Add smarter recursion limit checking

Author: trillllian

src/asar/asar.h

@@ -60,12 +60,15 @@ virtual_file_error asar_get_last_io_error();
 extern volatile int recursioncount;
 extern int pass;
 
+size_t check_stack_left();
+
 class recurseblock {
 public:
 	recurseblock()
 	{
 		recursioncount++;
-		if (recursioncount > 1000) asar_throw_error(pass, error_type_fatal, error_id_recursion_limit);
+		if(check_stack_left() < 32768 || recursioncount > 10000)
+			asar_throw_error(pass, error_type_fatal, error_id_recursion_limit);
 	}
 	~recurseblock()
 	{

src/asar/platform/generic/thread-helpers-pthread.h

@@ -55,3 +55,18 @@ bool run_as_thread(functor&& callback) {
 
 	return wrapper.result;
 }
+
+size_t check_stack_left() {
+	pthread_attr_t attrs;
+	void *stack_start;
+	size_t stack_size;
+
+	pthread_getattr_np(pthread_self(), &attrs);
+	pthread_attr_getstack(&attrs, &stack_start, &stack_size);
+	pthread_attr_destroy(&attrs);
+
+	// using a random local as a rough estimate for current top-of-stack
+	size_t stack_left = (char*)&stack_size - (char*)stack_start;
+	return stack_left;
+	if(stack_left < 32768) asar_throw_error(pass, error_type_fatal, error_id_recursion_limit);
+}

src/asar/platform/windows/thread-helpers-win32.h

@@ -82,4 +82,11 @@ bool run_as_thread(functor&& callback) {
 
 	return wrapper.result;
 }
+
+size_t check_stack_left() {
+	void *stack_low, *stack_high;
+	GetCurrentThreadStackLimits(&stack_low, &stack_high);
+	size_t stack_left = (char*)&stack_low - (char*)stack_low;
+	return stack_left;
+}
 #endif