liblzma: Add lzma_block_uncomp_encode().

This also adds a new internal function
lzma_block_buffer_bound64() which is similar to
lzma_block_buffer_bound() but uses uint64_t instead
of size_t.

src/liblzma/api/lzma/block.h

@@ -496,6 +496,24 @@ extern LZMA_API(lzma_ret) lzma_block_buffer_encode(
 		lzma_nothrow lzma_attr_warn_unused_result;
 
 
+/**
+ * \brief       Single-call uncompress .xz Block encoder
+ *
+ * This is like lzma_block_buffer_encode() except this doesn't try to
+ * compress the data and instead encodes the data using LZMA2 uncompressed
+ * chunks. The required output buffer size can be determined with
+ * lzma_block_buffer_bound().
+ *
+ * Since the data won't be compressed, this function ignores block->filters.
+ * This function doesn't take lzma_allocator because this function doesn't
+ * allocate any memory from the heap.
+ */
+extern LZMA_API(lzma_ret) lzma_block_uncomp_encode(lzma_block *block,
+		const uint8_t *in, size_t in_size,
+		uint8_t *out, size_t *out_pos, size_t out_size)
+		lzma_nothrow lzma_attr_warn_unused_result;
+
+
 /**
  * \brief       Single-call .xz Block decoder
  *

src/liblzma/common/block_buffer_encoder.c

@@ -10,6 +10,7 @@
 //
 ///////////////////////////////////////////////////////////////////////////////
 
+#include "block_buffer_encoder.h"
 #include "block_encoder.h"
 #include "filter_encoder.h"
 #include "lzma2_encoder.h"
@@ -28,8 +29,8 @@
 		+ LZMA_CHECK_SIZE_MAX + 3) & ~3)
 
 
-static lzma_vli
-lzma2_bound(lzma_vli uncompressed_size)
+static uint64_t
+lzma2_bound(uint64_t uncompressed_size)
 {
 	// Prevent integer overflow in overhead calculation.
 	if (uncompressed_size > COMPRESSED_SIZE_MAX)
@@ -39,7 +40,7 @@ lzma2_bound(lzma_vli uncompressed_size)
 	// uncompressed_size up to the next multiple of LZMA2_CHUNK_MAX,
 	// multiply by the size of per-chunk header, and add one byte for
 	// the end marker.
-	const lzma_vli overhead = ((uncompressed_size + LZMA2_CHUNK_MAX - 1)
+	const uint64_t overhead = ((uncompressed_size + LZMA2_CHUNK_MAX - 1)
 				/ LZMA2_CHUNK_MAX)
 			* LZMA2_HEADER_UNCOMPRESSED + 1;
 
@@ -51,30 +52,36 @@ lzma2_bound(lzma_vli uncompressed_size)
 }
 
 
-extern LZMA_API(size_t)
-lzma_block_buffer_bound(size_t uncompressed_size)
+extern uint64_t
+lzma_block_buffer_bound64(uint64_t uncompressed_size)
 {
-	// For now, if the data doesn't compress, we always use uncompressed
-	// chunks of LZMA2. In future we may use Subblock filter too, but
-	// but for simplicity we probably will still use the same bound
-	// calculation even though Subblock filter would have slightly less
-	// overhead.
-	lzma_vli lzma2_size = lzma2_bound(uncompressed_size);
+	// If the data doesn't compress, we always use uncompressed
+	// LZMA2 chunks.
+	uint64_t lzma2_size = lzma2_bound(uncompressed_size);
 	if (lzma2_size == 0)
 		return 0;
 
 	// Take Block Padding into account.
-	lzma2_size = (lzma2_size + 3) & ~LZMA_VLI_C(3);
+	lzma2_size = (lzma2_size + 3) & ~UINT64_C(3);
 
-#if SIZE_MAX < LZMA_VLI_MAX
-	// Catch the possible integer overflow on 32-bit systems. There's no
-	// overflow on 64-bit systems, because lzma2_bound() already takes
+	// No risk of integer overflow because lzma2_bound() already takes
 	// into account the size of the headers in the Block.
-	if (SIZE_MAX - HEADERS_BOUND < lzma2_size)
+	return HEADERS_BOUND + lzma2_size;
+}
+
+
+extern LZMA_API(size_t)
+lzma_block_buffer_bound(size_t uncompressed_size)
+{
+	uint64_t ret = lzma_block_buffer_bound64(uncompressed_size);
+
+#if SIZE_MAX < UINT64_MAX
+	// Catch the possible integer overflow on 32-bit systems.
+	if (ret > SIZE_MAX)
 		return 0;
 #endif
 
