init.c

gistfile1.txt

#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <sys/mount.h>

#define ROOT_DEVICE "/dev/mmcblk0p8"
#define ROOT_DIR "/linux"

// armv7a-hardfloat-linux-gnueabi-gcc init.c -static -o init

int main(int argc, char *argv[])
{
   int ret;

   printf("INIT: mount /dev\n");
   ret = mount(NULL, "/dev", "devtmpfs", 0, "mode=0755");
   if (ret != 0)
      goto error;

   printf("INIT: mount /root\n");
   ret = mount(ROOT_DEVICE, "/root", "ext4", 0, NULL);
   if (ret != 0)
      goto error;

   printf("INIT: umount /dev\n");
   ret = umount("/dev");
   if (ret != 0)
      goto error;

   printf("INIT: chrooting\n");
   ret = chroot("/root" ROOT_DIR);
   if (ret != 0)
      goto error;

   printf("INIT: mount /\n");
   ret = mount("/", "/", "rootfs", MS_BIND, NULL);
   if (ret != 0)
      goto error;

   printf("INIT: run rootfs init\n");
   ret = execv("/sbin/init", argv);

error:
   fprintf(stderr, "INIT ERROR: %s\n", strerror(errno));

   return ret;
}