fs/ext2/xattr.c

Source file repositories/reference/linux-study-clean/fs/ext2/xattr.c

File Facts

System
Linux kernel
Corpus path
fs/ext2/xattr.c
Extension
.c
Size
29173 bytes
Lines
1060
Domain
Core OS
Bucket
VFS And Filesystem Core
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

if (prefix) {
			size_t prefix_len = strlen(prefix);
			size_t size = prefix_len + entry->e_name_len + 1;

			if (buffer) {
				if (size > rest) {
					error = -ERANGE;
					goto cleanup;
				}
				memcpy(buffer, prefix, prefix_len);
				buffer += prefix_len;
				memcpy(buffer, entry->e_name, entry->e_name_len);
				buffer += entry->e_name_len;
				*buffer++ = 0;
			}
			rest -= size;
		}
	}
	error = buffer_size - rest;  /* total size */

cleanup:
	brelse(bh);
	up_read(&EXT2_I(inode)->xattr_sem);

	return error;
}

/*
 * Inode operation listxattr()
 *
 * d_inode(dentry)->i_mutex: don't care
 */
ssize_t
ext2_listxattr(struct dentry *dentry, char *buffer, size_t size)
{
	return ext2_xattr_list(dentry, buffer, size);
}

/*
 * If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is
 * not set, set it.
 */
static void ext2_xattr_update_super_block(struct super_block *sb)
{
	if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR))
		return;

	spin_lock(&EXT2_SB(sb)->s_lock);
	ext2_update_dynamic_rev(sb);
	EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR);
	spin_unlock(&EXT2_SB(sb)->s_lock);
	mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
}

/*
 * ext2_xattr_set()
 *
 * Create, replace or remove an extended attribute for this inode.  Value
 * is NULL to remove an existing extended attribute, and non-NULL to
 * either replace an existing extended attribute, or create a new extended
 * attribute. The flags XATTR_REPLACE and XATTR_CREATE
 * specify that an extended attribute must exist and must not exist
 * previous to the call, respectively.
 *
 * Returns 0, or a negative error number on failure.
 */
int
ext2_xattr_set(struct inode *inode, int name_index, const char *name,
	       const void *value, size_t value_len, int flags)
{
	struct super_block *sb = inode->i_sb;
	struct buffer_head *bh = NULL;
	struct ext2_xattr_header *header = NULL;
	struct ext2_xattr_entry *here = NULL, *last = NULL;
	size_t name_len, free, min_offs = sb->s_blocksize;
	int not_found = 1, error;
	char *end;
	
	/*
	 * header -- Points either into bh, or to a temporarily
	 *           allocated buffer.
	 * here -- The named entry found, or the place for inserting, within
	 *         the block pointed to by header.
	 * last -- Points right after the last named entry within the block
	 *         pointed to by header.
	 * min_offs -- The offset of the first value (values are aligned
	 *             towards the end of the block).
	 * end -- Points right after the block pointed to by header.
	 */

Annotation

Implementation Notes