Merge branch 'jk/combine-diff-cleanup'

Code clean-up for code paths around combined diff.

* jk/combine-diff-cleanup:
  tree-diff: make list tail-passing more explicit
  tree-diff: simplify emit_path() list management
  tree-diff: use the name "tail" to refer to list tail
  tree-diff: drop list-tail argument to diff_tree_paths()
  combine-diff: drop public declaration of combine_diff_path_size()
  tree-diff: inline path_appendnew()
  tree-diff: pass whole path string to path_appendnew()
  tree-diff: drop path_appendnew() alloc optimization
  run_diff_files(): de-mystify the size of combine_diff_path struct
  diff: add a comment about combine_diff_path.parent.path
  combine-diff: use pointer for parent paths
  tree-diff: clear parent array in path_appendnew()
  combine-diff: add combine_diff_path_new()
  run_diff_files(): delay allocation of combine_diff_path

Author: gitster

combine-diff.c

@@ -47,31 +47,20 @@ static struct combine_diff_path *intersect_paths(
 
 	if (!n) {
 		for (i = 0; i < q->nr; i++) {
-			int len;
-			const char *path;
 			if (diff_unmodified_pair(q->queue[i]))
 				continue;
-			path = q->queue[i]->two->path;
-			len = strlen(path);
-			p = xmalloc(combine_diff_path_size(num_parent, len));
-			p->path = (char *) &(p->parent[num_parent]);
-			memcpy(p->path, path, len);
-			p->path[len] = 0;
-			p->next = NULL;
-			memset(p->parent, 0,
-			       sizeof(p->parent[0]) * num_parent);
-
-			oidcpy(&p->oid, &q->queue[i]->two->oid);
-			p->mode = q->queue[i]->two->mode;
+			p = combine_diff_path_new(q->queue[i]->two->path,
+						  strlen(q->queue[i]->two->path),
+						  q->queue[i]->two->mode,
+						  &q->queue[i]->two->oid,
+						  num_parent);
 			oidcpy(&p->parent[n].oid, &q->queue[i]->one->oid);
 			p->parent[n].mode = q->queue[i]->one->mode;
 			p->parent[n].status = q->queue[i]->status;
 
 			if (combined_all_paths &&
 			    filename_changed(p->parent[n].status)) {
-				strbuf_init(&p->parent[n].path, 0);
-				strbuf_addstr(&p->parent[n].path,
-					      q->queue[i]->one->path);
+				p->parent[n].path = xstrdup(q->queue[i]->one->path);
 			}
 			*tail = p;
 			tail = &p->next;
@@ -92,9 +81,7 @@ static struct combine_diff_path *intersect_paths(
 			/* p->path not in q->queue[]; drop it */
 			*tail = p->next;
 			for (j = 0; j < num_parent; j++)
-				if (combined_all_paths &&
-				    filename_changed(p->parent[j].status))
-					strbuf_release(&p->parent[j].path);
+				free(p->parent[j].path);
 			free(p);
 			continue;
 		}
@@ -110,8 +97,7 @@ static struct combine_diff_path *intersect_paths(
 		p->parent[n].status = q->queue[i]->status;
 		if (combined_all_paths &&
 		    filename_changed(p->parent[n].status))
-			strbuf_addstr(&p->parent[n].path,
-				      q->queue[i]->one->path);
+			p->parent[n].path = xstrdup(q->queue[i]->one->path);
 
 		tail = &p->next;
 		i++;
@@ -996,8 +982,9 @@ static void show_combined_header(struct combine_diff_path *elem,
 
 	if (rev->combined_all_paths) {
 		for (i = 0; i < num_parent; i++) {
-			char *path = filename_changed(elem->parent[i].status)
-				? elem->parent[i].path.buf : elem->path;
+			const char *path = elem->parent[i].path ?
+					   elem->parent[i].path :
+					   elem->path;
 			if (elem->parent[i].status == DIFF_STATUS_ADDED)
 				dump_quoted_path("--- ", "", "/dev/null",
 						 line_prefix, c_meta, c_reset);
@@ -1278,12 +1265,10 @@ static void show_raw_diff(struct combine_diff_path *p, int num_parent, struct re
 
 	for (i = 0; i < num_parent; i++)
 		if (rev->combined_all_paths) {
-			if (filename_changed(p->parent[i].status))
-				write_name_quoted(p->parent[i].path.buf, stdout,
-						  inter_name_termination);
-			else
-				write_name_quoted(p->path, stdout,
-						  inter_name_termination);
+			const char *path = p->parent[i].path ?
+					   p->parent[i].path :
+					   p->path;
+			write_name_quoted(path, stdout, inter_name_termination);
 		}
 	write_name_quoted(p->path, stdout, line_termination);
 }
@@ -1443,22 +1428,19 @@ static struct combine_diff_path *find_paths_multitree(
 {
 	int i, nparent = parents->nr;
 	const struct object_id **parents_oid;
-	struct combine_diff_path paths_head;
+	struct combine_diff_path *paths;
 	struct strbuf base;
 
 	ALLOC_ARRAY(parents_oid, nparent);
 	for (i = 0; i < nparent; i++)
 		parents_oid[i] = &parents->oid[i];
 
