big

gistfile1.txt

#define _GNU_SOURCE
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/mount.h>
#include <stdio.h>
#include <sched.h>
#include <signal.h>
#include <unistd.h>
 
#define STACK_SIZE (1024 * 1024)
 
static char container_stack[STACK_SIZE];
char* const container_args[] = {
    "/bin/bash",
    "-l",
    NULL
};
 
int container_main(void* arg)
{
    printf("Container [%5d] - inside the container!\n", getpid());
 
    //set hostname
    sethostname("container",10);
 
    //remount "/proc" to make sure the "top" and "ps" show container's information
    if (mount("proc", "rootfs/proc", "proc", 0, NULL) !=0 ) {
        perror("proc");
    }
    if (mount("sysfs", "rootfs/sys", "sysfs", 0, NULL)!=0) {
        perror("sys");
    }
    if (mount("none", "rootfs/tmp", "tmpfs", 0, NULL)!=0) {
        perror("tmp");
    }
    if (mount("udev", "rootfs/dev", "devtmpfs", 0, NULL)!=0) {
        perror("dev");
    }
    if (mount("devpts", "rootfs/dev/pts", "devpts", 0, NULL)!=0) {
        perror("dev/pts");
    }
    if (mount("shm", "rootfs/dev/shm", "tmpfs", 0, NULL)!=0) {
        perror("dev/shm");
    }
    if (mount("tmpfs", "rootfs/run", "tmpfs", 0, NULL)!=0) {
        perror("run");
    }
    /* 
     * 模仿Docker的从外向容器里mount相关的配置文件 
     * 你可以查看：/var/lib/docker/containers/<container_id>/目录，
     * 你会看到docker的这些文件的。
     */
    if (mount("conf/hosts", "rootfs/etc/hosts", "none", MS_BIND, NULL)!=0 ||
          mount("conf/hostname", "rootfs/etc/hostname", "none", MS_BIND, NULL)!=0 ||
          mount("conf/resolv.conf", "rootfs/etc/resolv.conf", "none", MS_BIND, NULL)!=0 ) {
        perror("conf");
    }
    /* 模仿docker run命令中的 -v, --volume=[] 参数干的事 */
    if (mount("/tmp/t1", "rootfs/mnt", "none", MS_BIND, NULL)!=0) {
        perror("mnt");
    }
 
    /* chroot 隔离目录 */
    if ( chdir("./rootfs") != 0 || chroot("./") != 0 ){
        perror("chdir/chroot");
    }
 
    execv(container_args[0], container_args);
    perror("exec");
    printf("Something's wrong!\n");
    return 1;
}
 
int main()
{
    printf("Parent [%5d] - start a container!\n", getpid());
    int container_pid = clone(container_main, container_stack+STACK_SIZE, 
            CLONE_NEWUTS | CLONE_NEWIPC | CLONE_NEWPID | CLONE_NEWNS | SIGCHLD, NULL);
    waitpid(container_pid, NULL, 0);
    printf("Parent - container stopped!\n");
    return 0;
}