CODEWITHSUNDEEP
clinuxgccgdb
mathk
mathk

Reputation: 8133

Can gdb automatically attach a process on a SIGSEGV

I have a faulty program that when execute receive a SIGSEGV.

I can use gdb like this:

$ gdb ./prog

But I would prefer that gdb catch the SIGSEGV from prog and attach it automatically.

$ ./prog
Segmentation Fault
(gdb) ...

Is there a way to do that?

Thanks

Upvotes: 12

Views: 3859

Answers (3)

yugr
yugr

Reputation: 21886

To add to Mainframe's answer you can link your app with libdebugme (or simply LD_PRELOAD it) to achieve similar functionality. For example:

DEBUGME_OPTIONS=handle_signals=1 LD_PRELOAD=libdebugme.so ./app

Upvotes: 3

Nordic Mainframe
Nordic Mainframe

Reputation: 28737

Hmm. You can set up a signal handler to launch the debugger with the current process. That way you can inspect the whole state "live".

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

const char *prog=0;
void fn(int signum)
{

    char buf[256]; 
    snprintf(buf,255,"ddd %s %d",prog,getpid());
    system(buf);
}
int main(int argc, char **argv)
{
    prog=argv[0];
    signal(SIGSEGV,&fn);
    int *p=0; 
    int k=*p;
}

UPDATE: Chaged according to the suggestions of miedwar and Fanatic23. Current Ubuntu distributions are configured to disallow debugging of non-child processes. See https://askubuntu.com/questions/41629/after-upgrade-gdb-wont-attach-to-process for a fix.

Upvotes: 15

Praveen S
Praveen S

Reputation: 10393

Well you can always create a core file and then analyse the callstack using gdb on that core. You can check out the man page for ulimit to do so.

Check this link for more info.

Upvotes: 4

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