grub/util/getroot.c

/* getroot.c - Get root device */
/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 1999,2000,2001,2002,2003,2006,2007,2008,2009,2010,2011  Free Software Foundation, Inc.
 *
 *  GRUB is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  GRUB is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <config-util.h>
#include <config.h>

#include <sys/stat.h>
#include <sys/types.h>
#include <assert.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <dirent.h>
#include <errno.h>
#include <error.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#ifdef HAVE_LIMITS_H
#include <limits.h>
#endif
#include <grub/util/misc.h>

#include <grub/cryptodisk.h>
#include <grub/i18n.h>

#ifdef __linux__
#include <sys/ioctl.h>         /* ioctl */
#include <sys/mount.h>
#endif

#include <sys/types.h>

#ifdef USE_LIBZFS
# include <grub/util/libzfs.h>
# include <grub/util/libnvpair.h>
#endif

#include <grub/mm.h>
#include <grub/misc.h>
#include <grub/emu/misc.h>
#include <grub/emu/hostdisk.h>
#include <grub/emu/getroot.h>

#if defined (__FreeBSD__) || defined (__FreeBSD_kernel__)
#include <sys/mount.h>
#endif

#if defined(__NetBSD__) || defined(__OpenBSD__)
# include <sys/ioctl.h>
# include <sys/disklabel.h>    /* struct disklabel */
# include <sys/disk.h>    /* struct dkwedge_info */
#include <sys/param.h>
#include <sys/mount.h>
#endif /* defined(__NetBSD__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__) */

#if defined(__NetBSD__)
# include <sys/fdio.h>
#endif

grub_disk_addr_t
grub_util_find_partition_start (const char *dev)
{
#if GRUB_UTIL_FD_STAT_IS_FUNCTIONAL
  struct stat st;
  grub_disk_addr_t partition_start;

  if (stat (dev, &st) >= 0
      && grub_util_device_is_mapped_stat (&st)
      && grub_util_get_dm_node_linear_info (st.st_rdev, 0, 0, &partition_start))
    return partition_start;
#endif

  return grub_util_find_partition_start_os (dev);
}

void
grub_util_pull_device (const char *os_dev)
{
  enum grub_dev_abstraction_types ab;
  ab = grub_util_get_dev_abstraction (os_dev);
  switch (ab)
    {
    case GRUB_DEV_ABSTRACTION_LVM:
      grub_util_pull_lvm_by_command (os_dev);
      /* Fallthrough - in case that lvm-tools are unavailable.  */
    case GRUB_DEV_ABSTRACTION_LUKS:
      grub_util_pull_devmapper (os_dev);
      return;

    default:
      if (grub_util_pull_device_os (os_dev, ab))
	return;
      /* Fallthrough.  */
    case GRUB_DEV_ABSTRACTION_NONE:
      free (grub_util_biosdisk_get_grub_dev (os_dev));
      return;
    }
}

char *
grub_util_get_grub_dev (const char *os_dev)
{
  char *ret;

  grub_util_pull_device (os_dev);

  ret = grub_util_get_devmapper_grub_dev (os_dev);
  if (ret)
    return ret;
  ret = grub_util_get_grub_dev_os (os_dev);
  if (ret)
    return ret;
  return grub_util_biosdisk_get_grub_dev (os_dev);
}

int
grub_util_get_dev_abstraction (const char *os_dev)
{
  enum grub_dev_abstraction_types ret;

  /* User explicitly claims that this drive is visible by BIOS.  */
  if (grub_util_biosdisk_is_present (os_dev))
    return GRUB_DEV_ABSTRACTION_NONE;

  /* Check for LVM and LUKS.  */
  ret = grub_util_get_dm_abstraction (os_dev);

  if (ret != GRUB_DEV_ABSTRACTION_NONE)
    return ret;

  return grub_util_get_dev_abstraction_os (os_dev);
}

static char *
convert_system_partition_to_system_disk (const char *os_dev, int *is_part)
{
#if GRUB_UTIL_FD_STAT_IS_FUNCTIONAL
  struct stat st;

  if (stat (os_dev, &st) < 0)
    {
      const char *errstr = strerror (errno);
      grub_error (GRUB_ERR_BAD_DEVICE, N_("cannot stat `%s': %s"),
		  os_dev, errstr);
      grub_util_info (_("cannot stat `%s': %s"), os_dev, errstr);
      return 0;
    }

