Example of defer in C

defer.c

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

int do_something(const char *filename) {
    FILE *file = NULL;
    char *buffer = NULL;
    int result = -1;

    file = fopen(filename, "r");
    if (!file) {
        perror("fopen");
        goto defer;
    }

    buffer = malloc(1024);
    if (!buffer) {
        perror("malloc");
        goto defer;
    }

    // Do something with the file and buffer
    printf("File opened and buffer allocated.\n");

    // Success
    result = 0;

defer:
    // defer-style defer
    if (buffer) {
        free(buffer);
        printf("Buffer freed.\n");
    }

    if (file) {
        fclose(file);
        printf("File closed.\n");
    }

    return result;
}

int main() {
    if (do_something("test.txt") != 0) {
        printf("Operation failed.\n");
    } else {
        printf("Operation succeeded.\n");
    }

    return 0;
}