X-Git-Url: https://git.octo.it/?a=blobdiff_plain;f=delta.h;fp=delta.h;h=31d1820f80f2887d51808170fc86585ada42d42e;hb=dcde55bc58ae845307efbdce3a1071f75ccd758e;hp=bc3a220179cefd0af169ab4f2e6aeeb5675f900a;hpb=e5e3e0f5001f51fe388d530481e56651729add1a;p=git.git

diff --git a/delta.h b/delta.h
index bc3a2201..31d1820f 100644
--- a/delta.h
+++ b/delta.h
@@ -9,4 +9,26 @@ extern void *patch_delta(void *src_buf, unsigned long src_size,
 			 void *delta_buf, unsigned long delta_size,
 			 unsigned long *dst_size);
 
+/* the smallest possible delta size is 4 bytes */
+#define DELTA_SIZE_MIN	4
+
+/*
+ * This must be called twice on the delta data buffer, first to get the
+ * expected reference buffer size, and again to get the result buffer size.
+ */
+static inline unsigned long get_delta_hdr_size(const unsigned char **datap)
+{
+	const unsigned char *data = *datap;
+	unsigned char cmd = *data++;
+	unsigned long size = cmd & ~0x80;
+	int i = 7;
+	while (cmd & 0x80) {
+		cmd = *data++;
+		size |= (cmd & ~0x80) << i;
+		i += 7;
+	}
+	*datap = data;
+	return size;
+}
+
 #endif