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///////////////////////////////////////////////////////////////////////////////
//
/// \file erofs_decoder.c
/// \brief Decode EROFS LZMA format
//
// Author: Lasse Collin
//
// This file has been put into the public domain.
// You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////
#include "lzma_decoder.h"
#include "lz_decoder.h"
typedef struct {
/// LZMA1 decoder
lzma_next_coder lzma;
/// Uncompressed size of the stream as given by the application
lzma_vli uncomp_size;
/// LZMA dictionary size as given by the application
uint32_t dict_size;
/// True once the first byte of the EROFS LZMA stream
/// has been processed.
bool props_decoded;
} lzma_erofs_coder;
static lzma_ret
erofs_decode(void *coder_ptr, const 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)
{
lzma_erofs_coder *coder = coder_ptr;
if (!coder->props_decoded) {
// There must be at least one byte of input to decode
// the properties byte.
if (*in_pos >= in_size)
return LZMA_OK;
lzma_options_lzma options = {
.preset_dict = NULL,
.preset_dict_size = 0,
};
// The properties are stored as bitwise-negation
// of the typical encoding.
if (lzma_lzma_lclppb_decode(&options, ~in[*in_pos]))
return LZMA_OPTIONS_ERROR;
++*in_pos;
// Initialize the decoder.
options.dict_size = coder->dict_size;
lzma_filter_info filters[2] = {
{
.init = &lzma_lzma_decoder_init,
.options = &options,
}, {
.init = NULL,
}
};
return_if_error(lzma_next_filter_init(&coder->lzma,
allocator, filters));
// Use a hack to set the uncompressed size.
lzma_lz_decoder_uncompressed(coder->lzma.coder,
coder->uncomp_size);
// Pass one dummy 0x00 byte to the LZMA decoder since that
// is what it expects the first byte to be.
const uint8_t dummy_in = 0;
size_t dummy_in_pos = 0;
if (coder->lzma.code(coder->lzma.coder, allocator,
&dummy_in, &dummy_in_pos, 1,
out, out_pos, out_size, LZMA_RUN) != LZMA_OK)
return LZMA_PROG_ERROR;
assert(dummy_in_pos == 1);
coder->props_decoded = true;
}
// The rest is normal LZMA decoding.
return coder->lzma.code(coder->lzma.coder, allocator,
in, in_pos, in_size,
out, out_pos, out_size, action);
}
static void
erofs_decoder_end(void *coder_ptr, const lzma_allocator *allocator)
{
lzma_erofs_coder *coder = coder_ptr;
lzma_next_end(&coder->lzma, allocator);
lzma_free(coder, allocator);
return;
}
static lzma_ret
erofs_decoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
uint64_t uncomp_size, uint32_t dict_size)
{
lzma_next_coder_init(&erofs_decoder_init, next, allocator);
lzma_erofs_coder *coder = next->coder;
if (coder == NULL) {
coder = lzma_alloc(sizeof(lzma_erofs_coder), allocator);
if (coder == NULL)
return LZMA_MEM_ERROR;
next->coder = coder;
next->code = &erofs_decode;
next->end = &erofs_decoder_end;
coder->lzma = LZMA_NEXT_CODER_INIT;
}
if (uncomp_size > LZMA_VLI_MAX)
return LZMA_OPTIONS_ERROR;
coder->uncomp_size = uncomp_size;
coder->dict_size = dict_size;
coder->props_decoded = false;
return LZMA_OK;
}
extern LZMA_API(lzma_ret)
lzma_erofs_decoder(lzma_stream *strm, uint64_t uncomp_size, uint32_t dict_size)
{
lzma_next_strm_init(erofs_decoder_init, strm, uncomp_size, dict_size);
strm->internal->supported_actions[LZMA_RUN] = true;
strm->internal->supported_actions[LZMA_FINISH] = true;
return LZMA_OK;
}
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