# HG changeset patch
# User Paul Eggert <eggert@cs.ucla.edu>
# Date 1160084290 0
# Node ID e23b1333a117dd51319d2bea370c5720be48f5bf
# Parent  cb56735ed8f5597d31905e49330e1aaf7da01175
[lib/ChangeLog]
* fcntl_.h (O_NOFOLLOW): Don't depend on O_NOFOLLOW_IS_INEFFECTIVE;
we now test for that separately.
* fts.c (fts_safe_changedir): Inspect HAVE_WORKING_O_NOFOLLOW
rather than O_NOFOLLOW, when testing whether it's possible to
avoid a race condition reliably.
* savewd.c (savewd_chdir): Likewise.
[m4/ChangeLog]
* fcntl_h.m4 (gl_FCNTL_H): Define HAVE_WORKING_O_NOFOLLOW instead
of O_NOFOLLOW_IS_INEFFECTIVE.  Define HAVE_WORKING_O_NOATIME if
O_NOATIME works.

diff --git a/lib/ChangeLog b/lib/ChangeLog
--- a/lib/ChangeLog
+++ b/lib/ChangeLog
@@ -1,5 +1,12 @@
 2006-10-05  Paul Eggert  <eggert@cs.ucla.edu>
 
+	* fcntl_.h (O_NOFOLLOW): Don't depend on O_NOFOLLOW_IS_INEFFECTIVE;
+	we now test for that separately.
+	* fts.c (fts_safe_changedir): Inspect HAVE_WORKING_O_NOFOLLOW
+	rather than O_NOFOLLOW, when testing whether it's possible to
+	avoid a race condition reliably.
+	* savewd.c (savewd_chdir): Likewise.
+
 	Remove macros that are no longer needed now that stdint.h is
 	reliable.
 	* fsusage.c (UINTMAX_MAX): Remove.
diff --git a/lib/fcntl_.h b/lib/fcntl_.h
--- a/lib/fcntl_.h
+++ b/lib/fcntl_.h
@@ -59,9 +59,6 @@
 # define O_NOCTTY 0
 #endif
 
-#ifdef O_NOFOLLOW_IS_INEFFECTIVE
-# undef O_NOFOLLOW
-#endif
 #ifndef O_NOFOLLOW
 # define O_NOFOLLOW 0
 #endif
diff --git a/lib/fts.c b/lib/fts.c
--- a/lib/fts.c
+++ b/lib/fts.c
@@ -1421,7 +1421,7 @@
 	   general (when the target is not ".."), diropen's use of
 	   O_NOFOLLOW ensures we don't mistakenly follow a symlink,
 	   so we can avoid the expense of this fstat.  */
-	if (ISSET(FTS_LOGICAL) || O_NOFOLLOW == 0
+	if (ISSET(FTS_LOGICAL) || ! HAVE_WORKING_O_NOFOLLOW
 	    || (dir && STREQ (dir, "..")))
 	  {
 	    struct stat sb;
diff --git a/lib/savewd.c b/lib/savewd.c
--- a/lib/savewd.c
+++ b/lib/savewd.c
@@ -103,7 +103,8 @@
 
   /* Open the directory if requested, or if avoiding a race condition
      is requested and possible.  */
-  if (open_result || (options & (O_NOFOLLOW ? SAVEWD_CHDIR_NOFOLLOW : 0)))
+  if (open_result
+      || (options & (HAVE_WORKING_O_NOFOLLOW ? SAVEWD_CHDIR_NOFOLLOW : 0)))
     {
       fd = open (dir,
 		 (O_RDONLY | O_DIRECTORY | O_NOCTTY | O_NONBLOCK
diff --git a/m4/ChangeLog b/m4/ChangeLog
--- a/m4/ChangeLog
+++ b/m4/ChangeLog
@@ -1,3 +1,9 @@
+2006-10-05  Paul Eggert  <eggert@cs.ucla.edu>
+
+	* fcntl_h.m4 (gl_FCNTL_H): Define HAVE_WORKING_O_NOFOLLOW instead
+	of O_NOFOLLOW_IS_INEFFECTIVE.  Define HAVE_WORKING_O_NOATIME if
+	O_NOATIME works.
+
 2006-10-01  Bruno Haible  <bruno@clisp.org>
 
