usr/src/common/fs/decompress.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 /*
  28  * Decompression module for stand alone file systems.
  29  */
  30
  31 #include <sys/param.h>
  32 #include <sys/sysmacros.h>
  33 #include <sys/vnode.h>
  34 #include <sys/bootvfs.h>
  35 #include <sys/filep.h>
  36 #include <zmod/zlib.h>
  37
  38 #ifdef  _BOOT
  39 #include "../common/util.h"
  40 #else
  41 #include <sys/sunddi.h>
  42 #endif
  43
  44 #define MAX_DECOMP_BUFS         8
  45 #define GZIP_ID_BYTE_1          0x1f
  46 #define GZIP_ID_BYTE_2          0x8b
  47 #define GZIP_CM_DEFLATE         0x08
  48 #define SEEKBUFSIZE             8192
  49
  50 extern void prom_printf(const char *fmt, ...);
  51
  52 #ifdef  _BOOT
  53 #define dprintf if (cf_debug) prom_printf
  54 #else
  55 #define dprintf if (cf_debug) prom_printf
  56
  57 #endif
  58
  59 extern int bootrd_debug;
  60 extern void *bkmem_alloc(size_t);
  61 extern void bkmem_free(void *, size_t);
  62
  63 caddr_t scratch_bufs[MAX_DECOMP_BUFS];  /* array of free scratch mem bufs */
  64 int decomp_bufcnt;                      /* total no, of allocated decomp bufs */
  65 int free_dcomp_bufs;                    /* no. of free decomp bufs */
  66 char seek_scrbuf[SEEKBUFSIZE];          /* buffer for seeking */
  67 int cf_debug = 0;                       /* non-zero enables debug prints */
  68
  69 void *
  70 cf_alloc(void *opaque, unsigned int items, unsigned int size)
  71 {
  72         fileid_t *filep;
  73         unsigned int nbytes;
  74         caddr_t ptr;
  75
  76         filep = (fileid_t *)opaque;
  77         nbytes = roundup(items * size, sizeof (long));
  78         if (nbytes > (DECOMP_BUFSIZE - filep->fi_dcscrused)) {
  79                 ptr = bkmem_alloc(nbytes);
  80         } else {
  81                 ptr = &filep->fi_dcscrbuf[filep->fi_dcscrused];
  82                 filep->fi_dcscrused += nbytes;
  83         }
  84         bzero(ptr, nbytes);
  85         return (ptr);
  86 }
  87
  88 /*
  89  * Decompression scratch memory free routine, does nothing since we free
  90  * the entire scratch area all at once on file close.
  91  */
  92 /* ARGSUSED */
  93 void
  94 cf_free(void *opaque, void *addr)
  95 {
  96 }
  97
  98 /*
  99  * Read the first block of the file described by filep and determine if
 100  * the file is gzip-compressed.  If so, the compressed flag will be set
 101  * in the fileid_t struct pointed to by filep and it will be initialized
 102  * for doing decompression on reads to the file.
 103  */
 104 int
 105 cf_check_compressed(fileid_t *filep)
 106 {
 107         unsigned char *filebytes;
 108         z_stream *zsp;
 109
 110         /*
 111          * checking for a dcfs compressed file first would involve:
 112          *
 113          *      if (filep->fi_inode->i_cflags & ICOMPRESS)
 114          *              filep->fi_flags |= FI_COMPRESSED;
 115          */
 116
 117         /*
 118          * If the file is not long enough to check for a
 119          * decompression header then return not compressed.
 120          */
 121         if (filep->fi_inode->i_size < 3)
 122                 return (0);
 123         filep->fi_offset = 0;
 124         if ((filep->fi_getblock)(filep) == -1)
 125                 return (-1);
 126         filep->fi_offset = 0;
 127         filep->fi_count = 0;
 128         filep->fi_cfoff = 0;
 129         filebytes = (unsigned char *)filep->fi_memp;
 130         if (filebytes[0] != GZIP_ID_BYTE_1 ||
 131             filebytes[1] != GZIP_ID_BYTE_2 ||
 132             filebytes[2] != GZIP_CM_DEFLATE)
 133                 return (0); /* not compressed */
 134         filep->fi_flags |= FI_COMPRESSED;
 135
 136         dprintf("file %s is compressed\n", filep->fi_path);
 137
 138         /*
 139          * Allocate decompress scratch buffer
 140          */
 141         if (free_dcomp_bufs) {
 142                 filep->fi_dcscrbuf = scratch_bufs[--free_dcomp_bufs];
 143         } else {
 144                 filep->fi_dcscrbuf = bkmem_alloc(DECOMP_BUFSIZE);
 145                 decomp_bufcnt++;
 146         }
 147         filep->fi_dcscrused = 0;
 148         zsp = bkmem_alloc(sizeof (*zsp));
 149         filep->fi_dcstream = zsp;
 150         /*
 151          * Initialize the decompression stream. Adding 16 to the window size
 152          * indicates that zlib should expect a gzip header.
