New logging categories added to allow differentiation between

[rsync.git] / acls.c

/*
 * Handle passing Access Control Lists between systems.
 *
 * Copyright (C) 1996 Andrew Tridgell
 * Copyright (C) 1996 Paul Mackerras
 * Copyright (C) 2006 Wayne Davison
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, visit the http://fsf.org website.
 */

#include "rsync.h"
#include "lib/sysacls.h"

#ifdef SUPPORT_ACLS

extern int dry_run;
extern int am_root;
extern int read_only;
extern int list_only;
extern int orig_umask;
extern int numeric_ids;
extern int inc_recurse;

/* Flags used to indicate what items are being transmitted for an entry. */
#define XMIT_USER_OBJ (1<<0)
#define XMIT_GROUP_OBJ (1<<1)
#define XMIT_MASK_OBJ (1<<2)
#define XMIT_OTHER_OBJ (1<<3)
#define XMIT_NAME_LIST (1<<4)

#define NO_ENTRY ((uchar)0x80) /* Default value of a NON-name-list entry. */

#define NAME_IS_USER (1u<<31) /* Bit used only on a name-list entry. */

/* When we send the access bits over the wire, we shift them 2 bits to the
 * left and use the lower 2 bits as flags (relevant only to a name entry).
 * This makes the protocol more efficient than sending a value that would
 * be likely to have its hightest bits set. */
#define XFLAG_NAME_FOLLOWS 0x0001u
#define XFLAG_NAME_IS_USER 0x0002u

/* === ACL structures === */

typedef struct {
        id_t id;
        uint32 access;
} id_access;

typedef struct {
        id_access *idas;
        int count;
} ida_entries;

typedef struct {
        char *name;
        uchar len;
} idname;

typedef struct rsync_acl {
        ida_entries names;
        /* These will be NO_ENTRY if there's no such entry. */
        uchar user_obj;
        uchar group_obj;
        uchar mask_obj;
        uchar other_obj;
} rsync_acl;

typedef struct {
        rsync_acl racl;
        SMB_ACL_T sacl;
} acl_duo;

static const rsync_acl empty_rsync_acl = {
        {NULL, 0}, NO_ENTRY, NO_ENTRY, NO_ENTRY, NO_ENTRY
};

static item_list access_acl_list = EMPTY_ITEM_LIST;
static item_list default_acl_list = EMPTY_ITEM_LIST;

/* === Calculations on ACL types === */

static const char *str_acl_type(SMB_ACL_TYPE_T type)
{
        return type == SMB_ACL_TYPE_ACCESS ? "SMB_ACL_TYPE_ACCESS"
             : type == SMB_ACL_TYPE_DEFAULT ? "SMB_ACL_TYPE_DEFAULT"
             : "unknown SMB_ACL_TYPE_T";
}

static int calc_sacl_entries(const rsync_acl *racl)
{
        /* A System ACL always gets user/group/other permission entries. */
        return racl->names.count
#ifdef ACLS_NEED_MASK
             + 4;
#else
             + (racl->mask_obj != NO_ENTRY) + 3;
#endif
}

/* Extracts and returns the permission bits from the ACL.  This cannot be
 * called on an rsync_acl that has NO_ENTRY in any spot but the mask. */
static int rsync_acl_get_perms(const rsync_acl *racl)
{
        return (racl->user_obj << 6)
             + ((racl->mask_obj != NO_ENTRY ? racl->mask_obj : racl->group_obj) << 3)
             + racl->other_obj;
}

/* Removes the permission-bit entries from the ACL because these
 * can be reconstructed from the file's mode. */
static void rsync_acl_strip_perms(rsync_acl *racl)
{
        racl->user_obj = NO_ENTRY;
        if (racl->mask_obj == NO_ENTRY)
                racl->group_obj = NO_ENTRY;
        else {
                if (racl->group_obj == racl->mask_obj)
                        racl->group_obj = NO_ENTRY;
                racl->mask_obj = NO_ENTRY;
        }
        racl->other_obj = NO_ENTRY;
}

/* Given an empty rsync_acl, fake up the permission bits. */
static void rsync_acl_fake_perms(rsync_acl *racl, mode_t mode)
{
        racl->user_obj = (mode >> 6) & 7;
        racl->group_obj = (mode >> 3) & 7;
        racl->other_obj = mode & 7;
}

/* === Rsync ACL functions === */

static rsync_acl *create_racl(void)
{
        rsync_acl *racl = new(rsync_acl);

        if (!racl)
                out_of_memory("create_racl");
        *racl = empty_rsync_acl;

        return racl;
}

static BOOL ida_entries_equal(const ida_entries *ial1, const ida_entries *ial2)
{
        id_access *ida1, *ida2;
        int count = ial1->count;
        if (count != ial2->count)
                return False;
        ida1 = ial1->idas;
        ida2 = ial2->idas;
        for (; count--; ida1++, ida2++) {
                if (ida1->access != ida2->access || ida1->id != ida2->id)
                        return False;
        }
        return True;
}

static BOOL rsync_acl_equal(const rsync_acl *racl1, const rsync_acl *racl2)
{
        return racl1->user_obj == racl2->user_obj
            && racl1->group_obj == racl2->group_obj
            && racl1->mask_obj == racl2->mask_obj
            && racl1->other_obj == racl2->other_obj
            && ida_entries_equal(&racl1->names, &racl2->names);
}