  *is_part = 0;

  if (grub_util_device_is_mapped_stat (&st))
    return grub_util_devmapper_part_to_disk (&st, is_part, os_dev);

  *is_part = 0;

  return grub_util_part_to_disk (os_dev, &st, is_part);
#else
  *is_part = 0;

  return grub_util_part_to_disk (os_dev, NULL, is_part);
#endif
}

static const char *
find_system_device (const char *os_dev)
{
  char *os_disk;
  const char *drive;
  int is_part;

  os_disk = convert_system_partition_to_system_disk (os_dev, &is_part);
  if (! os_disk)
    return NULL;

  drive = grub_hostdisk_os_dev_to_grub_drive (os_disk, 0);
  free (os_disk);
  return drive;
}

static char *
make_device_name (const char *drive)
{
  char *ret, *ptr;
  const char *iptr;

  ret = xcalloc (2, strlen (drive));
  ptr = ret;
  for (iptr = drive; *iptr; iptr++)
    {
      if (*iptr == ',' || *iptr == '\\')
	*ptr++ = '\\';
      *ptr++ = *iptr;
    }
  *ptr = 0;

  return ret;
}

char *
grub_util_get_os_disk (const char *os_dev)
{
  int is_part;

  grub_util_info ("Looking for %s", os_dev);

  return convert_system_partition_to_system_disk (os_dev, &is_part);
}

#if !defined(__APPLE__)
/* Context for grub_util_biosdisk_get_grub_dev.  */
struct grub_util_biosdisk_get_grub_dev_ctx
{
  char *partname;
  grub_disk_addr_t start;
};

/* Helper for grub_util_biosdisk_get_grub_dev.  */
static int
find_partition (grub_disk_t dsk __attribute__ ((unused)),
		const grub_partition_t partition, void *data)
{
  struct grub_util_biosdisk_get_grub_dev_ctx *ctx = data;
  grub_disk_addr_t part_start = 0;
  grub_util_info ("Partition %d starts from %" GRUB_HOST_PRIuLONG_LONG,
		  partition->number, (unsigned long long) partition->start);

  part_start = grub_partition_get_start (partition);

  if (ctx->start == part_start)
    {
      ctx->partname = grub_partition_get_name (partition);
      return 1;
    }

  return 0;
}
#endif

char *
grub_util_biosdisk_get_grub_dev (const char *os_dev)
{
  const char *drive;
  char *sys_disk;
  int is_part;

  grub_util_info ("Looking for %s", os_dev);

  sys_disk = convert_system_partition_to_system_disk (os_dev, &is_part);

  if (!sys_disk)
    return 0;

  drive = grub_hostdisk_os_dev_to_grub_drive (sys_disk, 1);

  grub_util_info ("%s is a parent of %s", sys_disk, os_dev);
  if (!is_part)
    {
      free (sys_disk);
      return make_device_name (drive);
    }
  free (sys_disk);

#if defined(__APPLE__)
  /* Apple uses "/dev/r?disk[0-9]+(s[0-9]+)?".  */
  /*
   * Note: we do not use the new partition naming scheme as dos_part does not
   * necessarily correspond to an msdos partition.
   */
  {
    const char *p;
    char *dri, *ret;
    int part;
    int disk = (grub_memcmp (os_dev, "/dev/disk", sizeof ("/dev/disk") - 1)
		 == 0);
    int rdisk = (grub_memcmp (os_dev, "/dev/rdisk", sizeof ("/dev/rdisk") - 1)
		 == 0);

    dri = make_device_name (drive);

    if (!disk && !rdisk)
      return dri;

    p = os_dev + sizeof ("/dev/disk") + rdisk - 1;
    while (*p >= '0' && *p <= '9')
      p++;
    if (*p != 's')
      return dri;
    p++;

    part = strtol (p, NULL, 10);
    if (part == 0)
      return dri;

    ret = xasprintf ("%s,%d", dri, part);
    free (dri);

    return ret;
  }

#else

  /* Linux counts partitions uniformly, whether a BSD partition or a DOS
     partition, so mapping them to GRUB devices is not trivial.
     Here, get the start sector of a partition by HDIO_GETGEO, and
     compare it with each partition GRUB recognizes.

     Cygwin /dev/sdXN emulation uses Windows partition mapping. It
     does not count the extended partition and missing primary
     partitions.  Use same method as on Linux here.

