The R Project SVN R

///////////////////////////////////////////////////////////////////////////////
//
/// \file       block_buffer_decoder.c
/// \brief      Single-call .xz Block decoder
//
//  Author:     Lasse Collin
//
//  This file has been put into the public domain.
//  You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////

#include "block_decoder.h"


extern LZMA_API(lzma_ret)
lzma_block_buffer_decode(lzma_block *block, lzma_allocator *allocator,
        const uint8_t *in, size_t *in_pos, size_t in_size,
        uint8_t *out, size_t *out_pos, size_t out_size)
{
    if (in_pos == NULL || (in == NULL && *in_pos != in_size)
            || *in_pos > in_size || out_pos == NULL
            || (out == NULL && *out_pos != out_size)
            || *out_pos > out_size)
        return LZMA_PROG_ERROR;

    // Initialize the Block decoder.
    lzma_next_coder block_decoder = LZMA_NEXT_CODER_INIT;
    lzma_ret ret = lzma_block_decoder_init(
            &block_decoder, allocator, block);

    if (ret == LZMA_OK) {
        // Save the positions so that we can restore them in case
        // an error occurs.
        const size_t in_start = *in_pos;
        const size_t out_start = *out_pos;

        // Do the actual decoding.
        ret = block_decoder.code(block_decoder.coder, allocator,
                in, in_pos, in_size, out, out_pos, out_size,
                LZMA_FINISH);

        if (ret == LZMA_STREAM_END) {
            ret = LZMA_OK;
        } else {
            if (ret == LZMA_OK) {
                // Either the input was truncated or the
                // output buffer was too small.
                assert(*in_pos == in_size
                        || *out_pos == out_size);

                // If all the input was consumed, then the
                // input is truncated, even if the output
                // buffer is also full. This is because
                // processing the last byte of the Block
                // never produces output.
                //
                // NOTE: This assumption may break when new
                // filters are added, if the end marker of
                // the filter doesn't consume at least one
                // complete byte.
                if (*in_pos == in_size)
                    ret = LZMA_DATA_ERROR;
                else
                    ret = LZMA_BUF_ERROR;
            }

            // Restore the positions.
            *in_pos = in_start;
            *out_pos = out_start;
        }
    }

    // Free the decoder memory. This needs to be done even if
    // initialization fails, because the internal API doesn't
    // require the initialization function to free its memory on error.
    lzma_next_end(&block_decoder, allocator);

    return ret;
}