3.12 dup 不共享文件描述符属性

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字数： 138 阅读：≈ 1分钟
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/param.h>
#include <sys/syscall.h>
#include <sys/times.h>
#include <unistd.h>

extern int errno;

void
err_sys (const char *msg)
{
  perror (msg);
  exit (errno);
}

int
main (int argc, char **argv)
{
  int fd = open ("A.txt", O_WRONLY | O_CREAT | O_TRUNC,
                 S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH);
  if (fd == -1)
    err_sys ("open");
  
  int ret, fd2;
  if ((ret = fcntl (fd, F_SETFD, FD_CLOEXEC)) == -1)
    err_sys ("fcntl set fd failed");
  fd2 = dup (fd);
  if (fd2 == -1)
    err_sys ("dup");
  if ((ret = fcntl (fd, F_GETFD, FD_CLOEXEC)) == -1)
    err_sys ("fcntl get fd failed");
  printf ("ret=%d\n", ret);
  if ((ret = fcntl (fd2, F_GETFD, FD_CLOEXEC)) == -1)
    err_sys ("fcntl get fd2 failed");
  printf ("ret=%d\n", ret);
}

结果：

ret=1
ret=0

FD_CLOEXEC 被清理掉了。