ZLib Inflate（）与-3 Z_DATA_ERROR失败 [英] ZLib Inflate() failing with -3 Z_DATA_ERROR

问题描述

我试图通过调用inflate函数解压缩文件，但它总是失败与Z_DATA_ERROR，即使我使用示例程序从网站。我想，也许我的zip文件是不支持。我已附加了以下zip文件头的图片。

I am trying to unzip a file by calling the inflate function but it always fails with Z_DATA_ERROR even when I use the example program from the website. I am thinking that maybe the zip file I have is not supported. I have attached a picture of the zip header below.

这里是我写的用来执行解压缩的函数。我一次读取整个文件（大约34KB），并将其传递到此函数。注意我已经尝试传递整个zip文件与zip头，以及跳过zip文件头，只有传递压缩数据都失败与Z_DATA_ERROR当inflate（）被调用时。

And here is the function that I wrote to perform the unzipping. I read in the whole file at once (about 34KB) and pass it into this function. Note I have tried passing the whole zip file with the zip header as well as skipping over the zip file header and only passing the zipped data both fail with Z_DATA_ERROR when inflate() is called.

int CHttpDownloader::unzip(unsigned char * pDest, unsigned long * ulDestLen, unsigned char *  pSource, int iSourceLen)
{
int ret = 0;
unsigned int uiUncompressedBytes = 0; // Number of uncompressed bytes returned from inflate() function
unsigned char * pPositionDestBuffer = pDest; // Current position in dest buffer
unsigned char * pLastSource = &pSource[iSourceLen]; // Last position in source buffer
z_stream strm;

// Skip over local file header
SLocalFileHeader * header = (SLocalFileHeader *) pSource;
pSource += sizeof(SLocalFileHeader) + header->sFileNameLen + header->sExtraFieldLen;


// We should now be at the beginning of the stream data
/* allocate inflate state */
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.avail_in = 0;
strm.next_in = Z_NULL;
ret = inflateInit2(&strm, 16+MAX_WBITS);
if (ret != Z_OK)
{
return -1;
}

// Uncompress the data
strm.avail_in = header->iCompressedSize; //iSourceLen;
strm.next_in = pSource;

do {
strm.avail_out = *ulDestLen;
strm.next_out = pPositionDestBuffer;
ret = inflate(&strm, Z_NO_FLUSH);
assert(ret != Z_STREAM_ERROR);  /* state not clobbered */
switch (ret) {
case Z_NEED_DICT:
ret = Z_DATA_ERROR;     /* and fall through */
case Z_DATA_ERROR:
case Z_MEM_ERROR:
(void)inflateEnd(&strm);
return -2;
}
uiUncompressedBytes = *ulDestLen - strm.avail_out;
*ulDestLen -= uiUncompressedBytes; // ulDestSize holds number of free/empty bytes in buffer
pPositionDestBuffer += uiUncompressedBytes;
} while (strm.avail_out == 0);

// Close the decompression stream
inflateEnd(&strm);
ASSERT(ret == Z_STREAM_END);

return 0;
}

所以我的问题是，是我读的zip文件的类型支持ZLib的inflate（）函数？或者有什么问题，我的CHttpDownloader :: unzip（）函数？感谢任何帮助：）

So my question is, is the type of zip file I am reading in not supported by ZLib's inflate() function? Or is there something wrong with my CHttpDownloader::unzip() function? Thanks for any help :)

推荐答案

Inflate（）失败，因为它正在寻找不存在的GZip标头。如果您使用以下方式初始化流：

Inflate() was failing because it was looking for GZip headers which were not present. If you initialize the stream with:

ret = inflateInit2(&strm, -MAX_WBITS);

这篇关于ZLib Inflate（）与-3 Z_DATA_ERROR失败的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！