1 /* example.c -- usage example of the zlib compression library
2 * Copyright (C) 1995-2026 Jean-loup Gailly
3 * For conditions of distribution and use, see copyright notice in zlib.h
4 */
5
6 /* @(#) $Id$ */
7
8 #if defined(_WIN32) && !defined(_CRT_SECURE_NO_WARNINGS)
9 # define _CRT_SECURE_NO_WARNINGS
10 #endif
11
12 #include "zlib.h"
13 #include <stdio.h>
14
15 #ifdef STDC
16 # include <string.h>
17 # include <stdlib.h>
18 #endif
19
20 #if defined(VMS)
21 # define TESTFILE "foo-gz"
22 #elif defined(__riscos) && !defined(__TARGET_UNIXLIB__)
23 # define TESTFILE "foo/gz"
24 #else
25 # define TESTFILE "foo.gz"
26 #endif
27
28 #define CHECK_ERR(err, msg) { \
29 if (err != Z_OK) { \
30 fprintf(stderr, "%s error: %d\n", msg, err); \
31 exit(1); \
32 } \
33 }
34
35 static z_const char hello[] = "hello, hello!";
36 /* "hello world" would be more standard, but the repeated "hello"
37 * stresses the compression code better, sorry...
38 */
39
40 static const char dictionary[] = "hello";
41 static uLong dictId; /* Adler32 value of the dictionary */
42
43 #ifdef Z_SOLO
44
myalloc(void * q,unsigned n,unsigned m)45 static void *myalloc(void *q, unsigned n, unsigned m) {
46 (void)q;
47 return calloc(n, m);
48 }
49
myfree(void * q,void * p)50 static void myfree(void *q, void *p) {
51 (void)q;
52 free(p);
53 }
54
55 static alloc_func zalloc = myalloc;
56 static free_func zfree = myfree;
57
58 #else /* !Z_SOLO */
59
60 static alloc_func zalloc = (alloc_func)0;
61 static free_func zfree = (free_func)0;
62
63 /* ===========================================================================
64 * Test compress() and uncompress()
65 */
test_compress(Byte * compr,uLong comprLen,Byte * uncompr,uLong uncomprLen)66 static void test_compress(Byte *compr, uLong comprLen, Byte *uncompr,
67 uLong uncomprLen) {
68 int err;
69 uLong len = (uLong)strlen(hello)+1;
70
71 err = compress(compr, &comprLen, (const Bytef*)hello, len);
72 CHECK_ERR(err, "compress");
73
74 strcpy((char*)uncompr, "garbage");
75
76 err = uncompress(uncompr, &uncomprLen, compr, comprLen);
77 CHECK_ERR(err, "uncompress");
78
79 if (strcmp((char*)uncompr, hello)) {
80 fprintf(stderr, "bad uncompress\n");
81 exit(1);
82 } else {
83 printf("uncompress(): %s\n", (char *)uncompr);
84 }
85 }
86
87 /* ===========================================================================
88 * Test read/write of .gz files
89 */
test_gzio(const char * fname,Byte * uncompr,uLong uncomprLen)90 static void test_gzio(const char *fname, Byte *uncompr, uLong uncomprLen) {
91 #ifdef NO_GZCOMPRESS
92 fprintf(stderr, "NO_GZCOMPRESS -- gz* functions cannot compress\n");
93 #else
94 int err;
95 int len = (int)strlen(hello)+1;
96 gzFile file;
97 z_off_t pos;
98
99 file = gzopen(fname, "wb");
100 if (file == NULL) {
101 fprintf(stderr, "gzopen error\n");
102 exit(1);
103 }
104 gzputc(file, 'h');
105 if (gzputs(file, "ello") != 4) {
106 fprintf(stderr, "gzputs err: %s\n", gzerror(file, &err));
107 exit(1);
108 }
109 if (gzprintf(file, ", %s!", "hello") != 8) {
110 fprintf(stderr, "gzprintf err: %s\n", gzerror(file, &err));
111 exit(1);
112 }
113 gzseek(file, 1L, SEEK_CUR); /* add one zero byte */
114 gzclose(file);
115
116 file = gzopen(fname, "rb");
117 if (file == NULL) {
118 fprintf(stderr, "gzopen error\n");
119 exit(1);
