Originální popis anglicky:
listxattr, llistxattr, flistxattr - list extended attribute names
Návod, kniha: Linux Programmer's Manual
#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 filedes,
\ char *list, size_t size);
Extended attributes are name:value pairs associated with inodes (files,
directories, symlinks, 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 pointed
to by
filedes (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 characters), 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.
Andreas Gruenbacher, <
a.gruenbacher@computer.org> and the SGI XFS
development team, <
linux-xfs@oss.sgi.com>. Please send any bug
reports or comments to these addresses.
getfattr(1),
setfattr(1),
getxattr(2),
open(2),
removexattr(2),
setxattr(2),
stat(2),
attr(5)
