Cannot Write in Named Pipe

Question

In this code my program crashes in when I am opening the pipe for writing.

char pipe[30];
int fd, tmp = 2;
sprintf(pipe, "root_%d", getpid());
ret_val = mkfifo(pipe, 0666);
fd = open(pipe, O_WRONLY); //HERE IS CRASHING - SUDDENLY FREEZES
write(fd, &tmp, sizeof(int));
close(fd)

All seems good, but where is my mistake;

Please post a proper [MCVE](https://stackoverflow.com/help/mcve). — Acorn, Nov 18 '18 at 19:36
Add error checking and handling for starters. And what is `temp`? And what line is your debugger showing the crash on? For that matter, what do you mean by crash? — Shawn, Nov 18 '18 at 19:38

score 1 · Answer 1 · answered Nov 18 '18 at 20:08

It is an expected behavior. From man 7 fifo:

Normally, opening the FIFO blocks until the other end is opened also.

So your open does not return until somebody opens the same pipe for reading. You may want to add O_NONBLOCK flag (and likely get SIGPIPE on writing), or revisit the design.

Cannot Write in Named Pipe

1 Answers1