 153          */
 154         bzero(zsp, sizeof (*zsp));
 155         zsp->opaque = filep;
 156         zsp->zalloc = cf_alloc;
 157         zsp->zfree = cf_free;
 158         zsp->avail_in = 0;
 159         zsp->next_in = NULL;
 160         zsp->avail_out = 0;
 161         zsp->next_out = NULL;
 162         if (inflateInit2(zsp, MAX_WBITS | 0x20) != Z_OK) {
 163                 dprintf("inflateInit2() failed\n");
 164                 return (-1);
 165         }
 166         return (0);
 167 }
 168
 169 /*
 170  * If the file described by fileid_t struct at *filep is compressed
 171  * free any resources associated with the decompression.  (decompression
 172  * buffer, etc.).
 173  */
 174 void
 175 cf_close(fileid_t *filep)
 176 {
 177         if ((filep->fi_flags & FI_COMPRESSED) == 0)
 178                 return;
 179         dprintf("cf_close: %s\n", filep->fi_path);
 180         (void) inflateEnd(filep->fi_dcstream);
 181         bkmem_free(filep->fi_dcstream, sizeof (z_stream));
 182         if (free_dcomp_bufs == MAX_DECOMP_BUFS) {
 183                 bkmem_free(filep->fi_dcscrbuf, DECOMP_BUFSIZE);
 184         } else {
 185                 scratch_bufs[free_dcomp_bufs++] = filep->fi_dcscrbuf;
 186         }
 187 }
 188
 189 void
 190 cf_rewind(fileid_t *filep)
 191 {
 192         z_stream *zsp;
 193
 194         dprintf("cf_rewind: %s\n", filep->fi_path);
 195         zsp = filep->fi_dcstream;
 196         zsp->avail_in = 0;
 197         zsp->next_in = NULL;
 198         (void) inflateReset(zsp);
 199         filep->fi_cfoff = 0;
 200 }
 201
 202 #define FLG_FHCRC       0x02    /* crc field present */
 203 #define FLG_FEXTRA      0x04    /* "extra" field present */
 204 #define FLG_FNAME       0x08    /* file name field present */
 205 #define FLG_FCOMMENT    0x10    /* comment field present */
 206
 207 /*
 208  * Read at the current uncompressed offset from the compressed file described
 209  * by *filep.  Will return decompressed data.
 210  */
 211 int
 212 cf_read(fileid_t *filep, caddr_t buf, size_t count)
 213 {
 214         z_stream *zsp;
 215         struct inode *ip;
 216         int err = Z_OK;
 217         int infbytes;
 218         off_t soff;
 219         caddr_t smemp;
 220
 221         dprintf("cf_read: %s ", filep->fi_path);
 222         dprintf("%lx bytes\n", count);
 223         zsp = filep->fi_dcstream;
 224         ip = filep->fi_inode;
 225         dprintf("   reading at offset %lx\n", zsp->total_out);
 226         zsp->next_out = (unsigned char *)buf;
 227         zsp->avail_out = count;
 228         while (zsp->avail_out != 0) {
 229                 if (zsp->avail_in == 0 && filep->fi_cfoff < ip->i_size) {
 230                         /*
 231                          * read a block of the file to inflate
 232                          */
 233                         soff = filep->fi_offset;
 234                         smemp = filep->fi_memp;
 235                         filep->fi_memp = NULL;
 236                         filep->fi_offset = filep->fi_cfoff;
 237                         filep->fi_count = 0;
 238                         if ((*filep->fi_getblock)(filep) == -1)
 239                                 return (-1);
 240                         filep->fi_offset = soff;
 241                         zsp->next_in = (unsigned char *)filep->fi_memp;
 242                         zsp->avail_in = filep->fi_count;
 243                         filep->fi_memp = smemp;
 244                         filep->fi_cfoff += filep->fi_count;
 245                 }
 246                 infbytes = zsp->avail_out;
 247                 dprintf("attempting inflate of %x bytes to buf at: %lx\n",
 248                     zsp->avail_out, (unsigned long)zsp->next_out);
 249                 err = inflate(zsp, Z_NO_FLUSH);
 250                 infbytes -= zsp->avail_out;
 251                 dprintf("inflated %x bytes, errcode=%d\n", infbytes, err);
 252                 /*
 253                  * break out if we hit end of the compressed file
 254                  * or the end of the compressed byte stream
 255                  */
 256                 if (filep->fi_cfoff >= ip->i_size || err == Z_STREAM_END)
 257                         break;
 258         }
 259         dprintf("cf_read: returned %lx bytes\n", count - zsp->avail_out);
 260         return (count - zsp->avail_out);
 261 }
 262
 263 /*
 264  * Seek to the location specified by addr
 265  */
 266 void
 267 cf_seek(fileid_t *filep, off_t addr, int whence)
 268 {
 269         z_stream *zsp;
 270         int readsz;
 271
 272         dprintf("cf_seek: %s ", filep->fi_path);
 273         dprintf("to %lx\n", addr);
 274         zsp = filep->fi_dcstream;
 275         if (whence == SEEK_CUR)
 276                 addr += zsp->total_out;
 277         /*
 278          * To seek backwards, must rewind and seek forwards
 279          */
 280         if (addr < zsp->total_out) {
 281                 cf_rewind(filep);
 282                 filep->fi_offset = 0;
 283         } else {
 284                 addr -= zsp->total_out;
 285         }
 286         while (addr > 0) {
 287                 readsz = MIN(addr, SEEKBUFSIZE);
 288                 (void) cf_read(filep, seek_scrbuf, readsz);
 289                 addr -= readsz;
 290         }
 291 }