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ext/zstd/examples/dictionary_decompression.c  view on Meta::CPAN

     * content size is always written into the header, either use streaming
     * decompression, or ZSTD_decompressBound().
     */
    unsigned long long const rSize = ZSTD_getFrameContentSize(cBuff, cSize);
    CHECK(rSize != ZSTD_CONTENTSIZE_ERROR, "%s: not compressed by zstd!", fname);
    CHECK(rSize != ZSTD_CONTENTSIZE_UNKNOWN, "%s: original size unknown!", fname);
    void* const rBuff = malloc_orDie((size_t)rSize);

    /* Check that the dictionary ID matches.
     * If a non-zstd dictionary is used, then both will be zero.
     * By default zstd always writes the dictionary ID into the frame.
     * Zstd will check if there is a dictionary ID mismatch as well.
     */
    unsigned const expectedDictID = ZSTD_getDictID_fromDDict(ddict);
    unsigned const actualDictID = ZSTD_getDictID_fromFrame(cBuff, cSize);
    CHECK(actualDictID == expectedDictID,
          "DictID mismatch: expected %u got %u",
          expectedDictID,
          actualDictID);

    /* Decompress using the dictionary.
     * If you need to control the decompression parameters, then use the
     * advanced API: ZSTD_DCtx_setParameter(), ZSTD_DCtx_refDDict(), and
     * ZSTD_decompressDCtx().
     */
    ZSTD_DCtx* const dctx = ZSTD_createDCtx();
    CHECK(dctx != NULL, "ZSTD_createDCtx() failed!");
    size_t const dSize = ZSTD_decompress_usingDDict(dctx, rBuff, rSize, cBuff, cSize, ddict);
    CHECK_ZSTD(dSize);
    /* When zstd knows the content size, it will error if it doesn't match. */
    CHECK(dSize == rSize, "Impossible because zstd will check this condition!");

    /* success */
    printf("%25s : %6u -> %7u \n", fname, (unsigned)cSize, (unsigned)rSize);

    ZSTD_freeDCtx(dctx);
    free(rBuff);
    free(cBuff);
}


int main(int argc, const char** argv)
{
    const char* const exeName = argv[0];

    if (argc<3) {
        printf("wrong arguments\n");
        printf("usage:\n");
        printf("%s [FILES] dictionary\n", exeName);
        return 1;
    }

    /* load dictionary only once */
    const char* const dictName = argv[argc-1];
    ZSTD_DDict* const dictPtr = createDict_orDie(dictName);

    int u;
    for (u=1; u<argc-1; u++) decompress(argv[u], dictPtr);

    ZSTD_freeDDict(dictPtr);
    printf("All %u files correctly decoded (in memory) \n", argc-2);
    return 0;
}