MERGE: merge PR #67.

Original commit message:

Universal diffs as generated by git (for example) have some compatibility problems regarding what lcov --diff expects. This pull request fixes a few of those problems to make it easier to use git diffs. In particular:

 - Start-of-block lines are now allowed to have comments after the
   ending @@. Git sometimes uses this to give hints about the diff
   block location, like the function name.
 - The diff reader has been changed to track more state and to be
   a bit more flexible, due to git printing more info lines in between
   files and in the header, like when using git show.

Committed by:  Henry Cox ([email protected]) on behalf of Ricardo Garcia ([email protected])

Signed-off-by:  Ricardo Garcia <[email protected]>

Author: henry2cox

bin/lcov

@@ -2326,9 +2326,16 @@ sub read_diff($)
     my $file_old;             # Name of old file in diff section
     my $file_new;             # Name of new file in diff section
     my $filename;             # Name of common filename of diff section
-    my $in_block = 0;         # Non-zero while we are inside a diff block
     local *HANDLE;            # File handle for reading the diff file
 
+    use constant {
+                  IN_META  => 0,  # Out of any block or relevant header.
+                  HAVE_OLD => 1,  # After reading the --- line.
+                  HAVE_NEW => 2,  # After reading the +++ line after a --- line.
+                  IN_BLOCK => 3,  # Inside a diff block.
+    };
+    my $state = IN_META;          # Non-zero while we are inside a diff block
+
     info("Reading diff $diff_file\n");
 
     # Check if file exists and is readable
@@ -2355,74 +2362,77 @@ sub read_diff($)
             # --- <filename> <date>
             /^--- (\S+)/ && do {
                 $file_old = lcovutil::strip_directories($1, $strip);
+                $state    = HAVE_OLD;
                 last;
             };
             # Filename of new file:
             # +++ <filename> <date>
             /^\+\+\+ (\S+)/ && do {
-                # Add last file to resulting hash
-                if ($filename) {
-                    my %new_hash;
-                    $diff{$filename} = $mapping;
-                    $mapping = \%new_hash;
+                if ($state == HAVE_OLD) {
+                    # Add last file to resulting hash
+                    if ($filename) {
+                        my %new_hash;
+                        $diff{$filename} = $mapping;
+                        $mapping = \%new_hash;
+                    }
+                    $file_new         = lcovutil::strip_directories($1, $strip);
+                    $filename         = $file_old;
+                    $paths{$filename} = $file_new;
+                    $num_old          = 1;
+                    $num_new          = 1;
+                    $state            = HAVE_NEW;
+                } else {
+                    # +++ line out of place.
+                    $state = IN_META;
                 }
-                $file_new         = lcovutil::strip_directories($1, $strip);
-                $filename         = $file_old;
-                $paths{$filename} = $file_new;
-                $num_old          = 1;
-                $num_new          = 1;
                 last;
             };
             # Start of diff block:
             # @@ -old_start,old_num, +new_start,new_num @@
-            /^\@\@\s+-(\d+),(\d+)\s+\+(\d+),(\d+)\s+\@\@$/ && do {
-                $in_block = 1;
-                while ($num_old < $1) {
-                    $mapping->{$num_new} = $num_old;
-                    $num_old++;
-                    $num_new++;
+            /^\@\@\s+-(\d+),(\d+)\s+\+(\d+),(\d+)\s+\@\@/ && do {
+                if ($state == HAVE_NEW || $state == IN_BLOCK) {
+                    while ($num_old < $1) {
+                        $mapping->{$num_new} = $num_old;
+                        $num_old++;
+                        $num_new++;
+                    }
+                    $state = IN_BLOCK;
+                } else {
+                    # @@ line out of place.
+                    $state = IN_META;
                 }
                 last;
             };
             # Unchanged line
-            # <line starts with blank>
-            /^ / && do {
-                if ($in_block == 0) {
-                    last;
+            # <line starts with blank or is empty>
+            (/^ / || /^$/) && do {
+                if ($state == IN_BLOCK) {
+                    $mapping->{$num_new} = $num_old;
+                    $num_old++;
+                    $num_new++;
+                } else {
+                    # Back to the starting point.
+                    $state = IN_META;
                 }
-                $mapping->{$num_new} = $num_old;
-                $num_old++;
-                $num_new++;
                 last;
             };
-            # Line as seen in old file
+            # Line as seen in old file or new file.
             # <line starts with '-'>
-            /^-/ && do {
-                if ($in_block == 0) {
-                    last;
-                }
-                $num_old++;
-                last;
-            };
-            # Line as seen in new file
-            # <line starts with '+'>
-            /^\+/ && do {
-                if ($in_block == 0) {
-                    last;
-                }
-                $num_new++;
-                last;
-            };
-            # Empty line
-            /^$/ && do {
-                if ($in_block == 0) {
-                    last;
+            /^([-+])/ && do {
+                if ($state == IN_BLOCK) {
+                    if ($1 eq "-") {
+                        $num_old++;
+                    } else {
+                        $num_new++;
+                    }
+                } else {
+                    # Back to the starting point.
+                    $state = IN_META;
                 }
-                $mapping->{$num_new} = $num_old;
-                $num_old++;
-                $num_new++;
                 last;
             };
+            # With any other pattern, back to the starting point.
+            $state = IN_META;
         }
     }