Re: [PATCH v2 15/25] object_array_entry: fix memory handling of the name field

Signed-off-by: Michael Haggerty <redacted>
---
 bundle.c   |  2 +-
 object.c   | 26 +++++++++++++++++++++++---
 object.h   |  8 +++++++-
 revision.c |  6 ++++--
 4 files changed, 35 insertions(+), 7 deletions(-)

diff --git a/bundle.c b/bundle.c
index 4b0e5cd..3d64311 100644
--- a/bundle.c
+++ b/bundle.c

@@ -281,7 +281,7 @@ int create_bundle(struct bundle_header *header, const char *path,
 			if (!get_sha1_hex(buf.buf + 1, sha1)) {
 				struct object *object = parse_object_or_die(sha1, buf.buf);
 				object->flags |= UNINTERESTING;
-				add_pending_object(&revs, object, xstrdup(buf.buf));
+				add_pending_object(&revs, object, buf.buf);
 			}
 		} else if (!get_sha1_hex(buf.buf, sha1)) {
 			struct object *object = parse_object_or_die(sha1, buf.buf);

diff --git a/object.c b/object.c
index 10b5349..e4ff714 100644
--- a/object.c
+++ b/object.c

@@ -260,11 +260,18 @@ void add_object_array(struct object *obj, const char *name, struct object_array
 	add_object_array_with_mode(obj, name, array, S_IFINVALID);
 }
 
+/*
+ * A zero-length string to which object_array_entry::name can be
+ * initialized without requiring a malloc/free.
+ */
+char object_array_slopbuf[1];
+
 void add_object_array_with_mode(struct object *obj, const char *name, struct object_array *array, unsigned mode)
 {
 	unsigned nr = array->nr;
 	unsigned alloc = array->alloc;
 	struct object_array_entry *objects = array->objects;
+	struct object_array_entry *entry;
 
 	if (nr >= alloc) {
 		alloc = (alloc + 32) * 2;

@@ -272,9 +279,16 @@ void add_object_array_with_mode(struct object *obj, const char *name, struct obj
 		array->alloc = alloc;
 		array->objects = objects;
 	}
-	objects[nr].item = obj;
-	objects[nr].name = name;
-	objects[nr].mode = mode;
+	entry = &objects[nr];
+	entry->item = obj;
+	if (!name)
+		entry->name = NULL;
+	else if (!*name)
+		/* Use our own empty string instead of allocating one: */
+		entry->name = object_array_slopbuf;
+	else
+		entry->name = xstrdup(name);
+	entry->mode = mode;
 	array->nr = ++nr;
 }
 

@@ -289,6 +303,9 @@ void object_array_filter(struct object_array *array,
 			if (src != dst)
 				objects[dst] = objects[src];
 			dst++;
+		} else {
+			if (objects[src].name != object_array_slopbuf)
+				free(objects[src].name);
 		}
 	}
 	array->nr = dst;

@@ -319,6 +336,9 @@ void object_array_remove_duplicates(struct object_array *array)
 			if (src != array->nr)
 				objects[array->nr] = objects[src];
 			array->nr++;
+		} else {
+			if (objects[src].name != object_array_slopbuf)
+				free(objects[src].name);
 		}
 	}
 }

diff --git a/object.h b/object.h
index 6c1c27f..2ff68c5 100644
--- a/object.h
+++ b/object.h

@@ -11,7 +11,13 @@ struct object_array {
 	unsigned int alloc;
 	struct object_array_entry {
 		struct object *item;
-		const char *name;
+		/*
+		 * name or NULL.  If non-NULL, the memory pointed to
+		 * is owned by this object *except* if it points at
+		 * object_array_slopbuf, which is a static copy of the
+		 * empty string.
+		 */
+		char *name;
 		unsigned mode;
 	} *objects;
 };

diff --git a/revision.c b/revision.c
index be73cb4..4aeda33 100644
--- a/revision.c
+++ b/revision.c

@@ -88,7 +88,9 @@ void add_object(struct object *obj,
 		struct name_path *path,
 		const char *name)
 {
-	add_object_array(obj, path_name(path, name), p);
+	char *pn = path_name(path, name);
+	add_object_array(obj, pn, p);
+	free(pn);
 }
 
 static void mark_blob_uninteresting(struct blob *blob)

@@ -1288,7 +1290,7 @@ static void read_revisions_from_stdin(struct rev_info *revs,
 			}
 			die("options not supported in --stdin mode");
 		}
-		if (handle_revision_arg(xstrdup(sb.buf), revs, 0,
+		if (handle_revision_arg(sb.buf, revs, 0,
 					REVARG_CANNOT_BE_FILENAME))
 			die("bad revision '%s'", sb.buf);
 	}