source: vbox/trunk/src/libs/liblzma-5.6.4/common/stream_encoder.c@ 109046

// SPDX-License-Identifier: 0BSD

///////////////////////////////////////////////////////////////////////////////
//
/// \file       stream_encoder.c
/// \brief      Encodes .xz Streams
//
//  Author:     Lasse Collin
//
///////////////////////////////////////////////////////////////////////////////

#include "block_encoder.h"
#include "index_encoder.h"


typedef struct {
        enum {
                SEQ_STREAM_HEADER,
                SEQ_BLOCK_INIT,
                SEQ_BLOCK_HEADER,
                SEQ_BLOCK_ENCODE,
                SEQ_INDEX_ENCODE,
                SEQ_STREAM_FOOTER,
        } sequence;

        /// True if Block encoder has been initialized by
        /// stream_encoder_init() or stream_encoder_update()
        /// and thus doesn't need to be initialized in stream_encode().
        bool block_encoder_is_initialized;

        /// Block
        lzma_next_coder block_encoder;

        /// Options for the Block encoder
        lzma_block block_options;

        /// The filter chain currently in use
        lzma_filter filters[LZMA_FILTERS_MAX + 1];

        /// Index encoder. This is separate from Block encoder, because this
        /// doesn't take much memory, and when encoding multiple Streams
        /// with the same encoding options we avoid reallocating memory.
        lzma_next_coder index_encoder;

        /// Index to hold sizes of the Blocks
        lzma_index *index;

        /// Read position in buffer[]
        size_t buffer_pos;

        /// Total number of bytes in buffer[]
        size_t buffer_size;

        /// Buffer to hold Stream Header, Block Header, and Stream Footer.
        /// Block Header has biggest maximum size.
        uint8_t buffer[LZMA_BLOCK_HEADER_SIZE_MAX];
} lzma_stream_coder;


static lzma_ret
block_encoder_init(lzma_stream_coder *coder, const lzma_allocator *allocator)
{
        // Prepare the Block options. Even though Block encoder doesn't need
        // compressed_size, uncompressed_size, and header_size to be
        // initialized, it is a good idea to do it here, because this way
        // we catch if someone gave us Filter ID that cannot be used in
        // Blocks/Streams.
        coder->block_options.compressed_size = LZMA_VLI_UNKNOWN;
        coder->block_options.uncompressed_size = LZMA_VLI_UNKNOWN;

        return_if_error(lzma_block_header_size(&coder->block_options));

        // Initialize the actual Block encoder.
        return lzma_block_encoder_init(&coder->block_encoder, allocator,
                        &coder->block_options);
}


static lzma_ret
stream_encode(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_stream_coder *coder = coder_ptr;

        // Main loop
        while (*out_pos < out_size)
        switch (coder->sequence) {
        case SEQ_STREAM_HEADER:
        case SEQ_BLOCK_HEADER:
        case SEQ_STREAM_FOOTER:
                lzma_bufcpy(coder->buffer, &coder->buffer_pos,
                                coder->buffer_size, out, out_pos, out_size);
                if (coder->buffer_pos < coder->buffer_size)
                        return LZMA_OK;

                if (coder->sequence == SEQ_STREAM_FOOTER)
                        return LZMA_STREAM_END;

                coder->buffer_pos = 0;
                ++coder->sequence;
                break;

        case SEQ_BLOCK_INIT: {
                if (*in_pos == in_size) {
                        // If we are requested to flush or finish the current
                        // Block, return LZMA_STREAM_END immediately since
                        // there's nothing to do.
                        if (action != LZMA_FINISH)
                                return action == LZMA_RUN
                                                ? LZMA_OK : LZMA_STREAM_END;

                        // The application had used LZMA_FULL_FLUSH to finish
                        // the previous Block, but now wants to finish without
                        // encoding new data, or it is simply creating an
                        // empty Stream with no Blocks.
                        //
                        // Initialize the Index encoder, and continue to
                        // actually encoding the Index.
                        return_if_error(lzma_index_encoder_init(
                                        &coder->index_encoder, allocator,
                                        coder->index));
                        coder->sequence = SEQ_INDEX_ENCODE;
                        break;
                }

                // Initialize the Block encoder unless it was already
                // initialized by stream_encoder_init() or
                // stream_encoder_update().
                if (!coder->block_encoder_is_initialized)
                        return_if_error(block_encoder_init(coder, allocator));

                // Make it false so that we don't skip the initialization
                // with the next Block.
                coder->block_encoder_is_initialized = false;

                // Encode the Block Header. This shouldn't fail since we have
                // already initialized the Block encoder.
                if (lzma_block_header_encode(&coder->block_options,
                                coder->buffer) != LZMA_OK)
                        return LZMA_PROG_ERROR;

                coder->buffer_size = coder->block_options.header_size;
                coder->sequence = SEQ_BLOCK_HEADER;
                break;
        }

        case SEQ_BLOCK_ENCODE: {
                static const lzma_action convert[LZMA_ACTION_MAX + 1] = {
                        LZMA_RUN,
                        LZMA_SYNC_FLUSH,
                        LZMA_FINISH,
                        LZMA_FINISH,
                        LZMA_FINISH,
                };

                const lzma_ret ret = coder->block_encoder.code(
                                coder->block_encoder.coder, allocator,
                                in, in_pos, in_size,
                                out, out_pos, out_size, convert[action]);
                if (ret != LZMA_STREAM_END || action == LZMA_SYNC_FLUSH)
                        return ret;

