propagator/init.c

/*
 * Guillaume Cottenceau (gc@mandrakesoft.com)
 *
 * Copyright 2000 MandrakeSoft
 *
 * This software may be freely redistributed under the terms of the GNU
 * public license.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

/*
 * Portions from Erik Troan (ewt@redhat.com)
 *
 * Copyright 1996 Red Hat Software 
 *
 */

#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <dirent.h>
#include <fcntl.h>
#include <sys/klog.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/vfs.h>
#include <sys/wait.h>
#include <linux/vt.h>

#include "config-stage1.h"
#include "lomount.h"

#define MKDEV(ma,mi)    ((ma)<<8 | (mi))
#define RAMFS_MAGIC 0x858458f6
#define TMPFS_MAGIC 0x01021994

#ifndef MNT_DETACH /* sys/mount.h still doesn't define it */
#define MNT_DETACH 2
#endif

char * env[] = {
	"PATH=/usr/bin:/bin:/sbin:/usr/sbin",
	"HOME=/",
	"TERM=linux",
	"TERMINFO=/etc/terminfo",
	NULL
};

char ** myenv = NULL;

char *udevd[] = {"/sbin/udevd", "udevd", NULL};
char *udevtrigger[] = {"/sbin/udevadm", "udevadm", "trigger", NULL};
char *udevsettle[] = {"/sbin/udevadm", "udevadm", "settle", NULL};

extern void stage1();
void fatal(const char *) __attribute__((noreturn));

/* 
 * this needs to handle the following cases:
 *
 *  1) run from a CD root filesystem
 *  2) run from a read only nfs rooted filesystem
 *  3) run from a floppy
 *  4) run from a floppy that's been loaded into a ramdisk 
 */

void fatal(const char *msg)
{
	printf("FATAL ERROR IN INIT: %s\nI can't recover from this,"
		   "please reboot manually and send bugreport.\n", msg);
	while (1);
}

void warn(char *msg)
{
	printf("W: %s\n", msg);
}

/* fork to:
 *   (1) watch /proc/kmsg and copy the stuff to /dev/tty4
 *   (2) listens to /dev/log and copy also this stuff (log from programs)
 */
pid_t doklog()
{
	int in, out, i, ii;
	pid_t pid;
	char buf[1024];

	/* open kernel message logger */
	if ((in = open("/proc/kmsg", O_RDONLY, 0)) < 0)
		fatal("failed to open /proc/kmsg");

	if (mknod("/dev/tty4", S_IFCHR, MKDEV(4, 4)) < 0 ||
		(out = open("/dev/tty4", O_WRONLY, 0)) < 0)
		fatal("failed to open /dev/tty4");

	if ((pid = fork())) {
		if (pid < 0) fatal("doklog");
		close(in);
		close(out);
		return pid;
	}

	/* child */
	close(0);
	close(1);
	close(2);

	/* disable on-console syslog output */
	klogctl(8, NULL, 1);

	while (1)
		if ((i = read(in, buf, sizeof(buf))) > 0) 
			ii = write(out, buf, i);
}

pid_t spawn(char *av[])
{
	pid_t pid;
	if ((pid = fork())) {
		if (pid < 0) fatal(av[0]);
		return pid;
	} else {
		execve(av[0], &av[1], env);
		perror(av[0]);
		exit(1);
	}
}

void take_env(int fd)
{
	static char buf[PIPE_BUF];
	char *p = buf;
	char **ep;
	int i;

	if ((i = read(fd, buf, sizeof(buf))) < 0) {
		warn("failed to read env from pipe");
		myenv = env;
		return;
	}

	close(fd);
	buf[i] = '\0';

	if ((ep = myenv = malloc(sizeof(char *) * 32)) == NULL) {
		warn("can't malloc env");
		myenv = env;
		return;
	}

	do {
		*ep++ = p;
		p += strlen(p);
	} while(++p < buf+i);
	*ep = NULL;
}

/*
  initramfs cleaner
*/
static int nuke(const char *what);

static int nuke_dirent(int len, const char *dir, const char *name, dev_t me)
{
	int bytes = len+strlen(name)+2;
	char path[bytes];
	int xlen;
	struct stat st;
	
