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listxattr(2)


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).



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