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

.\"
.\" Copyright (c) 2004 Apple Computer, Inc. All rights reserved.
.\"
.\" @APPLE_LICENSE_OSREFERENCE_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.  The rights granted to you under the 
.\" License may not be used to create, or enable the creation or 
.\" redistribution of, unlawful or unlicensed copies of an Apple operating 
.\" system, or to circumvent, violate, or enable the circumvention or 
.\" violation of, any terms of an Apple operating system software license 
.\" agreement.
.\"
.\" 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_OSREFERENCE_HEADER_END@
.\"
.Dd Oct 19, 2004
.Dt SETXATTR 2
.Os "Mac OS X"
.Sh NAME
.Nm setxattr,
.Nm fsetxattr
.Nd set an extended attribute value
.Sh SYNOPSIS
.Fd #include <sys/xattr.h>
.Ft int
.Fn setxattr "const char *path" "const char *name" "void *value" "size_t size" "u_int32_t position" "int options"
.Ft int
.Fn fsetxattr "int fd" "const char *name" "void *value" "size_t size" "u_int32_t position" "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 setxattr
associates
.Fa name
and
.Fa data
together as an attribute of
.Fa path .
.Pp
An extended attribute's
.Fa name
is a simple NULL-terminated UTF-8 string.
.Fa Value
is a pointer to a data buffer of
.Fa size
bytes containing textual or binary data to be associated with the
extended attribute.
.Fa Position
specifies the offset within the extended attribute.  In the current
implementation, only the resource fork extended attribute makes use of
this argument.  For all others,
.Fa position
is reserved and should be
set to zero.
.Pp
.Fa options
controls how the attribute is set:
.Pp
.Bl -tag -width XATTR_NOFOLLOW
.It Dv XATTR_NOFOLLOW
do not follow symbolic links.
.Fn setxattr
normally sets attributes on the target of
.Fa path
if it is a symbolic link.
With this option,
.Fn setxattr
will act on the link itself.
.It Dv XATTR_CREATE
fail if the named attribute already exists.
.It Dv XATTR_REPLACE
fail if the named attribute does not exist.  Failure to specify
.Dv XATTR_REPLACE
or
.Dv XATTR_CREATE
allows creation and replacement.
.El
.Pp
.Fn fsetxattr
is identical to
.Fn setxattr ,
except that it sets an extended attribute on an open file referenced by
file descriptor
.Fa fd .
.Sh RETURN VALUES
On success, 0 is returned.  On failure, -1 is returned and the global
variable
.Va errno
is set as follows.
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er EEXIST
.Fa options
contains
.Em XATTR_CREATE
and the named attribute already exists.
.It Bq Er ENOATTR
.Fa options
is set to
.Em XATTR_REPLACE
and the named attribute does not exist.
.It Bq Er ENOTSUP
The file system does not support extended attributes or has them disabled.
.It Bq Er EROFS
The file system is mounted read-only.
.It Bq Er ERANGE
The data size of the attribute is out of range (some attributes have size
restrictions).
.It Bq Er EPERM
.\" EFTYPE could be more specific but isn't POSIX
Attributes cannot be associated with this type of object.  For example,
attributes are not allowed for resource forks.
.It Bq Er EINVAL
.Fa name
or
.Fa options
is invalid.
.Fa name
must be valid UTF-8 and
.Fa options
must make sense.
.It Bq Er ENOTDIR
A component of
.Fa path
is not a directory.
.It Bq Er ENAMETOOLONG
.Fa name
exceeded
.Dv XATTR_MAXNAMELEN
UTF-8 bytes, or a component of
.Fa path
exceeded
.Dv NAME_MAX
characters, or the entire
.Fa path
exceeded
.Dv PATH_MAX
characters.
.It Bq Er EACCES
Search permission is denied for a component of
.Fa path
or permission to set the attribute is denied.
.It Bq Er ELOOP
Too many symbolic links were encountered resolving
.Fa path .
.It Bq Er EFAULT
.Fa path
or
.Fa name
points to an invalid address.
.It Bq Er EIO
An I/O error occurred while reading from or writing to the file system.
.It Bq Er E2BIG
The data size of the extended attribute is too large.
.It Bq Er ENOSPC
Not enough space left on the file system.
.El
.Sh SEE ALSO
.Xr getxattr 2 ,
.Xr removexattr 2 ,
.Xr listxattr 2
.Sh HISTORY
.Fn setxattr
and
.Fn fsetxattr
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	.\"
8ad349bb A	4	.\" @APPLE_LICENSE_OSREFERENCE_HEADER_START@
	5	.\"
	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. The rights granted to you under the
	10	.\" License may not be used to create, or enable the creation or
	11	.\" redistribution of, unlawful or unlicensed copies of an Apple operating
	12	.\" system, or to circumvent, violate, or enable the circumvention or
	13	.\" violation of, any terms of an Apple operating system software license
	14	.\" agreement.
