[apple/xnu.git] / bsd / man / man2 / listxattr.2

.\"
.\" Copyright (c) 2004 Apple Computer, Inc. All rights reserved.
.\"
.\" @APPLE_LICENSE_HEADER_START@
.\"
.\" This file contains Original Code and/or Modifications of Original Code
.\" as defined in and that are subject to the Apple Public Source License
.\" Version 2.0 (the 'License'). You may not use this file except in
.\" compliance with the License. Please obtain a copy of the License at
.\" http://www.opensource.apple.com/apsl/ and read it before using this
.\" file.
.\"
.\" The Original Code and all software distributed under the License are
.\" distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
.\" EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
.\" INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
.\" FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
.\" Please see the License for the specific language governing rights and
.\" limitations under the License.
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.\" @APPLE_LICENSE_HEADER_END@
.\"
.Dd Oct 19, 2004
.Dt LISTXATTR 2
.Os "Mac OS X"
.Sh NAME
.Nm listxattr,
.Nm flistxattr
.Nd list extended attribute names
.Sh SYNOPSIS
.Fd #include <sys/xattr.h>
.Ft ssize_t
.Fn listxattr "const char *path" "char *namebuf" "size_t size" "int options"
.Ft ssize_t
.Fn flistxattr "int fd" "char *namebuf" "size_t size" "int options"
.Sh DESCRIPTION
Extended attributes extend the basic attributes associated with files and
directories in the file system.  They are stored as name:data pairs associated
with file system objects (files, directories, symlinks, etc).
.Pp
.Fn listxattr
retrieves a list of names of extended attributes associated with the given
.Fa path
in the file system.
.Pp
.Fa namebuf
is a data buffer of
.Pa size
bytes for the names of the extended attributes associated with
.Fa path .
The extended attribute names are simple NULL-terminated UTF-8 strings and
are returned in arbitrary order.  No extra padding is provided between
names in the buffer.  The list will only include names of extended
attributes to which the calling process has access.  The function returns
the size of the list of names.
.Pp
.Fa options
controls how the attribute list is generated:
.Pp
.Bl -tag -width XATTR_NOFOLLOW
.It Dv XATTR_NOFOLLOW
do not follow symbolic links.
.Fn listxattr
normally lists attributes of the target of
.Fa path
if it is a symbolic link.  With this option,
.Fn listxattr
will list attributes of the link itself.
.It Dv XATTR_SHOWCOMPRESSION
.Fn listxattr
and 
.Fn flistxattr
will list HFS Plus Compression extended attribute(s) (if present) for the file referred to by
.Fa path
or
.Fa fd .
.El
.Pp
If
.Fa namebuf
is set to NULL,
the function returns the size of the list of extended attribute names.
This facility can be used to determine the size of a buffer sufficiently
large to hold the names of the attributes currently associated with
.Fa path .
.Pp
.Fn flistxattr
is identical to
.Fn listxattr ,
except that it returns the list of extended attribute names associated
with the open file referenced by file descriptor
.Fa fd .
.Sh RETURN VALUES
On success, the size of the extended attribute name list is returned.  If
no accessible extended attributes are associated with the given
.Fa path
or
.Fa fd ,
the function returns zero.  On failure, -1 is returned and the global
variable
.Va errno
is set as follows.
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er ENOTSUP
The file system does not support extended attributes or has the feature
disabled.
.It Bq Er ERANGE
.Fa namebuf
(as indicated by
.Fa size )
is too small to hold the list of names.
.It Bq Er EPERM
.Fa path
or
.Fa fd
refer to a file system object that does not support extended attributes.
For example, resource forks don't support extended attributes.
.\" If only EFTYPE was a POSIX error
.It Bq Er ENOTDIR
A component of
.Fa path 's
prefix is not a directory.
.It Bq Er ENAMETOOLONG
.Fa name
exceeds
.Dv XATTR_MAXNAMELEN
UTF-8 bytes, or a component of
.Fa path
exceeds
.Dv NAME_MAX
characters, or the entire
.Fa path
exceeds
.Dv PATH_MAX
characters.
.It Bq Er EACCES
Search permission is denied for a component of
.Fa path
or permission is denied to read the list of attributes from this file.
.It Bq Er ELOOP
Too many symbolic links were encountered resolving
.Fa path .
.It Bq Er EFAULT
.Fa path
points to an invalid address.
.It Bq Er EIO
An I/O error occurred.
.It Bq Er EINVAL
.Fa options
does not make sense.
.El
.Sh SEE ALSO
.Xr getxattr 2 ,
.Xr removexattr 2 ,
.Xr setxattr 2
.Sh HISTORY
.Fn listxattr
and
.Fn flistxattr
first appeared in Mac OS X 10.4.
Commit	Line	Data
91447636 A	1	.\"
	2	.\" Copyright (c) 2004 Apple Computer, Inc. All rights reserved.
