[PATCH] Add merge detection to git-cvsimport

Added -m and -M flags for git-cvsimport to detect merge commits in cvs.
While this trusts the commit message, in repositories where merge commits
indicate 'merged from FOOBRANCH' the import works surprisingly well.

Even if some merges from CVS are bogus or incomplete, the resulting
branches are in better state to go forward (and merge) than without any
merge detection.

Signed-off-by: Martin Langhoff <martin.langhoff@gmail.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 44 insertions, 4 deletions

diff --git a/git-cvsimport-script b/git-cvsimport-script
index 2f39af33d9..1f36acea22 100755
--- a/git-cvsimport-script
+++ b/git-cvsimport-script
@@ -28,19 +28,19 @@ use POSIX qw(strftime dup2);
 $SIG{'PIPE'}="IGNORE";
 $ENV{'TZ'}="UTC";
 
-our($opt_h,$opt_o,$opt_v,$opt_k,$opt_d,$opt_p,$opt_C,$opt_z,$opt_i,$opt_s);
+our($opt_h,$opt_o,$opt_v,$opt_k,$opt_d,$opt_p,$opt_C,$opt_z,$opt_i,$opt_s,$opt_m,$opt_M);
 
 sub usage() {
 	print STDERR <<END;
 Usage: ${\basename $0}     # fetch/update GIT from CVS
        [ -o branch-for-HEAD ] [ -h ] [ -v ] [ -d CVSROOT ]
        [ -p opts-for-cvsps ] [ -C GIT_repository ] [ -z fuzz ]
-       [ -i ] [ -k ] [-s subst] [ CVS_module ]
+       [ -i ] [ -k ] [-s subst] [ -m ] [ -M regex] [ CVS_module ]
 END
 	exit(1);
 }
 
-getopts("hivko:d:p:C:z:s:") or usage();
+getopts("hivmko:d:p:C:z:s:M:") or usage();
 usage if $opt_h;
 
 @ARGV <= 1 or usage();
@@ -71,11 +71,19 @@ if ($#ARGV == 0) {
 	    die 'Failed to open CVS/Repository';
 	$cvs_tree = <$f>;
 	chomp $cvs_tree;
-	close $f
+	close $f;
 } else {
 	usage();
 }
 
+our @mergerx = ();
+if ($opt_m) {
+	@mergerx = ( qr/\W(?:from|of|merge|merging|merged) (\w+)/i );
+}
+if ($opt_M) {
+	push (@mergerx, qr/$opt_M/);
+}
+
 select(STDERR); $|=1; select(STDOUT);
 
 
@@ -375,6 +383,22 @@ sub getwd() {
 	return $pwd;
 }
 
+
+sub get_headref($$) {
+    my $name    = shift;
+    my $git_dir = shift; 
+    my $sha;
+    
+    if (open(C,"$git_dir/refs/heads/$name")) {
+	chomp($sha = <C>);
+	close(C);
+	length($sha) == 40
+	    or die "Cannot get head id for $name ($sha): $!\n";
+    }
+    return $sha;
+}
+
+
 -d $git_tree
 	or mkdir($git_tree,0777)
 	or die "Could not create $git_tree: $!";
@@ -549,6 +573,22 @@ my $commit = sub {
 
 		my @par = ();
 		@par = ("-p",$parent) if $parent;
+
+		# loose detection of merges
+		# based on the commit msg
+		foreach my $rx (@mergerx) {
+			if ($logmsg =~ $rx) {
+				my $mparent = $1;
+				if ($mparent eq 'HEAD') { $mparent = 'origin'};
+				if ( -e "$git_dir/refs/heads/$mparent") {
+					$mparent = get_headref($mparent, $git_dir);
+					push @par, '-p', $mparent;
+					# printing here breaks import # 
+					# # print "Merge parent branch: $mparent\n" if $opt_v;
+				}
+		    	} 
+		}
+
 		exec("env",
 			"GIT_AUTHOR_NAME=$author",
 			"GIT_AUTHOR_EMAIL=$author",