From e877a260796d62b11117a118db743f63351dc14d Mon Sep 17 00:00:00 2001 From: Jim Meyering Date: Tue, 1 Nov 1994 14:50:16 +0000 Subject: Initial revision --- lib/euidaccess.c | 203 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 203 insertions(+) create mode 100644 lib/euidaccess.c (limited to 'lib/euidaccess.c') diff --git a/lib/euidaccess.c b/lib/euidaccess.c new file mode 100644 index 000000000..1073c9741 --- /dev/null +++ b/lib/euidaccess.c @@ -0,0 +1,203 @@ +/* euidaccess -- 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 +#endif + +#include +#include + +#ifdef HAVE_UNISTD_H +#include +#endif + +#ifdef _POSIX_VERSION +#include +#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 getuid (); +gid_t getgid (); +uid_t geteuid (); +gid_t getegid (); +#include +#if !defined(NGROUPS_MAX) && defined(NGROUPS) +#define NGROUPS_MAX NGROUPS +#endif /* not NGROUPS_MAX and NGROUPS */ +#endif /* not POSIX_VERSION */ + +#include +#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 + +#include "safe-stat.h" + +/* The user's real user id. */ +static uid_t uid; + +/* The user's real group id. */ +static gid_t gid; + +/* The user's effective user id. */ +static uid_t euid; + +/* The user's effective group id. */ +static gid_t egid; + +int group_member (); + +/* Nonzero if UID, GID, EUID, and EGID have valid values. */ +static int have_ids = 0; + +/* Like euidaccess, except that a pointer to a filled-in stat structure + describing the file is provided instead of a filename. + Because this function is almost guaranteed to fail on systems that + use ACLs, a third argument *PATH may be used. If it is non-NULL, + it is assumed to be the name of the file corresponding to STATP. + Then, if the user is not running set-uid or set-gid, use access + instead of attempting a manual and non-portable comparison. */ + +int +eaccess_stat (statp, mode, path) + struct stat *statp; + int mode; + char *path; +{ + int granted; + + mode &= (X_OK | W_OK | R_OK); /* Clear any bogus bits. */ + + if (mode == F_OK) + return 0; /* The file exists. */ + + if (have_ids == 0) + { + have_ids = 1; + uid = getuid (); + gid = getgid (); + euid = geteuid (); + egid = getegid (); + } + + if (path && uid == euid && gid == egid) + { + return access (path, mode); + } + + /* 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 & (S_IXUSR | S_IXGRP | S_IXOTH)))) + return 0; + + if (euid == statp->st_uid) + granted = (unsigned) (statp->st_mode & (mode << 6)) >> 6; + else if (egid == statp->st_gid +#ifdef HAVE_GETGROUPS + || group_member (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; +} + +/* 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 +euidaccess (path, mode) + char *path; + int mode; +{ + struct stat stats; + + if (have_ids == 0) + { + have_ids = 1; + uid = getuid (); + gid = getgid (); + euid = geteuid (); + egid = getegid (); + } + + if (uid == euid && gid == egid) + { + return access (path, mode); + } + + if (SAFE_STAT (path, &stats)) + return -1; + + return eaccess_stat (&stats, mode, path); +} + +#ifdef TEST +#include +#include + +void error (); + +char *program_name; + +int +main (argc, argv) + int argc; + char **argv; +{ + char *file; + int mode; + int err; + + program_name = argv[0]; + 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 -- cgit v1.2.3-54-g00ecf