# [PATCH] Add merge detection to git-cvsimport

4 messages from 2005-08-16 to 2005-08-17. Participants: Martin Langhoff, Sven Verdoolaege, Matthias Urlichs.
Thread: https://gitlist.dev/t/1533

## Martin Langhoff, 2005-08-16 10:35

Subject: [PATCH] Add merge detection to git-cvsimport
Message-ID: <20050816103527.F420A33010C@ng.eduforge.org>
URL: https://gitlist.dev/e/20050816103527.F420A33010C%40ng.eduforge.org

```
[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>
---

 Documentation/git-cvsimport-script.txt |   13 ++++++++-
 git-cvsimport-script                   |   48 +++++++++++++++++++++++++++++---
 2 files changed, 56 insertions(+), 5 deletions(-)

066d2cb2435a963ee40e4899a76848ea51e972d2
diff --git a/Documentation/git-cvsimport-script.txt b/Documentation/git-cvsimport-script.txt
--- a/Documentation/git-cvsimport-script.txt
+++ b/Documentation/git-cvsimport-script.txt
@@ -11,7 +11,8 @@ SYNOPSIS
 --------
 'git-cvsimport-script' [ -o <branch-for-HEAD> ] [ -h ] [ -v ]
 			[ -d <CVSROOT> ] [ -p <options-for-cvsps> ]
-			[ -C <GIT_repository> ] [ -i ] [ -k ] [ <CVS_module> ]
+			[ -C <GIT_repository> ] [ -i ] [ -k ] 
+			[ -m ] [ -M regex ] [ <CVS_module> ]
 
 
 DESCRIPTION
@@ -57,6 +58,16 @@ OPTIONS
 
 	If you need to pass multiple options, separate them with a comma.
 
+-m::    
+	Attempt to detect merges based on the commit message. This option
+	will enable default regexes that try to capture the name source 
+	branch name from the commit message. 
+
+-M <regex>::
+	Attempt to detect merges based on the commit message with a custom
+	regex. It can be used with -m to also see the default regexes. 
+	You must escape forward slashes. 
+
 -v::
 	Verbosity: let 'cvsimport' report what it is doing.
 
diff --git a/git-cvsimport-script b/git-cvsimport-script
--- 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,$opt_i);
+our($opt_h,$opt_o,$opt_v,$opt_k,$opt_d,$opt_p,$opt_C,$opt_z,$opt_i,$opt_m,$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 ] [ CVS_module ]
+       [ -i ] [ -k ] [ -m ] [ -M regex] [ CVS_module ]
 END
 	exit(1);
 }
 
-getopts("hivko:d:p:C:z:") or usage();
+getopts("hivmko:d:p:C:z:M:") or usage();
 usage if $opt_h;
 
 @ARGV <= 1 or usage();
@@ -70,11 +70,19 @@ 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);
 
 
@@ -374,6 +382,22 @@ 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: $!";
@@ -548,6 +572,22 @@ 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",

```

## Sven Verdoolaege, 2005-08-16 11:07

Subject: Re: [PATCH] Add merge detection to git-cvsimport
Message-ID: <20050816110725.GL11882MdfPADPa@garage.linux.student.kuleuven.ac.be>
URL: https://gitlist.dev/e/20050816110725.GL11882MdfPADPa%40garage.linux.student.kuleuven.ac.be
In-Reply-To: <20050816103527.F420A33010C@ng.eduforge.org>

```
On Tue, Aug 16, 2005 at 10:35:27PM +1200, Martin Langhoff wrote:
> +
> +sub get_headref($$) {

If you want to check whether a ref is valid, then
it is better to use git-rev-parse...

> +    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";

... but if you're just going to die, then why not simply
let git-commit-tree do the test ?

> +				if ($mparent eq 'HEAD') { $mparent = 'origin'};

Please don't hardcode 'origin' here.

skimo

```

## Martin Langhoff, 2005-08-16 21:36

Subject: Re: [PATCH] Add merge detection to git-cvsimport
Message-ID: <46a038f9050816143646fa4137@mail.gmail.com>
URL: https://gitlist.dev/e/46a038f9050816143646fa4137%40mail.gmail.com
In-Reply-To: <20050816110725.GL11882MdfPADPa@garage.linux.student.kuleuven.ac.be>

```
On 8/16/05, Sven Verdoolaege <skimo@kotnet.org> wrote:
> On Tue, Aug 16, 2005 at 10:35:27PM +1200, Martin Langhoff wrote:
> > +
> > +sub get_headref($$) {
> 
> If you want to check whether a ref is valid, then
> it is better to use git-rev-parse...

We are reading/writing directly to .git/refs/heads/ a lot in this
script. Not changing that for the time being.

> > +    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";
> 
> ... but if you're just going to die, then why not simply
> let git-commit-tree do the test ?

Because we get the head names from cvsps output, and we want to have a
specific error when cvsps has given us a bogus branch name.
git-commit-tree could fail for a number of reasons, this one is the
most likely one to be from a bug in cvsps or the cvsimport logic.
 
> > +                             if ($mparent eq 'HEAD') { $mparent = 'origin'};
> 
> Please don't hardcode 'origin' here.

Duh! Patch submitted. Juniooooo! 


martin

```

## Matthias Urlichs, 2005-08-17 17:29

Subject: Re: [PATCH] Add merge detection to git-cvsimport
Message-ID: <pan.2005.08.17.17.29.26.687298@smurf.noris.de>
URL: https://gitlist.dev/e/pan.2005.08.17.17.29.26.687298%40smurf.noris.de
In-Reply-To: <46a038f9050816143646fa4137@mail.gmail.com>

```
Hi, Martin Langhoff wrote:

> this one is the
> most likely one to be from a bug in cvsps or the cvsimport logic.

That's not a bug in the import logic, just a failure of the CVS-merging
person to be consistent. (Which is hardly news. :-/ )

-- 
Matthias Urlichs   |   {M:U} IT Design @ m-u-it.de   |  smurf@smurf.noris.de
Disclaimer: The quote was selected randomly. Really. | http://smurf.noris.de
 - -
Reason:
	Bad, toxic entity, that foolish people use when they ought to use
	their inner voice, or angels, or intuition, or a gut feeling, or
	their hearts, or the I Ching.
		-- Fashionable Dictionary (www.butterfliesandwheels.com)

```