How to catch segmentation fault in Linux?

Question

I need to catch segmentation fault in third party library cleanup operations. This happens sometimes just before my program exits, and I cannot fix the real reason of this. In Windows programming I could do this with __try - __catch. Is there cross-platform or platform-specific way to do the same? I need this in Linux, gcc.

Answer 1

On Linux we can have these as exceptions, too.

Normally, when your program performs a segmentation fault, it is sent a SIGSEGV signal. You can set up your own handler for this signal and mitigate the consequences. Of course you should really be sure that you can recover from the situation. In your case, I think, you should debug your code instead.

Back to the topic. I recently encountered a library (short manual) that transforms such signals to exceptions, so you can write code like this:

try
{
    *(int*) 0 = 0;
}
catch (std::exception& e)
{
    std::cerr << "Exception catched : " << e.what() << std::endl;
}

Didn't check it, though. Works on my x86-64 Gentoo box. It has a platform-specific backend (borrowed from gcc's java implementation), so it can work on many platforms. It just supports x86 and x86-64 out of the box, but you can get backends from libjava, which resides in gcc sources.

Answer 2

Here's an example of how to do it in C.

#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void segfault_sigaction(int signal, siginfo_t *si, void *arg)
{
    printf("Caught segfault at address %p\n", si->si_addr);
    exit(0);
}

int main(void)
{
    int *foo = NULL;
    struct sigaction sa;

    memset(&sa, 0, sizeof(sigaction));
    sigemptyset(&sa.sa_mask);
    sa.sa_sigaction = segfault_sigaction;
    sa.sa_flags   = SA_SIGINFO;

    sigaction(SIGSEGV, &sa, NULL);

    /* Cause a seg fault */
    *foo = 1;

    return 0;
}