gumjs: Add limit option to Thread.backtrace()

Co-authored-by: Ole André Vadla Ravnås <[email protected]>

bindings/gumjs/gumquickthread.c

@@ -1,5 +1,6 @@
 /*
- * Copyright (C) 2020 Ole André Vadla Ravnås <[email protected]>
+ * Copyright (C) 2020-2024 Ole André Vadla Ravnås <[email protected]>
+ * Copyright (C) 2024 DaVinci <[email protected]>
  *
  * Licence: wxWindows Library Licence, Version 3.1
  */
@@ -19,7 +20,7 @@ GUMJS_DECLARE_FUNCTION (gumjs_thread_sleep)
 
 static const JSCFunctionListEntry gumjs_thread_entries[] =
 {
-  JS_CFUNC_DEF ("backtrace", 0, gumjs_thread_backtrace),
+  JS_CFUNC_DEF ("_backtrace", 0, gumjs_thread_backtrace),
   JS_CFUNC_DEF ("sleep", 0, gumjs_thread_sleep),
 };
 
@@ -74,21 +75,22 @@ GUMJS_DEFINE_FUNCTION (gumjs_thread_backtrace)
 {
   JSValue result;
   GumQuickThread * self;
-  GumCpuContext * cpu_context = NULL;
-  gint selector = GUM_BACKTRACER_ACCURATE;
+  GumCpuContext * cpu_context;
+  gint type;
+  guint limit;
   GumBacktracer * backtracer;
   GumReturnAddressArray ret_addrs;
   guint i;
 
   self = gumjs_get_parent_module (core);
 
-  if (!_gum_quick_args_parse (args, "|C?i", &cpu_context, &selector))
+  if (!_gum_quick_args_parse (args, "C?iu", &cpu_context, &type, &limit))
     return JS_EXCEPTION;
 
-  if (selector != GUM_BACKTRACER_ACCURATE && selector != GUM_BACKTRACER_FUZZY)
-    goto invalid_selector;
+  if (type != GUM_BACKTRACER_ACCURATE && type != GUM_BACKTRACER_FUZZY)
+    goto invalid_type;
 
-  if (selector == GUM_BACKTRACER_ACCURATE)
+  if (type == GUM_BACKTRACER_ACCURATE)
   {
     if (self->accurate_backtracer == NULL)
       self->accurate_backtracer = gum_backtracer_make_accurate ();
@@ -103,7 +105,15 @@ GUMJS_DEFINE_FUNCTION (gumjs_thread_backtrace)
   if (backtracer == NULL)
     goto not_available;
 
-  gum_backtracer_generate (backtracer, cpu_context, &ret_addrs);
+  if (limit != 0)
+  {
+    gum_backtracer_generate_with_limit (backtracer, cpu_context, &ret_addrs,
+        limit);
+  }
+  else
+  {
+    gum_backtracer_generate (backtracer, cpu_context, &ret_addrs);
+  }
 
   result = JS_NewArray (ctx);
 
@@ -116,13 +126,13 @@ GUMJS_DEFINE_FUNCTION (gumjs_thread_backtrace)
 
   return result;
 
-invalid_selector:
+invalid_type:
   {
     return _gum_quick_throw_literal (ctx, "invalid backtracer enum value");
   }
 not_available:
   {
-    return _gum_quick_throw_literal (ctx, (selector == GUM_BACKTRACER_ACCURATE)
+    return _gum_quick_throw_literal (ctx, (type == GUM_BACKTRACER_ACCURATE)
         ? "backtracer not yet available for this platform; "
         "please try Thread.backtrace(context, Backtracer.FUZZY)"
         : "backtracer not yet available for this platform; "

bindings/gumjs/gumv8thread.cpp

@@ -1,5 +1,6 @@
 /*
- * Copyright (C) 2010-2022 Ole André Vadla Ravnås <[email protected]>
+ * Copyright (C) 2010-2024 Ole André Vadla Ravnås <[email protected]>
+ * Copyright (C) 2024 DaVinci <[email protected]>
  *
  * Licence: wxWindows Library Licence, Version 3.1
  */
@@ -17,7 +18,7 @@ GUMJS_DECLARE_FUNCTION (gumjs_thread_sleep)
 
 static const GumV8Function gumjs_thread_functions[] =
 {
-  { "backtrace", gumjs_thread_backtrace },
+  { "_backtrace", gumjs_thread_backtrace },
   { "sleep", gumjs_thread_sleep },
 
