Imported to git.

1 files changed, 55 insertions, 0 deletions

diff --git a/src/liblzma/common/vli_reverse_decoder.c b/src/liblzma/common/vli_reverse_decoder.c
new file mode 100644
index 00000000..68ca6a42
--- /dev/null
+++ b/src/liblzma/common/vli_reverse_decoder.c
@@ -0,0 +1,55 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       vli_reverse_decoder.c
+/// \brief      Decodes variable-length integers starting at end of the buffer
+//
+//  Copyright (C) 2007 Lasse Collin
+//
+//  This library is free software; you can redistribute it and/or
+//  modify it under the terms of the GNU Lesser General Public
+//  License as published by the Free Software Foundation; either
+//  version 2.1 of the License, or (at your option) any later version.
+//
+//  This library is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+//  Lesser General Public License for more details.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "common.h"
+
+
+extern LZMA_API lzma_ret
+lzma_vli_reverse_decode(lzma_vli *vli, const uint8_t *in, size_t *in_size)
+{
+	if (*in_size == 0)
+		return LZMA_BUF_ERROR;
+
+	size_t i = *in_size - 1;
+	*vli = in[i] & 0x7F;
+
+	if (!(in[i] & 0x80)) {
+		*in_size = i;
+		return LZMA_OK;
+	}
+
+	const size_t end = *in_size > LZMA_VLI_BYTES_MAX
+			? *in_size - LZMA_VLI_BYTES_MAX : 0;
+
+	do {
+		if (i-- == end) {
+			if (*in_size < LZMA_VLI_BYTES_MAX)
+				return LZMA_BUF_ERROR;
+
+			return LZMA_DATA_ERROR;
+		}
+
+		*vli <<= 7;
+		*vli = in[i] & 0x7F;
+
+	} while (!(in[i] & 0x80));
+
+	*in_size = i;
+	return LZMA_OK;
+}