[unix-history] / lib / libc / sys / readlink.2

.\" Copyright (c) 1983, 1991 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)readlink.2	6.8 (Berkeley) 3/10/91
.\"
.Dd March 10, 1991
.Dt READLINK 2
.Os BSD 4.2
.Sh NAME
.Nm readlink
.Nd read value of a symbolic link
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft int
.Fn readlink "const char *path" "char *buf" "int bufsiz"
.Sh DESCRIPTION
.Fn Readlink
places the contents of the symbolic link
.Fa path
in the buffer
.Fa buf ,
which has size
.Fa bufsiz .
.Nm Readlink
does not append a
.Dv NUL
character to
.Fa buf .
.Sh RETURN VALUES
The call returns the count of characters placed in the buffer
if it succeeds, or a -1 if an error occurs, placing the error
code in the global variable
.Va errno .
.Sh ERRORS
.Fn Readlink
will fail if:
.Bl -tag -width ENAMETOOLONG
.It Bq Er ENOTDIR
A component of the path prefix is not a directory.
.It Bq Er EINVAL
The pathname contains a character with the high-order bit set.
.It Bq Er ENAMETOOLONG
A component of a pathname exceeded 255 characters,
or an entire path name exceeded 1023 characters.
.It Bq Er ENOENT
The named file does not exist.
.It Bq Er EACCES
Search permission is denied for a component of the path prefix.
.It Bq Er ELOOP
Too many symbolic links were encountered in translating the pathname.
.It Bq Er EINVAL
The named file is not a symbolic link.
.It Bq Er EIO
An I/O error occurred while reading from the file system.
.It Bq Er EFAULT
.Fa Buf
extends outside the process's allocated address space.
.El
.Sh SEE ALSO
.Xr stat 2 ,
.Xr lstat 2 ,
.Xr symlink 2
.Sh HISTORY
The
.Nm
function call appeared in
.Bx 4.2 .
Commit	Line	Data
15637ed4 RG	1	.\" Copyright (c) 1983, 1991 The Regents of the University of California.
	2	.\" All rights reserved.
	3	.\"
	4	.\" Redistribution and use in source and binary forms, with or without
	5	.\" modification, are permitted provided that the following conditions
	6	.\" are met:
	7	.\" 1. Redistributions of source code must retain the above copyright
	8	.\" notice, this list of conditions and the following disclaimer.
	9	.\" 2. Redistributions in binary form must reproduce the above copyright
	10	.\" notice, this list of conditions and the following disclaimer in the
	11	.\" documentation and/or other materials provided with the distribution.
	12	.\" 3. All advertising materials mentioning features or use of this software
	13	.\" must display the following acknowledgement:
	14	.\" This product includes software developed by the University of
	15	.\" California, Berkeley and its contributors.
	16	.\" 4. Neither the name of the University nor the names of its contributors
	17	.\" may be used to endorse or promote products derived from this software
	18	.\" without specific prior written permission.
	19	.\"
	20	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	21	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	22	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	23	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	24	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	25	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	26	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	27	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	28	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	29	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	30	.\" SUCH DAMAGE.
	31	.\"
	32	.\" @(#)readlink.2 6.8 (Berkeley) 3/10/91
	33	.\"
	34	.Dd March 10, 1991
	35	.Dt READLINK 2
	36	.Os BSD 4.2
	37	.Sh NAME
	38	.Nm readlink
	39	.Nd read value of a symbolic link
	40	.Sh SYNOPSIS
	41	.Fd #include <unistd.h>
	42	.Ft int
	43	.Fn readlink "const char path" "char buf" "int bufsiz"
	44	.Sh DESCRIPTION
	45	.Fn Readlink
	46	places the contents of the symbolic link
	47	.Fa path
	48	in the buffer
	49	.Fa buf ,
	50	which has size
	51	.Fa bufsiz .
	52	.Nm Readlink
	53	does not append a
	54	.Dv NUL
	55	character to
	56	.Fa buf .
	57	.Sh RETURN VALUES
	58	The call returns the count of characters placed in the buffer
	59	if it succeeds, or a -1 if an error occurs, placing the error
	60	code in the global variable
	61	.Va errno .
	62	.Sh ERRORS
	63	.Fn Readlink
	64	will fail if:
65	.Bl -tag -width ENAMETOOLONG
66	.It Bq Er ENOTDIR
67	A component of the path prefix is not a directory.
68	.It Bq Er EINVAL
69	The pathname contains a character with the high-order bit set.
70	.It Bq Er ENAMETOOLONG
71	A component of a pathname exceeded 255 characters,
72	or an entire path name exceeded 1023 characters.
73	.It Bq Er ENOENT
74	The named file does not exist.
75	.It Bq Er EACCES
76	Search permission is denied for a component of the path prefix.
77	.It Bq Er ELOOP
78	Too many symbolic links were encountered in translating the pathname.
79	.It Bq Er EINVAL
80	The named file is not a symbolic link.
81	.It Bq Er EIO
82	An I/O error occurred while reading from the file system.
83	.It Bq Er EFAULT
84	.Fa Buf
85	extends outside the process's allocated address space.
86	.El
87	.Sh SEE ALSO
88	.Xr stat 2 ,
89	.Xr lstat 2 ,
90	.Xr symlink 2
91	.Sh HISTORY
92	The
93	.Nm
94	function call appeared in
95	.Bx 4.2 .