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/* eaccess -- check if effective user id can access file
Copyright (C) 1990, 1991 Free Software Foundation, Inc.
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 2, 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, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
/* Written by David MacKenzie and Torbjorn Granlund. */
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <sys/types.h>
#include <sys/stat.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef _POSIX_VERSION
#include <limits.h>
#if !defined(NGROUPS_MAX) || NGROUPS_MAX < 1
#undef NGROUPS_MAX
#define NGROUPS_MAX sysconf (_SC_NGROUPS_MAX)
#endif /* NGROUPS_MAX */
#else /* not _POSIX_VERSION */
uid_t geteuid ();
gid_t getegid ();
#include <sys/param.h>
#if !defined(NGROUPS_MAX) && defined(NGROUPS)
#define NGROUPS_MAX NGROUPS
#endif /* not NGROUPS_MAX and NGROUPS */
#endif /* not POSIX_VERSION */
#include <errno.h>
#ifndef STDC_HEADERS
extern int errno;
#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
int eaccess_stat ();
/* The user's effective user id. */
static uid_t euid;
/* The user's effective group id. */
static gid_t egid;
#ifdef NGROUPS_MAX
char *xmalloc ();
static int in_group ();
/* Array of group id's that the user is in. */
static GETGROUPS_T *groups = 0;
/* The number of valid elements in `groups'. */
static int ngroups;
#endif
/* Nonzero if the other static variables have valid values. */
static int initialized = 0;
/* Return 0 if the user has permission of type MODE on file PATH;
otherwise, return -1 and set `errno' to EACCESS.
Like access, except that it uses the effective user and group
id's instead of the real ones, and it does not check for read-only
filesystem, text busy, etc. */
int
eaccess (path, mode)
char *path;
int mode;
{
struct stat stats;
if (stat (path, &stats))
return -1;
return eaccess_stat (&stats, mode);
}
/* Like eaccess, except that a pointer to a filled-in stat structure
describing the file is provided instead of a filename. */
int
eaccess_stat (statp, mode)
struct stat *statp;
int mode;
{
int granted;
mode &= (X_OK | W_OK | R_OK); /* Clear any bogus bits. */
if (mode == F_OK)
return 0; /* The file exists. */
if (initialized == 0)
{
initialized = 1;
euid = geteuid ();
egid = getegid ();
#ifdef NGROUPS_MAX
groups = (GETGROUPS_T *)
xmalloc ((unsigned) NGROUPS_MAX * sizeof (GETGROUPS_T));
ngroups = getgroups ((int) NGROUPS_MAX, groups);
#endif
}
/* The super-user can read and write any file, and execute any file
that anyone can execute. */
if (euid == 0 && ((mode & X_OK) == 0 || (statp->st_mode & 0111)))
return 0;
if (euid == statp->st_uid)
granted = (unsigned) (statp->st_mode & (mode << 6)) >> 6;
else if (egid == statp->st_gid
#ifdef NGROUPS_MAX
|| in_group (statp->st_gid)
#endif
)
granted = (unsigned) (statp->st_mode & (mode << 3)) >> 3;
else
granted = (statp->st_mode & mode);
if (granted == mode)
return 0;
errno = EACCESS;
return -1;
}
#ifdef NGROUPS_MAX
static int
in_group (gid)
GETGROUPS_T gid;
{
int i;
for (i = 0; i < ngroups; i++)
if (gid == groups[i])
return 1;
return 0;
}
#endif
#ifdef TEST
main (argc, argv)
char **argv;
{
printf ("%d\n", eaccess (argv[1], atoi (argv[2])));
}
#endif
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