                // Add a new Index Record.
                const lzma_vli unpadded_size = lzma_block_unpadded_size(
                                &coder->block_options);
                assert(unpadded_size != 0);
                return_if_error(lzma_index_append(coder->index, allocator,
                                unpadded_size,
                                coder->block_options.uncompressed_size));

                coder->sequence = SEQ_BLOCK_INIT;
                break;
        }

        case SEQ_INDEX_ENCODE: {
                // Call the Index encoder. It doesn't take any input, so
                // those pointers can be NULL.
                const lzma_ret ret = coder->index_encoder.code(
                                coder->index_encoder.coder, allocator,
                                NULL, NULL, 0,
                                out, out_pos, out_size, LZMA_RUN);
                if (ret != LZMA_STREAM_END)
                        return ret;

                // Encode the Stream Footer into coder->buffer.
                const lzma_stream_flags stream_flags = {
                        .version = 0,
                        .backward_size = lzma_index_size(coder->index),
                        .check = coder->block_options.check,
                };

                if (lzma_stream_footer_encode(&stream_flags, coder->buffer)
                                != LZMA_OK)
                        return LZMA_PROG_ERROR;

                coder->buffer_size = LZMA_STREAM_HEADER_SIZE;
                coder->sequence = SEQ_STREAM_FOOTER;
                break;
        }

        default:
                assert(0);
                return LZMA_PROG_ERROR;
        }

        return LZMA_OK;
}


static void
stream_encoder_end(void *coder_ptr, const lzma_allocator *allocator)
{
        lzma_stream_coder *coder = coder_ptr;

        lzma_next_end(&coder->block_encoder, allocator);
        lzma_next_end(&coder->index_encoder, allocator);
        lzma_index_end(coder->index, allocator);

        lzma_filters_free(coder->filters, allocator);

        lzma_free(coder, allocator);
        return;
}


static lzma_ret
stream_encoder_update(void *coder_ptr, const lzma_allocator *allocator,
                const lzma_filter *filters,
                const lzma_filter *reversed_filters)
{
        lzma_stream_coder *coder = coder_ptr;
        lzma_ret ret;

        // Make a copy to a temporary buffer first. This way it is easier
        // to keep the encoder state unchanged if an error occurs with
        // lzma_filters_copy().
        lzma_filter temp[LZMA_FILTERS_MAX + 1];
        return_if_error(lzma_filters_copy(filters, temp, allocator));

        if (coder->sequence <= SEQ_BLOCK_INIT) {
                // There is no incomplete Block waiting to be finished,
                // thus we can change the whole filter chain. Start by
                // trying to initialize the Block encoder with the new
                // chain. This way we detect if the chain is valid.
                coder->block_encoder_is_initialized = false;
                coder->block_options.filters = temp;
                ret = block_encoder_init(coder, allocator);
                coder->block_options.filters = coder->filters;
                if (ret != LZMA_OK)
                        goto error;

                coder->block_encoder_is_initialized = true;

        } else if (coder->sequence <= SEQ_BLOCK_ENCODE) {
                // We are in the middle of a Block. Try to update only
                // the filter-specific options.
                ret = coder->block_encoder.update(
                                coder->block_encoder.coder, allocator,
                                filters, reversed_filters);
                if (ret != LZMA_OK)
                        goto error;
        } else {
                // Trying to update the filter chain when we are already
                // encoding Index or Stream Footer.
                ret = LZMA_PROG_ERROR;
                goto error;
        }

        // Free the options of the old chain.
        lzma_filters_free(coder->filters, allocator);

        // Copy the new filter chain in place.
        memcpy(coder->filters, temp, sizeof(temp));

        return LZMA_OK;

error:
        lzma_filters_free(temp, allocator);
        return ret;
}


static lzma_ret
stream_encoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
                const lzma_filter *filters, lzma_check check)
{
        lzma_next_coder_init(&stream_encoder_init, next, allocator);

        if (filters == NULL)
                return LZMA_PROG_ERROR;

        lzma_stream_coder *coder = next->coder;

        if (coder == NULL) {
                coder = lzma_alloc(sizeof(lzma_stream_coder), allocator);
                if (coder == NULL)
                        return LZMA_MEM_ERROR;

                next->coder = coder;
                next->code = &stream_encode;
                next->end = &stream_encoder_end;
                next->update = &stream_encoder_update;

                coder->filters[0].id = LZMA_VLI_UNKNOWN;
                coder->block_encoder = LZMA_NEXT_CODER_INIT;
                coder->index_encoder = LZMA_NEXT_CODER_INIT;
                coder->index = NULL;
        }

        // Basic initializations
        coder->sequence = SEQ_STREAM_HEADER;
        coder->block_options.version = 0;
        coder->block_options.check = check;

        // Initialize the Index
        lzma_index_end(coder->index, allocator);
        coder->index = lzma_index_init(allocator);
        if (coder->index == NULL)
                return LZMA_MEM_ERROR;

        // Encode the Stream Header
        lzma_stream_flags stream_flags = {
                .version = 0,
                .check = check,
        };
        return_if_error(lzma_stream_header_encode(
                        &stream_flags, coder->buffer));

        coder->buffer_pos = 0;
        coder->buffer_size = LZMA_STREAM_HEADER_SIZE;

        // Initialize the Block encoder. This way we detect unsupported
        // filter chains when initializing the Stream encoder instead of
        // giving an error after Stream Header has already been written out.
        return stream_encoder_update(coder, allocator, filters, NULL);
}


extern LZMA_API(lzma_ret)
lzma_stream_encoder(lzma_stream *strm,
                const lzma_filter *filters, lzma_check check)
{
        lzma_next_strm_init(stream_encoder_init, strm, filters, check);

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

        return LZMA_OK;
}