PNG savestate loading

src/gba/gba-serialize.c

@@ -10,6 +10,7 @@
 #include "util/vfs.h"
 
 #include <fcntl.h>
+#include <png.h>
 #include <zlib.h>
 
 const uint32_t GBA_SAVESTATE_MAGIC = 0x01000000;
@@ -110,6 +111,33 @@ static bool _savePNGState(struct GBA* gba, struct VFile* vf) {
 	return state && png && info && buffer;
 }
 
+static int _loadPNGChunkHandler(png_structp png, png_unknown_chunkp chunk) {
+	if (strcmp((const char*) chunk->name, "gbAs") != 0) {
+		return 0;
+	}
+	struct GBASerializedState state;
+	uLongf len = sizeof(state);
+	uncompress((Bytef*) &state, &len, chunk->data, chunk->size);
+	GBADeserialize(png_get_user_chunk_ptr(png), &state);
+	return 1;
+}
+
+static bool _loadPNGState(struct GBA* gba, struct VFile* vf) {
+	png_structp png = PNGReadOpen(vf, PNG_HEADER_BYTES);
+	png_infop info = png_create_info_struct(png);
+	png_infop end = png_create_info_struct(png);
+	if (!png || !info || !end) {
+		PNGReadClose(png, info, end);
+		return false;
+	}
+	PNGInstallChunkHandler(png, gba, _loadPNGChunkHandler, "gbAs");
+	PNGReadHeader(png, info);
+	PNGIgnorePixels(png, info);
+	PNGReadFooter(png, end);
+	PNGReadClose(png, info, end);
+	return true;
+}
+
 bool GBASaveState(struct GBA* gba, struct VDir* dir, int slot, bool screenshot) {
 	struct VFile* vf = _getStateVf(gba, dir, slot, true);
 	if (!vf) {
@@ -133,9 +161,13 @@ bool GBALoadState(struct GBA* gba, struct VDir* dir, int slot) {
 	if (!vf) {
 		return false;
 	}
-	struct GBASerializedState* state = vf->map(vf, sizeof(struct GBASerializedState), MAP_READ);
-	GBADeserialize(gba, state);
-	vf->unmap(vf, state, sizeof(struct GBASerializedState));
+	if (!isPNG(vf)) {
+		struct GBASerializedState* state = vf->map(vf, sizeof(struct GBASerializedState), MAP_READ);
+		GBADeserialize(gba, state);
+		vf->unmap(vf, state, sizeof(struct GBASerializedState));
+	} else {
+		_loadPNGState(gba, vf);
+	}
 	vf->close(vf);
 	return true;
 }

src/platform/sdl/sdl-events.c

@@ -163,7 +163,7 @@ static void _GBASDLHandleKeypress(struct GBAThread* context, struct GBASDLEvents
 				case SDLK_F9:
 				case SDLK_F10:
 					GBAThreadInterrupt(context);
-					GBASaveState(context->gba, context->stateDir, event->keysym.sym - SDLK_F1, false);
+					GBASaveState(context->gba, context->stateDir, event->keysym.sym - SDLK_F1, true);
 					GBAThreadContinue(context);
 					break;
 				default:

src/util/png-io.c

@@ -10,6 +10,14 @@ static void _pngWrite(png_structp png, png_bytep buffer, png_size_t size) {
 	}
 }
 
+static void _pngRead(png_structp png, png_bytep buffer, png_size_t size) {
+	struct VFile* vf = png_get_io_ptr(png);
+	size_t read = vf->read(vf, buffer, size);
+	if (read != size) {
+		png_error(png, "Could not read PNG");
+	}
+}
+
 png_structp PNGWriteOpen(struct VFile* source) {
 	png_structp png = png_create_write_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0);
 	if (!png) {
@@ -71,6 +79,70 @@ bool PNGWriteCustomChunk(png_structp png, const char* name, size_t size, void* d
 }
 
 void PNGWriteClose(png_structp png, png_infop info) {
-	png_write_end(png, info);
+	if (!setjmp(png_jmpbuf(png))) {
+		png_write_end(png, info);
+	}
 	png_destroy_write_struct(&png, &info);
 }
+
+bool isPNG(struct VFile* source) {
+	png_byte header[PNG_HEADER_BYTES];
+	source->read(source, header, PNG_HEADER_BYTES);
+	return !png_sig_cmp(header, 0, PNG_HEADER_BYTES);
+}
+
+png_structp PNGReadOpen(struct VFile* source, unsigned offset) {
+	png_structp png = png_create_read_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0);
+	if (!png) {
+		return 0;
+	}
+	if (setjmp(png_jmpbuf(png))) {
+		png_destroy_read_struct(&png, 0, 0);
+		return 0;
+	}
+	png_set_read_fn(png, source, _pngRead);
+	png_set_sig_bytes(png, offset);
+	return png;
+}
+
+bool PNGInstallChunkHandler(png_structp png, void* context, ChunkHandler handler, const char* chunkName) {
+	if (setjmp(png_jmpbuf(png))) {
+		return false;
+	}
+	png_set_read_user_chunk_fn(png, context, handler);
+	png_set_keep_unknown_chunks(png, PNG_HANDLE_CHUNK_ALWAYS, (png_const_bytep) chunkName, 1);
+	return true;
+}
+
+bool PNGReadHeader(png_structp png, png_infop info) {
+	if (setjmp(png_jmpbuf(png))) {
+		return false;
+	}
+	png_read_info(png, info);
+	return true;
+}
+
+bool PNGIgnorePixels(png_structp png, png_infop info) {
+	if (setjmp(png_jmpbuf(png))) {
+		return false;
+	}
+
+	unsigned height = png_get_image_height(png, info);
+	unsigned i;
+	for (i = 0; i < height; ++i) {
+		png_read_row(png, 0, 0);
+	}
+	return true;
+}
+
+bool PNGReadFooter(png_structp png, png_infop end) {
+	if (setjmp(png_jmpbuf(png))) {
+		return false;
+	}
+	png_read_end(png, end);
+	return true;
+}
+
+void PNGReadClose(png_structp png, png_infop info, png_infop end) {
+	png_destroy_read_struct(&png, &info, &end);
+}

src/util/png-io.h

@@ -7,10 +7,24 @@
 
 struct VFile;
 
+enum {
+	PNG_HEADER_BYTES = 8
+};
+
 png_structp PNGWriteOpen(struct VFile* source);
 png_infop PNGWriteHeader(png_structp png, unsigned width, unsigned height);
 bool PNGWritePixels(png_structp png, unsigned width, unsigned height, unsigned stride, void* pixels);
 bool PNGWriteCustomChunk(png_structp png, const char* name, size_t size, void* data);
 void PNGWriteClose(png_structp png, png_infop info);
 
+typedef int (*ChunkHandler)(png_structp, png_unknown_chunkp);
+
+bool isPNG(struct VFile* source);
+png_structp PNGReadOpen(struct VFile* source, unsigned offset);
+bool PNGInstallChunkHandler(png_structp png, void* context, ChunkHandler handler, const char* chunkName);
+bool PNGReadHeader(png_structp png, png_infop info);
+bool PNGIgnorePixels(png_structp png, png_infop info);
+bool PNGReadFooter(png_structp png, png_infop end);
+void PNGReadClose(png_structp png, png_infop info, png_infop end);
+
 #endif