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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 retrieved list is placed in list, a caller-allocated buffer
whose size (in bytes) is specified in the argument size. 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 nonnegative number is returned indicating
the size of the extended attribute name list. On failure,
−1 is returned and errno
is set appropriately.
Extended attributes are not supported by the filesystem, or are disabled.
The size of
the list buffer
is too small to hold the result.
In addition, the errors documented in stat(2) can also occur.
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), symlink(7)
This page is part of release 3.54 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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Copyright (C) Andreas Gruenbacher, February 2001 Copyright (C) Silicon Graphics Inc, September 2001 %%%LICENSE_START(GPLv2+_DOC_FULL) 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, see <http://www.gnu.org/licenses/>. %%%LICENSE_END |