Add -k option to cvsexportcommit to revert expanded CVS keywords in CVS working tree before applying commit patch

Depending on how your CVS->GIT conversion went you will have some
unexpanded CVS keywords in your GIT repo. If any of your git commits
touch these lines then the patch application will fail. This patch
addresses that by adding an option that will revert and expanded CVS
keywords to files in the working CVS directory that are affected by
the commit being applied.

Signed-off-by: Alex Bennée <alex@bennee.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-cvsexportcommit.txt

@@ -63,6 +63,10 @@ OPTIONS
 -u::
 	Update affected files from CVS repository before attempting export.
 
+-k::
+	Reverse CVS keyword expansion (e.g. $Revision: 1.2.3.4$
+	becomes $Revision$) in working CVS checkout before applying patch.
+
 -w::
 	Specify the location of the CVS checkout to use for the export. This
 	option does not require GIT_DIR to be set before execution if the

git-cvsexportcommit.perl

@@ -8,9 +8,9 @@ use File::Basename qw(basename dirname);
 use File::Spec;
 use Git;
 
-our ($opt_h, $opt_P, $opt_p, $opt_v, $opt_c, $opt_f, $opt_a, $opt_m, $opt_d, $opt_u, $opt_w, $opt_W);
+our ($opt_h, $opt_P, $opt_p, $opt_v, $opt_c, $opt_f, $opt_a, $opt_m, $opt_d, $opt_u, $opt_w, $opt_W, $opt_k);
 
-getopts('uhPpvcfam:d:w:W');
+getopts('uhPpvcfkam:d:w:W');
 
 $opt_h && usage();
 
@@ -287,7 +287,26 @@ foreach my $f (@files) {
 	$dirty = 1;
 	warn "File $f not up to date but has status '$cvsstat{$f}' in your CVS checkout!\n";
     }
+
+    # Depending on how your GIT tree got imported from CVS you may
+    # have a conflict between expanded keywords in your CVS tree and
+    # unexpanded keywords in the patch about to be applied.
+    if ($opt_k) {
+	my $orig_file ="$f.orig";
+	rename $f, $orig_file;
+	open(FILTER_IN, "<$orig_file") or die "Cannot open $orig_file\n";
+	open(FILTER_OUT, ">$f") or die "Cannot open $f\n";
+	while (<FILTER_IN>)
+	{
+	    my $line = $_;
+	    $line =~ s/\$([A-Z][a-z]+):[^\$]+\$/\$\1\$/g;
+	    print FILTER_OUT $line;
+	}
+	close FILTER_IN;
+	close FILTER_OUT;
+    }
 }
+
 if ($dirty) {
     if ($opt_f) {	warn "The tree is not clean -- forced merge\n";
 	$dirty = 0;
@@ -391,7 +410,7 @@ sleep(1);
 
 sub usage {
 	print STDERR <<END;
-Usage: GIT_DIR=/path/to/.git git cvsexportcommit [-h] [-p] [-v] [-c] [-f] [-u] [-w cvsworkdir] [-m msgprefix] [ parent ] commit
+Usage: GIT_DIR=/path/to/.git git cvsexportcommit [-h] [-p] [-v] [-c] [-f] [-u] [-k] [-w cvsworkdir] [-m msgprefix] [ parent ] commit
 END
 	exit(1);
 }