	xlen = snprintf(path, bytes, "%s/%s", dir, name);
	/* assert(xlen < bytes); */
	
	if ( lstat(path, &st) )
		return ENOENT;		/* Return 0 since already gone? */
	
	if ( st.st_dev != me )
		return 0;			/* DO NOT recurse down mount points!!!!! */
	
	return nuke(path);
}

/* Wipe the contents of a directory, but not the directory itself */
static int nuke_dir(const char *what)
{
	int len = strlen(what);
	DIR *dir;
	struct dirent *d;
	int err = 0;
	struct stat st;
	
	if ( lstat(what, &st) )
		return errno;
	
	if ( !S_ISDIR(st.st_mode) )
		return ENOTDIR;
	
	if ( !(dir = opendir(what)) ) {
		/* EACCES means we can't read it.  Might be empty and removable;
		   if not, the rmdir() in nuke() will trigger an error. */
		return (errno == EACCES) ? 0 : errno;
	}
	
	while ( (d = readdir(dir)) ) {
		/* Skip . and .. */
		if ( d->d_name[0] == '.' &&
			 (d->d_name[1] == '\0' ||
			  (d->d_name[1] == '.' && d->d_name[2] == '\0')) )
			continue;
		
		err = nuke_dirent(len, what, d->d_name, st.st_dev);
		if ( err ) {
			closedir(dir);
			return err;
		}
	}
	
	closedir(dir);
	
	return 0;
}

static int nuke(const char *what)
{
	int rv;
	int err = 0;
	
	rv = unlink(what);
	if ( rv < 0 ) {
		if ( errno == EISDIR ) {
			/* It's a directory. */
			err = nuke_dir(what);
			if ( !err ) err = rmdir(what) ? errno : err;
		} else {
			err = errno;
		}
	}
	
	if ( err ) {
		errno = err;
		fatal(what);
	}
	return 0;
}

struct filesystem
{
	char * dev;
	char * name;
	char * fs;
	int mounted;
};

/* attempt to unmount all filesystems in /proc/mounts */
void unmount_filesystems(void)
{
	int fd, size;
	char buf[65535];			/* this should be big enough */
	char *p;
	struct filesystem fs[500];
	int numfs = 0;
	int i, nb;
	
	printf("unmounting filesystems...\n"); 
	
	fd = open("/proc/mounts", O_RDONLY, 0);
	if (fd < 1) {
		warn("failed to open /proc/mounts");
		sleep(2);
		return;
	}

	size = read(fd, buf, sizeof(buf) - 1);
	buf[size] = '\0';

	close(fd);

	p = buf;
	while (*p) {
		fs[numfs].mounted = 1;
		fs[numfs].dev = p;
		while (*p != ' ') p++;
		*p++ = '\0';
		fs[numfs].name = p;
		while (*p != ' ') p++;
		*p++ = '\0';
		fs[numfs].fs = p;
		while (*p != ' ') p++;
		*p++ = '\0';
		while (*p != '\n') p++;
		p++;
		if (strcmp(fs[numfs].name, "/") != 0) numfs++; /* skip if root, no need to take initrd root in account */
	}

	/* Pixel's ultra-optimized sorting algorithm:
	   multiple passes trying to umount everything until nothing moves
	   anymore (a.k.a holy shotgun method) */
	do {
		nb = 0;
		for (i = 0; i < numfs; i++) {
			/*printf("trying with %s\n", fs[i].name);*/
			if (fs[i].mounted && umount(fs[i].name) == 0) { 
				if (strncmp(fs[i].dev + sizeof("/dev/") - 1, "loop",
					    sizeof("loop") - 1) == 0)
					del_loop(fs[i].dev);
				
				printf("\t%s\n", fs[i].name);
				fs[i].mounted = 0;
				nb++;
			}
		}
	} while (nb);
	
	for (i = nb = 0; i < numfs; i++)
		if (fs[i].mounted) {
			printf("\t%s umount failed\n", fs[i].name);
			if (strcmp(fs[i].fs, "ext2") == 0) nb++; /* don't count not-ext2 umount failed */
		}
	
