Program received signal SIGPIPE, Broken pipe

Question

I write a client program based on posix sockets. The program creates multiple threads and is going to lock the server. But during debug in gdb time the program gives an info

Answer 1

You have written to a connection that has already been closed by the peer.

Answer 2

I sort of experienced the same problem and it let me to this SO post. I got sporadic SIGPIPE signals causing crashes of my fastcgi C program run by nginx. I tried to signal(SIGPIPE, SIG_IGN); without luck, it kept crashing.

The reason was that nginx's temp dir had a permission problem. Fixing the permissions solved the SIGPIPE problem. Details here on how to fix and more here.

Answer 3

The process received a SIGPIPE. The default behaviour for this signal is to end the process.

A SIGPIPE is sent to a process if it tried to write to a socket that had been shutdown for writing or isn't connected (anymore).

To avoid that the program ends in this case, you could either

• make the process ignore SIGPIPE

  #include <signal.h>
  
  int main(void)
  {
    sigaction(SIGPIPE, &(struct sigaction){SIG_IGN}, NULL);
  
    ...
  

  or

• install an explicit handler for SIGPIPE (typically doing nothing):

  #include <signal.h>
  
  void sigpipe_handler(int unused)
  {
  }
  
  int main(void)
  {
    sigaction(SIGPIPE, &(struct sigaction){sigpipe_handler}, NULL);
  
    ...
  

In both cases send*()/write() would return -1 and set errno to EPIPE.

Answer 4

A workaround for SIGPIPE, you can ignore this signal by this code:

#include <signal.h>

/* Catch Signal Handler functio */
void signal_callback_handler(int signum){

        printf("Caught signal SIGPIPE %d\n",signum);
}

in your code (main or globally)

/* Catch Signal Handler SIGPIPE */
signal(SIGPIPE, signal_callback_handler);

Answer 5

When debugging with 'gdb', it is possible to manually disable SIGPIPE as follows:

(gdb) handle SIGPIPE nostop