* io/fcntl.h [__USE_ATFILE] (AT_EACCESS): New macro.

* posix/unistd.h [__USE_ATFILE]: Declare faccessat.
	* io/faccessat.c: New file.
	* sysdeps/unix/sysv/linux/faccessat.c: New file.
	* io/Makefile (routines): Add faccessat.
	* io/Versions (libc: GLIBC_2.4): Likewise.
	* io/tst-faccessat.c: New file.
	* io/Makefile (tests): Add it.

	* io/sys/stat.h: Likewise.

ChangeLog

@@ -1,5 +1,14 @@
 2006-01-06  Roland McGrath  <roland@redhat.com>
 
+	* io/fcntl.h [__USE_ATFILE] (AT_EACCESS): New macro.
+	* posix/unistd.h [__USE_ATFILE]: Declare faccessat.
+	* io/faccessat.c: New file.
+	* sysdeps/unix/sysv/linux/faccessat.c: New file.
+	* io/Makefile (routines): Add faccessat.
+	* io/Versions (libc: GLIBC_2.4): Likewise.
+	* io/tst-faccessat.c: New file.
+	* io/Makefile (tests): Add it.
+
 	* scripts/check-local-headers.sh: Revert last change.
 
 	* io/euidaccess.c: Add eaccess as an alias.
@@ -67,6 +76,7 @@
 	* libio/stdio.h: Likewise.
 	* posix/unistd.h: Likewise.
 	* time/sys/time.h: Likewise.
+	* io/sys/stat.h: Likewise.
 
 	* io/sys/stat.h [__USE_GNU]: Declare fchmodat.
 	* io/fchmodat.c: New file.

io/Makefile

@@ -35,10 +35,10 @@ routines :=								\
 	fxstatat fxstatat64						\
 	statfs fstatfs statfs64 fstatfs64				\
 	statvfs fstatvfs statvfs64 fstatvfs64				\
-	umask chmod fchmod lchmod fchmodat \
+	umask chmod fchmod lchmod fchmodat				\
 	mkdir mkdirat							\
 	open open64 openat openat64 close				\
-	read write lseek lseek64 access euidaccess			\
+	read write lseek lseek64 access euidaccess faccessat		\
 	fcntl flock lockf lockf64					\
 	dup dup2 pipe							\
 	creat creat64							\
@@ -64,7 +64,7 @@ test-srcs	:= ftwtest
 tests		:= test-utime test-stat test-stat2 test-lfs tst-getcwd \
 		   tst-fcntl bug-ftw1 bug-ftw2 bug-ftw3 bug-ftw4 tst-statvfs \
 		   tst-openat tst-unlinkat tst-fstatat tst-futimesat \
-		   tst-renameat tst-fchownat tst-fchmodat
+		   tst-renameat tst-fchownat tst-fchmodat tst-faccessat
 
 distribute	:= ftwtest-sh
 

io/Versions

@@ -100,6 +100,7 @@ libc {
   GLIBC_2.4 {
     eaccess;
 
+    faccessat;
     fchmodat;
     fchownat;
     __fxstatat; __fxstatat64;

io/faccessat.c

@@ -0,0 +1,51 @@
+/* Test for access to file, relative to open directory.  Stub 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 <unistd.h>
+#include <sys/types.h>
+
+int
+faccessat (fd, file, type, flag)
+     int fd;
+     const char *file;
+     int type;
+     int flag;
+{
+  if (file == NULL || (flag & ~(AT_SYMLINK_NOFOLLOW | AT_EACCESS)) != 0
+      || (type & ~(R_OK|W_OK|X_OK|F_OK)) != 0)
+    {
+      __set_errno (EINVAL);
+      return -1;
+    }
+
+  if (fd < 0 && fd != AT_FDCWD)
+    {
+      __set_errno (EBADF);
+      return -1;
+    }
+
+  __set_errno (ENOSYS);
+  return -1;
+}
+stub_warning (faccessat)
+
+#include <stub-tag.h>

io/fcntl.h

@@ -63,6 +63,8 @@ __BEGIN_DECLS
 # define AT_SYMLINK_NOFOLLOW	0x100	/* Do not follow symbolic links.  */
 # define AT_REMOVEDIR		0x200	/* Remove directory instead of
 					   unlinking file.  */
+# define AT_EACCESS		0x200	/* Test access permitted for
+					   effective IDs, not real IDs.  */
 #endif
 
