Signal Handling

When an application crashes due to a Segmentation Fault or Abort signal, the default behavior is often to terminate silently or leave a cryptic core dump. We provides an API to install the signal handlers and dump the traceback automatically when your program fails.

API

`ctb_install_signal_handler` Function

Install signal handlers for C Traceback.


void ctb_install_signal_handler(void);

This will works 99% of the time, but it can fails. To dump the traceback, we will have to access the thread-local context with static storage, which is not async-signal-safe. You may lose the core dump if it fails.

Usage


#include <stdio.h>
 
#include "c_traceback.h"
 
void some_function(void)
{
    int *ptr = NULL;
    THROW(CTB_BLOCKING_IO_ERROR, "Hello! This is another test error before segfault.");
    printf("value: %d\n", *ptr); // This will cause a segmentation fault
}
 
int main(void)
{
    ctb_install_signal_handler();
    THROW(CTB_BUFFER_ERROR, "Hello! This is a test error before segfault.");
 
    TRACE(some_function());
 
    return 0;
}

Output

The output is a bit ugly as we lose access to many functions due to limitations of signal handler.


 
--------------------------------------------------------------------------------
(#00) Traceback (most recent call last):
  (#00) File "/home/alvinng/Desktop/c_traceback/examples/example_seg_fault.c", line 15 in main:
    <Error thrown here>
BufferError: Hello! This is a test error before segfault.
 
During handling of the above exception, another exception occurred:
 
(#01) Traceback (most recent call last):
  (#00) File "/home/alvinng/Desktop/c_traceback/examples/example_seg_fault.c", line 17 in main:
    some_function()
  (#01) File "/home/alvinng/Desktop/c_traceback/examples/example_seg_fault.c", line 8 in some_function:
    <Error thrown here>
BlockingIOError: Hello! This is another test error before segfault.
 
During handling of the above exception, another exception occurred:
 
(#02) Traceback (most recent call last):
  (#00) File "/home/alvinng/Desktop/c_traceback/examples/example_seg_fault.c", line 17 in main:
    some_function()
SignalSegmentationFault
--------------------------------------------------------------------------------

`ctb_dump_traceback_signal` Function

Dump the traceback to stderr on signal error.


void ctb_dump_traceback_signal(ctb_sig);

You can use this to write your own signal handler. As mentioned in ctb_install_signal_handler, it works 99% of the time but is slightly unsafe.

Parameters

Name	Type	Description
`ctb_error`	`CTB_Error`	The signal error type.