posix_acl_xattr.h

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/*
  File: linux/posix_acl_xattr.h

  Extended attribute system call representation of Access Control Lists.

  Copyright (C) 2000 by Andreas Gruenbacher <[email protected]>
  Copyright (C) 2002 SGI - Silicon Graphics, Inc <[email protected]>
 */
#ifndef _POSIX_ACL_XATTR_H
#define _POSIX_ACL_XATTR_H

#include <linux/posix_acl.h>

/* Extended attribute names */
#define POSIX_ACL_XATTR_ACCESS  "system.posix_acl_access"
#define POSIX_ACL_XATTR_DEFAULT "system.posix_acl_default"

/* Supported ACL a_version fields */
#define POSIX_ACL_XATTR_VERSION 0x0002


/* An undefined entry e_id value */
#define ACL_UNDEFINED_ID    (-1)

typedef struct {
    __le16          e_tag;
    __le16          e_perm;
    __le32          e_id;
} posix_acl_xattr_entry;

typedef struct {
    __le32          a_version;
    posix_acl_xattr_entry   a_entries[0];
} posix_acl_xattr_header;


static inline size_t
posix_acl_xattr_size(int count)
{
    return (sizeof(posix_acl_xattr_header) +
        (count * sizeof(posix_acl_xattr_entry)));
}

static inline int
posix_acl_xattr_count(size_t size)
{
    if (size < sizeof(posix_acl_xattr_header))
        return -1;
    size -= sizeof(posix_acl_xattr_header);
    if (size % sizeof(posix_acl_xattr_entry))
        return -1;
    return size / sizeof(posix_acl_xattr_entry);
}

#ifdef CONFIG_FS_POSIX_ACL
void posix_acl_fix_xattr_from_user(void *value, size_t size);
void posix_acl_fix_xattr_to_user(void *value, size_t size);
#else
static inline void posix_acl_fix_xattr_from_user(void *value, size_t size)
{
}
static inline void posix_acl_fix_xattr_to_user(void *value, size_t size)
{
}
#endif

struct posix_acl *posix_acl_from_xattr(struct user_namespace *user_ns, 
                       const void *value, size_t size);
int posix_acl_to_xattr(struct user_namespace *user_ns,
               const struct posix_acl *acl, void *buffer, size_t size);

#endif  /* _POSIX_ACL_XATTR_H */