/* Are the extended (non-permission-bit) entries equal?  If so, the rest of
 * the ACL will be handled by the normal mode-preservation code.  This is
 * only meaningful for access ACLs!  Note: the 1st arg is a fully-populated
 * rsync_acl, but the 2nd parameter can be a condensed rsync_acl, which means
 * that it might have several of its permission objects set to NO_ENTRY. */
static BOOL rsync_acl_equal_enough(const rsync_acl *racl1,
                                   const rsync_acl *racl2, mode_t m)
{
        if ((racl1->mask_obj ^ racl2->mask_obj) & NO_ENTRY)
                return False; /* One has a mask and the other doesn't */

        /* When there's a mask, the group_obj becomes an extended entry. */
        if (racl1->mask_obj != NO_ENTRY) {
                /* A condensed rsync_acl with a mask can only have no
                 * group_obj when it was identical to the mask.  This
                 * means that it was also identical to the group attrs
                 * from the mode. */
                if (racl2->group_obj == NO_ENTRY) {
                        if (racl1->group_obj != ((m >> 3) & 7))
                                return False;
                } else if (racl1->group_obj != racl2->group_obj)
                        return False;
        }
        return ida_entries_equal(&racl1->names, &racl2->names);
}

static void rsync_acl_free(rsync_acl *racl)
{
        if (racl->names.idas)
                free(racl->names.idas);
        *racl = empty_rsync_acl;
}

void free_acl(stat_x *sxp)
{
        if (sxp->acc_acl) {
                rsync_acl_free(sxp->acc_acl);
                free(sxp->acc_acl);
                sxp->acc_acl = NULL;
        }
        if (sxp->def_acl) {
                rsync_acl_free(sxp->def_acl);
                free(sxp->def_acl);
                sxp->def_acl = NULL;
        }
}

#ifdef SMB_ACL_NEED_SORT
static int id_access_sorter(const void *r1, const void *r2)
{
        id_access *ida1 = (id_access *)r1;
        id_access *ida2 = (id_access *)r2;
        id_t rid1 = ida1->id, rid2 = ida2->id;
        if ((ida1->access ^ ida2->access) & NAME_IS_USER)
                return ida1->access & NAME_IS_USER ? -1 : 1;
        return rid1 == rid2 ? 0 : rid1 < rid2 ? -1 : 1;
}
#endif

/* === System ACLs === */

/* Unpack system ACL -> rsync ACL verbatim.  Return whether we succeeded. */
static BOOL unpack_smb_acl(SMB_ACL_T sacl, rsync_acl *racl)
{
        static item_list temp_ida_list = EMPTY_ITEM_LIST;
        SMB_ACL_ENTRY_T entry;
        const char *errfun;
        int rc;

        errfun = "sys_acl_get_entry";
        for (rc = sys_acl_get_entry(sacl, SMB_ACL_FIRST_ENTRY, &entry);
             rc == 1;
             rc = sys_acl_get_entry(sacl, SMB_ACL_NEXT_ENTRY, &entry)) {
                SMB_ACL_TAG_T tag_type;
                uint32 access;
                id_t g_u_id;
                id_access *ida;
                if ((rc = sys_acl_get_info(entry, &tag_type, &access, &g_u_id)) != 0) {
                        errfun = "sys_acl_get_info";
                        break;
                }
                /* continue == done with entry; break == store in temporary ida list */
                switch (tag_type) {
#ifndef HAVE_OSX_ACLS
                case SMB_ACL_USER_OBJ:
                        if (racl->user_obj == NO_ENTRY)
                                racl->user_obj = access;
                        else
                                rprintf(FINFO, "unpack_smb_acl: warning: duplicate USER_OBJ entry ignored\n");
                        continue;
                case SMB_ACL_GROUP_OBJ:
                        if (racl->group_obj == NO_ENTRY)
                                racl->group_obj = access;
                        else
                                rprintf(FINFO, "unpack_smb_acl: warning: duplicate GROUP_OBJ entry ignored\n");
                        continue;
                case SMB_ACL_MASK:
                        if (racl->mask_obj == NO_ENTRY)
                                racl->mask_obj = access;
                        else
                                rprintf(FINFO, "unpack_smb_acl: warning: duplicate MASK entry ignored\n");
                        continue;
                case SMB_ACL_OTHER:
                        if (racl->other_obj == NO_ENTRY)
                                racl->other_obj = access;
                        else
                                rprintf(FINFO, "unpack_smb_acl: warning: duplicate OTHER entry ignored\n");
                        continue;
#endif
                case SMB_ACL_USER:
                        access |= NAME_IS_USER;
                        break;
                case SMB_ACL_GROUP:
                        break;
                default:
                        rprintf(FINFO, "unpack_smb_acl: warning: entry with unrecognized tag type ignored\n");
                        continue;
                }
                ida = EXPAND_ITEM_LIST(&temp_ida_list, id_access, -10);
                ida->id = g_u_id;
                ida->access = access;
        }
        if (rc) {
                rsyserr(FERROR_XFER, errno, "unpack_smb_acl: %s()", errfun);
                rsync_acl_free(racl);
                return False;
        }