	3	.\"
6601e61a	4	.\" @APPLE_LICENSE_HEADER_START@
91447636	5	.\"
8f6c56a5 A	6	.\" This file contains Original Code and/or Modifications of Original Code
	7	.\" as defined in and that are subject to the Apple Public Source License
	8	.\" Version 2.0 (the 'License'). You may not use this file except in
	9	.\" compliance with the License. Please obtain a copy of the License at
	10	.\" http://www.opensource.apple.com/apsl/ and read it before using this
91447636 A	11	.\" file.
91447636 A	12	.\"
8f6c56a5 A	13	.\" The Original Code and all software distributed under the License are
	14	.\" distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
	15	.\" EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
	16	.\" INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
	17	.\" FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	18	.\" Please see the License for the specific language governing rights and
91447636 A	19	.\" limitations under the License.
91447636 A	20	.\"
6601e61a	21	.\" @APPLE_LICENSE_HEADER_END@
91447636 A	22	.\"
	23	.Dd Oct 19, 2004
	24	.Dt LISTXATTR 2
	25	.Os "Mac OS X"
	26	.Sh NAME
	27	.Nm listxattr,
	28	.Nm flistxattr
b0d623f7	29	.Nd list extended attribute names
91447636 A	30	.Sh SYNOPSIS
	31	.Fd #include <sys/xattr.h>
	32	.Ft ssize_t
	33	.Fn listxattr "const char path" "char namebuf" "size_t size" "int options"
	34	.Ft ssize_t
	35	.Fn flistxattr "int fd" "char *namebuf" "size_t size" "int options"
	36	.Sh DESCRIPTION
	37	Extended attributes extend the basic attributes associated with files and
	38	directories in the file system. They are stored as name:data pairs associated
	39	with file system objects (files, directories, symlinks, etc).
	40	.Pp
	41	.Fn listxattr
	42	retrieves a list of names of extended attributes associated with the given
	43	.Fa path
	44	in the file system.
	45	.Pp
	46	.Fa namebuf
	47	is a data buffer of
	48	.Pa size
	49	bytes for the names of the extended attributes associated with
	50	.Fa path .
	51	The extended attribute names are simple NULL-terminated UTF-8 strings and
	52	are returned in arbitrary order. No extra padding is provided between
	53	names in the buffer. The list will only include names of extended
	54	attributes to which the calling process has access. The function returns
	55	the size of the list of names.
	56	.Pp
	57	.Fa options
	58	controls how the attribute list is generated:
	59	.Pp
	60	.Bl -tag -width XATTR_NOFOLLOW
	61	.It Dv XATTR_NOFOLLOW
	62	do not follow symbolic links.
	63	.Fn listxattr
	64	normally lists attributes of the target of
	65	.Fa path
	66	if it is a symbolic link. With this option,
	67	.Fn listxattr
	68	will list attributes of the link itself.
b0d623f7 A	69	.It Dv XATTR_SHOWCOMPRESSION
	70	.Fn listxattr
	71	and
	72	.Fn flistxattr
	73	will list HFS Plus Compression extended attribute(s) (if present) for the file referred to by
	74	.Fa path
	75	or
	76	.Fa fd .
91447636 A	77	.El
	78	.Pp
	79	If
	80	.Fa namebuf
	81	is set to NULL,
	82	the function returns the size of the list of extended attribute names.
	83	This facility can be used to determine the size of a buffer sufficiently
	84	large to hold the names of the attributes currently associated with
	85	.Fa path .
	86	.Pp
	87	.Fn flistxattr
	88	is identical to
	89	.Fn listxattr ,
	90	except that it returns the list of extended attribute names associated
	91	with the open file referenced by file descriptor
	92	.Fa fd .
	93	.Sh RETURN VALUES
	94	On success, the size of the extended attribute name list is returned. If
	95	no accessible extended attributes are associated with the given
	96	.Fa path
	97	or
	98	.Fa fd ,
	99	the function returns zero. On failure, -1 is returned and the global
	100	variable
	101	.Va errno
	102	is set as follows.
	103	.Sh ERRORS
	104	.Bl -tag -width Er
	105	.It Bq Er ENOTSUP
	106	The file system does not support extended attributes or has the feature
	107	disabled.
	108	.It Bq Er ERANGE
	109	.Fa namebuf
	110	(as indicated by
	111	.Fa size )
	112	is too small to hold the list of names.
	113	.It Bq Er EPERM
	114	.Fa path
	115	or
	116	.Fa fd
	117	refer to a file system object that does not support extended attributes.
	118	For example, resource forks don't support extended attributes.
	119	.\" If only EFTYPE was a POSIX error
	120	.It Bq Er ENOTDIR
	121	A component of
	122	.Fa path 's
	123	prefix is not a directory.
	124	.It Bq Er ENAMETOOLONG
	125	.Fa name
	126	exceeds
	127	.Dv XATTR_MAXNAMELEN
	128	UTF-8 bytes, or a component of
	129	.Fa path
	130	exceeds
	131	.Dv NAME_MAX
	132	characters, or the entire
	133	.Fa path
	134	exceeds
	135	.Dv PATH_MAX
	136	characters.
	137	.It Bq Er EACCES
	138	Search permission is denied for a component of
	139	.Fa path
	140	or permission is denied to read the list of attributes from this file.
141	.It Bq Er ELOOP
142	Too many symbolic links were encountered resolving
143	.Fa path .
144	.It Bq Er EFAULT
145	.Fa path
146	points to an invalid address.
147	.It Bq Er EIO
148	An I/O error occurred.
149	.It Bq Er EINVAL
150	.Fa options
151	does not make sense.
152	.El
153	.Sh SEE ALSO
91447636	154	.Xr getxattr 2 ,
2d21ac55 A	155	.Xr removexattr 2 ,
2d21ac55 A	156	.Xr setxattr 2
91447636 A	157	.Sh HISTORY
	158	.Fn listxattr
	159	and
	160	.Fn flistxattr
	161	first appeared in Mac OS X 10.4.