HTTP(socket)下载遇到valgrind提示的错误： Conditional jump or move depends on uninitialised value(s)

我写了个http下载函数，下载txt、jpg都正常，就是下载php有问题：valgrind会报错Conditional jump or move depends on uninitialised value(s)，
 
函数定义：
char* httpdown(char *domain, int port, char *uri, int *length) ；
 
调用：
strcpy(uri, "/net.php");
rtn = httpdown("192.168.1.24", 80, uri, &len);    
printf("File saved %s ", rtn);
 

大概发现printf这句会报那个错，如果uri是个txt或者jpg都不会报 。

经过一番折腾后发现是memcpy的问题，改成strncpy就可以了，但那样如果是图片又不能正确处理，所以，就只好判断下返回数据类型了，具体代码：

char* httpdown(char *domain, int port, char *uri, int *length) {
	char buffer[RECEIVE_BUF + 1];
	//memset(buffer, '', RECEIVE_BUF + 1);
	char* rtn;
	rtn = malloc(DOWNLOAD_BUF);
	rtn[0] = 0;
	(*length) = 0;
	int sockfd = openRequest(domain, port, uri, rtn, buffer);

#ifdef DEBUG
	if (sockfd < 0){
		printf("Connect to %s:%d failed
", domain, port);
		return rtn;
	}
#else
	if (sockfd < 0)
		return rtn;
#endif

#ifdef DEBUG
	printf("Init connect to %s:%d done, fd=%d
", domain, port, sockfd);
#endif

	int len, needLen, dataLen=0;
	int current_buffer_size = DOWNLOAD_BUF;

	rtn[0] = 0;
	buffer[0] = 0;
	int type = -1;
	char * tmp;
	while (1) {
		len = recv(sockfd, buffer, RECEIVE_BUF, 0);
		if(type<0){//如果没有取得返回数据类型
			tmp = strstr(buffer, "Content-Type");//如果已经获得content-type——潜在bug如果content-type和他的值没有一起返回则会出问题，不管了
			if(tmp!=NULL){
				tmp = strstr(tmp, "text");
				if(tmp==NULL)
					type=1;
				else
					type=0;
			}
		}
		if (len > 0) {
			needLen = dataLen + len;
			while (current_buffer_size <= needLen) {
				current_buffer_size += DOWNLOAD_BUF;
#ifdef DEBUG
				printf("realloc to %d
", current_buffer_size);
#endif
				rtn = realloc(rtn, current_buffer_size);
				rtn[dataLen] = 0;
			}
#ifdef DEBUG
			printf("http sockect received %d data
", len);
#endif
			if(type<1)//字符串用strncat
				strncat(rtn+dataLen, buffer, len);
			else
				memcpy(rtn+dataLen, buffer, len);
			dataLen+=len;
		} else {
			if (len < 0) {
				if(errno>0)
				sprintf(rtn, "消息接收失败！错误代码是%d，错误信息是'%s'
", errno,
						strerror(errno));
				return rtn;
			}
#ifdef DEBUG
		printf("Read data from %s:%d, complete
", domain, port);
#endif
			break;
		}
	}

	close(sockfd);
	(*length) = dataLen;
	return rtn;
}