        /* Transfer the count id_access items out of the temp_ida_list
         * into the names ida_entries list in racl. */
        if (temp_ida_list.count) {
#ifdef SMB_ACL_NEED_SORT
                if (temp_ida_list.count > 1) {
                        qsort(temp_ida_list.items, temp_ida_list.count,
                              sizeof (id_access), id_access_sorter);
                }
#endif
                if (!(racl->names.idas = new_array(id_access, temp_ida_list.count)))
                        out_of_memory("unpack_smb_acl");
                memcpy(racl->names.idas, temp_ida_list.items,
                       temp_ida_list.count * sizeof (id_access));
        } else
                racl->names.idas = NULL;

        racl->names.count = temp_ida_list.count;

        /* Truncate the temporary list now that its idas have been saved. */
        temp_ida_list.count = 0;

#ifdef ACLS_NEED_MASK
        if (!racl->names.count && racl->mask_obj != NO_ENTRY) {
                /* Throw away a superfluous mask, but mask off the
                 * group perms with it first. */
                racl->group_obj &= racl->mask_obj;
                racl->mask_obj = NO_ENTRY;
        }
#endif

        return True;
}

/* Synactic sugar for system calls */

#define CALL_OR_ERROR(func,args,str) \
        do { \
                if (func args) { \
                        errfun = str; \
                        goto error_exit; \
                } \
        } while (0)

#define COE(func,args) CALL_OR_ERROR(func,args,#func)
#define COE2(func,args) CALL_OR_ERROR(func,args,NULL)

#ifndef HAVE_OSX_ACLS
/* Store the permissions in the system ACL entry. */
static int store_access_in_entry(uint32 access, SMB_ACL_ENTRY_T entry)
{
        if (sys_acl_set_access_bits(entry, access)) {
                rsyserr(FERROR_XFER, errno, "store_access_in_entry sys_acl_set_access_bits()");
                return -1;
        }
        return 0;
}
#endif

/* Pack rsync ACL -> system ACL verbatim.  Return whether we succeeded. */
static BOOL pack_smb_acl(SMB_ACL_T *smb_acl, const rsync_acl *racl)
{
#ifdef ACLS_NEED_MASK
        uchar mask_bits;
#endif
        size_t count;
        id_access *ida;
        const char *errfun = NULL;
        SMB_ACL_ENTRY_T entry;

        if (!(*smb_acl = sys_acl_init(calc_sacl_entries(racl)))) {
                rsyserr(FERROR_XFER, errno, "pack_smb_acl: sys_acl_init()");
                return False;
        }

#ifndef HAVE_OSX_ACLS
        COE( sys_acl_create_entry,(smb_acl, &entry) );
        COE( sys_acl_set_info,(entry, SMB_ACL_USER_OBJ, racl->user_obj & ~NO_ENTRY, 0) );
#endif

        for (ida = racl->names.idas, count = racl->names.count; count; ida++, count--) {
#ifdef SMB_ACL_NEED_SORT
                if (!(ida->access & NAME_IS_USER))
                        break;
#endif
                COE( sys_acl_create_entry,(smb_acl, &entry) );
                COE( sys_acl_set_info,
                    (entry,
                     ida->access & NAME_IS_USER ? SMB_ACL_USER : SMB_ACL_GROUP,
                     ida->access & ~NAME_IS_USER, ida->id) );
        }

#ifndef HAVE_OSX_ACLS
        COE( sys_acl_create_entry,(smb_acl, &entry) );
        COE( sys_acl_set_info,(entry, SMB_ACL_GROUP_OBJ, racl->group_obj & ~NO_ENTRY, 0) );

#ifdef SMB_ACL_NEED_SORT
        for ( ; count; ida++, count--) {
                COE( sys_acl_create_entry,(smb_acl, &entry) );
                COE( sys_acl_set_info,(entry, SMB_ACL_GROUP, ida->access, ida->id) );
        }
#endif

