gitweb: check given hash before trying to create snapshot

Makes things nicer in cases when you hand craft the snapshot URL but
make a typo in defining the hash variable (e.g. netx instead of next);
you will now get an error message instead of a broken tarball.

Tests for t9501 are included to demonstrate added functionality.

Signed-off-by: Mark Rada <marada@uwaterloo.ca>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

1 files changed, 5 insertions, 2 deletions

diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index 24b219310a..8d4a2ae600 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -5196,8 +5196,11 @@ sub git_snapshot {
 		die_error(403, "Unsupported snapshot format");
 	}
 
-	if (!defined $hash) {
-		$hash = git_get_head_hash($project);
+	my $type = git_get_type("$hash^{}");
+	if (!$type) {
+		die_error(404, 'Object does not exist');
+	}  elsif ($type eq 'blob') {
+		die_error(400, 'Object is not a tree-ish');
 	}
 
 	my $name = $project;