biosdisk.c

最新的grub2源代码

/* biosdisk.c - emulate biosdisk */
/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 1999,2000,2001,2002,2003,2004  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 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <grub/machine/biosdisk.h>
#include <grub/disk.h>
#include <grub/partition.h>
#include <grub/pc_partition.h>
#include <grub/types.h>
#include <grub/err.h>
#include <grub/util/misc.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <assert.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <limits.h>

#ifdef __linux__
# include <sys/ioctl.h>         /* ioctl */
# if !defined(__GLIBC__) || \
        ((__GLIBC__ < 2) || ((__GLIBC__ == 2) && (__GLIBC_MINOR__ < 1)))
/* Maybe libc doesn't have large file support.  */
#  include <linux/unistd.h>     /* _llseek */
# endif /* (GLIBC < 2) || ((__GLIBC__ == 2) && (__GLIBC_MINOR < 1)) */
# ifndef BLKFLSBUF
#  define BLKFLSBUF     _IO (0x12,97)   /* flush buffer cache */
# endif /* ! BLKFLSBUF */
# include <sys/ioctl.h>		/* ioctl */
# ifndef HDIO_GETGEO
#  define HDIO_GETGEO	0x0301	/* get device geometry */
/* If HDIO_GETGEO is not defined, it is unlikely that hd_geometry is
   defined.  */
struct hd_geometry
{
  unsigned char heads;
  unsigned char sectors;
  unsigned short cylinders;
  unsigned long start;
};
# endif /* ! HDIO_GETGEO */
# ifndef BLKGETSIZE
#  define BLKGETSIZE    _IO(0x12,96)    /* return device size */
# endif /* ! BLKGETSIZE */
# ifndef MAJOR
#  ifndef MINORBITS
#   define MINORBITS	8
#  endif /* ! MINORBITS */
#  define MAJOR(dev)	((unsigned) ((dev) >> MINORBITS))
# endif /* ! MAJOR */
# ifndef FLOPPY_MAJOR
#  define FLOPPY_MAJOR	2
# endif /* ! FLOPPY_MAJOR */
# ifndef LOOP_MAJOR
#  define LOOP_MAJOR	7
# endif /* ! LOOP_MAJOR */
#endif /* __linux__ */

static char *map[256];

#ifdef __linux__
/* Check if we have devfs support.  */
static int
have_devfs (void)
{
  static int dev_devfsd_exists = -1;

  if (dev_devfsd_exists < 0)
    {
      struct stat st;

      dev_devfsd_exists = stat ("/dev/.devfsd", &st) == 0;
    }

  return dev_devfsd_exists;
}
#endif /* __linux__ */

static int
get_drive (const char *name)
{
  unsigned long drive;
  char *p;
  
  if ((name[0] != 'f' && name[0] != 'h') || name[1] != 'd')
    goto fail;

  drive = strtoul (name + 2, &p, 10);
  if (p == name + 2)
    goto fail;

  if (name[0] == 'h')
    drive += 0x80;

  if (drive > sizeof (map) / sizeof (map[0]))
    goto fail;
  
  return (int) drive;

 fail:
  grub_error (GRUB_ERR_UNKNOWN_DEVICE, "not a biosdisk");
  return -1;
}

static int
call_hook (int (*hook) (const char *name), int drive)
{
  char name[10];

  sprintf (name, (drive & 0x80) ? "hd%d" : "fd%d", drive & (~0x80));
  return hook (name);
}

static int
grub_util_biosdisk_iterate (int (*hook) (const char *name))
{
  unsigned i;

  for (i = 0; i < sizeof (map) / sizeof (map[0]); i++)
    if (map[i] && call_hook (hook, i))
      return 1;

  return 0;
}

static grub_err_t
grub_util_biosdisk_open (const char *name, grub_disk_t disk)
{
  int drive;
  struct stat st;
  
  drive = get_drive (name);
  if (drive < 0)
    return grub_errno;

  if (! map[drive])
    return grub_error (GRUB_ERR_BAD_DEVICE,
		       "no mapping exists for `%s'", name);
  
  disk->has_partitions = (drive & 0x80);
  disk->id = drive;

  /* Get the size.  */
#ifdef __linux__
  {
    unsigned long nr;
    int fd;

    fd = open (map[drive], O_RDONLY);
    if (! fd)
      return grub_error (GRUB_ERR_BAD_DEVICE, "cannot open `%s'", map[drive]);

    if (fstat (fd, &st) < 0 || ! S_ISBLK (st.st_mode))
      {
	close (fd);
	goto fail;
      }
    
    if (ioctl (fd, BLKGETSIZE, &nr))
      {
	close (fd);
	goto fail;
      }

    close (fd);
    disk->total_sectors = nr;
    
    grub_util_info ("the size of %s is %lu", name, disk->total_sectors);
    
    return GRUB_ERR_NONE;
  }

 fail:
  /* In GNU/Hurd, stat() will return the right size.  */
#elif !defined (__GNU__)
# warning "No special routine to get the size of a block device is implemented for your OS. This is not possibly fatal."
#endif
  if (stat (map[drive], &st) < 0)
    return grub_error (GRUB_ERR_BAD_DEVICE, "cannot stat `%s'", map[drive]);

  disk->total_sectors = st.st_size >> GRUB_DISK_SECTOR_BITS;
  
  grub_util_info ("the size of %s is %lu", name, disk->total_sectors);
  
  return GRUB_ERR_NONE;
}

#ifdef __linux__
static int
linux_find_partition (char *dev, unsigned long sector)
{
  size_t len = strlen (dev);
  const char *format;
  char *p;
  int i;
  char *real_dev;

