///////////////////////////////////////////////////////////////////////////////
//
/// \file block_encoder.c
/// \brief Encodes .lzma Blocks
//
// 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 "block_encoder.h"
#include "filter_encoder.h"
#include "check.h"
/// The maximum size of a single Block is limited by the maximum size of
/// a Stream, which is 2^63 - 1 bytes (i.e. LZMA_VLI_MAX). We could
/// take into account the headers etc. to determine the exact maximum size
/// of the Compressed Data field, but the complexity would give us nothing
/// useful. Instead, limit the size of Compressed Data so that even with
/// biggest possible Block Header and Check fields the total size of the
/// Block stays as valid VLI. This way we don't produce incorrect output
/// if someone will really try creating a Block of 8 EiB.
///
/// ~LZMA_VLI_C(3) is to guarantee that if we need padding at the end of
/// the Compressed Data field, it will still stay in the proper limit.
#define COMPRESSED_SIZE_MAX ((LZMA_VLI_MAX - LZMA_BLOCK_HEADER_SIZE_MAX \
- LZMA_CHECK_SIZE_MAX) & ~LZMA_VLI_C(3))
struct lzma_coder_s {
/// The filters in the chain; initialized with lzma_raw_decoder_init().
lzma_next_coder next;
/// Encoding options; we also write Total Size, Compressed Size, and
/// Uncompressed Size back to this structure when the encoding has
/// been finished.
lzma_block *options;
enum {
SEQ_CODE,
SEQ_PADDING,
SEQ_CHECK,
} sequence;
/// Compressed Size calculated while encoding
lzma_vli compressed_size;
/// Uncompressed Size calculated while encoding
lzma_vli uncompressed_size;
/// Position when writing out the Check field
size_t check_pos;
/// Check of the uncompressed data
lzma_check_state check;
};
static lzma_ret
block_encode(lzma_coder *coder, lzma_allocator *allocator,
const uint8_t *restrict in, size_t *restrict in_pos,
size_t in_size, uint8_t *restrict out,
size_t *restrict out_pos, size_t out_size, lzma_action action)
{
// Check that our amount of input stays in proper limits.
if (LZMA_VLI_MAX - coder->uncompressed_size < in_size - *in_pos)
return LZMA_PROG_ERROR;
switch (coder->sequence) {
case SEQ_CODE: {
const size_t in_start = *in_pos;
const size_t out_start = *out_pos;
const lzma_ret ret = coder->next.code(coder->next.coder,
allocator, in, in_pos, in_size,
out, out_pos, out_size, action);
const size_t in_used = *in_pos - in_start;
const size_t out_used = *out_pos - out_start;
if (COMPRESSED_SIZE_MAX - coder->compressed_size < out_used)
return LZMA_DATA_ERROR;
coder->compressed_size += out_used;
// No need to check for overflow because we have already
// checked it at the beginning of this function.
coder->uncompressed_size += in_used;
lzma_check_update(&coder->check, coder->options->check,
in + in_start, in_used);
if (ret != LZMA_STREAM_END || action == LZMA_SYNC_FLUSH)
return ret;
assert(*in_pos == in_size);
assert(action == LZMA_FINISH);
coder->sequence = SEQ_PADDING;
}
// Fall through
case SEQ_PADDING:
// Pad Compressed Data to a multiple of four bytes.
while (coder->compressed_size & 3) {
if (*out_pos >= out_size)
return LZMA_OK;
out[*out_pos] = 0x00;
++*out_pos;
// No need to use check for overflow here since we
// have already checked in SEQ_CODE that Compressed
// Size will stay in proper limits.
++coder->compressed_size;
}
// Copy the values into coder->options. The caller
// may use this information to construct Index.
coder->options->compressed_size = coder->compressed_size;
coder->options->uncompressed_size = coder->uncompressed_size;
if (coder->options->check == LZMA_CHECK_NONE)
return LZMA_STREAM_END;
lzma_check_finish(&coder->check, coder->options->check);
coder->sequence = SEQ_CHECK;
// Fall through
case SEQ_CHECK: {
const uint32_t check_size
= lzma_check_size(coder->options->check);
while (*out_pos < out_size) {
out[*out_pos] = coder->check.buffer.u8[
coder->check_pos];
++*out_pos;
if (++coder->check_pos == check_size)
return LZMA_STREAM_END;
}
return LZMA_OK;
}
}
return LZMA_PROG_ERROR;
}
static void
block_encoder_end(lzma_coder *coder, lzma_allocator *allocator)
{
lzma_next_end(&coder->next, allocator);
lzma_free(coder, allocator);
return;
}
extern lzma_ret
lzma_block_encoder_init(lzma_next_coder *next, lzma_allocator *allocator,
lzma_block *options)
{
lzma_next_coder_init(lzma_block_encoder_init, next, allocator);
// If the Check ID is not supported, we cannot calculate the check and
// thus not create a proper Block.
if ((unsigned)(options->check) > LZMA_CHECK_ID_MAX)
return LZMA_PROG_ERROR;
if (!lzma_check_is_supported(options->check))
return LZMA_UNSUPPORTED_CHECK;
// Allocate and initialize *next->coder if needed.
if (next->coder == NULL) {
next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
if (next->coder == NULL)
return LZMA_MEM_ERROR;
next->code = &block_encode;
next->end = &block_encoder_end;
next->coder->next = LZMA_NEXT_CODER_INIT;
}
// Basic initializations
next->coder->sequence = SEQ_CODE;
next->coder->options = options;
next->coder->compressed_size = 0;
next->coder->uncompressed_size = 0;
// Initialize the check
next->coder->check_pos = 0;
lzma_check_init(&next->coder->check, options->check);
// Initialize the requested filters.
return lzma_raw_encoder_init(&next->coder->next, allocator,
options->filters);
}
extern LZMA_API lzma_ret
lzma_block_encoder(lzma_stream *strm, lzma_block *options)
{
lzma_next_strm_init(lzma_block_encoder_init, strm, options);
strm->internal->supported_actions[LZMA_RUN] = true;
strm->internal->supported_actions[LZMA_FINISH] = true;
return LZMA_OK;
}
