linux网络编程基础API(二)

编写网络程序处除了要理解各种地址和必要的函数，还要检测程序出错。如果每次调用一个基本的socket函数都要判断其结果是否正确，会给编程带来麻烦。因此大多数都会定义包裹函数，对每一个基本socket函数进行封装。下面是借鉴了《linux C编程一站式学习》中的代码进行整理：

#include <stdlib.h>
#include <errno.h>
#include <sys/socket.h>
#include <unistd.h>
#include <stdio.h>

#include "wrap.h"

void perr_exit(const char *s)
{
perror(s);
exit(1);
}

int Socket(int family, int type, int protocol)
{
int n;

if ( (n = socket(family, type, protocol)) < 0)
perr_exit("socket error");
return n;
}
void Connect(int fd, const struct sockaddr *sa, socklen_t salen)
{
if (connect(fd, sa, salen) < 0)
perr_exit("connect error");
}
void Bind(int fd, const struct sockaddr *sa, socklen_t salen)
{
if (bind(fd, sa, salen) < 0)
perr_exit("bind error");
}

void Listen(int fd, int backlog)
{
if (listen(fd, backlog) < 0)
perr_exit("listen error");
}
int Accept(int fd, struct sockaddr *sa, socklen_t *salenptr){int n;
again:
if ( (n = accept(fd, sa, salenptr)) < 0) {
if ((errno == ECONNABORTED) || (errno == EINTR))
goto again;
else
perr_exit("accept error");
}
return n;
}
//有Readn就不用它了
ssize_t Read(int fd, void *ptr, size_t nbytes)
{
ssize_t n;

again:
if ( (n = read(fd, ptr, nbytes)) == -1) {
if (errno == EINTR)
goto again;
else
return -1;
}
return n;
}
//有Writen就不用它了
ssize_t Write(int fd, const void *ptr, size_t nbytes)
{
ssize_t n;

again:
if ( (n = write(fd, ptr, nbytes)) == -1) {
if (errno == EINTR)
goto again;
else
return -1;
}
return n;
}

void Close(int fd)
{
if (close(fd) == -1)
perr_exit("close error");
}
//读n个字节到prt中，返回实际读到的字节数，-1代表出错
ssize_t Readn(int fd, void *vptr, size_t n)
{
size_t nleft;
ssize_t nread;
char *ptr;
ptr = vptr;
nleft = n;//剩下nleft未读
while (nleft > 0) {
if ( (nread = read(fd, ptr, nleft)) < 0) {
if (errno == EINTR)
nread = 0;
else
return -1;//出错
} else if (nread == 0)
break;//读完
nleft -= nread;
ptr += nread;
}
return n - nleft;//读出的字节数
}
ssize_t Writen(int fd, const void *vptr, size_t n)
{
size_t nleft;
ssize_t nwritten;
const char *ptr;
ptr = vptr;
nleft = n;
while (nleft > 0) {
if ( (nwritten = write(fd, ptr, nleft)) <= 0) {
if (nwritten < 0 && errno == EINTR)
nwritten = 0;
else
return -1;
}
nleft -= nwritten;
ptr += nwritten;
}
return n;
}