fs/ext3/xattr_user.c

   1 /*
   2  * linux/fs/ext3/xattr_user.c
   3  * Handler for extended user attributes.
   4  *
   5  * Copyright (C) 2001 by Andreas Gruenbacher, <a.gruenbacher@computer.org>
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/string.h>
  10 #include <linux/fs.h>
  11 #include <linux/smp_lock.h>
  12 #include <linux/ext3_jbd.h>
  13 #include <linux/ext3_fs.h>
  14 #include "xattr.h"
  15
  16 #define XATTR_USER_PREFIX "user."
  17
  18 static size_t
  19 ext3_xattr_user_list(struct inode *inode, char *list, size_t list_size,
  20                      const char *name, size_t name_len)
  21 {
  22         const size_t prefix_len = sizeof(XATTR_USER_PREFIX)-1;
  23         const size_t total_len = prefix_len + name_len + 1;
  24
  25         if (!test_opt(inode->i_sb, XATTR_USER))
  26                 return 0;
  27
  28         if (list && total_len <= list_size) {
  29                 memcpy(list, XATTR_USER_PREFIX, prefix_len);
  30                 memcpy(list+prefix_len, name, name_len);
  31                 list[prefix_len + name_len] = '\0';
  32         }
  33         return total_len;
  34 }
  35
  36 static int
  37 ext3_xattr_user_get(struct inode *inode, const char *name,
  38                     void *buffer, size_t size)
  39 {
  40         int error;
  41
  42         if (strcmp(name, "") == 0)
  43                 return -EINVAL;
  44         if (!test_opt(inode->i_sb, XATTR_USER))
  45                 return -EOPNOTSUPP;
  46         error = permission(inode, MAY_READ, NULL);
  47         if (error)
  48                 return error;
  49
  50         return ext3_xattr_get(inode, EXT3_XATTR_INDEX_USER, name, buffer, size);
  51 }
  52
  53 static int
  54 ext3_xattr_user_set(struct inode *inode, const char *name,
  55                     const void *value, size_t size, int flags)
  56 {
  57         int error;
  58
  59         if (strcmp(name, "") == 0)
  60                 return -EINVAL;
  61         if (!test_opt(inode->i_sb, XATTR_USER))
  62                 return -EOPNOTSUPP;
  63         if ( !S_ISREG(inode->i_mode) &&
  64             (!S_ISDIR(inode->i_mode) || inode->i_mode & S_ISVTX))
  65                 return -EPERM;
  66         error = permission(inode, MAY_WRITE, NULL);
  67         if (error)
  68                 return error;
  69
  70         return ext3_xattr_set(inode, EXT3_XATTR_INDEX_USER, name,
  71                               value, size, flags);
  72 }
  73
  74 struct xattr_handler ext3_xattr_user_handler = {
  75         .prefix = XATTR_USER_PREFIX,
  76         .list   = ext3_xattr_user_list,
  77         .get    = ext3_xattr_user_get,
  78         .set    = ext3_xattr_user_set,
  79 };