最近在用c++写一个爬虫程序,遇到一个问题,不能解压服务器返回的压缩数据,解压数据的函数是在网上看的,如下:
bool GzipDecompress(Byte *source, uLong source_length, Byte *dest, uLong *dest_length)
{
int err = 0;
z_stream d_stream = {0};
static char dummy_head[2] =
{
0x8 + 0x7 * 0x10,
(((0x8 + 0x7 * 0x10) * 0x100 + 30) / 31 * 31) & 0xFF,
};
d_stream.zalloc = (alloc_func)0;
d_stream.zfree = (free_func)0;
d_stream.opaque = (voidpf)0;
d_stream.next_in = source;
d_stream.avail_in = 0;
d_stream.next_out = dest;
if(inflateInit2(&d_stream, 47) != Z_OK)
return false;
while (d_stream.total_out < *dest_length && d_stream.total_in < source_length) {
d_stream.avail_in = d_stream.avail_out = 1;
if((err = inflate(&d_stream, Z_NO_FLUSH)) == Z_STREAM_END)
break;
if(err != Z_OK )
{
if(err == Z_DATA_ERROR)
{
d_stream.next_in = (Bytef*) dummy_head;
d_stream.avail_in = sizeof(dummy_head);
if((err = inflate(&d_stream, Z_NO_FLUSH)) != Z_OK)
{
return false;
}
}
else
return false;
}
}
if(inflateEnd(&d_stream) != Z_OK)
return false;
*dest_length = d_stream.total_out;
return true;
}
然后我是这样调用的,
bool HttpHandle::Decompress(ofstream &out_stream)
{
out_stream << "Decompress() is called" << endl;
char *tmp_buffer = new char[BufferSize];
memset(tmp_buffer, 0, BufferSize);
unsigned long data_length = 0;
if (!GzipDecompress((Byte*)m_content_begin, m_content_length,
(Byte*)tmp_buffer, &data_length))
return false;
m_content_begin = tmp_buffer;
m_content_length = data_length;
// out_stream << "content--------\n" << tmp_buffer;
// out_stream << "end------------" << endl;
return true;
}
GzipDecompress总是可以成功返回,但是,tmp_buffer里面却什么都没有,解压后的数据长度data_length也是0. 然而把收到的压缩数据写入文件,却可以用命令gzip成功解压。
现在找不出是哪个位置出了问题,希望懂得的人能够帮我一下。