-	/* fake list head, so worker can assume it is non-NULL */
-	paths_head.next = NULL;
-
 	strbuf_init(&base, PATH_MAX);
-	diff_tree_paths(&paths_head, oid, parents_oid, nparent, &base, opt);
+	paths = diff_tree_paths(oid, parents_oid, nparent, &base, opt);
 
 	strbuf_release(&base);
 	free(parents_oid);
-	return paths_head.next;
+	return paths;
 }
 
 static int match_objfind(struct combine_diff_path *path,
@@ -1645,9 +1627,7 @@ void diff_tree_combined(const struct object_id *oid,
 		struct combine_diff_path *tmp = paths;
 		paths = paths->next;
 		for (i = 0; i < num_parent; i++)
-			if (rev->combined_all_paths &&
-			    filename_changed(tmp->parent[i].status))
-				strbuf_release(&tmp->parent[i].path);
+			free(tmp->parent[i].path);
 		free(tmp);
 	}
 
@@ -1667,3 +1647,25 @@ void diff_tree_combined_merge(const struct commit *commit,
 	diff_tree_combined(&commit->object.oid, &parents, rev);
 	oid_array_clear(&parents);
 }
+
+struct combine_diff_path *combine_diff_path_new(const char *path,
+						size_t path_len,
+						unsigned int mode,
+						const struct object_id *oid,
+						size_t num_parents)
+{
+	struct combine_diff_path *p;
+	size_t parent_len = st_mult(sizeof(p->parent[0]), num_parents);
+
+	p = xmalloc(st_add4(sizeof(*p), path_len, 1, parent_len));
+	p->path = (char *)&(p->parent[num_parents]);
+	memcpy(p->path, path, path_len);
+	p->path[path_len] = 0;
+	p->next = NULL;
+	p->mode = mode;
+	oidcpy(&p->oid, oid);
+
+	memset(p->parent, 0, parent_len);
+
+	return p;
+}

diff-lib.c

@@ -153,21 +153,8 @@ void run_diff_files(struct rev_info *revs, unsigned int option)
 			struct diff_filepair *pair;
 			unsigned int wt_mode = 0;
 			int num_compare_stages = 0;
-			size_t path_len;
 			struct stat st;
 
-			path_len = ce_namelen(ce);
-
-			dpath = xmalloc(combine_diff_path_size(5, path_len));
-			dpath->path = (char *) &(dpath->parent[5]);
-
-			dpath->next = NULL;
-			memcpy(dpath->path, ce->name, path_len);
-			dpath->path[path_len] = '\0';
-			oidclr(&dpath->oid, the_repository->hash_algo);
-			memset(&(dpath->parent[0]), 0,
-			       sizeof(struct combine_diff_parent)*5);
-
 			changed = check_removed(ce, &st);
 			if (!changed)
 				wt_mode = ce_mode_from_stat(ce, st.st_mode);
@@ -178,7 +165,14 @@ void run_diff_files(struct rev_info *revs, unsigned int option)
 				}
 				wt_mode = 0;
 			}
-			dpath->mode = wt_mode;
+
+			/*
+			 * Allocate space for two parents, which will come from
+			 * index stages #2 and #3, if present. Below we'll fill
+			 * these from (stage - 2).
+			 */
+			dpath = combine_diff_path_new(ce->name, ce_namelen(ce),
+						      wt_mode, null_oid(), 2);
 
 			while (i < entries) {
 				struct cache_entry *nce = istate->cache[i];
@@ -405,16 +399,10 @@ static int show_modified(struct rev_info *revs,
 	if (revs->combine_merges && !cached &&
 	    (!oideq(oid, &old_entry->oid) || !oideq(&old_entry->oid, &new_entry->oid))) {
 		struct combine_diff_path *p;
-		int pathlen = ce_namelen(new_entry);
-
-		p = xmalloc(combine_diff_path_size(2, pathlen));
-		p->path = (char *) &p->parent[2];
-		p->next = NULL;
-		memcpy(p->path, new_entry->name, pathlen);
-		p->path[pathlen] = 0;
-		p->mode = mode;
-		oidclr(&p->oid, the_repository->hash_algo);
-		memset(p->parent, 0, 2 * sizeof(struct combine_diff_parent));
+
+		p = combine_diff_path_new(new_entry->name,
+					  ce_namelen(new_entry),
+					  mode, null_oid(), 2);
 		p->parent[0].status = DIFF_STATUS_MODIFIED;
 		p->parent[0].mode = new_entry->ce_mode;
 		oidcpy(&p->parent[0].oid, &new_entry->oid);

diff.h

@@ -462,7 +462,7 @@ const char *diff_line_prefix(struct diff_options *);
 extern const char mime_boundary_leader[];
 
 struct combine_diff_path *diff_tree_paths(
-	struct combine_diff_path *p, const struct object_id *oid,
+	const struct object_id *oid,
 	const struct object_id **parents_oid, int nparent,
 	struct strbuf *base, struct diff_options *opt);
 void diff_tree_oid(const struct object_id *old_oid,
@@ -480,12 +480,20 @@ struct combine_diff_path {
 		char status;
 		unsigned int mode;
 		struct object_id oid;
-		struct strbuf path;
+		/*
+		 * This per-parent path is filled only when doing a combined
+		 * diff with revs.combined_all_paths set, and only if the path
+		 * differs from the post-image (e.g., a rename or copy).
+		 * Otherwise it is left NULL.
+		 */
+		char *path;
 	} parent[FLEX_ARRAY];
 };
-#define combine_diff_path_size(n, l) \
-	st_add4(sizeof(struct combine_diff_path), (l), 1, \
-		st_mult(sizeof(struct combine_diff_parent), (n)))
+struct combine_diff_path *combine_diff_path_new(const char *path,
+						size_t path_len,
+						unsigned int mode,
+						const struct object_id *oid,
+						size_t num_parents);
 
 void show_combined_diff(struct combine_diff_path *elem, int num_parent,
 			struct rev_info *);