 	Make it possible to invoke AC_GNU_SOURCE after gl_LOCK_EARLY.
diff --git a/m4/fcntl_h.m4 b/m4/fcntl_h.m4
--- a/m4/fcntl_h.m4
+++ b/m4/fcntl_h.m4
@@ -15,6 +15,9 @@
 	   #include <sys/stat.h>
 	   #include <unistd.h>
 	   #include <fcntl.h>
+	   #ifndef O_NOATIME
+	    #define O_NOATIME 0
+	   #endif
 	   #ifndef O_NOFOLLOW
 	    #define O_NOFOLLOW 0
 	   #endif
@@ -24,23 +27,52 @@
 	      O_NONBLOCK, O_SYNC, O_ACCMODE, O_RDONLY, O_RDWR, O_WRONLY
 	    };
 	  ]],
-	  [[static char const sym[] = "conftest.sym";
-	    if (O_NOFOLLOW)
-	      {
-		if (symlink (".", sym) != 0)
-		  return 1;
-		if (0 <= open (sym, O_RDONLY | O_NOFOLLOW))
-		  return 1;
-	      }
-	    return !constants;]])],
+	  [[
+	    int status = !constants;
+	    {
+	      static char const sym[] = "conftest.sym";
+	      if (symlink (".", sym) != 0
+		  || close (open (sym, O_RDONLY | O_NOFOLLOW)) == 0)
+		status |= 32;
+	    }
+	    {
+	      static char const file[] = "confdefs.h";
+	      int fd = open (file, O_RDONLY | O_NOATIME);
+	      char c;
+	      struct stat st0, st1;
+	      if (fd < 0
+		  || fstat (fd, &st0) != 0
+		  || sleep (1) != 0
+		  || read (fd, &c, 1) != 1
+		  || close (fd) != 0
+		  || stat (file, &st1) != 0
+		  || st1.st_mtime <= st0.st_mtime
+		  || close (fd) != 0)
+		status |= 64;
+	    }
+	    return status;]])],
        [gl_cv_header_working_fcntl_h=yes],
-       [gl_cv_header_working_fcntl_h=no],
+       [case $? in #(
+	32) gl_cv_header_working_fcntl_h='no (bad O_NOFOLLOW)';; #(
+	64) gl_cv_header_working_fcntl_h='no (bad O_NOATIME)';; #(
+	96) gl_cv_header_working_fcntl_h='no (bad O_NOATIME, O_NOFOLLOW)';; #(
+	 *) gl_cv_header_working_fcntl_h='no';;
+	esac],
        [gl_cv_header_working_fcntl_h=cross-compiling])])
 
-  if test $gl_cv_header_working_fcntl_h != yes; then
-    AC_DEFINE([O_NOFOLLOW_IS_INEFFECTIVE], 1,
-      [Define to 1 if O_NOFOLLOW is ineffective.])
-  fi
+  case $gl_cv_header_working_fcntl_h in #(
+  *O_NOATIME* | no | cross-compiling) ac_val=0;; #(
+  *) ac_val=1;;
+  esac
+  AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOATIME], [$ac_val],
+    [Define to 1 if O_NOATIME works.])
+
+  case $gl_cv_header_working_fcntl_h in #(
+  *O_NOFOLLOW* | no | cross-compiling) ac_val=0;; #(
+  *) ac_val=1;;
+  esac
+  AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOFOLLOW], [$ac_val],
+    [Define to 1 if O_NOFOLLOW works.])
 
   gl_ABSOLUTE_HEADER([fcntl.h])
   ABSOLUTE_FCNTL_H=\"$gl_cv_absolute_fcntl_h\"