d", (int)patseq_len);

        // Sequence of patterns
        zz_init_with_len(&czz_patseq, zz, patseq_len);

        do_pattern_sequence(c, d, &czz_patseq);

        zz->pos += patseq_len;

        de_dbg_indent(c, -1);
}

// .asl format, "Styles" object
static void do_asl_patterns_and_styles(deark *c, lctx *d, zztype *zz)
{
        zztype czz;
        i64 num_styles;
        i64 style_idx;
        i64 style_len;

        zz->pos += 4; // 8BSL signature

        zz_init(&czz, zz);
        do_asl_patterns(c, d, &czz);
        zz->pos += zz_used(&czz);

        de_dbg(c, "styles at %d", (int)zz->pos);
        de_dbg_indent(c, 1);

        num_styles = psd_getu32zz(zz);
        de_dbg(c, "number of styles: %d", (int)num_styles);

        for(style_idx=0; style_idx<=num_styles; style_idx++) {
                if(zz_avail(zz)<4) break;

                de_dbg(c, "style[%d] at %d", (int)style_idx, (int)zz->pos);
                de_dbg_indent(c, 1);

                style_len = psd_getu32zz(zz);
                de_dbg(c, "style length: %d", (int)style_len);

                zz_init_with_len(&czz, zz, style_len);
                read_descriptor(c, d, &czz, 1, " (for style identification)");
                read_descriptor(c, d, &czz, 1, " (for style information)");

                zz->pos += style_len;
                de_dbg_indent(c, -1);
        }

        de_dbg_indent(c, -1);
}

static void de_run_ps_styles(deark *c, de_module_params *mparams)
{
        lctx *d = NULL;
        zztype *zz = NULL;
        i64 asl_ver;

        de_declare_fmt(c, "Photoshop Styles");

        d = de_malloc(c, sizeof(lctx));
        d->version = 1;
        init_version_specific_info(c, d);

        zz = de_malloc(c, sizeof(zztype));
        zz_init_absolute(zz, 0, c->infile->len);

        asl_ver = psd_getu16zz(zz);
        de_dbg(c, "file version: %d", (int)asl_ver);
        if(asl_ver!=2) {
                de_err(c, "Unsupported Photoshop Styles file version: %d", (int)asl_ver);
                goto done;
        }

        do_asl_patterns_and_styles(c, d, zz);

done:
        de_free(c, zz);
        de_free(c, d);
}

static void do_abr_v1(deark *c, lctx *d, zztype *zz)
{
        i64 num_brushes;
        i64 i;

        zz->pos += 2;
        num_brushes = psd_getu16zz(zz);
        de_dbg(c, "number of brushes: %d", (int)num_brushes);

        for(i=0; i<num_brushes; i++) {
                i64 brushtype;
                i64 bdeflen;

                if(zz->pos >= zz->endpos) break;

                de_dbg(c, "brush definition[%d] at %d", (int)i, (int)zz->pos);
                de_dbg_indent(c, 1);

                brushtype = psd_getu16zz(zz);
                de_dbg(c, "brush type: %d", (int)brushtype);
                bdeflen = psd_getu32zz(zz);
                de_dbg(c, "brush definition data dpos=%d, dlen=%d", (int)zz->pos, (int)bdeflen);

                zz->pos += bdeflen;

                de_dbg_indent(c, -1);
        }

}

static void do_abr_v6(deark *c, lctx *d, zztype *zz)
{
        u32 sig;
        zztype czz;

        zz->pos += 4; // Version numbers(?), already read
        sig = (u32)psd_getu32(zz->pos);
        if(sig!=CODE_8BIM) {
                de_err(c, "Bad signature or unsupported Brush format");
                goto done;
        }

        zz_init(&czz, zz);
        do_tagged_blocks(c, d, &czz, 2);

done:
        ;
}

static void de_run_ps_brush(deark *c, de_module_params *mparams)
{
        lctx *d = NULL;
        zztype *zz = NULL;
        int has_8bim_sig;

        d = de_malloc(c, sizeof(lctx));
        d->version = 1;
        init_version_specific_info(c, d);

        zz = de_malloc(c, sizeof(zztype));
        zz_init_absolute(zz, 0, c->infile->len);

        d->abr_major_ver = (int)psd_getu16(0);
        de_dbg(c, "file version: %d", (int)d->abr_major_ver);

        has_8bim_sig = (psd_getu32(4) == CODE_8BIM);

