root/src/liblzma/common/stream_buffer_decoder.c

DEFINITIONS

1. LZMA_API

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

#include "stream_decoder.h"


extern LZMA_API(lzma_ret)
lzma_stream_buffer_decode(uint64_t *memlimit, uint32_t flags,
                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)
{
        // Sanity checks
        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;

        // Catch flags that are not allowed in buffer-to-buffer decoding.
        if (flags & LZMA_TELL_ANY_CHECK)
                return LZMA_PROG_ERROR;

        // Initialize the Stream decoder.
        // TODO: We need something to tell the decoder that it can use the
        // output buffer as workspace, and thus save significant amount of RAM.
        lzma_next_coder stream_decoder = LZMA_NEXT_CODER_INIT;
        lzma_ret ret = lzma_stream_decoder_init(
                        &stream_decoder, allocator, *memlimit, flags);

        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 = stream_decoder.code(stream_decoder.coder, allocator,
                                in, in_pos, in_size, out, out_pos, out_size,
                                LZMA_FINISH);

                if (ret == LZMA_STREAM_END) {
                        ret = LZMA_OK;
                } else {
                        // Something went wrong, restore the positions.
                        *in_pos = in_start;
                        *out_pos = out_start;

                        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 Stream
                                // never produces output.
                                if (*in_pos == in_size)
                                        ret = LZMA_DATA_ERROR;
                                else
                                        ret = LZMA_BUF_ERROR;

                        } else if (ret == LZMA_MEMLIMIT_ERROR) {
                                // Let the caller know how much memory would
                                // have been needed.
                                uint64_t memusage;
                                (void)stream_decoder.memconfig(
                                                stream_decoder.coder,
                                                memlimit, &memusage, 0);
                        }
                }
        }

        // 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(&stream_decoder, allocator);

        return ret;
}