如何使文件描述符阻塞?

我已经有一段时间没玩C了,但你可以用 fcntl() 函数用于更改文件描述符的标志:

#include <unistd.h>
#include <fcntl.h>

// Save the existing flags

saved_flags = fcntl(fd, F_GETFL);

// Set the new flags with O_NONBLOCK masked out

fcntl(fd, F_SETFL, saved_flags & ~O_NONBLOCK);

O_NONBLOCK flag应将文件描述符还原为默认模式,即阻塞:

/* Makes the given file descriptor non-blocking.
 * Returns 1 on success, 0 on failure.
*/
int make_blocking(int fd)
{
  int flags;

  flags = fcntl(fd, F_GETFL, 0);
  if(flags == -1) /* Failed? */
   return 0;
  /* Clear the blocking flag. */
  flags &= ~O_NONBLOCK;
  return fcntl(fd, F_SETFL, flags) != -1;
}