120 }
121 strcpy((char*)uncompr, "garbage");
122
123 if (gzread(file, uncompr, (unsigned)uncomprLen) != len) {
124 fprintf(stderr, "gzread err: %s\n", gzerror(file, &err));
125 exit(1);
126 }
127 if (strcmp((char*)uncompr, hello)) {
128 fprintf(stderr, "bad gzread: %s\n", (char*)uncompr);
129 exit(1);
130 } else {
131 printf("gzread(): %s\n", (char*)uncompr);
132 }
133
134 pos = gzseek(file, -8L, SEEK_CUR);
135 if (pos != 6 || gztell(file) != pos) {
136 fprintf(stderr, "gzseek error, pos=%ld, gztell=%ld\n",
137 (long)pos, (long)gztell(file));
138 exit(1);
139 }
140
141 if (gzgetc(file) != ' ') {
142 fprintf(stderr, "gzgetc error\n");
143 exit(1);
144 }
145
146 if (gzungetc(' ', file) != ' ') {
147 fprintf(stderr, "gzungetc error\n");
148 exit(1);
149 }
150
151 gzgets(file, (char*)uncompr, (int)uncomprLen);
152 if (strlen((char*)uncompr) != 7) { /* " hello!" */
153 fprintf(stderr, "gzgets err after gzseek: %s\n", gzerror(file, &err));
154 exit(1);
155 }
156 if (strcmp((char*)uncompr, hello + 6)) {
157 fprintf(stderr, "bad gzgets after gzseek\n");
158 exit(1);
159 } else {
160 printf("gzgets() after gzseek: %s\n", (char*)uncompr);
161 }
162
163 gzclose(file);
164 #endif
165 }
166
167 #endif /* Z_SOLO */
168
169 /* ===========================================================================
170 * Test deflate() with small buffers
171 */
test_deflate(Byte * compr,uLong comprLen)172 static void test_deflate(Byte *compr, uLong comprLen) {
173 z_stream c_stream; /* compression stream */
174 int err;
175 uLong len = (uLong)strlen(hello)+1;
176
177 c_stream.zalloc = zalloc;
178 c_stream.zfree = zfree;
179 c_stream.opaque = (voidpf)0;
180
181 err = deflateInit(&c_stream, Z_DEFAULT_COMPRESSION);
182 CHECK_ERR(err, "deflateInit");
183
184 c_stream.next_in = (z_const unsigned char *)hello;
185 c_stream.next_out = compr;
186
187 while (c_stream.total_in != len && c_stream.total_out < comprLen) {
188 c_stream.avail_in = c_stream.avail_out = 1; /* force small buffers */
189 err = deflate(&c_stream, Z_NO_FLUSH);
190 CHECK_ERR(err, "deflate");
191 }
192 /* Finish the stream, still forcing small buffers: */
193 for (;;) {
194 c_stream.avail_out = 1;
195 err = deflate(&c_stream, Z_FINISH);
196 if (err == Z_STREAM_END) break;
197 CHECK_ERR(err, "deflate");
198 }
199
200 err = deflateEnd(&c_stream);
201 CHECK_ERR(err, "deflateEnd");
202 }
203
204 /* ===========================================================================
205 * Test inflate() with small buffers
206 */
test_inflate(Byte * compr,uLong comprLen,Byte * uncompr,uLong uncomprLen)207 static void test_inflate(Byte *compr, uLong comprLen, Byte *uncompr,
208 uLong uncomprLen) {
209 int err;
210 z_stream d_stream; /* decompression stream */
211
212 strcpy((char*)uncompr, "garbage");
213
214 d_stream.zalloc = zalloc;
215 d_stream.zfree = zfree;
216 d_stream.opaque = (voidpf)0;
217
218 d_stream.next_in = compr;
219 d_stream.avail_in = 0;
220 d_stream.next_out = uncompr;
221
222 err = inflateInit(&d_stream);
223 CHECK_ERR(err, "inflateInit");
224
225 while (d_stream.total_out < uncomprLen && d_stream.total_in < comprLen) {
226 d_stream.avail_in = d_stream.avail_out = 1; /* force small buffers */
227 err = inflate(&d_stream, Z_NO_FLUSH);
228 if (err == Z_STREAM_END) break;
229 CHECK_ERR(err, "inflate");
