Change application core dump directory with c program

I have one scenario where I want to change directory for core dumps by current application using c program.

I have one option to do chdir() to specified directory. But this changes the home directory of application. And I am looking for some APIs which can change directory for core dumps only.

Answer

You can change core dump pattern globally through /proc/sys/kernel/core_pattern.

But if you only want to change the core dump directory of one process, you can do what Apache web server does – register a signal handler that changes the current directory right before core dumping:

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <sys/resource.h>


#define COREDUMP_DIR "/tmp"


static void sig_coredump (int sig)
{
    struct sigaction sa;

    // Change to the directory we want the core to be dumped
    chdir (COREDUMP_DIR);

    // Clear the signal handler for the signal
    memset (&sa, 0, sizeof (sa));
    sa.sa_handler = SIG_DFL;
    sigemptyset (&sa.sa_mask);
    sigaction (sig, &sa, NULL);

    // Send the signal again
    raise (sig);
}


int main (int argc, char **argv)
{
    struct sigaction sa;

    // Set up the signal handler for all signals that
    // can cause the core dump
    memset (&sa, 0, sizeof (sa));
    sa.sa_handler = sig_coredump;

    sigemptyset (&sa.sa_mask);
    sigaction (SIGSEGV, &sa, NULL);
    sigaction (SIGBUS, &sa, NULL);
    sigaction (SIGABRT, &sa, NULL);
    sigaction (SIGILL, &sa, NULL);
    sigaction (SIGFPE, &sa, NULL);

    // Enable core dump
    struct rlimit core_limit;
    core_limit.rlim_cur = RLIM_INFINITY;
    core_limit.rlim_max = RLIM_INFINITY;

    if (setrlimit (RLIMIT_CORE, &core_limit) == -1) {
        perror ("setrlimit");
    }

    // Trigger core dump
    raise (SIGSEGV);

    return 0;
}

Note that as this relies on the crashing application itself setting up and being able to run the signal handler, it can’t be 100% bullet-proof – signal may be delivered before signal handler is set up or signal handling itself may get corrupted.