The R Project SVN R

///////////////////////////////////////////////////////////////////////////////
//
/// \file       alone_decoder.c
/// \brief      Decoder for LZMA_Alone files
//
//  Author:     Lasse Collin
//
//  This file has been put into the public domain.
//  You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////

#include "common.h"
#include "lzma_encoder.h"


#define ALONE_HEADER_SIZE (1 + 4 + 8)


struct lzma_coder_s {
    lzma_next_coder next;

    enum {
        SEQ_HEADER,
        SEQ_CODE,
    } sequence;

    size_t header_pos;
    uint8_t header[ALONE_HEADER_SIZE];
};


static lzma_ret
alone_encode(lzma_coder *coder,
        lzma_allocator *allocator lzma_attribute((unused)),
        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)
{
    while (*out_pos < out_size)
    switch (coder->sequence) {
    case SEQ_HEADER:
        lzma_bufcpy(coder->header, &coder->header_pos,
                ALONE_HEADER_SIZE,
                out, out_pos, out_size);
        if (coder->header_pos < ALONE_HEADER_SIZE)
            return LZMA_OK;

        coder->sequence = SEQ_CODE;
        break;

    case SEQ_CODE:
        return coder->next.code(coder->next.coder,
                allocator, in, in_pos, in_size,
                out, out_pos, out_size, action);

    default:
        assert(0);
        return LZMA_PROG_ERROR;
    }

    return LZMA_OK;
}


static void
alone_encoder_end(lzma_coder *coder, lzma_allocator *allocator)
{
    lzma_next_end(&coder->next, allocator);
    lzma_free(coder, allocator);
    return;
}


// At least for now, this is not used by any internal function.
static lzma_ret
alone_encoder_init(lzma_next_coder *next, lzma_allocator *allocator,
        const lzma_options_lzma *options)
{
    lzma_next_coder_init(&alone_encoder_init, next, allocator);

    if (next->coder == NULL) {
        next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
        if (next->coder == NULL)
            return LZMA_MEM_ERROR;

        next->code = &alone_encode;
        next->end = &alone_encoder_end;
        next->coder->next = LZMA_NEXT_CODER_INIT;
    }

    // Basic initializations
    next->coder->sequence = SEQ_HEADER;
    next->coder->header_pos = 0;

    // Encode the header:
    // - Properties (1 byte)
    if (lzma_lzma_lclppb_encode(options, next->coder->header))
        return LZMA_OPTIONS_ERROR;

    // - Dictionary size (4 bytes)
    if (options->dict_size < LZMA_DICT_SIZE_MIN)
        return LZMA_OPTIONS_ERROR;

    // Round up to to the next 2^n or 2^n + 2^(n - 1) depending on which
    // one is the next unless it is UINT32_MAX. While the header would
    // allow any 32-bit integer, we do this to keep the decoder of liblzma
    // accepting the resulting files.
    uint32_t d = options->dict_size - 1;
    d |= d >> 2;
    d |= d >> 3;
    d |= d >> 4;
    d |= d >> 8;
    d |= d >> 16;
    if (d != UINT32_MAX)
        ++d;

    unaligned_write32le(next->coder->header + 1, d);

    // - Uncompressed size (always unknown and using EOPM)
    memset(next->coder->header + 1 + 4, 0xFF, 8);

    // Initialize the LZMA encoder.
    const lzma_filter_info filters[2] = {
        {
            .init = &lzma_lzma_encoder_init,
            .options = (void *)(options),
        }, {
            .init = NULL,
        }
    };

    return lzma_next_filter_init(&next->coder->next, allocator, filters);
}


/*
extern lzma_ret
lzma_alone_encoder_init(lzma_next_coder *next, lzma_allocator *allocator,
        const lzma_options_alone *options)
{
    lzma_next_coder_init(&alone_encoder_init, next, allocator, options);
}
*/


extern LZMA_API(lzma_ret)
lzma_alone_encoder(lzma_stream *strm, const lzma_options_lzma *options)
{
    lzma_next_strm_init(alone_encoder_init, strm, options);

    strm->internal->supported_actions[LZMA_RUN] = true;
    strm->internal->supported_actions[LZMA_FINISH] = true;

    return LZMA_OK;
}