        if(has_8bim_sig && d->abr_major_ver>=3) {
                d->abr_minor_ver = (int)psd_getu16(2);
                de_declare_fmt(c, "Photoshop Brush (new format)");
                do_abr_v6(c, d, zz);
        }
        else if(d->abr_major_ver<=5) {
                de_declare_fmt(c, "Photoshop Brush (old format)");
                do_abr_v1(c, d, zz);
        }
        else {
                de_err(c, "Unsupported Photoshop Brush format (version=%d)", (int)d->abr_major_ver);
                goto done;
        }

done:
        de_free(c, zz);
        de_free(c, d);
}

static void do_custom_shape(deark *c, lctx *d, zztype *zz)
{
        de_ucstring *s = NULL;
        i64 dlen;
        i64 saved_pos;
        zztype datazz;
        zztype pathinfozz;

        s = ucstring_create(c);
        saved_pos = zz->pos;
        read_unicode_string(c, d, s, zz);
        de_dbg(c, "name: \"%s\"", ucstring_getpsz_d(s));
        // This Unicode String is padded to a multiple of 4 bytes, unlike pretty much
        // every other Unicode String in every Photoshop format.
        zz->pos = saved_pos + de_pad_to_4(zz->pos - saved_pos);

        zz->pos += 4; // Unknown field

        dlen = psd_getu32zz(zz);
        de_dbg(c, "shape data length: %d", (int)dlen);

        zz_init_with_len(&datazz, zz, dlen);
        // We expect this length to be a multiple of 4. I don't know what to do if
        // it's not.
        zz->pos += dlen;

        ucstring_empty(s);
        read_pascal_string_to_ucstring(c, d, s, &datazz);
        de_dbg(c, "id: \"%s\"", ucstring_getpsz(s));

        read_rectangle_tlbr(c, d, &datazz, "bounds");

        de_dbg(c, "path records at %d", (int)datazz.pos);
        zz_init(&pathinfozz, &datazz);
        de_dbg_indent(c, 1);
        do_pathinfo(c, d, &pathinfozz);
        de_dbg_indent(c, -1);

        ucstring_destroy(s);
}

static void de_run_ps_csh(deark *c, de_module_params *mparams)
{
        lctx *d = NULL;
        zztype *zz = NULL;
        i64 csh_ver;
        i64 num_shapes;
        i64 i;
        zztype czz;

        d = de_malloc(c, sizeof(lctx));
        d->version = 1;
        init_version_specific_info(c, d);

        zz = de_malloc(c, sizeof(zztype));
        zz_init_absolute(zz, 0, c->infile->len);

        zz->pos += 4; // Skip over 'cush' signature

        csh_ver = psd_getu32zz(zz);
        de_dbg(c, "file version: %d", (int)csh_ver);

        if(csh_ver!=2) {
                de_warn(c, "CSH v%d format might not be supported correctly", (int)csh_ver);
        }

        num_shapes = psd_getu32zz(zz);
        de_dbg(c, "number of shapes: %d", (int)num_shapes);

        for(i=0; i<num_shapes; i++) {
                if(zz_avail(zz)<28) break;
                de_dbg(c, "shape[%d] at %d", (int)i, (int)zz->pos);
                zz_init(&czz, zz);
                de_dbg_indent(c, 1);
                do_custom_shape(c, d, &czz);
                de_dbg_indent(c, -1);
                zz->pos += zz_used(&czz);
        }

        de_free(c, zz);
        de_free(c, d);
}

static void de_run_ps_pattern(deark *c, de_module_params *mparams)
{
        lctx *d = NULL;
        zztype *zz = NULL;
        i64 pat_ver;
        i64 num_patterns;
        i64 i;
        zztype czz;

        d = de_malloc(c, sizeof(lctx));
        d->version = 1;
        init_version_specific_info(c, d);

        zz = de_malloc(c, sizeof(zztype));
        zz_init_absolute(zz, 0, c->infile->len);

        zz->pos += 4; // Skip over '8BPT' signature

        pat_ver = psd_getu16zz(zz);
        de_dbg(c, "file version: %d", (int)pat_ver);

        if(pat_ver!=1) {
                de_warn(c, "PAT v%d format might not be supported correctly", (int)pat_ver);
        }

        num_patterns = psd_getu32zz(zz);
        de_dbg(c, "number of patterns: %d", (int)num_patterns);

