From: Alexandre Duret-Lutz <adl@gnu.org>
Date: Fri, 4 Aug 2006 08:42:54 +0000 (+0000)
Subject: * aclocal.in (install_file): Cannot use /dev/null while diffing
X-Git-Tag: v1.10.2~193
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=76542b15689ffa5b24587f3ea4d2e3c0fef37586;p=platform%2Fupstream%2Fautomake.git

* aclocal.in (install_file): Cannot use /dev/null while diffing
new files, because Tru64's diff do not handle /dev/null.  So
create an empty destination file before running diff on a new
file, and erase it afterward.  Fall back to using /dev/null only
if we cannot create this file.
Report and initial patch from Ralf Wildenhues.
(unlink_tmp): New function.
* test/acloca18.test: Make sure the empty file has been erased.
---

diff --git a/ChangeLog b/ChangeLog
index 5a73452..922599a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2006-08-04  Alexandre Duret-Lutz  <adl@gnu.org>
+
+	* aclocal.in (install_file): Cannot use /dev/null while diffing
+	new files, because Tru64's diff do not handle /dev/null.  So
+	create an empty destination file before running diff on a new
+	file, and erase it afterward.  Fall back to using /dev/null only
+	if we cannot create this file.
+	Report and initial patch from Ralf Wildenhues.
+	(unlink_tmp): New function.
+	* test/acloca18.test: Make sure the empty file has been erased.
+
 2006-08-04  Ralf Wildenhues  <Ralf.Wildenhues@gmx.de>
 
 	* automake.in (handle_LIBOBJS_or_ALLOCA): With subdir-objects,
diff --git a/aclocal.in b/aclocal.in
index acb05d2..5cc280f 100644
--- a/aclocal.in
+++ b/aclocal.in
@@ -144,9 +144,25 @@ my $serial_number_rx = '^\d+(?:\.\d+)*$';
 # Autoconf version
 # Set by trace_used_macros.
 my $ac_version;
+
+# If set, names a temporary file that must be erased on abnormal exit.
+my $erase_me;
 
 ################################################################
 
+# Erase temporary file ERASE_ME.
+sub unlink_tmp
+{
+  if (defined $erase_me && -e $erase_me && !unlink ($erase_me))
+    {
+      fatal "could not remove `$erase_me': $!";
+    }
+  undef $erase_me;
+}
+
+$SIG{'INT'} = $SIG{'TERM'} = $SIG{'QUIT'} = $SIG{'HUP'} = 'unlink_tmp';
+END { unlink_tmp }
+
 # Check macros in acinclude.m4.  If one is not used, warn.
 sub check_acinclude ()
 {
@@ -180,7 +196,7 @@ sub reset_maps ()
 sub install_file ($$)
 {
   my ($src, $dest) = @_;
-  my $diff_dest = $dest;
+  my $diff_dest;
 
   if ($force_output
       || !exists $file_contents{$dest}
@@ -189,21 +205,48 @@ sub install_file ($$)
       if (-e $dest)
 	{
 	  msg 'note', "overwriting `$dest' with `$src'";
+	  $diff_dest = $dest;
 	}
       else
 	{
 	  msg 'note', "installing `$dest' from `$src'";
-	  $diff_dest = '/dev/null';
 	}
 
       if (@diff_command)
 	{
+	  if (! defined $diff_dest)
+	    {
+	      # $dest does not exist.  We create an empty one just to
+	      # run diff, and we erase it afterward.  Using the real
+	      # the destination file (rather than a temporary file) is
+	      # good when diff is run with options that display the
+	      # file name.
+	      #
+	      # If creating $dest fails, fall back to /dev/null.  At
+	      # least one diff implementation (Tru64's) cannot deal
+	      # with /dev/null.  However working around this is not
+	      # worth the trouble since nobody run aclocal on a
+	      # read-only tree anyway.
+	      $erase_me = $dest;
+	      my $f = new IO::File "> $dest";
+	      if (! defined $f)
+		{
+		  undef $erase_me;
+		  $diff_dest = '/dev/null';
+		}
+	      else
+		{
+		  $diff_dest = $dest;
+		  $f->close;
+		}
+	    }
 	  my @cmd = (@diff_command, $diff_dest, $src);
 	  $! = 0;
 	  verb "running: @cmd";
 	  my $res = system (@cmd);
 	  Automake::FileUtils::handle_exec_errors "@cmd", 1
 	    if $res;
+	  unlink_tmp;
 	}
       elsif (!$dry_run)
 	{
diff --git a/tests/acloca18.test b/tests/acloca18.test
index 42ee8e6..0b6dfe2 100755
--- a/tests/acloca18.test
+++ b/tests/acloca18.test
@@ -1,5 +1,5 @@
 #! /bin/sh
-# Copyright (C) 2005  Free Software Foundation, Inc.
+# Copyright (C) 2005, 2006  Free Software Foundation, Inc.
 #
 # This file is part of GNU Automake.
 #
@@ -109,6 +109,9 @@ AC_DEFUN([AM_MACRO1], [echo macro1d >> foo])
 AC_DEFUN([AM_MACRO2], [echo macro2d >> foo])
 EOF
 rm -f foo
-$ACLOCAL --diff=diff >output
+$ACLOCAL --diff=diff >output 2>stderr
+cat stderr
 cat output
 grep '#serial 456' output
+test ! -f 4/m1.m4
+grep 'installing.*4/m1.m4' stderr