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/*
* Copyright (c) 2017-present, 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).
*/
#include <stdlib.h> // malloc, exit
#include <stdio.h> // fprintf, perror, feof
#include <string.h> // strerror
#include <errno.h> // errno
#define ZSTD_STATIC_LINKING_ONLY
#include <zstd.h> // presumes zstd library is installed
#include <zstd_errors.h>
#include "zstd_seekable.h"
#define MIN(a, b) ((a) < (b) ? (a) : (b))
#define MAX_FILE_SIZE (8 * 1024 * 1024)
static void* malloc_orDie(size_t size)
{
void* const buff = malloc(size);
if (buff) return buff;
/* error */
perror("malloc");
exit(1);
}
static void* realloc_orDie(void* ptr, size_t size)
{
ptr = realloc(ptr, size);
if (ptr) return ptr;
/* error */
perror("realloc");
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(3);
}
static size_t fread_orDie(void* buffer, size_t sizeToRead, FILE* file)
{
size_t const readSize = fread(buffer, 1, sizeToRead, file);
if (readSize == sizeToRead) return readSize; /* good */
if (feof(file)) return readSize; /* good, reached end of file */
/* error */
perror("fread");
exit(4);
}
static size_t fwrite_orDie(const void* buffer, size_t sizeToWrite, FILE* file)
{
size_t const writtenSize = fwrite(buffer, 1, sizeToWrite, file);
if (writtenSize == sizeToWrite) return sizeToWrite; /* good */
/* error */
perror("fwrite");
exit(5);
}
static size_t fclose_orDie(FILE* file)
{
if (!fclose(file)) return 0;
/* error */
perror("fclose");
exit(6);
}
static void fseek_orDie(FILE* file, long int offset, int origin) {
if (!fseek(file, offset, origin)) {
if (!fflush(file)) return;
}
/* error */
perror("fseek");
exit(7);
}
static void decompressFile_orDie(const char* fname, off_t startOffset, off_t endOffset)
{
FILE* const fin = fopen_orDie(fname, "rb");
FILE* const fout = stdout;
// Just for demo purposes, assume file is <= MAX_FILE_SIZE
void* const buffIn = malloc_orDie(MAX_FILE_SIZE);
size_t const inSize = fread_orDie(buffIn, MAX_FILE_SIZE, fin);
size_t const buffOutSize = ZSTD_DStreamOutSize(); /* Guarantee to successfully flush at least one complete compressed block in all circumstances. */
void* const buffOut = malloc_orDie(buffOutSize);
ZSTD_seekable* const seekable = ZSTD_seekable_create();
if (seekable==NULL) { fprintf(stderr, "ZSTD_seekable_create() error \n"); exit(10); }
size_t const initResult = ZSTD_seekable_initBuff(seekable, buffIn, inSize);
if (ZSTD_isError(initResult)) { fprintf(stderr, "ZSTD_seekable_init() error : %s \n", ZSTD_getErrorName(initResult)); exit(11); }
while (startOffset < endOffset) {
size_t const result = ZSTD_seekable_decompress(seekable, buffOut, MIN(endOffset - startOffset, buffOutSize), startOffset);
if (ZSTD_isError(result)) {
fprintf(stderr, "ZSTD_seekable_decompress() error : %s \n",
ZSTD_getErrorName(result));
exit(12);
}
fwrite_orDie(buffOut, result, fout);
startOffset += result;
}
ZSTD_seekable_free(seekable);
fclose_orDie(fin);
fclose_orDie(fout);
free(buffIn);
free(buffOut);
}
int main(int argc, const char** argv)
{
const char* const exeName = argv[0];
if (argc!=4) {
fprintf(stderr, "wrong arguments\n");
fprintf(stderr, "usage:\n");
fprintf(stderr, "%s FILE START END\n", exeName);
return 1;
}
{
const char* const inFilename = argv[1];
off_t const startOffset = atoll(argv[2]);
off_t const endOffset = atoll(argv[3]);
decompressFile_orDie(inFilename, startOffset, endOffset);
}
return 0;
}
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