Root/fs/xattr_acl.c

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/slab.h>
10#include <linux/fs.h>
11#include <linux/posix_acl_xattr.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_KERNEL);
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

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