#ifdef ACLS_NEED_MASK
        mask_bits = racl->mask_obj == NO_ENTRY ? racl->group_obj & ~NO_ENTRY : racl->mask_obj;
        COE( sys_acl_create_entry,(smb_acl, &entry) );
        COE( sys_acl_set_info,(entry, SMB_ACL_MASK, mask_bits, NULL) );
#else
        if (racl->mask_obj != NO_ENTRY) {
                COE( sys_acl_create_entry,(smb_acl, &entry) );
                COE( sys_acl_set_info,(entry, SMB_ACL_MASK, racl->mask_obj, 0) );
        }
#endif

        COE( sys_acl_create_entry,(smb_acl, &entry) );
        COE( sys_acl_set_info,(entry, SMB_ACL_OTHER, racl->other_obj & ~NO_ENTRY, 0) );
#endif

#ifdef DEBUG
        if (sys_acl_valid(*smb_acl) < 0)
                rprintf(FERROR_XFER, "pack_smb_acl: warning: system says the ACL I packed is invalid\n");
#endif

        return True;

  error_exit:
        if (errfun) {
                rsyserr(FERROR_XFER, errno, "pack_smb_acl %s()", errfun);
        }
        sys_acl_free_acl(*smb_acl);
        return False;
}

static int find_matching_rsync_acl(const rsync_acl *racl, SMB_ACL_TYPE_T type,
                                   const item_list *racl_list)
{
        static int access_match = -1, default_match = -1;
        int *match = type == SMB_ACL_TYPE_ACCESS ? &access_match : &default_match;
        size_t count = racl_list->count;

        /* If this is the first time through or we didn't match the last
         * time, then start at the end of the list, which should be the
         * best place to start hunting. */
        if (*match == -1)
                *match = racl_list->count - 1;
        while (count--) {
                rsync_acl *base = racl_list->items;
                if (rsync_acl_equal(base + *match, racl))
                        return *match;
                if (!(*match)--)
                        *match = racl_list->count - 1;
        }

        *match = -1;
        return *match;
}

static int get_rsync_acl(const char *fname, rsync_acl *racl,
                         SMB_ACL_TYPE_T type, mode_t mode)
{
        SMB_ACL_T sacl;

#ifdef SUPPORT_XATTRS
        /* --fake-super support: load ACLs from an xattr. */
        if (am_root < 0) {
                char *buf;
                size_t len;
                int cnt;

                if ((buf = get_xattr_acl(fname, type == SMB_ACL_TYPE_ACCESS, &len)) == NULL)
                        return 0;
                cnt = (len - 4*4) / (4+4);
                if (len < 4*4 || len != (size_t)cnt*(4+4) + 4*4) {
                        free(buf);
                        return -1;
                }

                racl->user_obj = IVAL(buf, 0);
                racl->group_obj = IVAL(buf, 4);
                racl->mask_obj = IVAL(buf, 8);
                racl->other_obj = IVAL(buf, 12);

                if (cnt) {
                        char *bp = buf + 4*4;
                        id_access *ida;
                        if (!(ida = racl->names.idas = new_array(id_access, cnt)))
                                out_of_memory("get_rsync_acl");
                        racl->names.count = cnt;
                        for ( ; cnt--; ida++, bp += 4+4) {
                                ida->id = IVAL(bp, 0);
                                ida->access = IVAL(bp, 4);
                        }
                }
                free(buf);
                return 0;
        }
#endif

        if ((sacl = sys_acl_get_file(fname, type)) != 0) {
                BOOL ok = unpack_smb_acl(sacl, racl);

                sys_acl_free_acl(sacl);
                if (!ok) {
                        return -1;
                }
        } else if (no_acl_syscall_error(errno)) {
                /* ACLs are not supported, so pretend we have a basic ACL. */
                if (type == SMB_ACL_TYPE_ACCESS)
                        rsync_acl_fake_perms(racl, mode);
        } else {
                rsyserr(FERROR_XFER, errno, "get_acl: sys_acl_get_file(%s, %s)",
                        fname, str_acl_type(type));
                return -1;
        }

        return 0;
}

/* Return the Access Control List for the given filename. */
int get_acl(const char *fname, stat_x *sxp)
{
        sxp->acc_acl = create_racl();
        if (get_rsync_acl(fname, sxp->acc_acl, SMB_ACL_TYPE_ACCESS,
                          sxp->st.st_mode) < 0) {
                free_acl(sxp);
                return -1;
        }

        if (S_ISDIR(sxp->st.st_mode)) {
                sxp->def_acl = create_racl();
                if (get_rsync_acl(fname, sxp->def_acl, SMB_ACL_TYPE_DEFAULT,
                                  sxp->st.st_mode) < 0) {
                        free_acl(sxp);
                        return -1;
                }
        }

        return 0;
}

/* === Send functions === */

/* Send the ida list over the file descriptor. */
static void send_ida_entries(const ida_entries *idal, int f)
{
        id_access *ida;
        size_t count = idal->count;

        write_varint(f, idal->count);

        for (ida = idal->idas; count--; ida++) {
                uint32 xbits = ida->access << 2;
                char *name;
                if (ida->access & NAME_IS_USER) {
                        xbits |= XFLAG_NAME_IS_USER;
                        name = add_uid(ida->id);
                } else
                        name = add_gid(ida->id);
                write_varint(f, ida->id);
                if (inc_recurse && name) {
                        int len = strlen(name);
                        write_varint(f, xbits | XFLAG_NAME_FOLLOWS);
                        write_byte(f, len);
                        write_buf(f, name, len);
                } else
                        write_varint(f, xbits);
        }
}

static void send_rsync_acl(rsync_acl *racl, SMB_ACL_TYPE_T type,
                           item_list *racl_list, int f)
{
        int ndx = find_matching_rsync_acl(racl, type, racl_list);

