[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
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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 an extended attribute value
.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.
.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
	29	.Nd list an extended attribute value
	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.
	69	.El
	70	.Pp
	71	If
	72	.Fa namebuf
	73	is set to NULL,
	74	the function returns the size of the list of extended attribute names.
	75	This facility can be used to determine the size of a buffer sufficiently
	76	large to hold the names of the attributes currently associated with
	77	.Fa path .
	78	.Pp
	79	.Fn flistxattr
	80	is identical to
	81	.Fn listxattr ,
	82	except that it returns the list of extended attribute names associated
	83	with the open file referenced by file descriptor
	84	.Fa fd .
	85	.Sh RETURN VALUES
86	On success, the size of the extended attribute name list is returned. If
87	no accessible extended attributes are associated with the given
88	.Fa path
89	or
90	.Fa fd ,
91	the function returns zero. On failure, -1 is returned and the global
92	variable
93	.Va errno
94	is set as follows.
95	.Sh ERRORS
96	.Bl -tag -width Er
97	.It Bq Er ENOTSUP
98	The file system does not support extended attributes or has the feature
99	disabled.
100	.It Bq Er ERANGE
101	.Fa namebuf
102	(as indicated by
103	.Fa size )
104	is too small to hold the list of names.
105	.It Bq Er EPERM
106	.Fa path
107	or
108	.Fa fd
109	refer to a file system object that does not support extended attributes.
110	For example, resource forks don't support extended attributes.
111	.\" If only EFTYPE was a POSIX error
112	.It Bq Er ENOTDIR
113	A component of
114	.Fa path 's
115	prefix is not a directory.
116	.It Bq Er ENAMETOOLONG
117	.Fa name
118	exceeds
119	.Dv XATTR_MAXNAMELEN
120	UTF-8 bytes, or a component of
121	.Fa path
122	exceeds
123	.Dv NAME_MAX
124	characters, or the entire
125	.Fa path
126	exceeds
127	.Dv PATH_MAX
128	characters.
129	.It Bq Er EACCES
130	Search permission is denied for a component of
131	.Fa path
132	or permission is denied to read the list of attributes from this file.
133	.It Bq Er ELOOP
134	Too many symbolic links were encountered resolving
135	.Fa path .
136	.It Bq Er EFAULT
137	.Fa path
138	points to an invalid address.
139	.It Bq Er EIO
140	An I/O error occurred.
141	.It Bq Er EINVAL
142	.Fa options
143	does not make sense.
144	.El
145	.Sh SEE ALSO
91447636	146	.Xr getxattr 2 ,
2d21ac55 A	147	.Xr removexattr 2 ,
2d21ac55 A	148	.Xr setxattr 2
91447636 A	149	.Sh HISTORY
	150	.Fn listxattr
	151	and
	152	.Fn flistxattr
	153	first appeared in Mac OS X 10.4.