230 }
231
232 err = inflateEnd(&d_stream);
233 CHECK_ERR(err, "inflateEnd");
234
235 if (strcmp((char*)uncompr, hello)) {
236 fprintf(stderr, "bad inflate\n");
237 exit(1);
238 } else {
239 printf("inflate(): %s\n", (char *)uncompr);
240 }
241 }
242
243 /* ===========================================================================
244 * Test deflate() with large buffers and dynamic change of compression level
245 */
test_large_deflate(Byte * compr,uLong comprLen,Byte * uncompr,uLong uncomprLen)246 static void test_large_deflate(Byte *compr, uLong comprLen, Byte *uncompr,
247 uLong uncomprLen) {
248 z_stream c_stream; /* compression stream */
249 int err;
250
251 c_stream.zalloc = zalloc;
252 c_stream.zfree = zfree;
253 c_stream.opaque = (voidpf)0;
254
255 err = deflateInit(&c_stream, Z_BEST_SPEED);
256 CHECK_ERR(err, "deflateInit");
257
258 c_stream.next_out = compr;
259 c_stream.avail_out = (uInt)comprLen;
260
261 /* At this point, uncompr is still mostly zeroes, so it should compress
262 * very well:
263 */
264 c_stream.next_in = uncompr;
265 c_stream.avail_in = (uInt)uncomprLen;
266 err = deflate(&c_stream, Z_NO_FLUSH);
267 CHECK_ERR(err, "deflate");
268 if (c_stream.avail_in != 0) {
269 fprintf(stderr, "deflate not greedy\n");
270 exit(1);
271 }
272
273 /* Feed in already compressed data and switch to no compression: */
274 deflateParams(&c_stream, Z_NO_COMPRESSION, Z_DEFAULT_STRATEGY);
275 c_stream.next_in = compr;
276 c_stream.avail_in = (uInt)uncomprLen/2;
277 err = deflate(&c_stream, Z_NO_FLUSH);
278 CHECK_ERR(err, "deflate");
279
280 /* Switch back to compressing mode: */
281 deflateParams(&c_stream, Z_BEST_COMPRESSION, Z_FILTERED);
282 c_stream.next_in = uncompr;
283 c_stream.avail_in = (uInt)uncomprLen;
284 err = deflate(&c_stream, Z_NO_FLUSH);
285 CHECK_ERR(err, "deflate");
286
287 err = deflate(&c_stream, Z_FINISH);
288 if (err != Z_STREAM_END) {
289 fprintf(stderr, "deflate should report Z_STREAM_END\n");
290 exit(1);
291 }
292 err = deflateEnd(&c_stream);
293 CHECK_ERR(err, "deflateEnd");
294 }
295
296 /* ===========================================================================
297 * Test inflate() with large buffers
298 */
test_large_inflate(Byte * compr,uLong comprLen,Byte * uncompr,uLong uncomprLen)299 static void test_large_inflate(Byte *compr, uLong comprLen, Byte *uncompr,
300 uLong uncomprLen) {
301 int err;
302 z_stream d_stream; /* decompression stream */
303
304 strcpy((char*)uncompr, "garbage");
305
306 d_stream.zalloc = zalloc;
307 d_stream.zfree = zfree;
308 d_stream.opaque = (voidpf)0;
309
310 d_stream.next_in = compr;
311 d_stream.avail_in = (uInt)comprLen;
312
313 err = inflateInit(&d_stream);
314 CHECK_ERR(err, "inflateInit");
315
316 for (;;) {
317 d_stream.next_out = uncompr; /* discard the output */
318 d_stream.avail_out = (uInt)uncomprLen;
319 err = inflate(&d_stream, Z_NO_FLUSH);
320 if (err == Z_STREAM_END) break;
321 CHECK_ERR(err, "large inflate");
322 }
323
324 err = inflateEnd(&d_stream);
325 CHECK_ERR(err, "inflateEnd");
326
327 if (d_stream.total_out != 2*uncomprLen + uncomprLen/2) {
328 fprintf(stderr, "bad large inflate: %lu\n", d_stream.total_out);
329 exit(1);
330 } else {
331 printf("large_inflate(): OK\n");
332 }
333 }
334
335 /* ===========================================================================
