examples/simple_compression.c

/**
 * Copyright 2016-present, Yann Collet, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the license found in the
 * LICENSE-examples file in the root directory of this source tree.
 */



#include <stdlib.h>    // malloc, free, exit
#include <stdio.h>     // fprintf, perror, fopen, etc.
#include <string.h>    // strlen, strcat, memset, strerror
#include <errno.h>     // errno
#include <sys/stat.h>  // stat
#include <zstd.h>      // presumes zstd library is installed


static off_t fsize_orDie(const char *filename)
{
    struct stat st;
    if (stat(filename, &st) == 0) return st.st_size;
    /* error */
    perror(filename);
    exit(1);
}

static FILE* fopen_orDie(const char *filename, const char *instruction)
{
    FILE* const inFile = fopen(filename, instruction);
    if (inFile) return inFile;
    /* error */
    perror(filename);
    exit(2);
}

static void* malloc_orDie(size_t size)
{
    void* const buff = malloc(size);
    if (buff) return buff;
    /* error */
    perror(NULL);
    exit(3);
}

static void* loadFile_orDie(const char* fileName, size_t* size)
{
    off_t const fileSize = fsize_orDie(fileName);
    size_t const buffSize = (size_t)fileSize;
    if ((off_t)buffSize < fileSize) {   /* narrowcast overflow */
        fprintf(stderr, "%s : filesize too large \n", fileName);
        exit(4);
    }
    FILE* const inFile = fopen_orDie(fileName, "rb");
    void* const buffer = malloc_orDie(buffSize);
    size_t const readSize = fread(buffer, 1, buffSize, inFile);
    if (readSize != (size_t)buffSize) {
        fprintf(stderr, "fread: %s : %s \n", fileName, strerror(errno));
        exit(5);
    }
    fclose(inFile);  /* can't fail, read only */
    *size = buffSize;
    return buffer;
}


static void saveFile_orDie(const char* fileName, const void* buff, size_t buffSize)
{
    FILE* const oFile = fopen_orDie(fileName, "wb");
    size_t const wSize = fwrite(buff, 1, buffSize, oFile);
    if (wSize != (size_t)buffSize) {
        fprintf(stderr, "fwrite: %s : %s \n", fileName, strerror(errno));
        exit(6);
    }
    if (fclose(oFile)) {
        perror(fileName);
        exit(7);
    }
}


static void compress_orDie(const char* fname, const char* oname)
{
    size_t fSize;
    void* const fBuff = loadFile_orDie(fname, &fSize);
    size_t const cBuffSize = ZSTD_compressBound(fSize);
    void* const cBuff = malloc_orDie(cBuffSize);

    size_t const cSize = ZSTD_compress(cBuff, cBuffSize, fBuff, fSize, 1);
    if (ZSTD_isError(cSize)) {
        fprintf(stderr, "error compressing %s : %s \n", fname, ZSTD_getErrorName(cSize));
        exit(8);
    }

    saveFile_orDie(oname, cBuff, cSize);

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

    free(fBuff);
    free(cBuff);
}


static char* createOutFilename_orDie(const char* filename)
{
    size_t const inL = strlen(filename);
    size_t const outL = inL + 5;
    void* const outSpace = malloc_orDie(outL);
    memset(outSpace, 0, outL);
    strcat(outSpace, filename);
    strcat(outSpace, ".zst");
    return (char*)outSpace;
}

int main(int argc, const char** argv)
{
    const char* const exeName = argv[0];
    const char* const inFilename = argv[1];

    if (argc!=2) {
        printf("wrong arguments\n");
        printf("usage:\n");
        printf("%s FILE\n", exeName);
        return 1;
    }

    char* const outFilename = createOutFilename_orDie(inFilename);
    compress_orDie(inFilename, outFilename);
    free(outFilename);
    return 0;
}