3 files changed, 25 insertions, 31 deletions

diff --git a/src/liblzma/common/block_buffer_encoder.c b/src/liblzma/common/block_buffer_encoder.c
index ef6aeb82..4d90feef 100644
--- a/src/liblzma/common/block_buffer_encoder.c
+++ b/src/liblzma/common/block_buffer_encoder.c
@@ -290,6 +290,7 @@ lzma_block_buffer_encode(lzma_block *block, lzma_allocator *allocator,
 		lzma_check_update(&check, block->check, in, in_size);
 		lzma_check_finish(&check, block->check);
 
+		memcpy(block->raw_check, check.buffer.u8, check_size);
 		memcpy(out + *out_pos, check.buffer.u8, check_size);
 		*out_pos += check_size;
 	}
diff --git a/src/liblzma/common/block_decoder.c b/src/liblzma/common/block_decoder.c
index 9b998e63..a3ce6f49 100644
--- a/src/liblzma/common/block_decoder.c
+++ b/src/liblzma/common/block_decoder.c
@@ -146,26 +146,22 @@ block_decode(lzma_coder *coder, lzma_allocator *allocator,
 	// Fall through
 
 	case SEQ_CHECK: {
-		const bool chksup = lzma_check_is_supported(
-				coder->block->check);
-
-		while (*in_pos < in_size) {
-			// coder->check.buffer[] may be uninitialized when
-			// the Check ID is not supported.
-			if (chksup && coder->check.buffer.u8[coder->check_pos]
-					!= in[*in_pos]) {
-				++*in_pos;
-				return LZMA_DATA_ERROR;
-			}
-
-			++*in_pos;
-
-			if (++coder->check_pos == lzma_check_size(
-					coder->block->check))
-				return LZMA_STREAM_END;
-		}
+		const size_t check_size = lzma_check_size(coder->block->check);
+		lzma_bufcpy(in, in_pos, in_size, coder->block->raw_check,
+				&coder->check_pos, check_size);
+		if (coder->check_pos < check_size)
+			return LZMA_OK;
+
+		// Validate the Check only if we support it.
+		// coder->check.buffer may be uninitialized
+		// when the Check ID is not supported.
+		if (lzma_check_is_supported(coder->block->check)
+				&& memcmp(coder->block->raw_check,
+					coder->check.buffer.u8,
+					check_size) != 0)
+			return LZMA_DATA_ERROR;
 
-		return LZMA_OK;
+		return LZMA_STREAM_END;
 	}
 	}
 
diff --git a/src/liblzma/common/block_encoder.c b/src/liblzma/common/block_encoder.c
index 0d7b3ef2..567889aa 100644
--- a/src/liblzma/common/block_encoder.c
+++ b/src/liblzma/common/block_encoder.c
@@ -117,18 +117,15 @@ block_encode(lzma_coder *coder, lzma_allocator *allocator,
 	// Fall through
 
 	case SEQ_CHECK: {
-		const uint32_t check_size
-				= lzma_check_size(coder->block->check);
-
-		while (*out_pos < out_size) {
-			out[*out_pos] = coder->check.buffer.u8[coder->pos];
-			++*out_pos;
-
-			if (++coder->pos == check_size)
-				return LZMA_STREAM_END;
-		}
-
-		return LZMA_OK;
+		const size_t check_size = lzma_check_size(coder->block->check);
+		lzma_bufcpy(coder->check.buffer.u8, &coder->pos, check_size,
+				out, out_pos, out_size);
+		if (coder->pos < check_size)
+			return LZMA_OK;
+
+		memcpy(coder->block->raw_check, coder->check.buffer.u8,
+				check_size);
+		return LZMA_STREAM_END;
 	}
 	}