GB, GBA Savedata: Fix savestate-related save overwriting (fixes #834)

CHANGES

@@ -25,6 +25,7 @@ Bugfixes:
  - GB MBC: Fix RTC loading when file size is off
  - GB Serialize: Fix deserializing video STAT
  - Qt: Fix GL display when loading a game from CLI (fixes mgba.io/i/843)
+ - GB, GBA Savedata: Fix savestate-related save overwriting (fixes mgba.io/i/834)
 Misc:
  - GBA Timer: Use global cycles for timers
  - GBA: Extend oddly-sized ROMs to full address space (fixes mgba.io/i/722)

src/gb/gb.c

@@ -220,7 +220,7 @@ void GBResizeSram(struct GB* gb, size_t size) {
 
 void GBSramClean(struct GB* gb, uint32_t frameCount) {
 	// TODO: Share with GBASavedataClean
-	if (!gb->sramVf || gb->sramVf != gb->sramRealVf) {
+	if (!gb->sramVf) {
 		return;
 	}
 	if (gb->sramDirty & GB_SRAM_DIRT_NEW) {
@@ -230,6 +230,9 @@ void GBSramClean(struct GB* gb, uint32_t frameCount) {
 			gb->sramDirty |= GB_SRAM_DIRT_SEEN;
 		}
 	} else if ((gb->sramDirty & GB_SRAM_DIRT_SEEN) && frameCount - gb->sramDirtAge > CLEANUP_THRESHOLD) {
+		if (gb->sramMaskWriteback) {
+			GBSavedataUnmask(gb);
+		}
 		if (gb->memory.mbcType == GB_MBC3_RTC) {
 			GBMBCRTCWrite(gb);
 		}
@@ -259,7 +262,9 @@ void GBSavedataUnmask(struct GB* gb) {
 	gb->sramVf = gb->sramRealVf;
 	gb->memory.sram = gb->sramVf->map(gb->sramVf, gb->sramSize, MAP_WRITE);
 	if (gb->sramMaskWriteback) {
+		vf->seek(vf, 0, SEEK_SET);
 		vf->read(vf, gb->memory.sram, gb->sramSize);
+		gb->sramMaskWriteback = false;
 	}
 	vf->close(vf);
 }
@@ -287,6 +292,7 @@ void GBUnloadROM(struct GB* gb) {
 	gb->memory.mbcType = GB_MBC_AUTODETECT;
 	gb->isPristine = false;
 
+	gb->sramMaskWriteback = false;
 	GBSavedataUnmask(gb);
 	GBSramDeinit(gb);
 	if (gb->sramRealVf) {

src/gba/memory.c

@@ -92,6 +92,7 @@ void GBAMemoryDeinit(struct GBA* gba) {
 	if (gba->memory.rom) {
 		mappedMemoryFree(gba->memory.rom, gba->memory.romSize);
 	}
+	gba->memory.savedata.maskWriteback = false;
 	GBASavedataUnmask(&gba->memory.savedata);
 	GBASavedataDeinit(&gba->memory.savedata);
 	if (gba->memory.savedata.realVf) {