--- /dev/null
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file block_buffer_encoder.c
+/// \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.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "block_buffer_encoder.h"
+#include "block_encoder.h"
+#include "filter_encoder.h"
+#include "lzma2_encoder.h"
+#include "check.h"
+
+
+/// Estimate the maximum size of the Block Header and Check fields for
+/// a Block that uses LZMA2 uncompressed chunks. We could use
+/// lzma_block_header_size() but this is simpler.
+///
+/// Block Header Size + Block Flags + Compressed Size
+/// + Uncompressed Size + Filter Flags for LZMA2 + CRC32 + Check
+/// and round up to the next multiple of four to take Header Padding
+/// into account.
+#define HEADERS_BOUND ((1 + 1 + 2 * LZMA_VLI_BYTES_MAX + 3 + 4 \
+ + LZMA_CHECK_SIZE_MAX + 3) & ~3)
+
+
+static uint64_t
+lzma2_bound(uint64_t uncompressed_size)
+{
+ // Prevent integer overflow in overhead calculation.
+ if (uncompressed_size > COMPRESSED_SIZE_MAX)
+ return 0;
+
+ // Calculate the exact overhead of the LZMA2 headers: Round
+ // 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 uint64_t overhead = ((uncompressed_size + LZMA2_CHUNK_MAX - 1)
+ / LZMA2_CHUNK_MAX)
+ * LZMA2_HEADER_UNCOMPRESSED + 1;
+
+ // Catch the possible integer overflow.
+ if (COMPRESSED_SIZE_MAX - overhead < uncompressed_size)
+ return 0;
+
+ return uncompressed_size + overhead;
+}
+
+
+extern uint64_t
+lzma_block_buffer_bound64(uint64_t 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) & ~UINT64_C(3);
+
+ // No risk of integer overflow because lzma2_bound() already takes
+ // into account the size of the headers in the Block.
+ 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 ret;
+}
+
+
+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)
+{
+ // 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.
+ lzma_options_lzma lzma2 = {
+ .dict_size = LZMA_DICT_SIZE_MIN,
+ };
+
+ lzma_filter filters[2];
+ filters[0].id = LZMA_FILTER_LZMA2;
+ filters[0].options = &lzma2;
+ filters[1].id = LZMA_VLI_UNKNOWN;
+
+ // Set the above filter options to *block temporarily so that we can
+ // encode the Block Header.
+ lzma_filter *filters_orig = block->filters;
+ block->filters = filters;
+
+ if (lzma_block_header_size(block) != LZMA_OK) {
+ block->filters = filters_orig;
+ return LZMA_PROG_ERROR;
+ }
+
+ // Check that there's enough output space. The caller has already
+ // set block->compressed_size to what lzma2_bound() has returned,
+ // so we can reuse that value. We know that compressed_size is a
+ // known valid VLI and header_size is a small value so their sum
+ // will never overflow.
+ assert(block->compressed_size == lzma2_bound(in_size));
+ if (out_size - *out_pos
+ < block->header_size + block->compressed_size) {
+ block->filters = filters_orig;
+ return LZMA_BUF_ERROR;
+ }
+
+ if (lzma_block_header_encode(block, out + *out_pos) != LZMA_OK) {
+ block->filters = filters_orig;
+ return LZMA_PROG_ERROR;
+ }
+
+ block->filters = filters_orig;
+ *out_pos += block->header_size;
+
+ // Encode the data using LZMA2 uncompressed chunks.
+ size_t in_pos = 0;
+ uint8_t control = 0x01; // Dictionary reset
+
+ while (in_pos < in_size) {
+ // Control byte: Indicate uncompressed chunk, of which
+ // the first resets the dictionary.
+ out[(*out_pos)++] = control;
+ control = 0x02; // No dictionary reset
+
+ // Size of the uncompressed chunk
+ const size_t copy_size
+ = my_min(in_size - in_pos, LZMA2_CHUNK_MAX);
+ out[(*out_pos)++] = (copy_size - 1) >> 8;
+ out[(*out_pos)++] = (copy_size - 1) & 0xFF;
+
+ // The actual data
+ assert(*out_pos + copy_size <= out_size);
+ memcpy(out + *out_pos, in + in_pos, copy_size);
+
+ in_pos += copy_size;
+ *out_pos += copy_size;
+ }
+
+ // End marker
+ out[(*out_pos)++] = 0x00;
+ assert(*out_pos <= out_size);
+
+ return LZMA_OK;
+}
+
+
+static lzma_ret
+block_encode_normal(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)
+{
+ // Find out the size of the Block Header.