        /* Send 0 (-1 + 1) to indicate that literal ACL data follows. */
        write_varint(f, ndx + 1);

        if (ndx < 0) {
                rsync_acl *new_racl = EXPAND_ITEM_LIST(racl_list, rsync_acl, 1000);
                uchar flags = 0;

                if (racl->user_obj != NO_ENTRY)
                        flags |= XMIT_USER_OBJ;
                if (racl->group_obj != NO_ENTRY)
                        flags |= XMIT_GROUP_OBJ;
                if (racl->mask_obj != NO_ENTRY)
                        flags |= XMIT_MASK_OBJ;
                if (racl->other_obj != NO_ENTRY)
                        flags |= XMIT_OTHER_OBJ;
                if (racl->names.count)
                        flags |= XMIT_NAME_LIST;

                write_byte(f, flags);

                if (flags & XMIT_USER_OBJ)
                        write_varint(f, racl->user_obj);
                if (flags & XMIT_GROUP_OBJ)
                        write_varint(f, racl->group_obj);
                if (flags & XMIT_MASK_OBJ)
                        write_varint(f, racl->mask_obj);
                if (flags & XMIT_OTHER_OBJ)
                        write_varint(f, racl->other_obj);
                if (flags & XMIT_NAME_LIST)
                        send_ida_entries(&racl->names, f);

                /* Give the allocated data to the new list object. */
                *new_racl = *racl;
                *racl = empty_rsync_acl;
        }
}

/* Send the ACL from the stat_x structure down the indicated file descriptor.
 * This also frees the ACL data. */
void send_acl(stat_x *sxp, int f)
{
        if (!sxp->acc_acl) {
                sxp->acc_acl = create_racl();
                rsync_acl_fake_perms(sxp->acc_acl, sxp->st.st_mode);
        }
        /* Avoid sending values that can be inferred from other data. */
        rsync_acl_strip_perms(sxp->acc_acl);

        send_rsync_acl(sxp->acc_acl, SMB_ACL_TYPE_ACCESS, &access_acl_list, f);

        if (S_ISDIR(sxp->st.st_mode)) {
                if (!sxp->def_acl)
                        sxp->def_acl = create_racl();

                send_rsync_acl(sxp->def_acl, SMB_ACL_TYPE_DEFAULT, &default_acl_list, f);
        }
}

/* === Receive functions === */

static uint32 recv_acl_access(uchar *name_follows_ptr, int f)
{
        uint32 access = read_varint(f);

        if (name_follows_ptr) {
                int flags = access & 3;
                access >>= 2;
                if (am_root >= 0 && access & ~SMB_ACL_VALID_NAME_BITS)
                        goto value_error;
                if (flags & XFLAG_NAME_FOLLOWS)
                        *name_follows_ptr = 1;
                else
                        *name_follows_ptr = 0;
                if (flags & XFLAG_NAME_IS_USER)
                        access |= NAME_IS_USER;
        } else if (am_root >= 0 && access & ~SMB_ACL_VALID_OBJ_BITS) {
          value_error:
                rprintf(FERROR_XFER, "recv_acl_access: value out of range: %x\n",
                        access);
                exit_cleanup(RERR_STREAMIO);
        }

        return access;
}

static uchar recv_ida_entries(ida_entries *ent, int f)
{
        uchar computed_mask_bits = 0;
        int i, count = read_varint(f);

        if (count) {
                if (!(ent->idas = new_array(id_access, count)))
                        out_of_memory("recv_ida_entries");
        } else
                ent->idas = NULL;

        ent->count = count;

        for (i = 0; i < count; i++) {
                uchar has_name;
                id_t id = read_varint(f);
                uint32 access = recv_acl_access(&has_name, f);

                if (has_name) {
                        if (access & NAME_IS_USER)
                                id = recv_user_name(f, id);
                        else
                                id = recv_group_name(f, id, NULL);
                } else if (access & NAME_IS_USER) {
                        if (inc_recurse && am_root && !numeric_ids)
                                id = match_uid(id);
                } else {
                        if (inc_recurse && (!am_root || !numeric_ids))
                                id = match_gid(id, NULL);
                }

                ent->idas[i].id = id;
                ent->idas[i].access = access;
                computed_mask_bits |= access;
        }

