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man connect:
EINPROGRESS
The socket is non-blocking and the connection cannot be completed immediately. It is possible to select(2) or poll(2) for
completion by selecting the socket for writing. After select(2)
indicates writability, use getsockopt(2) to read the SO_ERROR
option at level SOL_SOCKET to determine whether connect() completed successfully (SO_ERROR is zero) or unsuccessfully(SO_ERROR is one of the usual error codes listed here, explaining the reason for the failure).
int connect_nonb(int sockfd, const SA *saptr, socklen_t salen, int nsec)
{
int flags, n, error;
socklen_t len;
fd_set rset, wset;
struct timeval tval;
flags = Fcntl(sockfd, F_GETFL, 0);
Fcntl(sockfd, F_SETFL, flags | O_NONBLOCK);
error = 0;
if ( (n = connect(sockfd, saptr, salen)) < 0)
if (errno != EINPROGRESS)
return (-1);
/* Do whatever we want while the connect is taking place. */
if (n == 0)
goto done; /* connect completed immediately */
FD_ZERO(&rset);
FD_SET(sockfd, &rset);
wset = rset;
tval.tv_sec = nsec;
tval.tv_usec = 0;
if ( (n = Select(sockfd + 1, &rset, &wset, NULL,
nsec ? &tval : NULL)) == 0) {
close(sockfd); /* timeout */
errno = ETIMEDOUT;
return (-1);
}
if (FD_ISSET(sockfd, &rset) || FD_ISSET(sockfd, &wset)) {
len = sizeof(error);
if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &error, &len) < 0)
return (-1); /* Solaris pending error */
} else
err_quit("select error: sockfd not set");
done:
Fcntl(sockfd, F_SETFL, flags); /* restore file status flags */
if (error) {
close(sockfd); /* just in case */
errno = error;
return (-1);
}
return (0);
}
之所以会出现operation now in process,是因为connect_non执行到select处,等待连接建立时,connect又被执行到了,所以会有错误operation now in process出现。
本错误解读基于作者的能力,有不对的地方敬请指正。
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