	if (nb) {
		fatal("failed to umount some filesystems\n");
	}
}

int main(int argc, char **argv)
{
	struct stat rst, cst, ist;
	struct statfs sfs;
	pid_t pid, klogpid, udevpid;
	sigset_t sig;
	int wait_status;
	int fd = -1;
	int fds[2];

	if (mount("/proc", "/proc", "proc", 0, NULL))
		fatal("failed to mount proc filesystem");
	if (mount("sysfs", "/sys", "sysfs", 0, NULL))
		fatal("failed to mount sysfs filesystem");
	if (mount("udev", "/dev", "tmpfs", 0, "size=10M,mode=0755"))
		fatal("failed to mount tmpfs filesystem");

	/* ignore Control-C and keyboard stop signals */
	sigemptyset(&sig);
	sigaddset(&sig, SIGINT);
	sigaddset(&sig, SIGTSTP);
	sigprocmask(SIG_BLOCK, &sig, NULL);

	if (mknod("/dev/console", S_IFCHR, MKDEV(5, 1)) < 0 ||
		(fd = open("/dev/console", O_RDWR, 0)) < 0) {
		fatal("failed to open /dev/console");
	}

	dup2(fd, 0);
	dup2(fd, 1);
	dup2(fd, 2);
	close(fd);

	if (mknod("/dev/null", S_IFCHR, MKDEV(1, 3)) < 0)
		fatal("failed to create /dev/null");

	/* I set me up as session leader (probably not necessary?) */
	setsid();
	if (ioctl(0, TIOCSCTTY, NULL)) {
		perror("TIOCSCTTY");
		warn("could not set new controlling tty");
	}

	if (sethostname("localhost.localdomain", sizeof("localhost.localdomain")) < 0)
		warn("could not set hostname");
		
	/* the default domainname (as of 2.0.35) is "(none)", which confuses glibc */
	if (setdomainname("", 0) < 0)
		warn("could not set domainname");
	
	if (mkdir("/dev/.initramfs", 0755) < 0 ||
		mkdir("/dev/pts", 0755) < 0 ||
		mkdir("/dev/shm", 0755) < 0)
		fatal("mkdir\n");

	if ((fd = open("/proc/sys/kernel/hotplug", O_WRONLY, 0)) < 0 ||
		write(fd, "\n", sizeof("\n")) < sizeof("\n"))
		fatal("/proc/sys/kernel/hotplug\n");
	close(fd);

	klogpid = doklog();

	if (mkdir("/dev/.udev", 0755) < 0 ||
		mkdir("/dev/.udev/db", 0755) < 0)
		fatal("/dev/.udev/db");

	printf("Spawning udevd...");

	udevpid = spawn(udevd);

	if (mkdir("/dev/.udev/queue", 0755) < 0 && errno != EEXIST)
		fatal("cannot create /dev/.udev/queue");

	if (waitpid(spawn(udevtrigger), &wait_status, 0) < 0 ||
		!(WIFEXITED(wait_status)))
		warn("udevtrigger");
	
	if (waitpid(spawn(udevsettle), &wait_status, 0) < 0 ||
		!(WIFEXITED(wait_status)))
		warn("udevsettle");

	printf("done\n");

	/* Go into normal init mode - keep going, and then do a orderly shutdown
	   when:
	   
	   1) install exits
	   2) we receive a SIGHUP 
	*/

	printf("Running stage1...\n"); 

	/* create a pipe for env passing */
	if (pipe(fds) < 0)
		fatal("failed to create env pipe");

	fcntl(fds[0], F_SETFD, 1);
	fcntl(fds[1], F_SETFD, 0);

	if ((pid = fork())) {
		if (pid < 0) fatal("Failed to spawn stage1");
		close(fds[1]);
		while (pid != wait(&wait_status));
	} else {
		stage1();
	}

	if (!(WIFEXITED(wait_status))) {
		/* something went wrong */
	
		printf("wait_status: %i, install exited abnormally ", wait_status);
		if (WIFSIGNALED(wait_status))
			printf("-- received signal %d", WTERMSIG(wait_status));
		printf("\n");
		
		sync(); sync();
		
		printf("sending termination signals...");
		kill(-1, 15);
		sleep(2);
		printf("done\n");
		
