///////////////////////////////////////////////////////////////////////////////
//
/// \file index_encoder.c
/// \brief Encodes the Index field
//
// Copyright (C) 2008 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 "index_encoder.h"
#include "index.h"
#include "check.h"
struct lzma_coder_s {
enum {
SEQ_INDICATOR,
SEQ_COUNT,
SEQ_UNPADDED,
SEQ_UNCOMPRESSED,
SEQ_NEXT,
SEQ_PADDING,
SEQ_CRC32,
} sequence;
/// Index given to us to encode. Note that we modify it in sense that
/// we read it, and read position is tracked in lzma_index structure.
lzma_index *index;
/// The current Index Record being encoded
lzma_index_record record;
/// Position in integers
size_t pos;
/// CRC32 of the List of Records field
uint32_t crc32;
};
static lzma_ret
index_encode(lzma_coder *coder,
lzma_allocator *allocator lzma_attribute((unused)),
const uint8_t *restrict in lzma_attribute((unused)),
size_t *restrict in_pos lzma_attribute((unused)),
size_t in_size lzma_attribute((unused)),
uint8_t *restrict out, size_t *restrict out_pos,
size_t out_size, lzma_action action lzma_attribute((unused)))
{
// Position where to start calculating CRC32. The idea is that we
// need to call lzma_crc32() only once per call to index_encode().
const size_t out_start = *out_pos;
// Return value to use if we return at the end of this function.
// We use "goto out" to jump out of the while-switch construct
// instead of returning directly, because that way we don't need
// to copypaste the lzma_crc32() call to many places.
lzma_ret ret = LZMA_OK;
while (*out_pos < out_size)
switch (coder->sequence) {
case SEQ_INDICATOR:
out[*out_pos] = 0x00;
++*out_pos;
coder->sequence = SEQ_COUNT;
break;
case SEQ_COUNT: {
const lzma_vli index_count = lzma_index_count(coder->index);
ret = lzma_vli_encode(index_count, &coder->pos,
out, out_pos, out_size);
if (ret != LZMA_STREAM_END)
goto out;
ret = LZMA_OK;
coder->pos = 0;
coder->sequence = SEQ_NEXT;
break;
}
case SEQ_NEXT:
if (lzma_index_read(coder->index, &coder->record)) {
// Get the size of the Index Padding field.
coder->pos = lzma_index_padding_size(coder->index);
assert(coder->pos <= 3);
coder->sequence = SEQ_PADDING;
break;
}
// Unpadded Size must be within valid limits.
if (coder->record.unpadded_size < UNPADDED_SIZE_MIN
|| coder->record.unpadded_size
> UNPADDED_SIZE_MAX)
return LZMA_PROG_ERROR;
coder->sequence = SEQ_UNPADDED;
// Fall through
case SEQ_UNPADDED:
case SEQ_UNCOMPRESSED: {
const lzma_vli size = coder->sequence == SEQ_UNPADDED
? coder->record.unpadded_size
: coder->record.uncompressed_size;
ret = lzma_vli_encode(size, &coder->pos,
out, out_pos, out_size);
if (ret != LZMA_STREAM_END)
goto out;
ret = LZMA_OK;
coder->pos = 0;
// Advance to SEQ_UNCOMPRESSED or SEQ_NEXT.
++coder->sequence;
break;
}
case SEQ_PADDING:
if (coder->pos > 0) {
--coder->pos;
out[(*out_pos)++] = 0x00;
break;
}
// Finish the CRC32 calculation.
coder->crc32 = lzma_crc32(out + out_start,
*out_pos - out_start, coder->crc32);
coder->sequence = SEQ_CRC32;
// Fall through
case SEQ_CRC32:
// We don't use the main loop, because we don't want
// coder->crc32 to be touched anymore.
do {
if (*out_pos == out_size)
return LZMA_OK;
out[*out_pos] = (coder->crc32 >> (coder->pos * 8))
& 0xFF;
++*out_pos;
} while (++coder->pos < 4);
return LZMA_STREAM_END;
default:
assert(0);
return LZMA_PROG_ERROR;
}
out:
// Update the CRC32.
coder->crc32 = lzma_crc32(out + out_start,
*out_pos - out_start, coder->crc32);
return ret;
}
static void
index_encoder_end(lzma_coder *coder, lzma_allocator *allocator)
{
lzma_free(coder, allocator);
return;
}
static void
index_encoder_reset(lzma_coder *coder, lzma_index *i)
{
lzma_index_rewind(i);
coder->sequence = SEQ_INDICATOR;
coder->index = i;
coder->pos = 0;
coder->crc32 = 0;
return;
}
extern lzma_ret
lzma_index_encoder_init(lzma_next_coder *next, lzma_allocator *allocator,
lzma_index *i)
{
lzma_next_coder_init(lzma_index_encoder_init, next, allocator);
if (i == NULL)
return LZMA_PROG_ERROR;
if (next->coder == NULL) {
next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
if (next->coder == NULL)
return LZMA_MEM_ERROR;
next->code = &index_encode;
next->end = &index_encoder_end;
}
index_encoder_reset(next->coder, i);
return LZMA_OK;
}
extern LZMA_API lzma_ret
lzma_index_encoder(lzma_stream *strm, lzma_index *i)
{
lzma_next_strm_init(lzma_index_encoder_init, strm, i);
strm->internal->supported_actions[LZMA_RUN] = true;
return LZMA_OK;
}
extern LZMA_API lzma_ret
lzma_index_buffer_encode(lzma_index *i,
uint8_t *out, size_t *out_pos, size_t out_size)
{
// Validate the arugments.
if (i == NULL || out == NULL || out_pos == NULL || *out_pos > out_size)
return LZMA_PROG_ERROR;
// Don't try to encode if there's not enough output space.
if (out_size - *out_pos < lzma_index_size(i))
return LZMA_BUF_ERROR;
// The Index encoder needs just one small data structure so we can
// allocate it on stack.
lzma_coder coder;
index_encoder_reset(&coder, i);
// Do the actual encoding. This should never fail, but store
// the original *out_pos just in case.
const size_t out_start = *out_pos;
lzma_ret ret = index_encode(&coder, NULL, NULL, NULL, 0,
out, out_pos, out_size, LZMA_RUN);
if (ret == LZMA_STREAM_END) {
ret = LZMA_OK;
} else {
// We should never get here, but just in case, restore the
// output position and set the error accordingly if something
// goes wrong and debugging isn't enabled.
assert(0);
*out_pos = out_start;
ret = LZMA_PROG_ERROR;
}
return ret;
}