        return computed_mask_bits & ~NO_ENTRY;
}

static int recv_rsync_acl(item_list *racl_list, SMB_ACL_TYPE_T type, int f)
{
        uchar computed_mask_bits = 0;
        acl_duo *duo_item;
        uchar flags;
        int ndx = read_varint(f);

        if (ndx < 0 || (size_t)ndx > racl_list->count) {
                rprintf(FERROR_XFER, "recv_acl_index: %s ACL index %d > %d\n",
                        str_acl_type(type), ndx, (int)racl_list->count);
                exit_cleanup(RERR_STREAMIO);
        }

        if (ndx != 0)
                return ndx - 1;
        
        ndx = racl_list->count;
        duo_item = EXPAND_ITEM_LIST(racl_list, acl_duo, 1000);
        duo_item->racl = empty_rsync_acl;

        flags = read_byte(f);

        if (flags & XMIT_USER_OBJ)
                duo_item->racl.user_obj = recv_acl_access(NULL, f);
        if (flags & XMIT_GROUP_OBJ)
                duo_item->racl.group_obj = recv_acl_access(NULL, f);
        if (flags & XMIT_MASK_OBJ)
                duo_item->racl.mask_obj = recv_acl_access(NULL, f);
        if (flags & XMIT_OTHER_OBJ)
                duo_item->racl.other_obj = recv_acl_access(NULL, f);
        if (flags & XMIT_NAME_LIST)
                computed_mask_bits |= recv_ida_entries(&duo_item->racl.names, f);

#ifdef HAVE_OSX_ACLS
        /* If we received a superfluous mask, throw it away. */
        duo_item->racl.mask_obj = NO_ENTRY;
#else
        if (!duo_item->racl.names.count) {
                /* If we received a superfluous mask, throw it away. */
                if (duo_item->racl.mask_obj != NO_ENTRY) {
                        /* Mask off the group perms with it first. */
                        duo_item->racl.group_obj &= duo_item->racl.mask_obj | NO_ENTRY;
                        duo_item->racl.mask_obj = NO_ENTRY;
                }
        } else if (duo_item->racl.mask_obj == NO_ENTRY) /* Must be non-empty with lists. */
                duo_item->racl.mask_obj = (computed_mask_bits | duo_item->racl.group_obj) & ~NO_ENTRY;
#endif

        duo_item->sacl = NULL;

        return ndx;
}

/* Receive the ACL info the sender has included for this file-list entry. */
void receive_acl(struct file_struct *file, int f)
{
        F_ACL(file) = recv_rsync_acl(&access_acl_list, SMB_ACL_TYPE_ACCESS, f);

        if (S_ISDIR(file->mode))
                F_DIR_DEFACL(file) = recv_rsync_acl(&default_acl_list, SMB_ACL_TYPE_DEFAULT, f);
}

static int cache_rsync_acl(rsync_acl *racl, SMB_ACL_TYPE_T type, item_list *racl_list)
{
        int ndx;

        if (!racl)
                ndx = -1;
        else if ((ndx = find_matching_rsync_acl(racl, type, racl_list)) == -1) {
                acl_duo *new_duo;
                ndx = racl_list->count;
                new_duo = EXPAND_ITEM_LIST(racl_list, acl_duo, 1000);
                new_duo->racl = *racl;
                new_duo->sacl = NULL;
                *racl = empty_rsync_acl;
        }

        return ndx;
}

/* Turn the ACL data in stat_x into cached ACL data, setting the index
 * values in the file struct. */
void cache_acl(struct file_struct *file, stat_x *sxp)
{
        F_ACL(file) = cache_rsync_acl(sxp->acc_acl,
                                      SMB_ACL_TYPE_ACCESS, &access_acl_list);

        if (S_ISDIR(sxp->st.st_mode)) {
                F_DIR_DEFACL(file) = cache_rsync_acl(sxp->def_acl,
                                      SMB_ACL_TYPE_DEFAULT, &default_acl_list);
        }
}

#ifndef HAVE_OSX_ACLS
static mode_t change_sacl_perms(SMB_ACL_T sacl, rsync_acl *racl, mode_t old_mode, mode_t mode)
{
        SMB_ACL_ENTRY_T entry;
        const char *errfun;
        int rc;

        if (S_ISDIR(mode)) {
                /* If the sticky bit is going on, it's not safe to allow all
                 * the new ACL to go into effect before it gets set. */
#ifdef SMB_ACL_LOSES_SPECIAL_MODE_BITS
                if (mode & S_ISVTX)
                        mode &= ~0077;
#else
                if (mode & S_ISVTX && !(old_mode & S_ISVTX))
                        mode &= ~0077;
        } else {
                /* If setuid or setgid is going off, it's not safe to allow all
                 * the new ACL to go into effect before they get cleared. */
                if ((old_mode & S_ISUID && !(mode & S_ISUID))
                 || (old_mode & S_ISGID && !(mode & S_ISGID)))
                        mode &= ~0077;
#endif
        }

