How to detect broken pipe in C (Linux)?
 

I am using pipes for IPC and have a main program opening pipes for 2 other processes. Each process is connected the main program by 2 pipes (read and write)

main <=a== process 1
main ==b=> process 1

The main program will wait at the read end of pipe a. When a process connects, the main program will open the write end of pipe b which process 1 had already opened.

Let's say process 1 terminates unexpectedly, then the main program crashes due to broken pipe b. Now the question is having 2 process connecting to main with 2 pairs of read-write pipes, how do main detect which pipe is broken and closes it without crashin?

using signal
 

You can try catching the signal "SIGPIPE". You can register to get this signal using the system call "signal".

Hope this solves your problem.

I have thought of signals, but it doesn't allow me to identify which pipe causes the error and to close it. I dun wan to close all pipes and reopen all of them.

Anyone to identify the pipe's FD if we are to use the signal handler's approach?

As you might be knowing the signal SIGPIPE is sent to the process which is trying to write into a pipe which has no readers.

In your case, to identify the exact pipe which is closed probably you can do the following:

- ignore the SIGPIPE signal i.e.

- now whenever a reader process exits, since writer process has opted to ignore the signal whenever writer tries to write into the pipe the "write" system call will fail & returns error (-1). The exact reason for the failure of "write" can be got if required ("errno" will be set to "EPIPE").

Hope this will solve your problem.

Yes it solves my problem! Thanks.