--dirstat-by-file: Make it faster and more correct

diff --git a/diff.c b/diff.c
index 3fd9e0c70315727f835f39d9a0230ee9f24e7ea8..4f5270b8dbc05c820c24075b499fe26afacf52a8 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -1539,9 +1539,27 @@ static void show_dirstat(struct diff_options *options)
                struct diff_filepair *p = q->queue[i];
                const char *name;
                unsigned long copied, added, damage;
+               int content_changed;
 
                name = p->one->path ? p->one->path : p->two->path;
 
+               if (p->one->sha1_valid && p->two->sha1_valid)
+                       content_changed = hashcmp(p->one->sha1, p->two->sha1);
+               else
+                       content_changed = 1;
+
+               if (DIFF_OPT_TST(options, DIRSTAT_BY_FILE)) {
+                       /*
+                        * In --dirstat-by-file mode, we don't really need to
+                        * look at the actual file contents at all.
+                        * The fact that the SHA1 changed is enough for us to
+                        * add this file to the list of results
+                        * (with each file contributing equal damage).
+                        */
+                       damage = content_changed ? 1 : 0;
+                       goto found_damage;
+               }
+
                if (DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
                        diff_populate_filespec(p->one, 0);
                        diff_populate_filespec(p->two, 0);
@@ -1564,14 +1582,11 @@ static void show_dirstat(struct diff_options *options)
                /*
                 * Original minus copied is the removed material,
                 * added is the new material.  They are both damages
-                * made to the preimage. In --dirstat-by-file mode, count
-                * damaged files, not damaged lines. This is done by
-                * counting only a single damaged line per file.
+                * made to the preimage.
                 */
                damage = (p->one->size - copied) + added;
-               if (DIFF_OPT_TST(options, DIRSTAT_BY_FILE) && damage > 0)
-                       damage = 1;
 
+found_damage:
                ALLOC_GROW(dir.files, dir.nr + 1, dir.alloc);
                dir.files[dir.nr].name = name;
                dir.files[dir.nr].changed = damage;