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Diffstat (limited to 'lib/euidaccess.c')
| -rw-r--r-- | lib/euidaccess.c | 221 |
1 files changed, 221 insertions, 0 deletions
diff --git a/lib/euidaccess.c b/lib/euidaccess.c new file mode 100644 index 0000000..5148a5b --- /dev/null +++ b/lib/euidaccess.c @@ -0,0 +1,221 @@ +/* euidaccess -- check if effective user id can access file + + Copyright (C) 1990, 1991, 1995, 1998, 2000, 2003, 2004, 2005, 2006 + 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 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ + +/* Written by David MacKenzie and Torbjorn Granlund. + Adapted for GNU C library by Roland McGrath. */ + +#ifndef _LIBC +# include <config.h> +# include "euidaccess.h" +#endif + +#include <sys/types.h> +#include <sys/stat.h> +#include <unistd.h> + +#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 + +#else + +# include "group-member.h" + +#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 defined EFF_ONLY_OK + return access (file, mode | EFF_ONLY_OK); +#elif defined ACC_SELF + return accessx (file, mode, ACC_SELF); +#elif HAVE_EACCESS + return eaccess (file, mode); +#else + + 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) + return stat (file, &stats); + 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) != 0) + return -1; + + /* The super-user can read and write any file, and execute any file + that anyone can execute. */ + if (euid == 0 && ((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> + +char *program_name; + +int +main (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 |