CODEWITHSUNDEEP
c
Chace Fields
Chace Fields

Reputation: 907

Why does waitpid() only return 1 for all child processes?

I have a handler for SIGCHLD in a process that spawns off many children.

This code is inside my handler and pid is always 1. I've read that pid should be the child process id. Why do I keep getting back 1?

int status;
pid_t pid;

while(pid = waitpid(-1, &status, WNOHANG) > 0)
{        
    if  (WIFEXITED(status))
        printf("Child %ld: Ended properly and returned %d\n", pid, WEXITSTATUS(status));
    else
        printf("Child crashed\n");
}

Code to initialize the handler.

void initSIGCHLDSignalHandler()
{
    struct sigaction act;

    memset(&act,'\0',sizeof(struct sigaction));
    sigemptyset(&act.sa_mask);
    act.sa_flags = SA_NOCLDSTOP | SA_RESTART;
    act.sa_handler = SIGCHLD_SignalHandler;

    sigaction(SIGCHLD, &act, NULL);
}

Upvotes: 0

Views: 175

Answers (1)

tabstop
tabstop

Reputation: 1761

I imagine you want

while((pid = waitpid(-1, &status, WNOHANG)) > 0)

since right now all you're getting is "true". (Your compiler probably warns about this, so be reading your compiler warnings.)

Upvotes: 1

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