X-Git-Url: https://git.verplant.org/?a=blobdiff_plain;ds=inline;f=delta.h;h=09b2e1eed5dfc772feb38715f051eff43570d4cb;hb=ae0b219c8e32aa8f34401252d845916b136a467b;hp=e073dff831ab5062638ddc33e32a7c7aae807c39;hpb=a310d4349467d78266f38d29e500c77b96ee5bef;p=git.git

diff --git a/delta.h b/delta.h
index e073dff8..09b2e1ee 100644
--- a/delta.h
+++ b/delta.h
@@ -1,6 +1,35 @@
-extern void *diff_delta(void *from_buf, unsigned long from_size,
-			void *to_buf, unsigned long to_size,
-		        unsigned long *delta_size);
+#ifndef DELTA_H
+#define DELTA_H
+
+/* handling of delta buffers */
+extern void *diff_delta(const void *from_buf, unsigned long from_size,
+			const void *to_buf, unsigned long to_size,
+		        unsigned long *delta_size, unsigned long max_size);
 extern void *patch_delta(void *src_buf, unsigned long src_size,
-			 void *delta_buf, unsigned long delta_size,
+			 const 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 *top)
+{
+	const unsigned char *data = *datap;
+	unsigned char cmd;
+	unsigned long size = 0;
+	int i = 0;
+	do {
+		cmd = *data++;
+		size |= (cmd & ~0x80) << i;
+		i += 7;
+	} while (cmd & 0x80 && data < top);
+	*datap = data;
+	return size;
+}
+
+#endif