/*
* Copyright (c) Meta Platforms, Inc. and affiliates.
* 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;
}