From e07f113726f46b8ab921ceecd4e282d93b39c2a2 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Sun, 9 Jul 2017 14:12:47 +0100
Subject: [PATCH] Dgit.pm: git_cat_file: Introduce $etype parameter

No functional change for existing callers.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---
 Debian/Dgit.pm | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/Debian/Dgit.pm b/Debian/Dgit.pm
index f299450b..abcf1236 100644
--- a/Debian/Dgit.pm
+++ b/Debian/Dgit.pm
@@ -348,11 +348,21 @@ sub git_rev_parse ($) {
     return cmdoutput qw(git rev-parse), "$_[0]~0";
 }
 
-sub git_cat_file ($) {
-    my ($objname) = @_;
+sub git_cat_file ($;$) {
+    my ($objname, $etype) = @_;
     # => ($type, $data) or ('missing', undef)
     # in scalar context, just the data
+    # if $etype defined, dies unless type is $etype or in @$etype
     our ($gcf_pid, $gcf_i, $gcf_o);
+    my $chk = sub {
+	my ($gtype, $data) = @_;
+	if ($etype) {
+	    $etype = [$etype] unless ref $etype;
+	    confess "$objname expected @$etype but is $gtype"
+		unless grep { $gtype eq $_ } @$etype;
+	}
+	return ($gtype, $data);
+    };
     if (!$gcf_pid) {
 	my @cmd = qw(git cat-file --batch);
 	debugcmd "GCF|", @cmd;
@@ -362,13 +372,13 @@ sub git_cat_file ($) {
     print $gcf_i $objname, "\n" or die $!;
     my $x = <$gcf_o>;
     printdebug "GCF<| ", $x;
-    if ($x =~ m/ (missing)$/) { return ($1, undef); }
+    if ($x =~ m/ (missing)$/) { return $chk->($1, undef); }
     my ($type, $size) = $x =~ m/^.* (\w+) (\d+)\n/ or die "$objname ?";
     my $data;
     (read $gcf_o, $data, $size) == $size or die "$objname $!";
     $x = <$gcf_o>;
     $x eq "\n" or die "$objname ($_) $!";
-    return ($type, $data);
+    return $chk->($type, $data);
 }
 
 sub git_for_each_ref ($$;$) {
-- 
2.30.2