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#define MAXLINE 1024
readn和writen是unp的作者定义的函数。实现如下:
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;
}
ssize_t /* Read "n" bytes from a descriptor. */
readn(int fd, void *vptr, size_t n)
{
size_t nleft;
ssize_t nread;
char *ptr;
ptr = vptr;
nleft = n;
while (nleft > 0) {
if ( (nread =read(fd, ptr, nleft)) < 0) {
if (errno == EINTR)
nread = 0; /* and call read() again */
else
return(-1);
} else if (nread == 0)
break; /* EOF */
nleft -= nread;
ptr += nread;
}
return(n - nleft); /* return >= 0 */
} |
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