Archive for October, 2023

Recovering from a segfault in C

by on Oct.21, 2023, under News

To return to a safe point in our program after a segmentation fault or other signal, we can make use of the setjmp() and longjmp() functions provided in the setjmp.h header. These functions allow us to jump back to a point in our program where setjmp() was called, bypassing the normal function call/return flow.

Here’s an example that demonstrates how to use setjmp() and longjmp() to recover from a segmentation fault:

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

static jmp_buf jump_buffer;

void segfault_handler(int signo) {
    printf("Caught segfault! Recovering...\n");
    longjmp(jump_buffer, 1);  // Jump back to where setjmp was called

int unsafe_function() {
    int *ptr = NULL;
    *ptr = 42;  // This will cause a segmentation fault
    return *ptr;

int main() {
    // Set up the segfault handler
    if (signal(SIGSEGV, segfault_handler) == SIG_ERR) {
        fprintf(stderr, "Can't set up segfault handler\n");

    printf("Setting up recovery point...\n");
    if (setjmp(jump_buffer) == 0) {
        printf("Running unsafe function...\n");
        int result = unsafe_function();
        printf("Result: %d\n", result);
    } else {
        printf("Recovered from segfault. Resuming normal operation.\n");

    printf("Continuing program...\n");
    // ... Rest of your program logic

    return 0;

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