        errfun = "sys_acl_get_entry";
        for (rc = sys_acl_get_entry(sacl, SMB_ACL_FIRST_ENTRY, &entry);
             rc == 1;
             rc = sys_acl_get_entry(sacl, SMB_ACL_NEXT_ENTRY, &entry)) {
                SMB_ACL_TAG_T tag_type;
                if ((rc = sys_acl_get_tag_type(entry, &tag_type)) != 0) {
                        errfun = "sys_acl_get_tag_type";
                        break;
                }
                switch (tag_type) {
                case SMB_ACL_USER_OBJ:
                        COE2( store_access_in_entry,((mode >> 6) & 7, entry) );
                        break;
                case SMB_ACL_GROUP_OBJ:
                        /* group is only empty when identical to group perms. */
                        if (racl->group_obj != NO_ENTRY)
                                break;
                        COE2( store_access_in_entry,((mode >> 3) & 7, entry) );
                        break;
                case SMB_ACL_MASK:
#ifndef ACLS_NEED_MASK
                        /* mask is only empty when we don't need it. */
                        if (racl->mask_obj == NO_ENTRY)
                                break;
#endif
                        COE2( store_access_in_entry,((mode >> 3) & 7, entry) );
                        break;
                case SMB_ACL_OTHER:
                        COE2( store_access_in_entry,(mode & 7, entry) );
                        break;
                }
        }
        if (rc) {
          error_exit:
                if (errfun) {
                        rsyserr(FERROR_XFER, errno, "change_sacl_perms: %s()",
                                errfun);
                }
                return (mode_t)~0;
        }

#ifdef SMB_ACL_LOSES_SPECIAL_MODE_BITS
        /* Ensure that chmod() will be called to restore any lost setid bits. */
        if (old_mode & (S_ISUID | S_ISGID | S_ISVTX)
         && BITS_EQUAL(old_mode, mode, CHMOD_BITS))
                old_mode &= ~(S_ISUID | S_ISGID | S_ISVTX);
#endif

        /* Return the mode of the file on disk, as we will set them. */
        return (old_mode & ~ACCESSPERMS) | (mode & ACCESSPERMS);
}
#endif

static int set_rsync_acl(const char *fname, acl_duo *duo_item,
                         SMB_ACL_TYPE_T type, stat_x *sxp, mode_t mode)
{
        if (type == SMB_ACL_TYPE_DEFAULT
         && duo_item->racl.user_obj == NO_ENTRY) {
                int rc;
#ifdef SUPPORT_XATTRS
                /* --fake-super support: delete default ACL from xattrs. */
                if (am_root < 0)
                        rc = del_def_xattr_acl(fname);
                else
#endif
                        rc = sys_acl_delete_def_file(fname);
                if (rc < 0) {
                        rsyserr(FERROR_XFER, errno, "set_acl: sys_acl_delete_def_file(%s)",
                                fname);
                        return -1;
                }
#ifdef SUPPORT_XATTRS
        } else if (am_root < 0) {
                /* --fake-super support: store ACLs in an xattr. */
                int cnt = duo_item->racl.names.count;
                size_t len = 4*4 + cnt * (4+4);
                char *buf = new_array(char, len);
                int rc;

                SIVAL(buf, 0, duo_item->racl.user_obj);
                SIVAL(buf, 4, duo_item->racl.group_obj);
                SIVAL(buf, 8, duo_item->racl.mask_obj);
                SIVAL(buf, 12, duo_item->racl.other_obj);

                if (cnt) {
                        char *bp = buf + 4*4;
                        id_access *ida = duo_item->racl.names.idas;
                        for ( ; cnt--; ida++, bp += 4+4) {
                                SIVAL(bp, 0, ida->id);
                                SIVAL(bp, 4, ida->access);
                        }
                }
                rc = set_xattr_acl(fname, type == SMB_ACL_TYPE_ACCESS, buf, len);
                free(buf);
                return rc;
#endif
        } else {
                mode_t cur_mode = sxp->st.st_mode;
                if (!duo_item->sacl
                 && !pack_smb_acl(&duo_item->sacl, &duo_item->racl))
                        return -1;
#ifdef HAVE_OSX_ACLS
                mode = 0; /* eliminate compiler warning */
#else
                if (type == SMB_ACL_TYPE_ACCESS) {
                        cur_mode = change_sacl_perms(duo_item->sacl, &duo_item->racl,
                                                     cur_mode, mode);
                        if (cur_mode == (mode_t)~0)
                                return 0;
                }
#endif
                if (sys_acl_set_file(fname, type, duo_item->sacl) < 0) {
                        rsyserr(FERROR_XFER, errno, "set_acl: sys_acl_set_file(%s, %s)",
                        fname, str_acl_type(type));
                        return -1;
                }
                if (type == SMB_ACL_TYPE_ACCESS)
                        sxp->st.st_mode = cur_mode;
        }

