Crash with purpose: a small example crash handling module in C to have useful error output when things go wrong. Check out the Hackaday article on the subject for more information.

On crash, the code will print your custom error message along with some details that looks something like this:

Error --------------------------------------------
    check for value failed: 110


Location -----------------------------------------
    main.c:11  foo()

Backtrace ----------------------------------------
 1  ./main(foo+0x57) [0x55d0f691a250]
 2  ./main(main+0x33) [0x55d0f691a285]
 3  /usr/lib/libc.so.6(__libc_start_main+0xf3) [0x7f905139b223]
 4  ./main(_start+0x2e) [0x55d0f691a12e]

• crash.h crash handler header file
• crash.c crash handler source file
• sample.c sample usage of the crash handler

The sample.c file has a very basic example of how to use the crash handler, but basically, you include the crash.h file and call the crash() macro whenever something crashworthy happens in your code.

#include "crash.h"

...

    if (!valid_data) {
        crash("invalid data %d", data);
    }

Add the crash.c when you compile and you're done:

$ gcc -o sample sample.c crash.c

That, however, won't give you the function names in the backtrace, so instead of ./main(foo+0x57) you will get ./main(+0x1250). To have the function names included, you need to add the -rdynamic compiler option:

$ gcc -o sample -rdynamic sample.c crash.c

If you don't want / need all the details about the location and backtrace, you can define the SIMPLE_CRASH macro:

$ gcc -o sample -rdynamic -DSIMPLE_CRASH sample.c crash.c

Now you will only get your custom error message as output:

check for value failed: 132