accept和accep4t的区别

版权声明：本文为博主艾露米婭娜原创文章，转载请注明出处https://blog.csdn.net/qq_17308321 https://blog.csdn.net/qq_17308321/article/details/83791336

SYNOPSIS
       #include <sys/types.h>          /* See NOTES */
       #include <sys/socket.h>

       int accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen);

       #define _GNU_SOURCE             /* See feature_test_macros(7) */
       #include <sys/socket.h>

       int accept4(int sockfd, struct sockaddr *addr,
                   socklen_t *addrlen, int flags);
 

       If flags is 0, then accept4() is the same as accept().  The following values can be bitwise ORed in flags to obtain different behavior:

如果flags为0  等同于 accept.

       SOCK_NONBLOCK   Set the O_NONBLOCK file status flag on the new open file description.  Using this flag saves extra calls to fcntl(2)  to  achieve  the  same result.

在新打开的文件描述符设置 O_NONBLOCK 标记。在 fcntl(2) 中保存这个标记可以得到相同的效果。

       SOCK_CLOEXEC    Set  the  close-on-exec  (FD_CLOEXEC) flag on the new file descriptor.  See the description of the O_CLOEXEC flag in open(2) for reasons why this may be useful.

在新打开的文件描述符里设置 close-on-exec (FD_CLOEXEC) 标记。参看在open(2) 里关于 O_CLOEXEC标记的描述来了解这为什么有用。

  int connfd = ::accept4(sockfd, (struct sockaddr *)(addr),
                         &addrlen, SOCK_NONBLOCK | SOCK_CLOEXEC);
 

就是会对返回的fd  connfd  设置SOCK_NONBLOCK | SOCK_CLOEXEC 标记.