  real_dev = xstrdup (dev);
  
  if (have_devfs () && strcmp (real_dev + len - 5, "/disc") == 0)
    {
      p = real_dev + len - 4;
      format = "part%d";
    }
  else if ((strncmp (real_dev + 5, "hd", 2) == 0
	    || strncmp (real_dev + 5, "sd", 2) == 0)
	   && real_dev[7] >= 'a' && real_dev[7] <= 'z')
    {
      p = real_dev + 8;
      format = "%d";
    }
  else if (strncmp (real_dev + 5, "rd/c", 4) == 0)
    {
      p = strchr (real_dev + 9, 'd');
      if (! p)
	return 0;

      p++;
      while (*p && isdigit (*p))
	p++;

      format = "p%d";
    }
  else
    {
      free (real_dev);
      return 0;
    }

  for (i = 1; i < 10000; i++)
    {
      int fd;
      struct hd_geometry hdg;
      
      sprintf (p, format, i);
      fd = open (real_dev, O_RDONLY);
      if (! fd)
	{
	  free (real_dev);
	  return 0;
	}

      if (ioctl (fd, HDIO_GETGEO, &hdg))
	{
	  close (fd);
	  free (real_dev);
	  return 0;
	}

      close (fd);
      
      if (hdg.start == sector)
	{
	  strcpy (dev, real_dev);
	  free (real_dev);
	  return 1;
	}
    }

  free (real_dev);
  return 0;
}
#endif /* __linux__ */

static int
open_device (const grub_disk_t disk, unsigned long sector, int flags)
{
  int fd;

#ifdef O_LARGEFILE
  flags |= O_LARGEFILE;
#endif
#ifdef O_SYNC
  flags |= O_SYNC;
#endif
#ifdef O_FSYNC
  flags |= O_FSYNC;
#endif
  
#ifdef __linux__
  /* Linux has a bug that the disk cache for a whole disk is not consistent
     with the one for a partition of the disk.  */
  {
    int is_partition = 0;
    char dev[PATH_MAX];
    
    strcpy (dev, map[disk->id]);
    if (disk->partition && strncmp (map[disk->id], "/dev/", 5) == 0)
      is_partition = linux_find_partition (dev, disk->partition->start);
    
    /* Open the partition.  */
    grub_util_info ("opening the device `%s'", dev);
    fd = open (dev, flags);
    if (fd < 0)
      {
	grub_error (GRUB_ERR_BAD_DEVICE, "cannot open `%s'", dev);
	return -1;
      }

    /* Make the buffer cache consistent with the physical disk.  */
    ioctl (fd, BLKFLSBUF, 0);
    
    if (is_partition)
      sector -= disk->partition->start;
  }
#else /* ! __linux__ */
  fd = open (map[disk->id], flags);
  if (fd < 0)
    {
      grub_error (GRUB_ERR_BAD_DEVICE, "cannot open `%s'", map[disk->id]);
      return -1;
    }
#endif /* ! __linux__ */

#if defined(__linux__) && (!defined(__GLIBC__) || \
        ((__GLIBC__ < 2) || ((__GLIBC__ == 2) && (__GLIBC_MINOR__ < 1))))
  /* Maybe libc doesn't have large file support.  */
  {
    loff_t offset, result;
    static int _llseek (uint filedes, ulong hi, ulong lo,
                        loff_t *res, uint wh);
    _syscall5 (int, _llseek, uint, filedes, ulong, hi, ulong, lo,
               loff_t *, res, uint, wh);

    offset = (loff_t) sector << GRUB_DISK_SECTOR_BITS;
    if (_llseek (fd, offset >> 32, offset & 0xffffffff, &result, SEEK_SET))
      {
	grub_error (GRUB_ERR_BAD_DEVICE, "cannot seek `%s'", map[disk->id]);
	close (fd);
	return -1;
      }
  }
#else
  {
    off_t offset = (off_t) sector << GRUB_DISK_SECTOR_BITS;

    if (lseek (fd, offset, SEEK_SET) != offset)
      {
	grub_error (GRUB_ERR_BAD_DEVICE, "cannot seek `%s'", map[disk->id]);
	close (fd);
	return -1;
      }
  }
#endif

  return fd;
}
  
/* Read LEN bytes from FD in BUF. Return less than or equal to zero if an
   error occurs, otherwise return LEN.  */
static ssize_t
nread (int fd, char *buf, size_t len)
{
  ssize_t size = len;
  
  while (len)
    {
      ssize_t ret = read (fd, buf, len);
      
      if (ret <= 0)
        {
          if (errno == EINTR)
            continue;
          else
            return ret;
        }
      
      len -= ret;
      buf += ret;
    }
  
  return size;
}

/* Write LEN bytes from BUF to FD. Return less than or equal to zero if an
   error occurs, otherwise return LEN.  */
static ssize_t
nwrite (int fd, const char *buf, size_t len)
{
  ssize_t size = len;
  
  while (len)
    {
      ssize_t ret = write (fd, buf, len);
      
      if (ret <= 0)
        {
          if (errno == EINTR)
            continue;
          else
            return ret;
        }
      
      len -= ret;
      buf += ret;
    }
  
  return size;
}

static grub_err_t
grub_util_biosdisk_read (grub_disk_t disk, unsigned long sector,
			 unsigned long size, char *buf)
{
  int fd;

  fd = open_device (disk, sector, O_RDONLY);
  if (fd < 0)
    return grub_errno;