在单个进程中使用命名管道
我正在尝试使用命名管道在进程内进行通信。 这是代码
#include <stdio.h>
#include <fcntl.h>
#include <signal.h>
void sigint(int num)
{
int fd = open("np", O_WRONLY);
write(fd, "y", 1);
close(fd);
}
main()
{
char ch[1];
int fd;
mkfifo("np", 0666);
signal(SIGINT, sigint);
fd = open("np", O_RDONLY);
read(fd, ch, 1);
close(fd);
printf("%c\n", ch[0]);
return;
}
我想要的是让 main 阻塞，直到有东西写入管道。 问题是信号处理程序 sigint() 在打开管道后也会阻塞。鉴于管道已经在 main() 之前打开以供读取，是否应该发生这种情况？
I am trying to use a named pipe for communication within a process.
Here is the code
#include <stdio.h>
#include <fcntl.h>
#include <signal.h>
void sigint(int num)
{
int fd = open("np", O_WRONLY);
write(fd, "y", 1);
close(fd);
}
main()
{
char ch[1];
int fd;
mkfifo("np", 0666);
signal(SIGINT, sigint);
fd = open("np", O_RDONLY);
read(fd, ch, 1);
close(fd);
printf("%c\n", ch[0]);
return;
}
What I want is for main to block till something is written to the pipe.
The problem is that the signal handler sigint() also blocks after opening the pipe. Is this supposed to happen given that the pipe is already opened for reading earlier in main() ?
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您在 open() 中阻塞，打开一个 fifo 来读取块，直到有人打开它进行写入。
并打开一个 fifo 来写入块，直到有人打开它来读取。
信号处理程序与 main() 在同一线程中运行，因此您会遇到死锁。两者都无法打开 fifo。
您可以通过在
strace下运行程序来检查发生了什么。You're blocking in open() , opening a fifo for reading blocks until someone opens it for writing.
And opening a fifo for writing blocks until someone opens it for reading.
the signal handler runs in the same thread as your main(), so you'll get a deadlock. Neither will be able to open the fifo.
You can check what's going on by running your program under
strace.从手册页：
和：
From the man page:
and: