LXR linux/fs/xattr

   1/*
   2 * linux/fs/xattr_acl.c
   3 *
   4 * Almost all from linux/fs/ext2/acl.c:
   5 * Copyright (C) 2001 by Andreas Gruenbacher, <a.gruenbacher@computer.org>
   6 */
   7
   8#include <linux/module.h>
   9#include <linux/fs.h>
  10#include <linux/posix_acl_xattr.h>
  11#include <linux/gfp.h>
  12
  13
  14/*
  15 * Convert from extended attribute to in-memory representation.
  16 */
  17struct posix_acl *
  18posix_acl_from_xattr(const void *value, size_t size)
  19{
  20        posix_acl_xattr_header *header = (posix_acl_xattr_header *)value;
  21        posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end;
  22        int count;
  23        struct posix_acl *acl;
  24        struct posix_acl_entry *acl_e;
  25
  26        if (!value)
  27                return NULL;
  28        if (size < sizeof(posix_acl_xattr_header))
  29                 return ERR_PTR(-EINVAL);
  30        if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
  31                return ERR_PTR(-EOPNOTSUPP);
  32
  33        count = posix_acl_xattr_count(size);
  34        if (count < 0)
  35                return ERR_PTR(-EINVAL);
  36        if (count == 0)
  37                return NULL;
  38        
  39        acl = posix_acl_alloc(count, GFP_NOFS);
  40        if (!acl)
  41                return ERR_PTR(-ENOMEM);
  42        acl_e = acl->a_entries;
  43        
  44        for (end = entry + count; entry != end; acl_e++, entry++) {
  45                acl_e->e_tag  = le16_to_cpu(entry->e_tag);
  46                acl_e->e_perm = le16_to_cpu(entry->e_perm);
  47
  48                switch(acl_e->e_tag) {
  49                        case ACL_USER_OBJ:
  50                        case ACL_GROUP_OBJ:
  51                        case ACL_MASK:
  52                        case ACL_OTHER:
  53                                acl_e->e_id = ACL_UNDEFINED_ID;
  54                                break;
  55
  56                        case ACL_USER:
  57                        case ACL_GROUP:
  58                                acl_e->e_id = le32_to_cpu(entry->e_id);
  59                                break;
  60
  61                        default:
  62                                goto fail;
  63                }
  64        }
  65        return acl;
  66
  67fail:
  68        posix_acl_release(acl);
  69        return ERR_PTR(-EINVAL);
  70}
  71EXPORT_SYMBOL (posix_acl_from_xattr);
  72
  73/*
  74 * Convert from in-memory to extended attribute representation.
  75 */
  76int
  77posix_acl_to_xattr(const struct posix_acl *acl, void *buffer, size_t size)
  78{
  79        posix_acl_xattr_header *ext_acl = (posix_acl_xattr_header *)buffer;
  80        posix_acl_xattr_entry *ext_entry = ext_acl->a_entries;
  81        int real_size, n;
  82
  83        real_size = posix_acl_xattr_size(acl->a_count);
  84        if (!buffer)
  85                return real_size;
  86        if (real_size > size)
  87                return -ERANGE;
  88        
  89        ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
  90
  91        for (n=0; n < acl->a_count; n++, ext_entry++) {
  92                ext_entry->e_tag  = cpu_to_le16(acl->a_entries[n].e_tag);
  93                ext_entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
  94                ext_entry->e_id   = cpu_to_le32(acl->a_entries[n].e_id);
  95        }
  96        return real_size;
  97}
  98EXPORT_SYMBOL (posix_acl_to_xattr);
  99