SparkOS/src/init.c

/*
 * SparkOS Init - Minimal init system for SparkOS
 * This is the first process that runs after the kernel boots
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/reboot.h>
#include <signal.h>
#include <errno.h>
#include <string.h>

static void signal_handler(int sig) {
    if (sig == SIGCHLD) {
        // Reap zombie processes
        while (waitpid(-1, NULL, WNOHANG) > 0);
    }
}

static void spawn_shell() {
    pid_t pid = fork();
    
    if (pid < 0) {
        perror("fork failed");
        return;
    }
    
    if (pid == 0) {
        // Child process - exec shell
        char *argv[] = {"/bin/sh", "-l", NULL};
        char *envp[] = {
            "HOME=/root",
            "PATH=/bin:/sbin:/usr/bin:/usr/sbin",
            "TERM=linux",
            "PS1=SparkOS# ",
            NULL
        };
        
        execve("/bin/sh", argv, envp);
        
        perror("failed to exec shell");
        exit(1);
    }
    
    // Parent process - wait for shell to exit
    int status;
    waitpid(pid, &status, 0);
}

int main(int argc, char *argv[]) {
    printf("SparkOS Init System Starting...\n");
    
    // Make sure we're PID 1
    if (getpid() != 1) {
        fprintf(stderr, "init must be run as PID 1\n");
        return 1;
    }
    
    // Set up signal handlers
    signal(SIGCHLD, signal_handler);
    
    // Mount essential filesystems
    printf("Mounting essential filesystems...\n");
    if (system("mount -t proc proc /proc 2>/dev/null") != 0) {
        fprintf(stderr, "Warning: Failed to mount /proc\n");
    }
    if (system("mount -t sysfs sys /sys 2>/dev/null") != 0) {
        fprintf(stderr, "Warning: Failed to mount /sys\n");
    }
    if (system("mount -t devtmpfs dev /dev 2>/dev/null") != 0) {
        fprintf(stderr, "Warning: Failed to mount /dev\n");
    }
    if (system("mount -t tmpfs tmpfs /tmp 2>/dev/null") != 0) {
        fprintf(stderr, "Warning: Failed to mount /tmp\n");
    }
    
    printf("Starting shell...\n");
    printf("Welcome to SparkOS!\n");
    printf("===================\n\n");
    
    // Main loop - keep respawning shell
    while (1) {
        spawn_shell();
        
        // If shell exits, ask if user wants to reboot
        printf("\nShell exited. Press Ctrl+Alt+Del to reboot or wait for new shell...\n");
        sleep(2);
    }
    
    return 0;
}