Luna/apps/src/init.c

#include <luna.h>
#include <setjmp.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>

int print_version()
{
    char version[4096];

    FILE* fp = fopen("/dev/version", "r");
    if (!fp)
    {
        perror("fopen");
        return 1;
    }

    size_t nread = fread(version, 4096, 1, fp);
    if (ferror(fp))
    {
        perror("fread");
        return 1;
    }

    version[nread] = 0;

    if (fclose(fp) < 0)
    {
        perror("fclose");
        return 1;
    }

    printf("Your kernel version is %s\n\n", version);

    return 0;
}

int main()
{
    if (getpid() != 1)
    {
        fprintf(stderr, "init should be started as PID 1\n");
        return 1;
    }

    printf("Welcome to Luna!\n");

    printf("Running as PID %ld\n", getpid());

    if (print_version()) return 1;

    sleep(1);

    pid_t child = fork();
    if (child < 0)
    {
        perror("fork");
        return 1;
    }
    if (child == 0)
    {
        execv("/bin/sh", NULL);
        perror("execv");
        return 1;
    }

    pid_t result;

    for (;;)
    {
        while ((result = wait(NULL)) == 0) // No child has exited yet
        {
            msleep(100);
        }
        if (result == child) { return 0; }
    }
}