     For NetBSD and FreeBSD, proceed as for Linux, except that the start
     sector is obtained from the disk label.  */
  {
    char *name;
    grub_disk_t disk;
    struct grub_util_biosdisk_get_grub_dev_ctx ctx;

    name = make_device_name (drive);

    ctx.start = grub_util_find_partition_start (os_dev);
    if (grub_errno != GRUB_ERR_NONE)
      {
	free (name);
	return 0;
      }

#if defined(__GNU__)
    /* Some versions of Hurd use badly glued Linux code to handle partitions
       resulting in partitions being promoted to disks.  */
    /* GNU uses "/dev/[hs]d[0-9]+(s[0-9]+[a-z]?)?".  */
    /*
     * Note: we do not use the new partition naming scheme as dos_part does not
     * necessarily correspond to an msdos partition.
     */
    if (ctx.start == (grub_disk_addr_t) -1)
      {
	char *p;
	char *dri;

	dri = make_device_name (drive);

	p = strrchr (os_dev + sizeof ("/dev/hd") - 1, 's');
	if (p)
	  {
	    long int n;
	    char *q;

	    p++;
	    n = strtol (p, &q, 10);
	    if (p != q && n > 0 && n != GRUB_LONG_MAX)
	      {
		char *t;
		t = dri;
		if (*q >= 'a' && *q <= 'g')
		  dri = xasprintf ("%s,%ld,%d", t, n, *q - 'a' + 1);
		else
		  dri = xasprintf ("%s,%ld", t, n);
		free (t);
	      }
	  }

	return dri;
      }
#endif

    grub_util_info ("%s starts from %" GRUB_HOST_PRIuLONG_LONG,
		    os_dev, (unsigned long long) ctx.start);

    grub_util_info ("opening the device %s", name);
    disk = grub_disk_open (name);
    free (name);

    if (! disk)
      {
	/* We already know that the partition exists.  Given that we already
	   checked the device map above, we can only get
	   GRUB_ERR_UNKNOWN_DEVICE at this point if the disk does not exist.
	   This can happen on Xen, where disk images in the host can be
	   assigned to devices that have partition-like names in the guest
	   but are really more like disks.  */
	if (grub_errno == GRUB_ERR_UNKNOWN_DEVICE)
	  {
	    char *canon;
	    grub_util_warn
	      (_("disk does not exist, so falling back to partition device %s"),
	       os_dev);
	    grub_errno = GRUB_ERR_NONE;

	    canon = grub_canonicalize_file_name (os_dev);
	    drive = grub_hostdisk_os_dev_to_grub_drive (canon ? : os_dev, 1);
	    if (canon)
	      free (canon);
	    return make_device_name (drive);
	  }
	else
	  return 0;
      }

    name = grub_util_get_ldm (disk, ctx.start);
    if (name)
      {
	grub_disk_close (disk);
	return name;
      }

    ctx.partname = NULL;

    grub_partition_iterate (disk, find_partition, &ctx);
    if (grub_errno != GRUB_ERR_NONE)
      {
	grub_disk_close (disk);
	return 0;
      }

    if (ctx.partname == NULL)
      {
	grub_disk_close (disk);
	grub_util_info ("cannot find the partition of `%s'", os_dev);
	grub_error (GRUB_ERR_BAD_DEVICE,
		    "cannot find the partition of `%s'", os_dev);
	return 0;
      }

    name = grub_xasprintf ("%s,%s", disk->name, ctx.partname);
    free (ctx.partname);
    grub_disk_close (disk);
    return name;
  }

#endif
}

int
grub_util_biosdisk_is_present (const char *os_dev)
{
  int ret = (find_system_device (os_dev) != NULL);
  grub_util_info ((ret ? "%s is present" : "%s is not present"),
		  os_dev);
  return ret;
}

#ifdef USE_LIBZFS
static libzfs_handle_t *__libzfs_handle;

static void
fini_libzfs (void)
{
  libzfs_fini (__libzfs_handle);
}

libzfs_handle_t *
grub_get_libzfs_handle (void)
{
  if (! __libzfs_handle)
    {
      __libzfs_handle = libzfs_init ();

      if (__libzfs_handle)
	atexit (fini_libzfs);
    }

  return __libzfs_handle;
}
#endif /* USE_LIBZFS */