How to recover from segmentation fault on C++? - c++

Question

I have some production-critical code that has to keep running.
think of the code as
while (true){
init();
do_important_things(); //segfault here
clean();
}
I can't trust the code to be bug-free, and I need to be able to log problems to investigate later.
This time, I know for a fact somewhere in the code there is a segmentation fault getting thrown, and I need to be able to at least log that, and then start everything over.
Reading here there are a few solutions, but following each one is a flame-war claiming the solution will actually do more harm than good, with no real explanation. I also found this answer which I consider using, but I'm not sure it is good for my use case.
So, what is the best way to recover from segmentation fault on C++?

Answer 1

I suggest that you create a very small program that you make really safe that monitors the buggy program. If the buggy program exits in a way you don't like, restart the program.
Posix example:
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <cstdio>
#include <iostream>
int main(int argc, char* argv[]) {
if(argc < 2) {
std::cerr << "USAGE: " << argv[0] << " program_to_monitor <arguments...>\n";
return 1;
}
while(true) {
pid_t child = fork(); // create a child process
if(child == -1) {
std::perror("fork");
return 1;
}
if(child == 0) {
execvp(argv[1], argv + 1); // start the buggy program
perror(argv[1]); // starting failed
std::exit(0); // exit with 0 to not trigger a retry
}
// Wait for the buggy program to terminate and check the status
// to see if it should be restarted.
if(int wstatus; waitpid(child, &wstatus, 0) != -1) {
if(WIFEXITED(wstatus)) {
if(WEXITSTATUS(wstatus) == 0) return 0; // normal exit, terminate
std::cerr << argv[0] << ": " << argv[1] << " exited with "
<< WEXITSTATUS(wstatus) << '\n';
}
if(WIFSIGNALED(wstatus)) {
std::cerr << argv[0] << ": " << argv[1]
<< " terminated by signal " << WTERMSIG(wstatus);
if(WCOREDUMP(wstatus)) std::cout << " (core dumped)";
std::cout << '\n';
}
std::cout << argv[0] << ": Restarting " << argv[1] << '\n';
} else {
std::perror("wait");
break;
}
}
}