luci-base: fix luci.http.close()

Ensure that `http.write()` or template rendering operations after a call
to `http.close()` do not produce additional output. This is required for
certain legacy Lua apps which invoke write and close operations in the
middle of a server side cbi rendering process.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

3 files changed, 17 insertions, 7 deletions

diff --git a/modules/luci-base/ucode/dispatcher.uc b/modules/luci-base/ucode/dispatcher.uc
index 86cab9b88f..8ac32c3d1d 100644
--- a/modules/luci-base/ucode/dispatcher.uc
+++ b/modules/luci-base/ucode/dispatcher.uc
@@ -775,7 +775,8 @@ function run_action(request_path, lang, tree, resolved, action) {
 		break;
 
 	case 'call':
-		http.write(render(() => {
+		http.write_headers();
+		http.output(render(() => {
 			runtime.call(action.module, action.function,
 				...(action.parameters ?? []),
 				...resolved.ctx.request_args
@@ -789,7 +790,8 @@ function run_action(request_path, lang, tree, resolved, action) {
 		assert(type(mod[action.function]) == 'function',
 			`Module '${action.module}' does not export function '${action.function}'`);
 
-		http.write(render(() => {
+		http.write_headers();
+		http.output(render(() => {
 			call(mod[action.function], mod, runtime.env,
 				...(action.parameters ?? []),
 				...resolved.ctx.request_args
@@ -798,7 +800,8 @@ function run_action(request_path, lang, tree, resolved, action) {
 		break;
 
 	case 'cbi':
-		http.write(render(() => {
+		http.write_headers();
+		http.output(render(() => {
 			runtime.call('luci.dispatcher', 'invoke_cbi_action',
 				action.path, null,
 				...resolved.ctx.request_args
@@ -807,7 +810,8 @@ function run_action(request_path, lang, tree, resolved, action) {
 		break;
 
 	case 'form':
-		http.write(render(() => {
+		http.write_headers();
+		http.output(render(() => {
 			runtime.call('luci.dispatcher', 'invoke_form_action',
 				action.path,
 				...resolved.ctx.request_args
diff --git a/modules/luci-base/ucode/http.uc b/modules/luci-base/ucode/http.uc
index 4856c47a0d..e8982e77a0 100644
--- a/modules/luci-base/ucode/http.uc
+++ b/modules/luci-base/ucode/http.uc
@@ -524,7 +524,7 @@ const Class = {
 
 	// If the content chunk is nil this function will automatically invoke close.
 	write: function(content) {
-		if (content != null) {
+		if (content != null && !this.closed) {
 			this.write_headers();
 			this.output(content);
 
diff --git a/modules/luci-base/ucode/runtime.uc b/modules/luci-base/ucode/runtime.uc
index ed330abcc1..da73d13fe4 100644
--- a/modules/luci-base/ucode/runtime.uc
+++ b/modules/luci-base/ucode/runtime.uc
@@ -48,8 +48,10 @@ const Class = {
 			let bridge = this.env.dispatcher.load_luabridge(optional);
 
 			if (bridge) {
+				let http = this.env.http;
+
 				this.L = bridge.create();
-				this.L.set('L', proto({ write: print }, this.env));
+				this.L.set('L', proto({ write: (...args) => http.closed || print(...args) }, this.env));
 				this.L.invoke('require', 'luci.ucodebridge');
 
 				this.env.lua_active = true;
@@ -61,7 +63,11 @@ const Class = {
 
 	render_ucode: function(path, scope) {
 		let tmplfunc = loadfile(path, { raw_mode: false });
-		call(tmplfunc, null, scope ?? {});
+
+		if (this.env.http.closed)
+			render(call, tmplfunc, null, scope ?? {});
+		else
+			call(tmplfunc, null, scope ?? {});
 	},
 
 	render_lua: function(path, scope) {