Function compressFile_orDie

freebsd/contrib/zstd/examples/streaming_compression.c:19–91

static void compressFile_orDie(const char* fname, const char* outName, int cLevel)
{
    /* Open the input and output files. */
    FILE* const fin  = fopen_orDie(fname, "rb");
    FILE* const fout = fopen_orDie(outName, "wb");
    /* Create the input and output buffers.
     * They may be any size, but we recommend using these functions to size them.
     * Performance will only suffer significantly for very tiny buffers.
     */
    size_t const buffInSize = ZSTD_CStreamInSize();
    void*  const buffIn  = malloc_orDie(buffInSize);
    size_t const buffOutSize = ZSTD_CStreamOutSize();
    void*  const buffOut = malloc_orDie(buffOutSize);

    /* Create the context. */
    ZSTD_CCtx* const cctx = ZSTD_createCCtx();
    CHECK(cctx != NULL, "ZSTD_createCCtx() failed!");

    /* Set any parameters you want.
     * Here we set the compression level, and enable the checksum.
     */
    CHECK_ZSTD( ZSTD_CCtx_setParameter(cctx, ZSTD_c_compressionLevel, cLevel) );
    CHECK_ZSTD( ZSTD_CCtx_setParameter(cctx, ZSTD_c_checksumFlag, 1) );
    ZSTD_CCtx_setParameter(cctx, ZSTD_c_nbWorkers, 4);

    /* This loop read from the input file, compresses that entire chunk,
     * and writes all output produced to the output file.
     */
    size_t const toRead = buffInSize;
    for (;;) {
        size_t read = fread_orDie(buffIn, toRead, fin);
        /* Select the flush mode.
         * If the read may not be finished (read == toRead) we use
         * ZSTD_e_continue. If this is the last chunk, we use ZSTD_e_end.
         * Zstd optimizes the case where the first flush mode is ZSTD_e_end,
         * since it knows it is compressing the entire source in one pass.
         */
        int const lastChunk = (read < toRead);
        ZSTD_EndDirective const mode = lastChunk ? ZSTD_e_end : ZSTD_e_continue;
        /* Set the input buffer to what we just read.
         * We compress until the input buffer is empty, each time flushing the
         * output.
         */
        ZSTD_inBuffer input = { buffIn, read, 0 };
        int finished;
        do {
            /* Compress into the output buffer and write all of the output to
             * the file so we can reuse the buffer next iteration.
             */
            ZSTD_outBuffer output = { buffOut, buffOutSize, 0 };
            size_t const remaining = ZSTD_compressStream2(cctx, &output , &input, mode);
            CHECK_ZSTD(remaining);
            fwrite_orDie(buffOut, output.pos, fout);
            /* If we're on the last chunk we're finished when zstd returns 0,
             * which means its consumed all the input AND finished the frame.
             * Otherwise, we're finished when we've consumed all the input.
             */
            finished = lastChunk ? (remaining == 0) : (input.pos == input.size);