-	return HEADERS_BOUND + lzma2_size;
+	return ret;
 }
 
 
@@ -82,9 +89,6 @@ static lzma_ret
 block_encode_uncompressed(lzma_block *block, const uint8_t *in, size_t in_size,
 		uint8_t *out, size_t *out_pos, size_t out_size)
 {
-	// TODO: Figure out if the last filter is LZMA2 or Subblock and use
-	// that filter to encode the uncompressed chunks.
-
 	// Use LZMA2 uncompressed chunks. We wouldn't need a dictionary at
 	// all, but LZMA2 always requires a dictionary, so use the minimum
 	// value to minimize memory usage of the decoder.
@@ -165,11 +169,6 @@ block_encode_normal(lzma_block *block, const lzma_allocator *allocator,
 		uint8_t *out, size_t *out_pos, size_t out_size)
 {
 	// Find out the size of the Block Header.
-	block->compressed_size = lzma2_bound(in_size);
-	if (block->compressed_size == 0)
-		return LZMA_DATA_ERROR;
-
-	block->uncompressed_size = in_size;
 	return_if_error(lzma_block_header_size(block));
 
 	// Reserve space for the Block Header and skip it for now.
@@ -221,10 +220,11 @@ block_encode_normal(lzma_block *block, const lzma_allocator *allocator,
 }
 
 
-extern LZMA_API(lzma_ret)
-lzma_block_buffer_encode(lzma_block *block, const lzma_allocator *allocator,
+static lzma_ret
+block_buffer_encode(lzma_block *block, const lzma_allocator *allocator,
 		const uint8_t *in, size_t in_size,
-		uint8_t *out, size_t *out_pos, size_t out_size)
+		uint8_t *out, size_t *out_pos, size_t out_size,
+		bool try_to_compress)
 {
 	// Validate the arguments.
 	if (block == NULL || (in == NULL && in_size != 0) || out == NULL
@@ -237,7 +237,7 @@ lzma_block_buffer_encode(lzma_block *block, const lzma_allocator *allocator,
 		return LZMA_OPTIONS_ERROR;
 
 	if ((unsigned int)(block->check) > LZMA_CHECK_ID_MAX
-			|| block->filters == NULL)
+			|| (try_to_compress && block->filters == NULL))
 		return LZMA_PROG_ERROR;
 
 	if (!lzma_check_is_supported(block->check))
@@ -258,9 +258,19 @@ lzma_block_buffer_encode(lzma_block *block, const lzma_allocator *allocator,
 
 	out_size -= check_size;
 
+	// Initialize block->uncompressed_size and calculate the worst-case
+	// value for block->compressed_size.
+	block->uncompressed_size = in_size;
+	block->compressed_size = lzma2_bound(in_size);
+	if (block->compressed_size == 0)
+		return LZMA_DATA_ERROR;
+
 	// Do the actual compression.
-	const lzma_ret ret = block_encode_normal(block, allocator,
+	lzma_ret ret = LZMA_BUF_ERROR;
+	if (try_to_compress)
+		ret = block_encode_normal(block, allocator,
 				in, in_size, out, out_pos, out_size);
+
 	if (ret != LZMA_OK) {
 		// If the error was something else than output buffer
 		// becoming full, return the error now.
@@ -303,3 +313,25 @@ lzma_block_buffer_encode(lzma_block *block, const lzma_allocator *allocator,
 
 	return LZMA_OK;
 }
+
+
+extern LZMA_API(lzma_ret)
+lzma_block_buffer_encode(lzma_block *block, const lzma_allocator *allocator,
+		const uint8_t *in, size_t in_size,
+		uint8_t *out, size_t *out_pos, size_t out_size)
+{
+	return block_buffer_encode(block, allocator,
+			in, in_size, out, out_pos, out_size, true);
+}
+
+
+extern LZMA_API(lzma_ret)
+lzma_block_uncomp_encode(lzma_block *block,
+		const uint8_t *in, size_t in_size,
+		uint8_t *out, size_t *out_pos, size_t out_size)
+{
+	// It won't allocate any memory from heap so no need
+	// for lzma_allocator.
+	return block_buffer_encode(block, NULL,
+			in, in_size, out, out_pos, out_size, false);
+}

src/liblzma/common/block_buffer_encoder.h

@@ -0,0 +1,24 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       block_buffer_encoder.h
+/// \brief      Single-call .xz Block encoder
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef LZMA_BLOCK_BUFFER_ENCODER_H
+#define LZMA_BLOCK_BUFFER_ENCODER_H
+
+#include "common.h"
+
+
+/// uint64_t version of lzma_block_buffer_bound(). It is used by
+/// stream_encoder_mt.c. Probably the original lzma_block_buffer_bound()
+/// should have been 64-bit, but fixing it would break the ABI.
+extern uint64_t lzma_block_buffer_bound64(uint64_t uncompressed_size);
+
+#endif

src/liblzma/liblzma.map

@@ -97,6 +97,7 @@ global:
 
 XZ_5.1.2alpha {
 global:
+	lzma_block_uncomp_encode;
 	lzma_get_progress;
 	lzma_stream_encoder_mt;
 	lzma_stream_encoder_mt_memusage;