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分享求大神指导关于gzip解压，出问题！
我从http上下载了gizp格式的数据，用解压缩软件已经解压成功，我现在想自己写解压代码，发现解压之后的都是空白，不知道什么原因，解压代码如下
#include <stdio.h>
#include "zlib.h"
#pragma comment(lib, "./zlib1.lib")
int main()
{
/* 原始数据 */
FILE* p=fopen("mysocket_test.gzip","rb+");
FILE* p2=fopen("123.txt","wb");
unsigned char buf[104857] = {0};
unsigned char strDst[104857] = {0};
unsigned long bufLen = sizeof(buf);
unsigned long dstLen = sizeof(strDst);
fread(buf,1,145910,p);
/* 解压缩 */
uncompress(strDst, &dstLen, buf, 145910);
printf("%s\n",strDst);
fwrite(strDst,1,dstLen,p2);
return 0;
}
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赵4老师 2013-03-27
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看调sample代码是程序员必须掌握的技能之一。
http://bbs.csdn.net/topics/390374955
根根小盆友 2013-03-26
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我把buf改成1048576，然后fread返回值是145910，然后返回值还是Z_DATA_ERROR
chuachua66 2013-03-26
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Z_DATA_ERROR if the input data was corrupted or incomplete，你输入的数据有问题啊，把你读入数据的buf搞大，然后看fread返回值，看看是不是有东西没读进来。
根根小盆友 2013-03-26
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大哥，分配的是不够，我改成了1048576，结果还是空白，返回值是Z_DATA_ERROR，怎么解决啊？实在是不了解zlib
chuachua66 2013-03-26
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大哥你压缩了以后都145910了，你解压的buffer才104857，肯定放不下 啊，另外，看Unconpress的返回值，zlib.h里有错误吗的描述。
根根小盆友 2013-03-26
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谢谢大家了，我解决这个问题了，因为http上的gzip多了个gzip头，不能直接用zlib进行解压，需要先处理一下。十分感谢大家
gqjjqg 2013-03-26
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zlib 里有sample code。请参阅。我看的是 V1.2.7的版本。
/* ===========================================================================
* Test compress() and uncompress()
*/
void test_compress(compr, comprLen, uncompr, uncomprLen)
Byte *compr, *uncompr;
uLong comprLen, uncomprLen;
{
int err;
uLong len = (uLong)strlen(hello)+1;
err = compress(compr, &comprLen, (const Bytef*)hello, len);
CHECK_ERR(err, "compress");
strcpy((char*)uncompr, "garbage");
err = uncompress(uncompr, &uncomprLen, compr, comprLen);
CHECK_ERR(err, "uncompress");
if (strcmp((char*)uncompr, hello)) {
fprintf(stderr, "bad uncompress\n");
exit(1);
} else {
printf("uncompress(): %s\n", (char *)uncompr);
}
}
/* ===========================================================================
* Usage: example [output.gz [input.gz]]
*/
int main(argc, argv)
int argc;
char *argv[];
{
Byte *compr, *uncompr;
uLong comprLen = 10000*sizeof(int); /* don't overflow on MSDOS */
uLong uncomprLen = comprLen;
static const char* myVersion = ZLIB_VERSION;
if (zlibVersion()[0] != myVersion[0]) {
fprintf(stderr, "incompatible zlib version\n");
exit(1);
} else if (strcmp(zlibVersion(), ZLIB_VERSION) != 0) {
fprintf(stderr, "warning: different zlib version\n");
}
printf("zlib version %s = 0x%04x, compile flags = 0x%lx\n",
ZLIB_VERSION, ZLIB_VERNUM, zlibCompileFlags());
compr = (Byte*)calloc((uInt)comprLen, 1);
uncompr = (Byte*)calloc((uInt)uncomprLen, 1);
/* compr and uncompr are cleared to avoid reading uninitialized
* data and to ensure that uncompr compresses well.
*/
if (compr == Z_NULL || uncompr == Z_NULL) {
printf("out of memory\n");
exit(1);
}
#ifdef Z_SOLO
argc = strlen(argv[0]);
#else
test_compress(compr, comprLen, uncompr, uncomprLen);
test_gzio((argc > 1 ? argv[1] : TESTFILE),
uncompr, uncomprLen);
#endif
test_deflate(compr, comprLen);
test_inflate(compr, comprLen, uncompr, uncomprLen);
test_large_deflate(compr, comprLen, uncompr, uncomprLen);
test_large_inflate(compr, comprLen, uncompr, uncomprLen);
test_flush(compr, &comprLen);
test_sync(compr, comprLen, uncompr, uncomprLen);
comprLen = uncomprLen;
test_dict_deflate(compr, comprLen);
test_dict_inflate(compr, comprLen, uncompr, uncomprLen);
free(compr);
free(uncompr);
return 0;
}
