read() 或 write() 系统调用在被 EINTR 信号中断后能否从中断处继续？

Question

ssize_t ret;
while (len != 0 && (ret = read (fd, buf, len)) != 0) {
  if (ret == -1) {
    if (errno == EINTR)
      continue;
    perror ("read");
    break;
  }
  len -= ret;
  buf += ret;
}

我想知道如果这段代码收到中断信号，它如何从中断处继续。在那种情况下，read() 系统调用必须重新开始，这不是让它从头开始吗？同样的事情也适用于 write() 系统调用。您能解释一下这些系统调用在这些情况下的行为吗？

Answer 1

https://linux.die.net/man/3/read

If a read() is interrupted by a signal before it reads any data, it shall return -1 with errno set to EINTR.

If a read() is interrupted by a signal after it has successfully read some data, it shall return the number of bytes read.

在任何一种情况下，对 read() 的下一次调用将继续读取调用中断前中断的位置。

If read() does not retrieve all the data in a message, the remaining data shall be left on the STREAM, and can be retrieved by the next read() call.

read() 或 write() 系统调用在被 EINTR 信号中断后能否从中断处继续？

Can a read() or write() system call continue where it left off after being interrupted by an EINTR signal?

c

unix

posix

system-calls

systems-programming