mirror of
https://git.savannah.gnu.org/git/emacs.git
synced 2024-12-14 09:39:42 +00:00
227 lines
6.1 KiB
C
227 lines
6.1 KiB
C
/* euidaccess -- check if effective user id can access file
|
||
|
||
Copyright (C) 1990-1991, 1995, 1998, 2000, 2003-2006, 2008-2021 Free
|
||
Software Foundation, Inc.
|
||
|
||
This file is part of the GNU C Library.
|
||
|
||
This program is free software: you can redistribute it and/or modify
|
||
it under the terms of the GNU General Public License as published by
|
||
the Free Software Foundation; either version 3 of the License, or
|
||
(at your option) any later version.
|
||
|
||
This program is distributed in the hope that it will be useful,
|
||
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||
GNU General Public License for more details.
|
||
|
||
You should have received a copy of the GNU General Public License
|
||
along with this program. If not, see <https://www.gnu.org/licenses/>. */
|
||
|
||
/* Written by David MacKenzie and Torbjorn Granlund.
|
||
Adapted for GNU C library by Roland McGrath. */
|
||
|
||
#ifndef _LIBC
|
||
# include <config.h>
|
||
#endif
|
||
|
||
#include <fcntl.h>
|
||
#include <sys/types.h>
|
||
#include <sys/stat.h>
|
||
#include <unistd.h>
|
||
#if defined _WIN32 && ! defined __CYGWIN__
|
||
# include <io.h>
|
||
#else
|
||
# include "root-uid.h"
|
||
#endif
|
||
|
||
#if HAVE_LIBGEN_H
|
||
# include <libgen.h>
|
||
#endif
|
||
|
||
#include <errno.h>
|
||
#ifndef __set_errno
|
||
# define __set_errno(val) errno = (val)
|
||
#endif
|
||
|
||
#if defined EACCES && !defined EACCESS
|
||
# define EACCESS EACCES
|
||
#endif
|
||
|
||
#ifndef F_OK
|
||
# define F_OK 0
|
||
# define X_OK 1
|
||
# define W_OK 2
|
||
# define R_OK 4
|
||
#endif
|
||
|
||
|
||
#ifdef _LIBC
|
||
|
||
# define access __access
|
||
# define getuid __getuid
|
||
# define getgid __getgid
|
||
# define geteuid __geteuid
|
||
# define getegid __getegid
|
||
# define group_member __group_member
|
||
# define euidaccess __euidaccess
|
||
# undef stat
|
||
# define stat stat64
|
||
|
||
#endif
|
||
|
||
/* Return 0 if the user has permission of type MODE on FILE;
|
||
otherwise, return -1 and set 'errno'.
|
||
Like access, except that it uses the effective user and group
|
||
id's instead of the real ones, and it does not always check for read-only
|
||
file system, text busy, etc. */
|
||
|
||
int
|
||
euidaccess (const char *file, int mode)
|
||
{
|
||
#if HAVE_FACCESSAT /* glibc, AIX 7, Solaris 11, Cygwin 1.7 */
|
||
return faccessat (AT_FDCWD, file, mode, AT_EACCESS);
|
||
#elif defined EFF_ONLY_OK /* IRIX, OSF/1, Interix */
|
||
return access (file, mode | EFF_ONLY_OK);
|
||
#elif defined ACC_SELF /* AIX */
|
||
return accessx (file, mode, ACC_SELF);
|
||
#elif HAVE_EACCESS /* FreeBSD */
|
||
return eaccess (file, mode);
|
||
#elif defined _WIN32 && ! defined __CYGWIN__ /* mingw */
|
||
return _access (file, mode);
|
||
#else /* Mac OS X, NetBSD, OpenBSD, HP-UX, Solaris, Cygwin, BeOS */
|
||
|
||
uid_t uid = getuid ();
|
||
gid_t gid = getgid ();
|
||
uid_t euid = geteuid ();
|
||
gid_t egid = getegid ();
|
||
struct stat stats;
|
||
|
||
# if HAVE_DECL_SETREGID && PREFER_NONREENTRANT_EUIDACCESS
|
||
|
||
/* Define PREFER_NONREENTRANT_EUIDACCESS if you prefer euidaccess to
|
||
return the correct result even if this would make it
|
||
nonreentrant. Define this only if your entire application is
|
||
safe even if the uid or gid might temporarily change. If your
|
||
application uses signal handlers or threads it is probably not
|
||
safe. */
|
||
|
||
if (mode == F_OK)
|
||
{
|
||
int result = stat (file, &stats);
|
||
return result != 0 && errno == EOVERFLOW ? 0 : result;
|
||
}
|
||
else
|
||
{
|
||
int result;
|
||
int saved_errno;
|
||
|
||
if (uid != euid)
|
||
setreuid (euid, uid);
|
||
if (gid != egid)
|
||
setregid (egid, gid);
|
||
|
||
result = access (file, mode);
|
||
saved_errno = errno;
|
||
|
||
/* Restore them. */
|
||
if (uid != euid)
|
||
setreuid (uid, euid);
|
||
if (gid != egid)
|
||
setregid (gid, egid);
|
||
|
||
errno = saved_errno;
|
||
return result;
|
||
}
|
||
|
||
# else
|
||
|
||
/* The following code assumes the traditional Unix model, and is not
|
||
correct on systems that have ACLs or the like. However, it's
|
||
better than nothing, and it is reentrant. */
|
||
|
||
unsigned int granted;
|
||
if (uid == euid && gid == egid)
|
||
/* If we are not set-uid or set-gid, access does the same. */
|
||
return access (file, mode);
|
||
|
||
if (stat (file, &stats) == -1)
|
||
return mode == F_OK && errno == EOVERFLOW ? 0 : -1;
|
||
|
||
/* The super-user can read and write any file, and execute any file
|
||
that anyone can execute. */
|
||
if (euid == ROOT_UID
|
||
&& ((mode & X_OK) == 0
|
||
|| (stats.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH))))
|
||
return 0;
|
||
|
||
/* Convert the mode to traditional form, clearing any bogus bits. */
|
||
if (R_OK == 4 && W_OK == 2 && X_OK == 1 && F_OK == 0)
|
||
mode &= 7;
|
||
else
|
||
mode = ((mode & R_OK ? 4 : 0)
|
||
+ (mode & W_OK ? 2 : 0)
|
||
+ (mode & X_OK ? 1 : 0));
|
||
|
||
if (mode == 0)
|
||
return 0; /* The file exists. */
|
||
|
||
/* Convert the file's permission bits to traditional form. */
|
||
if (S_IRUSR == (4 << 6) && S_IWUSR == (2 << 6) && S_IXUSR == (1 << 6)
|
||
&& S_IRGRP == (4 << 3) && S_IWGRP == (2 << 3) && S_IXGRP == (1 << 3)
|
||
&& S_IROTH == (4 << 0) && S_IWOTH == (2 << 0) && S_IXOTH == (1 << 0))
|
||
granted = stats.st_mode;
|
||
else
|
||
granted = ((stats.st_mode & S_IRUSR ? 4 << 6 : 0)
|
||
+ (stats.st_mode & S_IWUSR ? 2 << 6 : 0)
|
||
+ (stats.st_mode & S_IXUSR ? 1 << 6 : 0)
|
||
+ (stats.st_mode & S_IRGRP ? 4 << 3 : 0)
|
||
+ (stats.st_mode & S_IWGRP ? 2 << 3 : 0)
|
||
+ (stats.st_mode & S_IXGRP ? 1 << 3 : 0)
|
||
+ (stats.st_mode & S_IROTH ? 4 << 0 : 0)
|
||
+ (stats.st_mode & S_IWOTH ? 2 << 0 : 0)
|
||
+ (stats.st_mode & S_IXOTH ? 1 << 0 : 0));
|
||
|
||
if (euid == stats.st_uid)
|
||
granted >>= 6;
|
||
else if (egid == stats.st_gid || group_member (stats.st_gid))
|
||
granted >>= 3;
|
||
|
||
if ((mode & ~granted) == 0)
|
||
return 0;
|
||
__set_errno (EACCESS);
|
||
return -1;
|
||
|
||
# endif
|
||
#endif
|
||
}
|
||
#undef euidaccess
|
||
#ifdef weak_alias
|
||
weak_alias (__euidaccess, euidaccess)
|
||
#endif
|
||
|
||
#ifdef TEST
|
||
# include <error.h>
|
||
# include <stdio.h>
|
||
# include <stdlib.h>
|
||
|
||
int
|
||
main (int argc, char **argv)
|
||
{
|
||
char *file;
|
||
int mode;
|
||
int err;
|
||
|
||
if (argc < 3)
|
||
abort ();
|
||
file = argv[1];
|
||
mode = atoi (argv[2]);
|
||
|
||
err = euidaccess (file, mode);
|
||
printf ("%d\n", err);
|
||
if (err != 0)
|
||
error (0, errno, "%s", file);
|
||
exit (0);
|
||
}
|
||
#endif
|