        return 0;
}

/* Set ACL on indicated filename.
 *
 * This sets extended access ACL entries and default ACL.  If convenient,
 * it sets permission bits along with the access ACL and signals having
 * done so by modifying sxp->st.st_mode.
 *
 * Returns 1 for unchanged, 0 for changed, -1 for failed.  Call this
 * with fname set to NULL to just check if the ACL is unchanged. */
int set_acl(const char *fname, const struct file_struct *file, stat_x *sxp)
{
        int unchanged = 1;
        int32 ndx;
        BOOL eq;

        if (!dry_run && (read_only || list_only)) {
                errno = EROFS;
                return -1;
        }

        ndx = F_ACL(file);
        if (ndx >= 0 && (size_t)ndx < access_acl_list.count) {
                acl_duo *duo_item = access_acl_list.items;
                duo_item += ndx;
                eq = sxp->acc_acl
                  && rsync_acl_equal_enough(sxp->acc_acl, &duo_item->racl, file->mode);
                if (!eq) {
                        unchanged = 0;
                        if (!dry_run && fname
                         && set_rsync_acl(fname, duo_item, SMB_ACL_TYPE_ACCESS,
                                          sxp, file->mode) < 0)
                                unchanged = -1;
                }
        }

        if (!S_ISDIR(sxp->st.st_mode))
                return unchanged;

        ndx = F_DIR_DEFACL(file);
        if (ndx >= 0 && (size_t)ndx < default_acl_list.count) {
                acl_duo *duo_item = default_acl_list.items;
                duo_item += ndx;
                eq = sxp->def_acl && rsync_acl_equal(sxp->def_acl, &duo_item->racl);
                if (!eq) {
                        if (unchanged > 0)
                                unchanged = 0;
                        if (!dry_run && fname
                         && set_rsync_acl(fname, duo_item, SMB_ACL_TYPE_DEFAULT,
                                          sxp, file->mode) < 0)
                                unchanged = -1;
                }
        }

        return unchanged;
}

/* Non-incremental recursion needs to convert all the received IDs.
 * This is done in a single pass after receiving the whole file-list. */
static void match_racl_ids(const item_list *racl_list)
{
        int list_cnt, name_cnt;
        acl_duo *duo_item = racl_list->items;
        for (list_cnt = racl_list->count; list_cnt--; duo_item++) {
                ida_entries *idal = &duo_item->racl.names;
                id_access *ida = idal->idas;
                for (name_cnt = idal->count; name_cnt--; ida++) {
                        if (ida->access & NAME_IS_USER)
                                ida->id = match_uid(ida->id);
                        else
                                ida->id = match_gid(ida->id, NULL);
                }
        }
}

void match_acl_ids(void)
{
        match_racl_ids(&access_acl_list);
        match_racl_ids(&default_acl_list);
}

/* This is used by dest_mode(). */
int default_perms_for_dir(const char *dir)
{
        rsync_acl racl;
        SMB_ACL_T sacl;
        BOOL ok;
        int perms;

        if (dir == NULL)
                dir = ".";
        perms = ACCESSPERMS & ~orig_umask;
        /* Read the directory's default ACL.  If it has none, this will successfully return an empty ACL. */
        sacl = sys_acl_get_file(dir, SMB_ACL_TYPE_DEFAULT);
        if (sacl == NULL) {
                /* Couldn't get an ACL.  Darn. */
                switch (errno) {
#ifdef ENOTSUP
                case ENOTSUP:
#endif
                case ENOSYS:
                        /* No ACLs are available. */
                        break;
                case ENOENT:
                        if (dry_run) {
                                /* We're doing a dry run, so the containing directory
                                 * wasn't actually created.  Don't worry about it. */
                                break;
                        }
                        /* Otherwise fall through. */
                default:
                        rprintf(FWARNING,
                                "default_perms_for_dir: sys_acl_get_file(%s, %s): %s, falling back on umask\n",
                                dir, str_acl_type(SMB_ACL_TYPE_DEFAULT), strerror(errno));
                }
                return perms;
        }

        /* Convert it. */
        racl = empty_rsync_acl;
        ok = unpack_smb_acl(sacl, &racl);
        sys_acl_free_acl(sacl);
        if (!ok) {
                rprintf(FWARNING, "default_perms_for_dir: unpack_smb_acl failed, falling back on umask\n");
                return perms;
        }

        /* Apply the permission-bit entries of the default ACL, if any. */
        if (racl.user_obj != NO_ENTRY) {
                perms = rsync_acl_get_perms(&racl);
                if (verbose > 2)
                        rprintf(FINFO, "got ACL-based default perms %o for directory %s\n", perms, dir);
        }

        rsync_acl_free(&racl);
        return perms;
}

#endif /* SUPPORT_ACLS */