vm: support self-executing image file

vm/factor.cpp

@@ -10,6 +10,7 @@ void init_globals()
 
 void factor_vm::default_parameters(vm_parameters *p)
 {
+	p->embedded_image = false;
 	p->image_path = NULL;
 
 	p->datastack_size = 32 * sizeof(cell);
@@ -118,7 +119,15 @@ void factor_vm::init_factor(vm_parameters *p)
 		p->executable_path = executable_path;
 
 	if(p->image_path == NULL)
-		p->image_path = default_image_path();
+	{
+		if (embedded_image_p())
+		{
+			p->embedded_image = true;
+			p->image_path = p->executable_path;
+		}
+		else
+			p->image_path = default_image_path();
+	}
 
 	srand((unsigned int)nano_count());
 	init_ffi();

vm/image.cpp

@@ -219,11 +219,37 @@ void factor_vm::fixup_code(cell data_offset, cell code_offset)
 	code->allocator->iterate(updater,fixup);
 }
 
+FILE* factor_vm::open_image(vm_parameters *p)
+{
+	if (p->embedded_image)
+	{
+		FILE *file = OPEN_READ(p->executable_path);
+		if (file == NULL)
+		{
+			std::cout << "Cannot open embedded image" << std::endl;
+			std::cout << strerror(errno) << std::endl;
+			exit(1);
+		}
+		safe_fseek(file, -sizeof(embedded_image_footer), SEEK_END);
+		embedded_image_footer footer;
+		safe_fread(&footer, sizeof(embedded_image_footer), 1, file);
+		if (footer.magic != image_magic)
+		{
+			std::cout << "No embedded image" << std::endl;
+			exit(1);
+		}
+		safe_fseek(file, footer.image_offset, SEEK_SET);
+		return file;
+	}
+	else
+		return OPEN_READ(p->image_path);
+}
+
 /* Read an image file from disk, only done once during startup */
 /* This function also initializes the data and code heaps */
 void factor_vm::load_image(vm_parameters *p)
 {
-	FILE *file = OPEN_READ(p->image_path);
+	FILE *file = open_image(p);
 	if(file == NULL)
 	{
 		std::cout << "Cannot open image file: " << p->image_path << std::endl;
@@ -339,4 +365,19 @@ void factor_vm::primitive_save_image_and_exit()
 		exit(1);
 }
 
+bool factor_vm::embedded_image_p()
+{
+	const vm_char *vm_path = vm_executable_path();
+	if (!vm_path)
+		return false;
+	FILE *file = OPEN_READ(vm_path);
+	if (!file)
+		return false;
+	safe_fseek(file, -sizeof(embedded_image_footer), SEEK_END);
+	embedded_image_footer footer;
+	safe_fread(&footer, sizeof(embedded_image_footer), 1, file);
+	fclose(file);
+	return footer.magic == image_magic;
+}
+
 }

vm/image.hpp

@@ -4,6 +4,11 @@ namespace factor
 static const cell image_magic = 0x0f0e0d0c;
 static const cell image_version = 4;
 
+struct embedded_image_footer {
+	cell magic;
+	cell image_offset;
+};
+
 struct image_header {
 	cell magic;
 	cell version;
@@ -28,6 +33,7 @@ struct image_header {
 };
 
 struct vm_parameters {
+	bool embedded_image;
 	const vm_char *image_path;
 	const vm_char *executable_path;
 	cell datastack_size, retainstack_size, callstack_size;

vm/vm.hpp

@@ -610,7 +610,9 @@ struct factor_vm
 	void primitive_save_image_and_exit();
 	void fixup_data(cell data_offset, cell code_offset);
 	void fixup_code(cell data_offset, cell code_offset);
+	FILE *open_image(vm_parameters *p);
 	void load_image(vm_parameters *p);
+	bool embedded_image_p();
 
 	// callstack
 	template<typename Iterator> void iterate_callstack_object(callstack *stack_, Iterator &iterator);