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-rw-r--r--sysdeps/unix/sysv/linux/faccessat.c143
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
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+++ b/sysdeps/unix/sysv/linux/faccessat.c
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+/* 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;
+}