 /* Do the file control operation described by CMD on FD.

io/sys/stat.h

@@ -228,7 +228,7 @@ extern int stat64 (__const char *__restrict __file,
 extern int fstat64 (int __fd, struct stat64 *__buf) __THROW __nonnull ((2));
 #endif
 
-#ifdef __USE_GNU
+#ifdef __USE_ATFILE
 /* Similar to stat, get the attributes for FILE and put them in BUF.
    Relative path names are interpreted relative to FD unless FD is
    AT_FDCWD.  */
@@ -293,12 +293,12 @@ extern int lchmod (__const char *__file, __mode_t __mode)
 extern int fchmod (int __fd, __mode_t __mode) __THROW;
 #endif
 
-#ifdef __USE_GNU
+#ifdef __USE_ATFILE
 /* Set file access permissions of FILE relative to
    the directory FD is open on.  */
 extern int fchmodat (int __fd, __const char *__file, __mode_t mode, int __flag)
      __THROW __nonnull ((2)) __wur;
-#endif /* Use GNU.  */
+#endif /* Use ATFILE.  */
 
 
 
@@ -316,7 +316,7 @@ extern __mode_t getumask (void) __THROW;
 extern int mkdir (__const char *__path, __mode_t __mode)
      __THROW __nonnull ((1));
 
-#ifdef __USE_GNU
+#ifdef __USE_ATFILE
 /* Like mkdir, create a new directory with permission bits MODE.  But
    interpret relative PATH names relative to the directory associated
    with FD.  */
@@ -332,7 +332,7 @@ extern int mknod (__const char *__path, __mode_t __mode, __dev_t __dev)
      __THROW __nonnull ((1));
 #endif
 
-#ifdef __USE_GNU
+#ifdef __USE_ATFILE
 /* Like mknod, create a new device file with permission bits MODE and
    device number DEV.  But interpret relative PATH names relative to
    the directory associated with FD.  */
@@ -345,7 +345,7 @@ extern int mknodat (int __fd, __const char *__path, __mode_t __mode,
 extern int mkfifo (__const char *__path, __mode_t __mode)
      __THROW __nonnull ((1));
 
-#ifdef __USE_GNU
+#ifdef __USE_ATFILE
 /* Like mkfifo, create a new FIFO with permission bits MODE.  But
    interpret relative PATH names relative to the directory associated
    with FD.  */
@@ -450,7 +450,7 @@ __NTH (fstat (int __fd, struct stat *__statbuf))
   return __fxstat (_STAT_VER, __fd, __statbuf);
 }
 
-# ifdef __USE_GNU
+# ifdef __USE_ATFILE
 extern __inline__ int
 __NTH (fstatat (int __fd, __const char *__filename, struct stat *__statbuf,
 		int __flag))
@@ -467,7 +467,7 @@ __NTH (mknod (__const char *__path, __mode_t __mode, __dev_t __dev))
 }
 # endif
 
-# ifdef __USE_GNU
+# ifdef __USE_ATFILE
 extern __inline__ int
 __NTH (mknodat (int __fd, __const char *__path, __mode_t __mode,
 		__dev_t __dev))

