lua: fix memory leak in changes method

Configs returned by uci_list_configs call are not freed when not needed,
leading to the memory leak. While at it make the code cleaner.

Signed-off-by: Petr Štetiar <ynezz@true.cz>

3 files changed, 29 insertions, 7 deletions

diff --git a/lua/uci.c b/lua/uci.c
index 323f81a..42fe4b7 100644
--- a/lua/uci.c
+++ b/lua/uci.c
@@ -880,16 +880,17 @@ uci_lua_changes(lua_State *L)
 	lua_newtable(L);
 	if (package) {
 		uci_lua_changes_pkg(L, ctx, package);
-	} else {
-		if (uci_list_configs(ctx, &config) != 0)
-			goto done;
+		return 1;
+	}
 
-		for(i = 0; config[i] != NULL; i++) {
-			uci_lua_changes_pkg(L, ctx, config[i]);
-		}
+	if ((uci_list_configs(ctx, &config) != UCI_OK) || !config)
+		return 1;
+
+	for (i = 0; config[i] != NULL; i++) {
+		uci_lua_changes_pkg(L, ctx, config[i]);
 	}
 
-done:
+	free(config);
 	return 1;
 }
 
diff --git a/tests/cram/lua/test_cases/changes_doesnt_leak.lua b/tests/cram/lua/test_cases/changes_doesnt_leak.lua
new file mode 100644
index 0000000..68f0ed0
--- /dev/null
+++ b/tests/cram/lua/test_cases/changes_doesnt_leak.lua
@@ -0,0 +1,11 @@
+local A = assert
+local c = uci.cursor(os.getenv("CONFIG_DIR"))
+
+A(c:set("network", "lan", "dns", {
+	"ns1.king.banik.cz",
+	"ns2.openwrt.org",
+}))
+
+local changes = c:changes()
+A(changes.network.lan.dns[1] == "ns1.king.banik.cz")
+A(changes.network.lan.dns[2] == "ns2.openwrt.org")
diff --git a/tests/cram/test_ucilua_testcases.t b/tests/cram/test_ucilua_testcases.t
new file mode 100644
index 0000000..279dfce
--- /dev/null
+++ b/tests/cram/test_ucilua_testcases.t
@@ -0,0 +1,10 @@
+set LUA_CPATH and ucilua for convenience:
+
+  $ [ -n "$UCI_LUA" ] && export LUA_CPATH="$(dirname "$UCI_LUA")/?.so"
+  $ alias ucilua="valgrind --quiet --leak-check=full lua -luci"
+
+check that changes method doesnt leak memory:
+
+  $ cp -R "$TESTDIR/config" .
+  $ export CONFIG_DIR=$(pwd)/config
+  $ ucilua $TESTDIR/lua/test_cases/changes_doesnt_leak.lua