FreeBSD/Linux Kernel Cross Reference
sys/contrib/zstd/examples/simple_decompression.c

     /*
      * Copyright (c) Yann Collet, Facebook, Inc.
      * All rights reserved.
      *
      * This source code is licensed under both the BSD-style license (found in the
      * LICENSE file in the root directory of this source tree) and the GPLv2 (found
      * in the COPYING file in the root directory of this source tree).
      * You may select, at your option, one of the above-listed licenses.
      */
    
    #include <stdio.h>     // printf
    #include <stdlib.h>    // free
    #include <zstd.h>      // presumes zstd library is installed
    #include "common.h"    // Helper functions, CHECK(), and CHECK_ZSTD()
    
    static void decompress(const char* fname)
    {
        size_t cSize;
        void* const cBuff = mallocAndLoadFile_orDie(fname, &cSize);
        /* Read the content size from the frame header. For simplicity we require
         * that it is always present. By default, zstd will write the content size
         * in the header when it is known. If you can't guarantee that the frame
         * 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);
    
        /* Decompress.
         * If you are doing many decompressions, you may want to reuse the context
         * and use ZSTD_decompressDCtx(). If you want to set advanced parameters,
         * use ZSTD_DCtx_setParameter().
         */
        size_t const dSize = ZSTD_decompress(rBuff, rSize, cBuff, cSize);
        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);
    
        free(rBuff);
        free(cBuff);
    }
    
    int main(int argc, const char** argv)
    {
        const char* const exeName = argv[0];
    
        if (argc!=2) {
            printf("wrong arguments\n");
            printf("usage:\n");
            printf("%s FILE\n", exeName);
            return 1;
        }
    
        decompress(argv[1]);
    
        printf("%s correctly decoded (in memory). \n", argv[1]);
    
        return 0;
    }

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