336 * Test deflate() with full flush
337 */
test_flush(Byte * compr,uLong * comprLen)338 static void test_flush(Byte *compr, uLong *comprLen) {
339 z_stream c_stream; /* compression stream */
340 int err;
341 uInt len = (uInt)strlen(hello)+1;
342
343 c_stream.zalloc = zalloc;
344 c_stream.zfree = zfree;
345 c_stream.opaque = (voidpf)0;
346
347 err = deflateInit(&c_stream, Z_DEFAULT_COMPRESSION);
348 CHECK_ERR(err, "deflateInit");
349
350 c_stream.next_in = (z_const unsigned char *)hello;
351 c_stream.next_out = compr;
352 c_stream.avail_in = 3;
353 c_stream.avail_out = (uInt)*comprLen;
354 err = deflate(&c_stream, Z_FULL_FLUSH);
355 CHECK_ERR(err, "deflate");
356
357 compr[3]++; /* force an error in first compressed block */
358 c_stream.avail_in = len - 3;
359
360 err = deflate(&c_stream, Z_FINISH);
361 if (err != Z_STREAM_END) {
362 CHECK_ERR(err, "deflate");
363 }
364 err = deflateEnd(&c_stream);
365 CHECK_ERR(err, "deflateEnd");
366
367 *comprLen = c_stream.total_out;
368 }
369
370 /* ===========================================================================
371 * Test inflateSync()
372 */
test_sync(Byte * compr,uLong comprLen,Byte * uncompr,uLong uncomprLen)373 static void test_sync(Byte *compr, uLong comprLen, Byte *uncompr,
374 uLong uncomprLen) {
375 int err;
376 z_stream d_stream; /* decompression stream */
377
378 strcpy((char*)uncompr, "garbage");
379
380 d_stream.zalloc = zalloc;
381 d_stream.zfree = zfree;
382 d_stream.opaque = (voidpf)0;
383
384 d_stream.next_in = compr;
385 d_stream.avail_in = 2; /* just read the zlib header */
386
387 err = inflateInit(&d_stream);
388 CHECK_ERR(err, "inflateInit");
389
390 d_stream.next_out = uncompr;
391 d_stream.avail_out = (uInt)uncomprLen;
392
393 err = inflate(&d_stream, Z_NO_FLUSH);
394 CHECK_ERR(err, "inflate");
395
396 d_stream.avail_in = (uInt)comprLen-2; /* read all compressed data */
397 err = inflateSync(&d_stream); /* but skip the damaged part */
398 CHECK_ERR(err, "inflateSync");
399
400 err = inflate(&d_stream, Z_FINISH);
401 if (err != Z_STREAM_END) {
402 fprintf(stderr, "inflate should report Z_STREAM_END\n");
403 exit(1);
404 }
405 err = inflateEnd(&d_stream);
406 CHECK_ERR(err, "inflateEnd");
407
408 printf("after inflateSync(): hel%s\n", (char *)uncompr);
409 }
410
411 /* ===========================================================================
412 * Test deflate() with preset dictionary
413 */
test_dict_deflate(Byte * compr,uLong comprLen)414 static void test_dict_deflate(Byte *compr, uLong comprLen) {
415 z_stream c_stream; /* compression stream */
416 int err;
417
418 c_stream.zalloc = zalloc;
419 c_stream.zfree = zfree;
420 c_stream.opaque = (voidpf)0;
421
422 err = deflateInit(&c_stream, Z_BEST_COMPRESSION);
423 CHECK_ERR(err, "deflateInit");
424
425 err = deflateSetDictionary(&c_stream,
426 (const Bytef*)dictionary, (int)sizeof(dictionary));
427 CHECK_ERR(err, "deflateSetDictionary");
428
429 dictId = c_stream.adler;
430 c_stream.next_out = compr;
431 c_stream.avail_out = (uInt)comprLen;
432
433 c_stream.next_in = (z_const unsigned char *)hello;
434 c_stream.avail_in = (uInt)strlen(hello)+1;
435
436 err = deflate(&c_stream, Z_FINISH);
437 if (err != Z_STREAM_END) {
438 fprintf(stderr, "deflate should report Z_STREAM_END\n");