91447636	15	.\"
8ad349bb A	16	.\" Please obtain a copy of the License at
8ad349bb A	17	.\" http://www.opensource.apple.com/apsl/ and read it before using this
91447636 A	18	.\" file.
91447636 A	19	.\"
8ad349bb A	20	.\" The Original Code and all software distributed under the License are
	21	.\" distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
	22	.\" EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
	23	.\" INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
	24	.\" FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	25	.\" Please see the License for the specific language governing rights and
91447636 A	26	.\" limitations under the License.
91447636 A	27	.\"
8ad349bb	28	.\" @APPLE_LICENSE_OSREFERENCE_HEADER_END@
91447636 A	29	.\"
	30	.Dd Oct 19, 2004
	31	.Dt SETXATTR 2
	32	.Os "Mac OS X"
	33	.Sh NAME
	34	.Nm setxattr,
	35	.Nm fsetxattr
	36	.Nd set an extended attribute value
	37	.Sh SYNOPSIS
	38	.Fd #include <sys/xattr.h>
	39	.Ft int
	40	.Fn setxattr "const char path" "const char name" "void *value" "size_t size" "u_int32_t position" "int options"
	41	.Ft int
	42	.Fn fsetxattr "int fd" "const char name" "void value" "size_t size" "u_int32_t position" "int options"
	43	.Sh DESCRIPTION
	44	Extended attributes extend the basic attributes associated with files and
	45	directories in the file system. They are stored as name:data pairs
	46	associated with file system objects (files, directories, symlinks, etc).
	47	.Pp
	48	.Fn setxattr
	49	associates
	50	.Fa name
	51	and
	52	.Fa data
	53	together as an attribute of
	54	.Fa path .
	55	.Pp
	56	An extended attribute's
	57	.Fa name
	58	is a simple NULL-terminated UTF-8 string.
	59	.Fa Value
	60	is a pointer to a data buffer of
	61	.Fa size
	62	bytes containing textual or binary data to be associated with the
	63	extended attribute.
	64	.Fa Position
	65	specifies the offset within the extended attribute. In the current
	66	implementation, only the resource fork extended attribute makes use of
	67	this argument. For all others,
	68	.Fa position
	69	is reserved and should be
	70	set to zero.
	71	.Pp
	72	.Fa options
	73	controls how the attribute is set:
	74	.Pp
	75	.Bl -tag -width XATTR_NOFOLLOW
	76	.It Dv XATTR_NOFOLLOW
	77	do not follow symbolic links.
	78	.Fn setxattr
	79	normally sets attributes on the target of
	80	.Fa path
	81	if it is a symbolic link.
	82	With this option,
	83	.Fn setxattr
	84	will act on the link itself.
	85	.It Dv XATTR_CREATE
	86	fail if the named attribute already exists.
	87	.It Dv XATTR_REPLACE
	88	fail if the named attribute does not exist. Failure to specify
	89	.Dv XATTR_REPLACE
	90	or
	91	.Dv XATTR_CREATE
	92	allows creation and replacement.
93	.El
94	.Pp
95	.Fn fsetxattr
96	is identical to
97	.Fn setxattr ,
98	except that it sets an extended attribute on an open file referenced by
99	file descriptor
100	.Fa fd .
101	.Sh RETURN VALUES
102	On success, 0 is returned. On failure, -1 is returned and the global
103	variable
104	.Va errno
105	is set as follows.
106	.Sh ERRORS
107	.Bl -tag -width Er
108	.It Bq Er EEXIST
109	.Fa options
110	contains
111	.Em XATTR_CREATE
112	and the named attribute already exists.
113	.It Bq Er ENOATTR
114	.Fa options
115	is set to
116	.Em XATTR_REPLACE
117	and the named attribute does not exist.
118	.It Bq Er ENOTSUP
119	The file system does not support extended attributes or has them disabled.
120	.It Bq Er EROFS
121	The file system is mounted read-only.
122	.It Bq Er ERANGE
123	The data size of the attribute is out of range (some attributes have size
124	restrictions).
125	.It Bq Er EPERM
126	.\" EFTYPE could be more specific but isn't POSIX
127	Attributes cannot be associated with this type of object. For example,
128	attributes are not allowed for resource forks.
129	.It Bq Er EINVAL
130	.Fa name
131	or
132	.Fa options
133	is invalid.
134	.Fa name
135	must be valid UTF-8 and
136	.Fa options
137	must make sense.
138	.It Bq Er ENOTDIR
139	A component of
140	.Fa path
141	is not a directory.
142	.It Bq Er ENAMETOOLONG
143	.Fa name
144	exceeded
145	.Dv XATTR_MAXNAMELEN
146	UTF-8 bytes, or a component of
147	.Fa path
148	exceeded
149	.Dv NAME_MAX
150	characters, or the entire
151	.Fa path
152	exceeded
153	.Dv PATH_MAX
154	characters.
155	.It Bq Er EACCES
156	Search permission is denied for a component of
157	.Fa path
158	or permission to set the attribute is denied.
159	.It Bq Er ELOOP
160	Too many symbolic links were encountered resolving
161	.Fa path .
162	.It Bq Er EFAULT
163	.Fa path
164	or
165	.Fa name
166	points to an invalid address.
167	.It Bq Er EIO
168	An I/O error occurred while reading from or writing to the file system.
169	.It Bq Er E2BIG
170	The data size of the extended attribute is too large.
171	.It Bq Er ENOSPC
172	Not enough space left on the file system.
173	.El
174	.Sh SEE ALSO
175	.Xr getxattr 2 ,
176	.Xr removexattr 2 ,
177	.Xr listxattr 2
178	.Sh HISTORY
179	.Fn setxattr
180	and
181	.Fn fsetxattr
182	first appeared in Mac OS X 10.4.