Created
August 12, 2015 03:59
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| /** | |
| * readn - 读取固定字节数 | |
| * @fd: 文件描述符 | |
| * @buf: 接收缓冲区 | |
| * @count: 要读取的字节数 | |
| * 成功返回count，失败返回-1，读到EOF返回<count | |
| */ | |
| ssize_t readn(int fd, void *buf, size_t count) | |
| { | |
| size_t nleft = count; | |
| ssize_t nread; | |
| char *bufp = (char*)buf; | |
| while (nleft > 0) | |
| { | |
| if ((nread = read(fd, bufp, nleft)) < 0) | |
| { | |
| if (errno == EINTR) | |
| continue; | |
| return -1; | |
| } | |
| else if (nread == 0) | |
| return count - nleft; | |
| bufp += nread; | |
| nleft -= nread; | |
| } | |
| return count; | |
| } | |
| /** | |
| * writen - 发送固定字节数 | |
| * @fd: 文件描述符 | |
| * @buf: 发送缓冲区 | |
| * @count: 要读取的字节数 | |
| * 成功返回count，失败返回-1 | |
| */ | |
| ssize_t writen(int fd, const void *buf, size_t count) | |
| { | |
| size_t nleft = count; | |
| ssize_t nwritten; | |
| char *bufp = (char*)buf; | |
| while (nleft > 0) | |
| { | |
| if ((nwritten = write(fd, bufp, nleft)) < 0) | |
| { | |
| if (errno == EINTR) | |
| continue; | |
| return -1; | |
| } | |
| else if (nwritten == 0) | |
| continue; | |
| bufp += nwritten; | |
| nleft -= nwritten; | |
| } | |
| return count; | |
| } | |
| /** | |
| * recv_peek - 仅仅查看套接字缓冲区数据，但不移除数据 | |
| * @sockfd: 套接字 | |
| * @buf: 接收缓冲区 | |
| * @len: 长度 | |
| * 成功返回>=0，失败返回-1 | |
| */ | |
| static ssize_t recv_peek(int sockfd, void *buf, size_t len) { | |
| int nread; | |
| while (1) { | |
| //这个过程只成功调用一次 | |
| nread = recv(sockfd, buf, len, MSG_PEEK); | |
| if (nread < 0 && errno == EINTR) { //被中断则继续读取 | |
| continue; | |
| } | |
| if (nread < 0) { | |
| return -1; | |
| } | |
| break; | |
| } | |
| return nread; | |
| } | |
| /** | |
| * readline - 按行读取数据 | |
| * @sockfd: 套接字 | |
| * @buf: 接收缓冲区 | |
| * @maxline: 每行最大长度 | |
| * 成功返回>=0，失败返回-1 | |
| */ | |
| ssize_t readline(int sockfd, void *buf, size_t maxline) { | |
| int nread; //一次IO读取的数量 | |
| int nleft; //还剩余的字节数 | |
| char *ptr; //存放数据的指针的位置 | |
| int ret; //readn的返回值 | |
| int total = 0; //目前总共读取的字节数 | |
| nleft = maxline-1; | |
| ptr = buf; | |
| while (nleft > 0) { | |
| //这一次调用仅仅是预览数据 | |
| //并没有真的把数据从缓冲区中取走 | |
| ret = recv_peek(sockfd, ptr, nleft); | |
| //注意这里读取的字节不够，绝对不是错误！！！ | |
| if (ret <= 0) { | |
| return ret; | |
| } | |
| nread = ret; | |
| int i; | |
| for (i = 0; i < nread; ++i) { | |
| if (ptr[i] == '\n') { | |
| //这里才是真正的读取过程 | |
| ret = readn(sockfd, ptr, i + 1); | |
| if (ret != i + 1) { | |
| return -1; | |
| } | |
| total += ret; | |
| ptr += ret; | |
| *ptr = 0; | |
| return total; //返回此行的长度 '\n'包含在其中 | |
| } | |
| } | |
| //如果没有发现\n，这些数据应全部接收 | |
| ret = readn(sockfd, ptr, nread); | |
| if (ret != nread) { | |
| return -1; | |
| } | |
| nleft -= nread; | |
| total += nread; | |
| ptr += nread; | |
| } | |
| *ptr = 0; | |
| return maxline-1; | |
| } |
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