1 files changed, 43 insertions, 0 deletions
diff --git a/src/util/varint.c b/src/util/varint.c
new file mode 100644
index 000000000..9ffc1d744
--- /dev/null
+++ b/src/util/varint.c
@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#include "varint.h"
+
+uintmax_t git_decode_varint(const unsigned char *bufp, size_t *varint_len)
+{
+	const unsigned char *buf = bufp;
+	unsigned char c = *buf++;
+	uintmax_t val = c & 127;
+	while (c & 128) {
+		val += 1;
+		if (!val || MSB(val, 7)) {
+			/* This is not a valid varint_len, so it signals
+			   the error */
+			*varint_len = 0;
+			return 0; /* overflow */
+		}
+		c = *buf++;
+		val = (val << 7) + (c & 127);
+	}
+	*varint_len = buf - bufp;
+	return val;
+}
+
+int git_encode_varint(unsigned char *buf, size_t bufsize, uintmax_t value)
+{
+	unsigned char varint[16];
+	unsigned pos = sizeof(varint) - 1;
+	varint[pos] = value & 127;
+	while (value >>= 7)
+		varint[--pos] = 128 | (--value & 127);
+	if (buf) {
+		if (bufsize < (sizeof(varint) - pos))
+			return -1;
+		memcpy(buf, varint + pos, sizeof(varint) - pos);
+	}
+	return sizeof(varint) - pos;
+}