[PATCH] diff: Make numstat machine friendly also for renames (and copies)

[Jakub Narebski <jnareb@gmail.com>]

"git diff --numstat" used the same format as "git diff --stat" for
renamed (and copied) files, except that filenames were not shortened
when they didn't fit in the column width.  This format is suitable for
human consumption, but it cannot be unambiguously parsed.

Instead of that always use final file name ("to" name) for numstat.
It is possible to find name before rename when name after is known.

This required to use pprint_rename (pretty print rename) during output
(in the show_stats function) and not during parsing (in diffstat_add
function).

Adding from_name field to struct diffstat_t makes is_renamed bitfield
redundant; nevertheless for the sake of clarity, readability and
making this patch minimal (and because it would not reduce memory
footprint) it was not removed, and its used not replaced by checking
from_name field.

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
---
This would be useful for gitweb, later.

I hope I have made it in time before feature freeze...

 diff.c |   15 ++++++++++++---
 1 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/diff.c b/diff.c
index f780e3e..38b9367 100644
--- a/diff.c
+++ b/diff.c
@@ -735,6 +735,7 @@ struct diffstat_t {
 	int alloc;
 	struct diffstat_file {
 		char *name;
+		char *from_name;
 		unsigned is_unmerged:1;
 		unsigned is_binary:1;
 		unsigned is_renamed:1;
@@ -755,11 +756,14 @@ static struct diffstat_file *diffstat_add(struct diffstat_t *diffstat,
 	}
 	diffstat->files[diffstat->nr++] = x;
 	if (name_b) {
-		x->name = pprint_rename(name_a, name_b);
+		x->from_name = xstrdup(name_a);
+		x->name      = xstrdup(name_b);
 		x->is_renamed = 1;
 	}
-	else
+	else {
+		x->from_name = NULL;
 		x->name = xstrdup(name_a);
+	}
 	return x;
 }
 
@@ -837,7 +841,7 @@ static void show_stats(struct diffstat_t* data, struct diff_options *options)
 		struct diffstat_file *file = data->files[i];
 		int change = file->added + file->deleted;
 
-		if (!file->is_renamed) {  /* renames are already quoted by pprint_rename */
+		if (!file->is_renamed) {  /* renames will be quoted by pprint_rename */
 			struct strbuf buf;
 			strbuf_init(&buf, 0);
 			if (quote_c_style(file->name, &buf, NULL, 0)) {
@@ -846,6 +850,11 @@ static void show_stats(struct diffstat_t* data, struct diff_options *options)
 			} else {
 				strbuf_release(&buf);
 			}
+		} else {
+			char *qname = pprint_rename(file->from_name, file->name);
+			free(file->name);
+			free(file->from_name);
+			file->name = qname;
 		}
 
 		len = strlen(file->name);
-- 
1.5.3.7