Add the binary delta apply algorithm for pack style deltas

The git__delta_apply() function can be used to apply a Git style
delta, such as those used in pack files or in git patch files,
to recover the original object stream.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

1 files changed, 25 insertions, 0 deletions

diff --git a/src/delta-apply.h b/src/delta-apply.h
new file mode 100644
index 000000000..498bccdfe
--- /dev/null
+++ b/src/delta-apply.h
@@ -0,0 +1,25 @@
+#ifndef INCLUDE_delta_apply_h__
+#define INCLUDE_delta_apply_h__
+
+/**
+ * Apply a git binary delta to recover the original content.
+ *
+ * @param out the output buffer to receive the original data.
+ *		Only out->data and out->len are populated, as this is
+ *		the only information available in the delta.
+ * @param base the base to copy from during copy instructions.
+ * @param base_len number of bytes available at base.
+ * @param delta the delta to execute copy/insert instructions from.
+ * @param delta_len total number of bytes in the delta.
+ * @return
+ * - GIT_SUCCESS on a successful delta unpack.
+ * - GIT_ERROR if the delta is corrupt or doesn't match the base.
+ */
+extern int git__delta_apply(
+	git_obj *out,
+	const unsigned char *base,
+	size_t base_len,
+	const unsigned char *delta,
+	size_t delta_len);
+
+#endif