439 exit(1);
440 }
441 err = deflateEnd(&c_stream);
442 CHECK_ERR(err, "deflateEnd");
443 }
444
445 /* ===========================================================================
446 * Test inflate() with a preset dictionary
447 */
test_dict_inflate(Byte * compr,uLong comprLen,Byte * uncompr,uLong uncomprLen)448 static void test_dict_inflate(Byte *compr, uLong comprLen, Byte *uncompr,
449 uLong uncomprLen) {
450 int err;
451 z_stream d_stream; /* decompression stream */
452
453 strcpy((char*)uncompr, "garbage");
454
455 d_stream.zalloc = zalloc;
456 d_stream.zfree = zfree;
457 d_stream.opaque = (voidpf)0;
458
459 d_stream.next_in = compr;
460 d_stream.avail_in = (uInt)comprLen;
461
462 err = inflateInit(&d_stream);
463 CHECK_ERR(err, "inflateInit");
464
465 d_stream.next_out = uncompr;
466 d_stream.avail_out = (uInt)uncomprLen;
467
468 for (;;) {
469 err = inflate(&d_stream, Z_NO_FLUSH);
470 if (err == Z_STREAM_END) break;
471 if (err == Z_NEED_DICT) {
472 if (d_stream.adler != dictId) {
473 fprintf(stderr, "unexpected dictionary");
474 exit(1);
475 }
476 err = inflateSetDictionary(&d_stream, (const Bytef*)dictionary,
477 (int)sizeof(dictionary));
478 }
479 CHECK_ERR(err, "inflate with dict");
480 }
481
482 err = inflateEnd(&d_stream);
483 CHECK_ERR(err, "inflateEnd");
484
485 if (strcmp((char*)uncompr, hello)) {
486 fprintf(stderr, "bad inflate with dict\n");
487 exit(1);
488 } else {
489 printf("inflate with dictionary: %s\n", (char *)uncompr);
490 }
491 }
492
493 /* ===========================================================================
494 * Usage: example [output.gz [input.gz]]
495 */
496
main(int argc,char * argv[])497 int main(int argc, char *argv[]) {
498 Byte *compr, *uncompr;
499 uLong uncomprLen = 20000;
500 uLong comprLen = 3 * uncomprLen;
501 static const char* myVersion = ZLIB_VERSION;
502
503 if (zlibVersion()[0] != myVersion[0]) {
504 fprintf(stderr, "incompatible zlib version\n");
505 exit(1);
506
507 } else if (strcmp(zlibVersion(), ZLIB_VERSION) != 0) {
508 fprintf(stderr, "warning: different zlib version linked: %s\n",
509 zlibVersion());
510 }
511
512 printf("zlib version %s = 0x%04x, compile flags = 0x%lx\n",
513 ZLIB_VERSION, (unsigned)ZLIB_VERNUM, zlibCompileFlags());
514
515 compr = (Byte*)calloc((uInt)comprLen, 1);
516 uncompr = (Byte*)calloc((uInt)uncomprLen, 1);
517 /* compr and uncompr are cleared to avoid reading uninitialized
518 * data and to ensure that uncompr compresses well.
519 */
520 if (compr == Z_NULL || uncompr == Z_NULL) {
521 printf("out of memory\n");
522 exit(1);
523 }
524
525 #ifdef Z_SOLO
526 (void)argc;
527 (void)argv;
528 #else
529 test_compress(compr, comprLen, uncompr, uncomprLen);
530
531 test_gzio((argc > 1 ? argv[1] : TESTFILE),
532 uncompr, uncomprLen);
533 #endif
534
535 test_deflate(compr, comprLen);
536 test_inflate(compr, comprLen, uncompr, uncomprLen);
537
538 test_large_deflate(compr, comprLen, uncompr, uncomprLen);
539 test_large_inflate(compr, comprLen, uncompr, uncomprLen);
540
541 test_flush(compr, &comprLen);
542 test_sync(compr, comprLen, uncompr, uncomprLen);
543 comprLen = 3 * uncomprLen;
544
545 test_dict_deflate(compr, comprLen);
546 test_dict_inflate(compr, comprLen, uncompr, uncomprLen);
547
548 free(compr);
549 free(uncompr);
550
551 return 0;
552 }
553