getxattr, lgetxattr, fgetxattr — retrieve an extended attribute value
#include <sys/types.h> #include <sys/xattr.h>
ssize_t
getxattr( |
const char *path, |
| const char *name, | |
| void *value, | |
size_t size); |
ssize_t
lgetxattr( |
const char *path, |
| const char *name, | |
| void *value, | |
size_t size); |
ssize_t
fgetxattr( |
int fd, |
| const char *name, | |
| void *value, | |
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
xattr(7).
getxattr() retrieves the
value of the extended attribute identified by name and associated with the
given path in the
filesystem. The attribute value is placed in the buffer
pointed to by value;
size specifies the
size of that buffer. The return value of the call is the
number of bytes placed in value.
lgetxattr() is identical to
getxattr(), except in the case
of a symbolic link, where the link itself is interrogated,
not the file that it refers to.
fgetxattr() is identical to
getxattr(), only the open file
referred to by fd (as
returned by open(2)) is interrogated in
place of path.
An extended attribute name is a null-terminated
string. The name includes a namespace prefix; there may be
several, disjoint namespaces associated with an individual
inode. The value of an extended attribute is a chunk of
arbitrary textual or binary data that was assigned using
setxattr(2).
If size is
specified as zero, these calls return the current size of the
named extended attribute (and leave value unchanged). This can be
used to determine the size of the buffer that should be
supplied in a subsequent call. (But, bear in mind that there
is a possibility that the attribute value may change between
the two calls, so that it is still necessary to check the
return status from the second call.)
On success, these calls return a nonnegative value which
is the size (in bytes) of the extended attribute value. On
failure, −1 is returned and errno is set appropriately.
ENOATTRThe named attribute does not exist, or the process
has no access to this attribute. (ENOATTR is defined to be a synonym
for ENODATA in
<attr/xattr.h>
Extended attributes are not supported by the filesystem, or are disabled.
The size of
the value
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), listxattr(2), open(2), removexattr(2), setxattr(2), stat(2), symlink(7), xattr(7)
This page is part of release 4.07 of the Linux man-pages project. A
description of the project, information about reporting bugs,
and the latest version of this page, can be found at
https://www.kernel.org/doc/man−pages/.
|
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 |