io/tst-faccessat.c

@@ -0,0 +1,153 @@
+/* Test for faccessat function.  */
+
+#include <dirent.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+
+static void prepare (void);
+#define PREPARE(argc, argv) prepare ()
+
+static int do_test (void);
+#define TEST_FUNCTION do_test ()
+
+#include "../test-skeleton.c"
+
+static int dir_fd;
+
+static void
+prepare (void)
+{
+  size_t test_dir_len = strlen (test_dir);
+  static const char dir_name[] = "/tst-faccessat.XXXXXX";
+
+  size_t dirbuflen = test_dir_len + sizeof (dir_name);
+  char *dirbuf = malloc (dirbuflen);
+  if (dirbuf == NULL)
+    {
+      puts ("out of memory");
+      exit (1);
+    }
+
+  snprintf (dirbuf, dirbuflen, "%s%s", test_dir, dir_name);
+  if (mkdtemp (dirbuf) == NULL)
+    {
+      puts ("cannot create temporary directory");
+      exit (1);
+    }
+
+  add_temp_file (dirbuf);
+
+  dir_fd = open (dirbuf, O_RDONLY | O_DIRECTORY);
+  if (dir_fd == -1)
+    {
+      puts ("cannot open directory");
+      exit (1);
+    }
+}
+
+
+static int
+do_test (void)
+{
+  /* fdopendir takes over the descriptor, make a copy.  */
+  int dupfd = dup (dir_fd);
+  if (dupfd == -1)
+    {
+      puts ("dup failed");
+      return 1;
+    }
+  if (lseek (dupfd, 0, SEEK_SET) != 0)
+    {
+      puts ("1st lseek failed");
+      return 1;
+    }
+
+  /* The directory should be empty save the . and .. files.  */
+  DIR *dir = fdopendir (dupfd);
+  if (dir == NULL)
+    {
+      puts ("fdopendir failed");
+      return 1;
+    }
+  struct dirent64 *d;
+  while ((d = readdir64 (dir)) != NULL)
+    if (strcmp (d->d_name, ".") != 0 && strcmp (d->d_name, "..") != 0)
+      {
+	printf ("temp directory contains file \"%s\"\n", d->d_name);
+	return 1;
+      }
+  closedir (dir);
+
+  /* Try to create a file.  */
+  int fd = openat (dir_fd, "some-file", O_CREAT|O_RDWR|O_EXCL, 0666);
+  if (fd == -1)
+    {
+      if (errno == ENOSYS)
+	{
+	  puts ("*at functions not supported");
+	  return 0;
+	}
+
+      puts ("file creation failed");
+      return 1;
+    }
+  write (fd, "hello", 5);
+  puts ("file created");
+
+  close (fd);
+
+  int result = 0;
+
+  if (faccessat (dir_fd, "some-file", F_OK, AT_EACCESS))
+    {
+      printf ("faccessat F_OK: %m\n");
+      result = 1;
+    }
+  if (faccessat (dir_fd, "some-file", W_OK, AT_EACCESS))
+    {
+      printf ("faccessat W_OK: %m\n");
+      result = 1;
+    }
+
+  errno = 0;
+  if (faccessat (dir_fd, "some-file", X_OK, AT_EACCESS) == 0
+      || errno != EACCES)
+    {
+      printf ("faccessat X_OK on nonexecutable: %m\n");
+      result = 1;
+    }
+
+  if (fchmodat (dir_fd, "some-file", 0400, 0) != 0)
+    {
+      printf ("fchownat failed: %m\n");
+      return 1;
+    }
+
+  if (faccessat (dir_fd, "some-file", R_OK, AT_EACCESS))
+    {
+      printf ("faccessat R_OK: %m\n");
+      result = 1;
+    }
+
+  errno = 0;
+  if (faccessat (dir_fd, "some-file", W_OK, AT_EACCESS) == 0
+      || errno != EACCES)
+    {
+      printf ("faccessat W_OK on unwritable file: %m\n");
+      result = 1;
+    }
+
+  if (unlinkat (dir_fd, "some-file", 0) != 0)
+    {
+      puts ("unlinkat failed");
+      result = 1;
+    }
+
+  close (dir_fd);
+
+  return result;
+}

posix/unistd.h

@@ -266,6 +266,14 @@ extern int eaccess (__const char *__name, int __type)
      __THROW __nonnull ((1));
 #endif
 
+#ifdef __USE_ATFILE
+/* Test for access to FILE relative to the directory FD is open on.
+   If AT_EACCESS is set in FLAG, then use effective IDs like `eaccess',
+   otherwise use real IDs like `access'.  */
+extern int faccessat (int __fd, __const char *__file, int __type, int __flag)
+     __THROW __nonnull ((2)) __wur;
+#endif /* Use GNU.  */
+
 
 /* Values for the WHENCE argument to lseek.  */
 #ifndef	_STDIO_H		/* <stdio.h> has the same definitions.  */

sysdeps/unix/sysv/linux/faccessat.c

@@ -0,0 +1,123 @@
+/* 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 <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;
+    }
+
+  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;
+    }
+
+  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.  */
+
+      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;
+    }
+
+  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;
+}