listxattr, llistxattr, flistxattr — list extended attribute names
#include <sys/types.h> #include <attr/xattr.h>
ssize_t listxattr( |
const char * | path, |
| char * | list, | |
| size_t | size); |
ssize_t llistxattr( |
const char * | path, |
| char * | list, | |
| size_t | size); |
ssize_t flistxattr( |
int | fd, |
| char * | list, | |
| size_t | size); |
Extended attributes are name:value pairs associated with inodes (files, directories, symbolic links, etc.). They are extensions to the normal attributes which are associated with all inodes in the system (i.e., the stat(2) data). A complete overview of extended attributes concepts can be found in attr(5).
listxattr() retrieves the
list of extended
attribute names associated with the given path in the filesystem. The
list is the set of (null-terminated) names, one after the
other. Names of extended attributes to which the calling
process does not have access may be omitted from the list.
The length of the attribute name list is returned.
llistxattr() is identical to
listxattr(), except in the case
of a symbolic link, where the list of names of extended
attributes associated with the link itself is retrieved, not
the file that it refers to.
flistxattr() is identical to
listxattr(), only the open file
referred to by fd (as
returned by open(2)) is interrogated in
place of path.
A single extended attribute name is a simple
null-terminated string. The name includes a namespace prefix;
there may be several, disjoint namespaces associated with an
individual inode.
An empty buffer of size zero can be passed into
these calls to return the current size of the list of
extended attribute names, which can be used to estimate the
size of a buffer which is sufficiently large to hold the list
of names.
The list of
names is returned as an unordered array of null-terminated
character strings (attribute names are separated by null
bytes ('\0')), like this:
user.name1\0system.name1\0user.name2\0
Filesystems like ext2, ext3 and XFS which implement
POSIX ACLs using extended attributes, might return a
list like this:
system.posix_acl_access\0system.posix_acl_default\0
On success, a positive number is returned indicating the
size of the extended attribute name list. On failure,
−1 is returned and errno
is set appropriately.
If the size of the
list buffer is too
small to hold the result, errno
is set to ERANGE.
If extended attributes are not supported by the
filesystem, or are disabled, errno is set to ENOTSUP.
The errors documented for the stat(2) system call are also applicable here.
These system calls have been available on Linux since kernel 2.4; glibc support is provided since version 2.3.
getfattr(1), setfattr(1), getxattr(2), open(2), removexattr(2), setxattr(2), stat(2), attr(5)
This page is part of release 2.79 of the Linux man-pages project. A
description of the project, and information about reporting
bugs, can be found at
http://www.kernel.org/doc/man-pages/.
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Extended attributes system calls manual pages (C) Andreas Gruenbacher, February 2001 (C) Silicon Graphics Inc, September 2001 This is free documentation; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. The GNU General Public License's references to "object code" and "executables" are to be interpreted as the output of any document formatting or typesetting system, including intermediate and printed output. This manual is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this manual; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA. |