NAME

       listxattr, llistxattr, flistxattr - list extended attribute names

SYNOPSIS

       #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);

DESCRIPTION

       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.  list is a caller-allocated buffer of size size.

       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.

EXAMPLES

       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

RETURN VALUE

       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.

AUTHORS

       Andreas Gruenbacher, <a.gruenbacher@bestbits.at> and the SGI XFS development team, <linux-
       xfs@oss.sgi.com>.  Please send any bug reports or comments to these addresses.

SEE ALSO

       getfattr(1),  setfattr(1), open(2), stat(2), getxattr(2), setxattr(2), removexattr(2), and
       attr(5).