Improved the Stream Flags handling API.

1 files changed, 21 insertions, 7 deletions

diff --git a/src/liblzma/common/stream_flags_common.c b/src/liblzma/common/stream_flags_common.c
index c44b3ff2..aaa9fe02 100644
--- a/src/liblzma/common/stream_flags_common.c
+++ b/src/liblzma/common/stream_flags_common.c
@@ -24,17 +24,31 @@ const uint8_t lzma_header_magic[6] = { 0xFF, 0x4C, 0x5A, 0x4D, 0x41, 0x00 };
 const uint8_t lzma_footer_magic[2] = { 0x59, 0x5A };
 
 
-extern LZMA_API lzma_bool
-lzma_stream_flags_equal(const lzma_stream_flags *a, const lzma_stream_flags *b)
+extern LZMA_API lzma_ret
+lzma_stream_flags_compare(
+		const lzma_stream_flags *a, const lzma_stream_flags *b)
 {
+	// We can compare only version 0 structures.
+	if (a->version != 0 || b->version != 0)
+		return LZMA_HEADER_ERROR;
+
+	// Check type
+	if ((unsigned int)(a->check) > LZMA_CHECK_ID_MAX
+			|| (unsigned int)(b->check) > LZMA_CHECK_ID_MAX)
+		return LZMA_PROG_ERROR;
+
 	if (a->check != b->check)
-		return false;
+		return LZMA_DATA_ERROR;
 
 	// Backward Sizes are compared only if they are known in both.
 	if (a->backward_size != LZMA_VLI_VALUE_UNKNOWN
-			&& b->backward_size != LZMA_VLI_VALUE_UNKNOWN
-			&& a->backward_size != b->backward_size)
-		return false;
+			&& b->backward_size != LZMA_VLI_VALUE_UNKNOWN) {
+		if (!is_backward_size_valid(a) || !is_backward_size_valid(b))
+			return LZMA_PROG_ERROR;
+
+		if (a->backward_size != b->backward_size)
+			return LZMA_DATA_ERROR;
+	}
 
-	return true;
+	return LZMA_OK;
 }