        for(i=0; i<num_patterns; i++) {
                if(zz_avail(zz)<4) break;
                de_dbg(c, "pattern[%d] at %d", (int)i, (int)zz->pos);
                zz_init(&czz, zz);
                de_dbg_indent(c, 1);
                if(!do_pattern_internal(c, d, &czz)) break;
                de_dbg_indent(c, -1);
                zz->pos += zz_used(&czz);
        }

        de_free(c, zz);
        de_free(c, d);
}

static int de_identify_psd(deark *c)
{
        u8 buf[4];

        de_read(buf, 0, 4);
        if(!de_memcmp(buf, "8BPS", 4)) return 100;
        if(!de_memcmp(buf, "8BIM", 4)) {
                // We sometimes write .8bim files, so we want to identify them.
                // This is not necessarily a standard file format.
                if(de_input_file_has_ext(c, "8bim")) return 100;
                return 75;
        }
        return 0;
}

void de_module_psd(deark *c, struct deark_module_info *mi)
{
        mi->id = "psd";
        mi->desc = "Photoshop PSD";
        mi->run_fn = de_run_psd;
        mi->identify_fn = de_identify_psd;
}

static int de_identify_ps_action(deark *c)
{
        int ver=0;

        if(!dbuf_memcmp(c->infile, 0, "\x00\x00\x00\x10\x00\x00", 6)) {
                ver = 16;
        }
        else if(!dbuf_memcmp(c->infile, 0, "\x00\x00\x00\x0c", 4)) {
                ver = 12;
        }
        if(ver==0) return 0;
        if(!de_input_file_has_ext(c, "atn")) return 0;
        if(ver==16) return 100;
        return 5; // A version we don't support
}

void de_module_ps_action(deark *c, struct deark_module_info *mi)
{
        mi->id = "ps_action";
        mi->desc = "Photoshop Action";
        mi->run_fn = de_run_ps_action;
        mi->identify_fn = de_identify_ps_action;
}

static int de_identify_ps_gradient(deark *c)
{
        if(!dbuf_memcmp(c->infile, 0, "8BGR", 4)) {
                if(de_input_file_has_ext(c, "grd")) return 100;
                return 90;
        }
        return 0;
}

void de_module_ps_gradient(deark *c, struct deark_module_info *mi)
{
        mi->id = "ps_gradient";
        mi->desc = "Photoshop Gradient";
        mi->run_fn = de_run_ps_gradient;
        mi->identify_fn = de_identify_ps_gradient;
}

static int de_identify_ps_styles(deark *c)
{
        if(!dbuf_memcmp(c->infile, 2, "8BSL", 4)) {
                if(de_input_file_has_ext(c, "asl")) return 100;
                return 90;
        }
        return 0;
}

void de_module_ps_styles(deark *c, struct deark_module_info *mi)
{
        mi->id = "ps_styles";
        mi->desc = "Photoshop Styles";
        mi->run_fn = de_run_ps_styles;
        mi->identify_fn = de_identify_ps_styles;
}

static int de_identify_ps_brush(deark *c)
{
        i64 ver;

        ver = de_getu16be(0);
        if(ver==1 || ver==2 || ver==6 || ver==7) {
                if(de_input_file_has_ext(c, "abr")) return 80;
        }
        return 0;
}

void de_module_ps_brush(deark *c, struct deark_module_info *mi)
{
        mi->id = "ps_brush";
        mi->desc = "Photoshop Brush";
        mi->run_fn = de_run_ps_brush;
        mi->identify_fn = de_identify_ps_brush;
}

static int de_identify_ps_csh(deark *c)
{
        if(!dbuf_memcmp(c->infile, 0, "cush", 4)) {
                if(de_input_file_has_ext(c, "csh")) return 100;
                return 80;
        }
        return 0;
}

void de_module_ps_csh(deark *c, struct deark_module_info *mi)
{
        mi->id = "ps_csh";
        mi->desc = "Photoshop Custom Shape";
        mi->run_fn = de_run_ps_csh;
        mi->identify_fn = de_identify_ps_csh;
}

static int de_identify_ps_pattern(deark *c)
{
        if(!dbuf_memcmp(c->infile, 0, "8BPT", 4)) {
                if(de_input_file_has_ext(c, "pat")) return 100;
                return 90;
        }
        return 0;
}

void de_module_ps_pattern(deark *c, struct deark_module_info *mi)
{
        mi->id = "ps_pattern";
        mi->desc = "Photoshop Pattern";
        mi->run_fn = de_run_ps_pattern;
        mi->identify_fn = de_identify_ps_pattern;
}