How to programmatically cause a core dump in C/C++

Question

I would like to force a core dump at a specific location in my C++ application.

I know I can do it by doing something like:

int * crash = NULL;
*crash = 1;

But I would like to know if there is a cleaner way?

I am using Linux by the way.

Solution 1

Raising of signal number 6 (SIGABRT in Linux) is one way to do it (though keep in mind that SIGABRT is not required to be 6 in all POSIX implementations so you may want to use the SIGABRT value itself if this is anything other than quick'n'dirty debug code).

#include <signal.h>
: : :
raise (SIGABRT);

Calling abort() will also cause a core dump, and you can even do this without terminating your process by calling fork() followed by abort() in the child only - see this answer for details.

Solution 2

A few years ago, Google released the coredumper library.

Overview

The coredumper library can be compiled into applications to create core dumps of the running program -- without terminating. It supports both single- and multi-threaded core dumps, even if the kernel does not natively support multi-threaded core files.

Coredumper is distributed under the terms of the BSD License.

Example

This is by no means a complete example; it simply gives you a feel for what the coredumper API looks like.

#include <google/coredumper.h>
...
WriteCoreDump('core.myprogram');
/* Keep going, we generated a core file,
 * but we didn't crash.
 */

It's not what you were asking for, but maybe it's even better :)

Solution 3

As listed in the signal manpage, any signal with the action listed as 'core' will force a core dump. Some examples are:

SIGQUIT       3       Core    Quit from keyboard
SIGILL        4       Core    Illegal Instruction
SIGABRT       6       Core    Abort signal from abort(3)
SIGFPE        8       Core    Floating point exception
SIGSEGV      11       Core    Invalid memory reference

Make sure that you enable core dumps:

ulimit -c unlimited

Solution 4

#include <stdlib.h>   // C
//#include <cstdlib>  // C++

void core_dump(void)
{
    abort();
}

Solution 5

Invoke

abort();

Related, sometimes you'd like a back trace without an actual core dump, and allow the program to continue running: check out glibc backtrace() and backtrace_symbols() functions: http://www.gnu.org/s/libc/manual/html_node/Backtraces.html

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