		printf("sending kill signals...");
		kill(-1, 9);
		sleep(2);
		printf("done\n");
		
		unmount_filesystems();
		
		printf("you may safely reboot your system\n");
		while (1);
	}

	take_env(fds[0]);

	if (waitpid(spawn(udevsettle), &wait_status, 0) < 0 ||
		!(WIFEXITED(wait_status)))
		warn("udevsettle");

	kill(udevpid, 9);
	waitpid(udevpid, &wait_status, 0);
	nuke_dir("/dev/.udev/queue");

	if ((fd = open("/.udev_version", O_RDONLY, 0)) >0) {
		char buf[32];
		int n = read(fd, buf, sizeof(buf));
		close(fd);
		if ((fd = creat("/dev/.initramfs/udev_version", 0)) >0) {
			n = write(fd, buf, n);
			close(fd);
		} else fatal("creat()");
	}

	kill(klogpid, 9);
	waitpid(klogpid, &wait_status, 0);

	/* deallocate all unused consoles */
	ioctl(0, VT_DISALLOCATE, 0);

	printf("Spawning init ...");

	/* rest was seamlessy stolen from klibc */
	/* First, change to the new root directory */
	if (chdir(STAGE2_LOCATION))
		fatal("chdir to new root");

	/* This is a potentially highly destructive program.  Take some
	   extra precautions. */

	/* Make sure the current directory is not on the same filesystem
	   as the root directory */
	if ( stat("/", &rst) || stat(".", &cst) )
		fatal("stat");

	if ( rst.st_dev == cst.st_dev )
		fatal("current directory on the same filesystem as the root");

	/* The initramfs should have /init */
	if ( stat("/init", &ist) || !S_ISREG(ist.st_mode) )
		fatal("can't find /init on initramfs");

	/* Make sure we're on a ramfs */
	if ( statfs("/", &sfs) )
		fatal("statfs /");
	if ( sfs.f_type != RAMFS_MAGIC && sfs.f_type != TMPFS_MAGIC )
		fatal("rootfs not a ramfs or tmpfs");

	/* Okay, I think we should be safe... */

	/* overmount image under new root if needed */
	if ( statfs(IMAGE_LOCATION, &sfs) )
		fatal("statfs() on "IMAGE_LOCATION);
	/* if something is mounted under IMAGE_LOCATION ? */
	if ( sfs.f_type != RAMFS_MAGIC && sfs.f_type != TMPFS_MAGIC ) {
		if ( mount(IMAGE_LOCATION, "." IMAGE_LOCATION, NULL, MS_MOVE, NULL) )
			fatal("overmounting "IMAGE_LOCATION);
		/* test for nested mount: disk or nfs with iso image */
		if ( statfs(IMAGE_LOCATION, &sfs) )
			fatal("statfs() on nested "IMAGE_LOCATION);
		if ( sfs.f_type != RAMFS_MAGIC && sfs.f_type != TMPFS_MAGIC )
			if (umount2(IMAGE_LOCATION, MNT_DETACH))
				fatal("lazy umounting nested "IMAGE_LOCATION);
	}

	umount("/sys");
	umount("/proc/bus/usb");
	umount("/proc");

	if (mount("/dev", "./dev", NULL, MS_MOVE, NULL))
		fatal("overmounting /dev");

	/* Delete rootfs contents */
	if (nuke_dir("/"))
		fatal("nuking initramfs contents");

	/* Overmount the root */
	if (mount(".", "/", NULL, MS_MOVE, NULL))
		fatal("overmounting root");

	/* chroot, chdir */
	if (chroot(".") || chdir("/"))
		fatal("chroot");

	/* Check for given init */
	if (stat(STAGE2_BINNAME, &ist) || !S_ISREG(ist.st_mode))
		fatal("can't find init on root fs");

	/* Spawn init */
	printf(" done.\n");

	/* unblock signals */
	sigprocmask(SIG_UNBLOCK, &sig, NULL);

	argv[0] = STAGE2_BINNAME;
	execve(argv[0], argv, myenv);
	fatal("stage2");			/* Failed to spawn init */
	return 0;
}