1 /* euidaccess -- check if effective user id can access file
2 Copyright (C) 1990, 1991, 1995, 1998 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Library General Public License as
8 published by the Free Software Foundation; either version 2 of the
9 License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Library General Public License for more details.
16 You should have received a copy of the GNU Library General Public
17 License along with the GNU C Library; see the file COPYING.LIB. If
18 not, write to the Free Software Foundation, Inc., 59 Temple Place -
19 Suite 330, Boston, MA 02111-1307, USA. */
21 /* Written by David MacKenzie and Torbjorn Granlund.
22 Adapted for GNU C library by Roland McGrath. */
28 #include <sys/types.h>
33 # define S_IXUSR S_IEXEC
36 # define S_IXGRP (S_IEXEC >> 3)
39 # define S_IXOTH (S_IEXEC >> 6)
43 #if defined (HAVE_UNISTD_H) || defined (_LIBC)
49 # if !defined(NGROUPS_MAX) || NGROUPS_MAX < 1
51 # define NGROUPS_MAX sysconf (_SC_NGROUPS_MAX)
52 # endif /* NGROUPS_MAX */
54 #else /* not _POSIX_VERSION */
59 # include <sys/param.h>
60 # if !defined(NGROUPS_MAX) && defined(NGROUPS)
61 # define NGROUPS_MAX NGROUPS
62 # endif /* not NGROUPS_MAX and NGROUPS */
63 #endif /* not POSIX_VERSION */
70 #if defined(EACCES) && !defined(EACCESS)
71 # define EACCESS EACCES
81 #if !defined (S_IROTH) && defined (R_OK)
85 #if !defined (S_IWOTH) && defined (W_OK)
89 #if !defined (S_IXOTH) && defined (X_OK)
95 # define group_member __group_member
99 /* The user's real user id. */
102 /* The user's real group id. */
105 /* The user's effective user id. */
108 /* The user's effective group id. */
111 /* Nonzero if UID, GID, EUID, and EGID have valid values. */
112 static int have_ids = 0;
117 # define group_member(gid) 0
123 /* Return 0 if the user has permission of type MODE on file PATH;
124 otherwise, return -1 and set `errno' to EACCESS.
125 Like access, except that it uses the effective user and group
126 id's instead of the real ones, and it does not check for read-only
127 filesystem, text busy, etc. */
130 euidaccess (const char *path, int mode)
136 uid_t uid = getuid (), euid = geteuid ();
137 gid_t gid = getgid (), egid = getegid ();
149 if (uid == euid && gid == egid)
150 /* If we are not set-uid or set-gid, access does the same. */
151 return access (path, mode);
153 if (stat (path, &stats))
156 mode &= (X_OK | W_OK | R_OK); /* Clear any bogus bits. */
157 #if R_OK != S_IROTH || W_OK != S_IWOTH || X_OK != S_IXOTH
158 ?error Oops, portability assumptions incorrect.
162 return 0; /* The file exists. */
164 /* The super-user can read and write any file, and execute any file
165 that anyone can execute. */
166 if (euid == 0 && ((mode & X_OK) == 0
167 || (stats.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH))))
170 if (euid == stats.st_uid)
171 granted = (unsigned) (stats.st_mode & (mode << 6)) >> 6;
172 else if (egid == stats.st_gid || group_member (stats.st_gid))
173 granted = (unsigned) (stats.st_mode & (mode << 3)) >> 3;
175 granted = (stats.st_mode & mode);