genhtml: Support relative source filenames in SF keys

Some tools which generate .info files generate relative filenames for
the ‘SF’ keys. For example, nodeunit’s lcov output does. When genhtml is
run with --output-directory, it calls chdir() which breaks relative
lookup of the source files. Fix that by resolving all source filenames
to absolute paths when loading an info file, resolving any relative ones
using the info file’s path as a base.

Signed-off-by: Philip Withnall <[email protected]>

Author: Philip Withnall

bin/genhtml

@@ -1476,6 +1476,7 @@ sub read_info_file($)
 	my $line_checksum;		# Checksum of current line
 	my $br_found;
 	my $br_hit;
+	my $notified_about_relative_paths;
 	local *INFO_HANDLE;		# Filehandle for .info file
 
 	info("Reading data file $tracefile\n");
@@ -1542,7 +1543,16 @@ sub read_info_file($)
 			{
 				# Filename information found
 				# Retrieve data for new entry
-				$filename = $1;
+				$filename = File::Spec->rel2abs($1, Cwd::cwd());
+
+				if (!File::Spec->file_name_is_absolute($1) &&
+				    !$notified_about_relative_paths)
+				{
+					info("Resolved relative source file ".
+					     "path \"$1\" with CWD to ".
+					     "\"$filename\".\n");
+					$notified_about_relative_paths = 1;
+				}
 
 				$data = $result{$filename};
 				($testdata, $sumcount, $funcdata, $checkdata,