install-reloc: Support multi-binary installation.

[gnulib.git] / lib / chdir-safer.c

diff --git a/lib/chdir-safer.c b/lib/chdir-safer.c
index 5c313bc..7c7b0c1 100644 (file)
--- a/lib/chdir-safer.c
+++ b/lib/chdir-safer.c
@@ -1,11 +1,11 @@
 /* much like chdir(2), but safer
 
-   Copyright (C) 2005, 2006 Free Software Foundation, Inc.
+   Copyright (C) 2005-2006, 2008-2013 Free Software Foundation, Inc.
 
-   This program is free software; you can redistribute it and/or modify
+   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.
+   the Free Software Foundation; either version 3 of the License, 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
@@ -13,14 +13,11 @@
    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.  */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 /* written by Jim Meyering */
 
-#ifdef HAVE_CONFIG_H
-# include <config.h>
-#endif
+#include <config.h>
 
 #include "chdir-safer.h"
 
@@ -32,46 +29,47 @@
 #include <sys/stat.h>
 #include "same-inode.h"
 
-#ifndef O_DIRECTORY
-# define O_DIRECTORY 0
-#endif
-
-#ifndef O_NOFOLLOW
-# define O_NOFOLLOW 0
+#ifndef HAVE_READLINK
+# define HAVE_READLINK 0
 #endif
 
 /* Like chdir, but fail if DIR is a symbolic link to a directory (or
-   similar funny business), or if DIR is not readable.  This avoids a
-   minor race condition between when a directory is created or statted
-   and when the process chdirs into it.  */
+   similar funny business).  This avoids a minor race condition
+   between when a directory is created or statted and when the process
+   chdirs into it.
+
+   On older systems lacking full support for O_SEARCH, this function
+   can also fail if DIR is not readable.  */
 int
 chdir_no_follow (char const *dir)
 {
   int result = 0;
   int saved_errno;
   int fd = open (dir,
-                O_RDONLY | O_DIRECTORY | O_NOCTTY | O_NOFOLLOW | O_NONBLOCK);
+                 O_SEARCH | O_DIRECTORY | O_NOCTTY | O_NOFOLLOW | O_NONBLOCK);
   if (fd < 0)
     return -1;
 
   /* If open follows symlinks, lstat DIR and fstat FD to ensure that
      they are the same file; if they are different files, set errno to
      ELOOP (the same value that open uses for symlinks with
-     O_NOFOLLOW) so the caller can report a failure.  */
-  if (! O_NOFOLLOW)
+     O_NOFOLLOW) so the caller can report a failure.
+     Skip this check if HAVE_READLINK == 0, which should be the case
+     on any system that lacks symlink support.  */
+  if (HAVE_READLINK && ! HAVE_WORKING_O_NOFOLLOW)
     {
       struct stat sb1;
       result = lstat (dir, &sb1);
       if (result == 0)
-       {
-         struct stat sb2;
-         result = fstat (fd, &sb2);
-         if (result == 0 && ! SAME_INODE (sb1, sb2))
-           {
-             errno = ELOOP;
-             result = -1;
-           }
-       }
+        {
+          struct stat sb2;
+          result = fstat (fd, &sb2);
+          if (result == 0 && ! SAME_INODE (sb1, sb2))
+            {
+              errno = ELOOP;
+              result = -1;
+            }
+        }
     }
 
   if (result == 0)