diff options
Diffstat (limited to 'sysdeps/unix/sysv/linux/faccessat.c')
| -rw-r--r-- | sysdeps/unix/sysv/linux/faccessat.c | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/faccessat.c b/sysdeps/unix/sysv/linux/faccessat.c new file mode 100644 index 0000000..10b903d --- /dev/null +++ b/sysdeps/unix/sysv/linux/faccessat.c @@ -0,0 +1,143 @@ +/* Test for access to file, relative to open directory. Linux version. + Copyright (C) 2006 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library 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 + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +#include <errno.h> +#include <fcntl.h> +#include <stddef.h> +#include <stdio.h> +#include <string.h> +#include <unistd.h> +#include <sys/types.h> +#include <alloca.h> +#include <kernel-features.h> +#include <sysdep.h> + + +int +faccessat (fd, file, mode, flag) + int fd; + const char *file; + int mode; + int flag; +{ + if (flag & ~(AT_SYMLINK_NOFOLLOW | AT_EACCESS)) + { + __set_errno (EINVAL); + return -1; + } + +#ifdef __NR_faccessat + if ((flag == 0 || ((flag & ~AT_EACCESS) == 0 && ! __libc_enable_secure)) +# ifndef __ASSUME_ATFCTS + && __have_atfcts >= 0 +# endif + ) + { + int result = INLINE_SYSCALL (faccessat, 3, fd, file, mode); +# ifndef __ASSUME_ATFCTS + if (result == -1 && errno == ENOSYS) + __have_atfcts = -1; + else +# endif + return result; + } +#endif + +#ifndef __ASSUME_ATFCTS + if ((!(flag & AT_EACCESS) || ! __libc_enable_secure) +# ifndef __NR_laccess /* Linux so far has no laccess syscall. */ + && !(flag & AT_SYMLINK_NOFOLLOW) +# endif + ) + { + /* If we are not set-uid or set-gid, access does the same. */ + char *buf = NULL; + + if (fd != AT_FDCWD && file[0] != '/') + { + size_t filelen = strlen (file); + static const char procfd[] = "/proc/self/fd/%d/%s"; + /* Buffer for the path name we are going to use. It consists of + - the string /proc/self/fd/ + - the file descriptor number + - the file name provided. + The final NUL is included in the sizeof. A bit of overhead + due to the format elements compensates for possible negative + numbers. */ + size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen; + buf = alloca (buflen); + + __snprintf (buf, buflen, procfd, fd, file); + file = buf; + } + + int result; + INTERNAL_SYSCALL_DECL (err); + +# ifdef __NR_laccess + if (flag & AT_SYMLINK_NOFOLLOW) + result = INTERNAL_SYSCALL (laccess, err, 2, file, mode); + else +# endif + result = INTERNAL_SYSCALL (access, err, 2, file, mode); + + if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 0)) + { + __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), fd, buf); + result = -1; + } + + return result; + } +#endif + + struct stat64 stats; + if (fstatat64 (fd, file, &stats, flag & AT_SYMLINK_NOFOLLOW)) + return -1; + + mode &= (X_OK | W_OK | R_OK); /* Clear any bogus bits. */ +#if R_OK != S_IROTH || W_OK != S_IWOTH || X_OK != S_IXOTH +# error Oops, portability assumptions incorrect. +#endif + + if (mode == F_OK) + return 0; /* The file exists. */ + + uid_t uid = (flag & AT_EACCESS) ? __geteuid () : __getuid (); + + /* The super-user can read and write any file, and execute any file + that anyone can execute. */ + if (uid == 0 && ((mode & X_OK) == 0 + || (stats.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH)))) + return 0; + + int granted = (uid == stats.st_uid + ? (unsigned int) (stats.st_mode & (mode << 6)) >> 6 + : (stats.st_gid == ((flag & AT_EACCESS) + ? __getegid () : __getgid ()) + || __group_member (stats.st_gid)) + ? (unsigned int) (stats.st_mode & (mode << 3)) >> 3 + : (stats.st_mode & mode)); + + if (granted == mode) + return 0; + + __set_errno (EACCES); + return -1; +} |