lorry.tar-importer: support hard links

Integrates support for hard links from the change made in upstream git
back in 2016.

Below is the body of the upstream commit
(04e0869876f726d5af9ac901911781d440e6aed2):

Previously, we simply treated hard links as if they were plain files
with size 0, ignoring the link type "1" and hence the link target.

What we should do instead, of course, is to use the link target to get
at the import mark for the contents, even if we cannot recreate the hard
link per se, as Git has no concept of hard links.

1 files changed, 20 insertions, 12 deletions

diff --git a/lorry.tar-importer b/lorry.tar-importer
index 10696bf..7ffdfa9 100755
--- a/lorry.tar-importer
+++ b/lorry.tar-importer
@@ -112,11 +112,7 @@ foreach my $tar_file (@ARGV)
 		$mtime = oct $mtime;
 		next if $typeflag == 5; # directory
 
-		if ($typeflag == 2) { # symbolic link
-			print FI "blob\n", "mark :$next_mark\n";
-			print FI "data ", length($linkname), "\n", $linkname;
-			$mode = 0120000;
-		} elsif ($typeflag eq 'x') { # extended header
+		if ($typeflag eq 'x') { # extended header
 			# If extended header, check for path
 			my $pax_header = '';
 			while ($size > 0 && read(I, $_, 512) == 512) {
@@ -136,15 +132,21 @@ foreach my $tar_file (@ARGV)
 		} elsif ($name =~ m{/\z}) {
 			# If it's a folder, ignore
 			next;
-		} else {
+		} elsif ($typeflag != 1) { # handle hard links later
 			print FI "blob\n", "mark :$next_mark\n";
-			print FI "data $size\n";
-			while ($size > 0 && read(I, $_, 512) == 512) {
-				print FI substr($_, 0, $size);
-				$size -= 512;
+			if ($typeflag == 2) { # symbolic link
+				print FI "data ", length($linkname), "\n",
+					$linkname;
+				$mode = 0120000;
+			} else {
+				print FI "data $size\n";
+				while ($size > 0 && read(I, $_, 512) == 512) {
+					print FI substr($_, 0, $size);
+					$size -= 512;
+				}
 			}
+			print FI "\n";
 		}
-		print FI "\n";
 
 		next if ($typeflag eq 'g'); # ignore global header
 
@@ -154,7 +156,13 @@ foreach my $tar_file (@ARGV)
 		} else {
 			$path = "$name";
 		}
-		$files{$path} = [$next_mark++, $mode];
+
+		if ($typeflag == 1) { # hard link
+			$linkname = "$prefix/$linkname" if $prefix;
+			$files{$path} = [ $files{$linkname}->[0], $mode ];
+		} else {
+			$files{$path} = [$next_mark++, $mode];
+		}
 
 		$author_time = $mtime if $mtime > $author_time;
 		$path =~ m,^([^/]+)/,;