C & Libevent：将二进制数据添加到输出缓冲区

Question

我有一个输出evbuffer，我想用以下数据填充:

HTTP/1.1 200 OK
Date: Tue, 06 Dec 2011 10:35:08 GMT
Server: Apache/2.2.14 (Ubuntu)
X-Powered-By: PHP/5.3.2-1ubuntu4.9
Vary: Accept-Encoding
Content-Encoding: gzip
Content-Length: 48
Content-Type: text/html
��(�ͱ���I�O����H�����ч��
                          �4�@�

我用的是evbuffer_add_printf(...)，

我有以下的C回调函数:

static void echo_read_cb(struct bufferevent *bev, void *ctx){
    /* This callback is invoked when there is data to read on bev. */
    struct evbuffer *input = bufferevent_get_input(bev);
    struct evbuffer *output = bufferevent_get_output(bev);
    ...
    char* response=NULL;
    response=applyGetReq(url,data,len);
    int contLen=0;
    contLen=getContentLength(response);
    char* binData=strstr(response,"rnrn");
    binData=binData+strlen("rnrn");
    fwrite(binData,sizeof(char),contLen,stdout);
    printf("n");
    evbuffer_add_printf(output,"%s",binData);   //I want to print binData as binary, not printf!!!
}

所以我有二进制数据指针(binData)，我有一个长度(contLen)，我如何将其打印到输出缓冲区?

提前致谢

Answer 1

不能使用evbuffer_add_printf安全地添加二进制数据。Try evbuffer_add function:

int
evbuffer_add(struct evbuffer *buf, const void *data, size_t datlen)
{
    size_t need = buf->misalign + buf->off + datlen;
    size_t oldoff = buf->off;
    if (buf->totallen < need) {
            if (evbuffer_expand(buf, datlen) == -1)
                    return (-1);
    }
    memcpy(buf->buffer + buf->off, data, datlen);
    buf->off += datlen;
    if (datlen && buf->cb != NULL)
            (*buf->cb)(buf, oldoff, buf->off, buf->cbarg);
    return (0);
}

找不到好的文档，除了源代码，我看到的最好的是:

http://transmission.sourcearchive.com/documentation/1.75/event_8h_b652a2f82d23509713258a6e44697164.html b652a2f82d23509713258a6e44697164

 int evbuffer_add   (   struct evbuffer *   ,
    const void *    ,
    size_t           
)           

将数据追加到evbuffer的末尾。

参数:

    buf     the event buffer to be appended to
    data    pointer to the beginning of the data buffer
    datlen  the number of bytes to be copied from the data buffer