ceph/src/zstd/examples/simple_decompression.c

   1 /*
   2  * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
   3  * All rights reserved.
   4  *
   5  * This source code is licensed under both the BSD-style license (found in the
   6  * LICENSE file in the root directory of this source tree) and the GPLv2 (found
   7  * in the COPYING file in the root directory of this source tree).
   8  * You may select, at your option, one of the above-listed licenses.
   9  */
  10
  11 #include <stdlib.h>    // malloc, exit
  12 #include <stdio.h>     // printf
  13 #include <string.h>    // strerror
  14 #include <errno.h>     // errno
  15 #include <sys/stat.h>  // stat
  16 #define ZSTD_STATIC_LINKING_ONLY   // ZSTD_findDecompressedSize
  17 #include <zstd.h>      // presumes zstd library is installed
  18
  19
  20 static off_t fsize_orDie(const char *filename)
  21 {
  22     struct stat st;
  23     if (stat(filename, &st) == 0) return st.st_size;
  24     /* error */
  25     fprintf(stderr, "stat: %s : %s \n", filename, strerror(errno));
  26     exit(1);
  27 }
  28
  29 static FILE* fopen_orDie(const char *filename, const char *instruction)
  30 {
  31     FILE* const inFile = fopen(filename, instruction);
  32     if (inFile) return inFile;
  33     /* error */
  34     fprintf(stderr, "fopen: %s : %s \n", filename, strerror(errno));
  35     exit(2);
  36 }
  37
  38 static void* malloc_orDie(size_t size)
  39 {
  40     void* const buff = malloc(size + !size);   /* avoid allocating size of 0 : may return NULL (implementation dependent) */
  41     if (buff) return buff;
  42     /* error */
  43     fprintf(stderr, "malloc: %s \n", strerror(errno));
  44     exit(3);
  45 }
  46
  47 static void* loadFile_orDie(const char* fileName, size_t* size)
  48 {
  49     off_t const buffSize = fsize_orDie(fileName);
  50     FILE* const inFile = fopen_orDie(fileName, "rb");
  51     void* const buffer = malloc_orDie(buffSize);
  52     size_t const readSize = fread(buffer, 1, buffSize, inFile);
  53     if (readSize != (size_t)buffSize) {
  54         fprintf(stderr, "fread: %s : %s \n", fileName, strerror(errno));
  55         exit(4);
  56     }
  57     fclose(inFile);   /* can't fail (read only) */
  58     *size = buffSize;
  59     return buffer;
  60 }
  61
  62
  63 static void decompress(const char* fname)
  64 {
  65     size_t cSize;
  66     void* const cBuff = loadFile_orDie(fname, &cSize);
  67     unsigned long long const rSize = ZSTD_findDecompressedSize(cBuff, cSize);
  68     if (rSize==ZSTD_CONTENTSIZE_ERROR) {
  69         fprintf(stderr, "%s : it was not compressed by zstd.\n", fname);
  70         exit(5);
  71     } else if (rSize==ZSTD_CONTENTSIZE_UNKNOWN) {
  72         fprintf(stderr,
  73                 "%s : original size unknown. Use streaming decompression instead.\n", fname);
  74         exit(6);
  75     }
  76
  77     void* const rBuff = malloc_orDie((size_t)rSize);
  78
  79     size_t const dSize = ZSTD_decompress(rBuff, rSize, cBuff, cSize);
  80
  81     if (dSize != rSize) {
  82         fprintf(stderr, "error decoding %s : %s \n", fname, ZSTD_getErrorName(dSize));
  83         exit(7);
  84     }
  85
  86     /* success */
  87     printf("%25s : %6u -> %7u \n", fname, (unsigned)cSize, (unsigned)rSize);
  88
  89     free(rBuff);
  90     free(cBuff);
  91 }
  92
  93
  94 int main(int argc, const char** argv)
  95 {
  96     const char* const exeName = argv[0];
  97
  98     if (argc!=2) {
  99         printf("wrong arguments\n");
 100         printf("usage:\n");
 101         printf("%s FILE\n", exeName);
 102         return 1;
 103     }
 104
 105     decompress(argv[1]);
 106
 107     printf("%s correctly decoded (in memory). \n", argv[1]);
 108
 109     return 0;
 110 }