[PATCH] git-svn: Add 'find-rev' command

Signed-off-by: Adam Roben <redacted>
---
This is an updated version of my previous patch that takes Eric and Junio's
comments into account.

 Documentation/git-svn.txt |    6 ++++++
 git-svn.perl              |   23 +++++++++++++++++++++++
 2 files changed, 29 insertions(+), 0 deletions(-)

diff --git a/Documentation/git-svn.txt b/Documentation/git-svn.txt
index a0d34e0..482c862 100644
--- a/Documentation/git-svn.txt
+++ b/Documentation/git-svn.txt

@@ -159,6 +159,12 @@ New features:
 Any other arguments are passed directly to `git log'
 
 --
+'find-rev'::
+	When given an SVN revision number of the form 'rN', returns the
+        corresponding git commit hash (this can optionally be followed by a
+        tree-ish to specify which branch should be searched).  When given a
+        tree-ish, returns the corresponding SVN revision number.
+
 'set-tree'::
 	You should consider using 'dcommit' instead of this command.
 	Commit specified commit or tree objects to SVN.  This relies on

diff --git a/git-svn.perl b/git-svn.perl
index 7b5f8ab..30e4a41 100755
--- a/git-svn.perl
+++ b/git-svn.perl

@@ -141,6 +141,8 @@ my %cmd = (
 			  'color' => \$Git::SVN::Log::color,
 			  'pager=s' => \$Git::SVN::Log::pager,
 			} ],
+	'find-rev' => [ \&cmd_find_rev, "Translate between SVN revision numbers and tree-ish",
+			{ } ],
 	'rebase' => [ \&cmd_rebase, "Fetch and rebase your working directory",
 			{ 'merge|m|M' => \$_merge,
 			  'verbose|v' => \$_verbose,

@@ -428,6 +430,27 @@ sub cmd_dcommit {
 	command_noisy(@finish, $gs->refname);
 }
 
+sub cmd_find_rev {
+	my $revision_or_hash = shift;
+	my $result;
+	if ($revision_or_hash =~ /^r\d+$/) {
+		my $head = shift;
+		$head ||= 'HEAD';
+		my @refs;
+		my (undef, undef, undef, $gs) = working_head_info($head, \@refs);
+		unless ($gs) {
+			die "Unable to determine upstream SVN information from ",
+			    "$head history\n";
+		}
+		my $desired_revision = substr($revision_or_hash, 1);
+		$result = $gs->rev_db_get($desired_revision);
+	} else {
+		my (undef, $rev, undef) = cmt_metadata($revision_or_hash);
+		$result = $rev;
+	}
+	print "$result\n" if $result;
+}
+
 sub cmd_rebase {
 	command_noisy(qw/update-index --refresh/);
 	my ($url, $rev, $uuid, $gs) = working_head_info('HEAD');