image_read returns size_t, so 0 when error or end of file

src/cold-flash.c

@@ -128,7 +128,7 @@ struct xloader_msg xloader_msg_create(uint32_t type, struct image * image) {
 			if ( need > sizeof(buffer) )
 				need = sizeof(buffer);
 			ret = image_read(image, buffer, need);
-			if ( ret < 0 )
+			if ( ret == 0 )
 				break;
 			msg.crc1 = crc32(buffer, ret, msg.crc1);
 			readed += ret;
@@ -188,7 +188,7 @@ static int send_2nd(usb_dev_handle * udev, struct image * image) {
 		if ( need > sizeof(buffer) )
 			need = sizeof(buffer);
 		ret = image_read(image, buffer, need);
-		if ( ret < 0 )
+		if ( ret == 0 )
 			break;
 		if ( usb_bulk_write(udev, WRITE_DEV, (char *)buffer, ret, WRITE_TIMEOUT) != ret )
 			ERROR_RETURN("Sending 2nd X-Loader image failed", -1);
@@ -230,7 +230,7 @@ static int send_secondary(usb_dev_handle * udev, struct image * image) {
 		if ( need > sizeof(buffer) )
 			need = sizeof(buffer);
 		ret = image_read(image, buffer, need);
-		if ( ret < 0 )
+		if ( ret == 0 )
 			break;
 		if ( usb_bulk_write(udev, WRITE_DEV, (char *)buffer, ret, WRITE_TIMEOUT) != ret )
 			ERROR_RETURN("Sending Secondary image failed", -1);

src/fiasco.c

@@ -457,7 +457,7 @@ int fiasco_write_to_file(struct fiasco * fiasco, const char * file) {
 		image_seek(image, 0);
 		while ( 1 ) {
 			size = image_read(image, buf, sizeof(buf));
-			if ( size < 1 )
+			if ( size == 0 )
 				break;
 			WRITE_OR_FAIL(file, fd, buf, size);
 		}
@@ -543,7 +543,7 @@ int fiasco_unpack(struct fiasco * fiasco, const char * dir) {
 		image_seek(image, 0);
 		while ( 1 ) {
 			size = image_read(image, buf, sizeof(buf));
-			if ( size < 1 )
+			if ( size == 0 )
 				break;
 			WRITE_OR_FAIL(name, fd, buf, size);
 		}

src/image.c

@@ -419,6 +419,7 @@ enum image_type image_type_from_data(struct image * image) {
 
 	unsigned char buf[512];
 
+	memset(buf, 0, sizeof(buf));
 	image_seek(image, 0);
 	image_read(image, buf, sizeof(buf));