1 /*
2 * Copyright (c) 2017-present, 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 */
9
10
11 #include <stdlib.h> // malloc, exit
12 #include <stdio.h> // fprintf, perror, feof
13 #include <string.h> // strerror
14 #include <errno.h> // errno
15 #define ZSTD_STATIC_LINKING_ONLY
16 #include <zstd.h> // presumes zstd library is installed
17 #include <zstd_errors.h>
18
19 #include "zstd_seekable.h"
20
21 #define MIN(a, b) ((a) < (b) ? (a) : (b))
22
23 #define MAX_FILE_SIZE (8 * 1024 * 1024)
24
malloc_orDie(size_t size)25 static void* malloc_orDie(size_t size)
26 {
27 void* const buff = malloc(size);
28 if (buff) return buff;
29 /* error */
30 perror("malloc");
31 exit(1);
32 }
33
realloc_orDie(void * ptr,size_t size)34 static void* realloc_orDie(void* ptr, size_t size)
35 {
36 ptr = realloc(ptr, size);
37 if (ptr) return ptr;
38 /* error */
39 perror("realloc");
40 exit(1);
41 }
42
fopen_orDie(const char * filename,const char * instruction)43 static FILE* fopen_orDie(const char *filename, const char *instruction)
44 {
45 FILE* const inFile = fopen(filename, instruction);
46 if (inFile) return inFile;
47 /* error */
48 perror(filename);
49 exit(3);
50 }
51
fread_orDie(void * buffer,size_t sizeToRead,FILE * file)52 static size_t fread_orDie(void* buffer, size_t sizeToRead, FILE* file)
53 {
54 size_t const readSize = fread(buffer, 1, sizeToRead, file);
55 if (readSize == sizeToRead) return readSize; /* good */
56 if (feof(file)) return readSize; /* good, reached end of file */
57 /* error */
58 perror("fread");
59 exit(4);
60 }
61
fwrite_orDie(const void * buffer,size_t sizeToWrite,FILE * file)62 static size_t fwrite_orDie(const void* buffer, size_t sizeToWrite, FILE* file)
63 {
64 size_t const writtenSize = fwrite(buffer, 1, sizeToWrite, file);
65 if (writtenSize == sizeToWrite) return sizeToWrite; /* good */
66 /* error */
67 perror("fwrite");
68 exit(5);
69 }
70
fclose_orDie(FILE * file)71 static size_t fclose_orDie(FILE* file)
72 {
73 if (!fclose(file)) return 0;
74 /* error */
75 perror("fclose");
76 exit(6);
77 }
78
fseek_orDie(FILE * file,long int offset,int origin)79 static void fseek_orDie(FILE* file, long int offset, int origin) {
80 if (!fseek(file, offset, origin)) {
81 if (!fflush(file)) return;
82 }
83 /* error */
84 perror("fseek");
85 exit(7);
86 }
87
88
decompressFile_orDie(const char * fname,off_t startOffset,off_t endOffset)89 static void decompressFile_orDie(const char* fname, off_t startOffset, off_t endOffset)
90 {
91 FILE* const fin = fopen_orDie(fname, "rb");
92 FILE* const fout = stdout;
93 // Just for demo purposes, assume file is <= MAX_FILE_SIZE
94 void* const buffIn = malloc_orDie(MAX_FILE_SIZE);
95 size_t const inSize = fread_orDie(buffIn, MAX_FILE_SIZE, fin);
96 size_t const buffOutSize = ZSTD_DStreamOutSize(); /* Guarantee to successfully flush at least one complete compressed block in all circumstances. */
97 void* const buffOut = malloc_orDie(buffOutSize);
98
99 ZSTD_seekable* const seekable = ZSTD_seekable_create();
100 if (seekable==NULL) { fprintf(stderr, "ZSTD_seekable_create() error \n"); exit(10); }
101
102 size_t const initResult = ZSTD_seekable_initBuff(seekable, buffIn, inSize);
103 if (ZSTD_isError(initResult)) { fprintf(stderr, "ZSTD_seekable_init() error : %s \n", ZSTD_getErrorName(initResult)); exit(11); }
104
105 while (startOffset < endOffset) {
106 size_t const result = ZSTD_seekable_decompress(seekable, buffOut, MIN(endOffset - startOffset, buffOutSize), startOffset);
107
108 if (ZSTD_isError(result)) {
109 fprintf(stderr, "ZSTD_seekable_decompress() error : %s \n",
110 ZSTD_getErrorName(result));
111 exit(12);
112 }
113 fwrite_orDie(buffOut, result, fout);
114 startOffset += result;
115 }
116
117 ZSTD_seekable_free(seekable);
118 fclose_orDie(fin);
119 fclose_orDie(fout);
120 free(buffIn);
121 free(buffOut);
122 }
123
124
main(int argc,const char ** argv)125 int main(int argc, const char** argv)
126 {
127 const char* const exeName = argv[0];
128
129 if (argc!=4) {
130 fprintf(stderr, "wrong arguments\n");
131 fprintf(stderr, "usage:\n");
132 fprintf(stderr, "%s FILE START END\n", exeName);
133 return 1;
134 }
135
136 {
137 const char* const inFilename = argv[1];
138 off_t const startOffset = atoll(argv[2]);
139 off_t const endOffset = atoll(argv[3]);
140 decompressFile_orDie(inFilename, startOffset, endOffset);
141 }
142
143 return 0;
144 }
145