push: release strbufs used for refspec formatting

map_refspec() either returns the passed in ref string or a detached
strbuf.  This makes it hard for callers to release the possibly
allocated memory, and set_refspecs() consequently leaks it.

Let map_refspec() append any refspecs directly and release its own
strbufs after use.  Rename it to refspec_append_mapped() and don't
return anything to reflect its increased responsibility.

set_refspecs() also leaks its strbufs.  Do the same here and directly
call refspec_append() in each if branch instead of holding onto a
detached strbuf, then dispose of the allocated memory after use.  We
need to add an else branch for the final call because all the other
conditional branches already add their formatted refspec now.

setup_push_upstream() and setup_push_current() forgot to release their
strbufs as well; plug these leaks, too, while at it.

None of these leaks were likely to impact users, because the number
and sizes of refspecs are usually small and the allocations are only
done once per program run.  Clean them up nevertheless, as another
step on the long road towards zero memory leaks.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/push.c

@@ -61,15 +61,17 @@ static struct refspec rs = REFSPEC_INIT_PUSH;
 
 static struct string_list push_options_config = STRING_LIST_INIT_DUP;
 
-static const char *map_refspec(const char *ref,
-			       struct remote *remote, struct ref *local_refs)
+static void refspec_append_mapped(struct refspec *refspec, const char *ref,
+				  struct remote *remote, struct ref *local_refs)
 {
 	const char *branch_name;
 	struct ref *matched = NULL;
 
 	/* Does "ref" uniquely name our ref? */
-	if (count_refspec_match(ref, local_refs, &matched) != 1)
-		return ref;
+	if (count_refspec_match(ref, local_refs, &matched) != 1) {
+		refspec_append(refspec, ref);
+		return;
+	}
 
 	if (remote->push.nr) {
 		struct refspec_item query;
@@ -80,7 +82,9 @@ static const char *map_refspec(const char *ref,
 			strbuf_addf(&buf, "%s%s:%s",
 				    query.force ? "+" : "",
 				    query.src, query.dst);
-			return strbuf_detach(&buf, NULL);
+			refspec_append(refspec, buf.buf);
+			strbuf_release(&buf);
+			return;
 		}
 	}
 
@@ -91,11 +95,13 @@ static const char *map_refspec(const char *ref,
 			struct strbuf buf = STRBUF_INIT;
 			strbuf_addf(&buf, "%s:%s",
 				    ref, branch->merge[0]->src);
-			return strbuf_detach(&buf, NULL);
+			refspec_append(refspec, buf.buf);
+			strbuf_release(&buf);
+			return;
 		}
 	}
 
-	return ref;
+	refspec_append(refspec, ref);
 }
 
 static void set_refspecs(const char **refs, int nr, const char *repo)
@@ -115,22 +121,24 @@ static void set_refspecs(const char **refs, int nr, const char *repo)
 				strbuf_addf(&tagref, ":refs/tags/%s", ref);
 			else
 				strbuf_addf(&tagref, "refs/tags/%s", ref);
-			ref = strbuf_detach(&tagref, NULL);
+			refspec_append(&rs, tagref.buf);
+			strbuf_release(&tagref);
 		} else if (deleterefs) {
 			struct strbuf delref = STRBUF_INIT;
 			if (strchr(ref, ':'))
 				die(_("--delete only accepts plain target ref names"));
 			strbuf_addf(&delref, ":%s", ref);
-			ref = strbuf_detach(&delref, NULL);
+			refspec_append(&rs, delref.buf);
+			strbuf_release(&delref);
 		} else if (!strchr(ref, ':')) {
 			if (!remote) {
 				/* lazily grab remote and local_refs */
 				remote = remote_get(repo);
 				local_refs = get_local_heads();
 			}
-			ref = map_refspec(ref, remote, local_refs);
-		}
-		refspec_append(&rs, ref);
+			refspec_append_mapped(&rs, ref, remote, local_refs);
+		} else
+			refspec_append(&rs, ref);
 	}
 }
 
@@ -221,6 +229,7 @@ static void setup_push_upstream(struct remote *remote, struct branch *branch,
 
 	strbuf_addf(&refspec, "%s:%s", branch->refname, branch->merge[0]->src);
 	refspec_append(&rs, refspec.buf);
+	strbuf_release(&refspec);
 }
 
 static void setup_push_current(struct remote *remote, struct branch *branch)
@@ -231,6 +240,7 @@ static void setup_push_current(struct remote *remote, struct branch *branch)
 		die(_(message_detached_head_die), remote->name);
 	strbuf_addf(&refspec, "%s:%s", branch->refname, branch->refname);
 	refspec_append(&rs, refspec.buf);
+	strbuf_release(&refspec);
 }
 
 static int is_workflow_triangular(struct remote *remote)