1 .\" Copyright (c) 1980, 1991, 1993
2 .\" The Regents of the University of California. All rights reserved.
4 .\" Redistribution and use in source and binary forms, with or without
5 .\" modification, are permitted provided that the following conditions
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.
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
32 .\" @(#)access.2 8.2 (Berkeley) 4/1/94
35 .Dd September 21, 2001
40 .Nd check accessibility of a file
46 .Fn access "const char *path" "int mode"
48 .Fn eaccess "const char *path" "int mode"
54 functions check the accessibility of the
59 for the access permissions indicated by
65 is either the bitwise-inclusive OR of the access permissions to be
70 for write permission, and
72 for execute/search permission),
76 For additional information, see the
77 .Sx "File Access Permission"
84 the effective user ID and the group access list
85 to authorize the request;
89 the real user ID in place of the effective user ID,
90 the real group ID in place of the effective group ID,
91 and the rest of the group access list.
93 Even if a process's real or effective user has appropriate privileges
94 and indicates success for
96 the file may not actually have execute permission bits set.
104 Access to the file is denied if:
107 A component of the path prefix is not a directory.
108 .It Bq Er ENAMETOOLONG
109 A component of a pathname exceeded 255 characters,
110 or an entire path name exceeded 1023 characters.
112 The named file does not exist.
114 Too many symbolic links were encountered in translating the pathname.
116 Write access is requested for a file on a read-only file system.
118 Write access is requested for a pure procedure (shared text)
119 file presently being executed.
121 Permission bits of the file mode do not permit the requested
122 access, or search permission is denied on a component of the
126 points outside the process's allocated address space.
128 An I/O error occurred while reading from or writing to the file system.
130 .Sh SECURITY CONSIDERATIONS
134 is a potential security hole due to race conditions and
135 should never be used.
136 Set-user-ID and set-group-ID applications should restore the
137 effective user or group ID,
138 and perform actions directly rather than use
140 to simulate access checks for the real user or group ID.
144 likewise may be subject to races if used inappropriately.
152 function call is expected to conform to
157 function call appeared in