   { NULL, NULL }
@@ -87,22 +88,28 @@ GUMJS_DEFINE_FUNCTION (gumjs_thread_backtrace)
   auto context = isolate->GetCurrentContext ();
 
   GumCpuContext * cpu_context = NULL;
-  Local<Value> selector;
-  if (!_gum_v8_args_parse (args, "|C?V", &cpu_context, &selector))
+  Local<Value> raw_type;
+  guint limit;
+  if (!_gum_v8_args_parse (args, "C?Vu", &cpu_context, &raw_type, &limit))
     return;
 
+  if (!raw_type->IsSymbol ())
+  {
+    _gum_v8_throw_ascii_literal (isolate, "invalid backtracer value");
+    return;
+  }
+  Local<Symbol> type = raw_type.As<Symbol> ();
   gboolean accurate = TRUE;
-  if (!selector.IsEmpty ())
+  if (type->StrictEquals (
+        Local<Symbol>::New (isolate, *module->fuzzy_enum_value)))
   {
-    if ((*module->fuzzy_enum_value) == selector)
-    {
-      accurate = FALSE;
-    }
-    else if ((*module->accurate_enum_value) != selector)
-    {
-      _gum_v8_throw_ascii_literal (isolate, "invalid backtracer enum value");
-      return;
-    }
+    accurate = FALSE;
+  }
+  else if (!type->StrictEquals (
+        Local<Symbol>::New (isolate, *module->accurate_enum_value)))
+  {
+    _gum_v8_throw_ascii_literal (isolate, "invalid backtracer enum value");
+    return;
   }
 
   GumBacktracer * backtracer;
@@ -129,7 +136,15 @@ GUMJS_DEFINE_FUNCTION (gumjs_thread_backtrace)
   }
 
   GumReturnAddressArray ret_addrs;
-  gum_backtracer_generate (backtracer, cpu_context, &ret_addrs);
+  if (limit != 0)
+  {
+    gum_backtracer_generate_with_limit (backtracer, cpu_context, &ret_addrs,
+        limit);
+  }
+  else
+  {
+    gum_backtracer_generate (backtracer, cpu_context, &ret_addrs);
+  }
 
   auto result = Array::New (isolate, ret_addrs.len);
   for (guint i = 0; i != ret_addrs.len; i++)

bindings/gumjs/runtime/core.js

@@ -485,6 +485,24 @@ if (Process.findRangeByAddress === undefined) {
   });
 }
 
+Object.defineProperties(Thread, {
+  backtrace: {
+    enumerable: true,
+    value: function (cpuContext = null, backtracerOrOptions = {}) {
+      const options = (typeof backtracerOrOptions === 'object')
+          ? backtracerOrOptions
+          : { backtracer: backtracerOrOptions };
+
+      const {
+        backtracer = Backtracer.ACCURATE,
+        limit = 0,
+      } = options;
+
+      return Thread._backtrace(cpuContext, backtracer, limit);
+    }
+  },
+});
+
 if (globalThis.Interceptor !== undefined) {
   Object.defineProperties(Interceptor, {
     attach: {

tests/gumjs/script.c

@@ -29,6 +29,7 @@ TESTLIST_BEGIN (script)
   TESTENTRY (rpc_can_be_performed)
   TESTENTRY (message_can_be_logged)
   TESTENTRY (thread_can_be_forced_to_sleep)
+  TESTENTRY (thread_backtrace_can_be_captured_with_limit)
   TESTENTRY (timeout_can_be_scheduled)
   TESTENTRY (timeout_can_be_cancelled)
   TESTENTRY (interval_can_be_scheduled)
@@ -6355,6 +6356,14 @@ TESTCASE (thread_can_be_forced_to_sleep)
   g_timer_destroy (timer);
 }
 
+TESTCASE (thread_backtrace_can_be_captured_with_limit)
+{
+  COMPILE_AND_LOAD_SCRIPT (
+      "send(Thread.backtrace(null, { limit: 2 }).length);");
+  EXPECT_SEND_MESSAGE_WITH ("2");
+  EXPECT_NO_MESSAGES ();
+}
+
 TESTCASE (timeout_can_be_scheduled)
 {
   COMPILE_AND_LOAD_SCRIPT (