VFS: Make VFile.truncate work growing files on PSV (fixes #885)

CHANGES

@@ -35,6 +35,7 @@ Misc:
  - GBA: Detect hardware for Pokémon FireRed ROM hacks
  - CMake: Fix CPack dependencies for libpng 1.6
  - Qt: Allow overrides to be saved before a game is loaded
+ - VFS: Make VFile.truncate work growing files on PSV (fixes mgba.io/i/885)
 
 0.6.0: (2017-07-16)
 Features:

src/platform/psp2/sce-vfs.c

@@ -120,7 +120,20 @@ static void _vfsceUnmap(struct VFile* vf, void* memory, size_t size) {
 
 static void _vfsceTruncate(struct VFile* vf, size_t size) {
 	struct VFileSce* vfsce = (struct VFileSce*) vf;
-	// TODO
+	SceOff cur = sceIoLseek(vfsce->fd, 0, SEEK_CUR);
+	SceOff end = sceIoLseek(vfsce->fd, 0, SEEK_END);
+	if (end < size) {
+		uint8_t buffer[2048] = {};
+		size_t write = size - end;
+		while (write >= sizeof(buffer)) {
+			sceIoWrite(vfsce->fd, buffer, sizeof(buffer));
+			write -= sizeof(buffer);
+		}
+		if (write) {
+			sceIoWrite(vfsce->fd, buffer, write);
+		}
+	} // TODO: Else
+	sceIoLseek(vfsce->fd, cur, SEEK_SET);
 }
 
 ssize_t _vfsceSize(struct VFile* vf) {