+ return_if_error(lzma_block_header_size(block));
+
+ // Reserve space for the Block Header and skip it for now.
+ if (out_size - *out_pos <= block->header_size)
+ return LZMA_BUF_ERROR;
+
+ const size_t out_start = *out_pos;
+ *out_pos += block->header_size;
+
+ // Limit out_size so that we stop encoding if the output would grow
+ // bigger than what uncompressed Block would be.
+ if (out_size - *out_pos > block->compressed_size)
+ out_size = *out_pos + block->compressed_size;
+
+ // TODO: In many common cases this could be optimized to use
+ // significantly less memory.
+ lzma_next_coder raw_encoder = LZMA_NEXT_CODER_INIT;
+ lzma_ret ret = lzma_raw_encoder_init(
+ &raw_encoder, allocator, block->filters);
+
+ if (ret == LZMA_OK) {
+ size_t in_pos = 0;
+ ret = raw_encoder.code(raw_encoder.coder, allocator,
+ in, &in_pos, in_size, out, out_pos, out_size,
+ LZMA_FINISH);
+ }
+
+ // NOTE: This needs to be run even if lzma_raw_encoder_init() failed.
+ lzma_next_end(&raw_encoder, allocator);
+
+ if (ret == LZMA_STREAM_END) {
+ // Compression was successful. Write the Block Header.
+ block->compressed_size
+ = *out_pos - (out_start + block->header_size);
+ ret = lzma_block_header_encode(block, out + out_start);
+ if (ret != LZMA_OK)
+ ret = LZMA_PROG_ERROR;
+
+ } else if (ret == LZMA_OK) {
+ // Output buffer became full.
+ ret = LZMA_BUF_ERROR;
+ }
+
+ // Reset *out_pos if something went wrong.
+ if (ret != LZMA_OK)
+ *out_pos = out_start;
+
+ return ret;
+}
+
+
+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,
+ bool try_to_compress)
+{
+ // Validate the arguments.
+ if (block == NULL || (in == NULL && in_size != 0) || out == NULL
+ || out_pos == NULL || *out_pos > out_size)
+ return LZMA_PROG_ERROR;
+
+ // The contents of the structure may depend on the version so
+ // check the version before validating the contents of *block.
+ if (block->version > 1)
+ return LZMA_OPTIONS_ERROR;
+
+ if ((unsigned int)(block->check) > LZMA_CHECK_ID_MAX
+ || (try_to_compress && block->filters == NULL))
+ return LZMA_PROG_ERROR;
+
+ if (!lzma_check_is_supported(block->check))
+ return LZMA_UNSUPPORTED_CHECK;
+
+ // Size of a Block has to be a multiple of four, so limit the size
+ // here already. This way we don't need to check it again when adding
+ // Block Padding.
+ out_size -= (out_size - *out_pos) & 3;
+
+ // Get the size of the Check field.
+ const size_t check_size = lzma_check_size(block->check);
+ assert(check_size != UINT32_MAX);
+
+ // Reserve space for the Check field.
+ if (out_size - *out_pos <= check_size)
+ return LZMA_BUF_ERROR;
+
+ 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.
+ 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.
+ if (ret != LZMA_BUF_ERROR)
+ return ret;
+
+ // The data was uncompressible (at least with the options
+ // given to us) or the output buffer was too small. Use the
+ // uncompressed chunks of LZMA2 to wrap the data into a valid
+ // Block. If we haven't been given enough output space, even
+ // this may fail.
+ return_if_error(block_encode_uncompressed(block, in, in_size,
+ out, out_pos, out_size));
+ }
+
+ assert(*out_pos <= out_size);
+
+ // Block Padding. No buffer overflow here, because we already adjusted
+ // out_size so that (out_size - out_start) is a multiple of four.
+ // Thus, if the buffer is full, the loop body can never run.
+ for (size_t i = (size_t)(block->compressed_size); i & 3; ++i) {
+ assert(*out_pos < out_size);
+ out[(*out_pos)++] = 0x00;
+ }
+
+ // If there's no Check field, we are done now.
+ if (check_size > 0) {
+ // Calculate the integrity check. We reserved space for
+ // the Check field earlier so we don't need to check for
+ // available output space here.
+ lzma_check_state check;
+ lzma_check_init(&check, block->check);
+ 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;
+ }
+
+ 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);
+}
projects / zpackage / blobdiff