extlinux.c

linux内核

#ident "$Id$"
/* ----------------------------------------------------------------------- *
 *   
 *   Copyright 1998-2005 H. Peter Anvin - All Rights Reserved
 *
 *   This program 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, Inc., 53 Temple Place Ste 330,
 *   Boston MA 02111-1307, USA; either version 2 of the License, or
 *   (at your option) any later version; incorporated herein by reference.
 *
 * ----------------------------------------------------------------------- */

/*
 * extlinux.c
 *
 * Install the extlinux boot block on an ext2/3 filesystem
 */

#define  _GNU_SOURCE		/* Enable everything */
#include <inttypes.h>
/* This is needed to deal with the kernel headers imported into glibc 3.3.3. */
typedef uint64_t u64;
#include <alloca.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <mntent.h>
#include <stdlib.h>
#include <string.h>
#include <getopt.h>
#include <sysexits.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/mount.h>

#include <linux/fd.h>		/* Floppy geometry */
#include <linux/hdreg.h>	/* Hard disk geometry */
#include <linux/fs.h>		/* FIGETBSZ, FIBMAP */

#include "ext2_fs.h"
#include "../version.h"

#ifdef DEBUG
# define dprintf printf
#else
# define dprintf(...) ((void)0)
#endif

/* Global option handling */

const char *program;

/* These are the options we can set and their values */
struct my_options {
  unsigned int sectors;
  unsigned int heads;
} opt = {
  .sectors = 0,
  .heads = 0,
};

static void __attribute__((noreturn)) usage(int rv)
{
  fprintf(stderr,
	  "Usage: %s [options] directory\n"
	  "  --install    -i  Install over the current bootsector\n"
	  "  --update     -U  Update a previous EXTLINUX installation\n"
	  "  --zip        -z  Force zipdrive geometry (-H 64 -S 32)\n"
	  "  --sectors=#  -S  Force the number of sectors per track\n"
	  "  --heads=#    -H  Force number of heads\n"
	  "\n"
	  "  Note: geometry is determined at boot time for devices which\n"
	  "  are considered hard disks by the BIOS.  Unfortunately, this is\n"
	  "  not possible for devices which are considered floppy disks,\n"
	  "  which includes zipdisks and LS-120 superfloppies.\n"
	  "\n"
	  "  The -z option is useful for USB devices which are considered\n"
	  "  hard disks by some BIOSes and zipdrives by other BIOSes.\n",
	  program);

  exit(rv);
}

static const struct option long_options[] = {
  { "install",  0, NULL, 'i' },
  { "update",   0, NULL, 'U' },
  { "zipdrive", 0, NULL, 'z' },
  { "sectors",  1, NULL, 'S' },
  { "heads",    1, NULL, 'H' },
  { "version",  0, NULL, 'v' },
  { "help",     0, NULL, 'h' },
  { 0, 0, 0, 0 }
};
    
static const char short_options[] = "iUuzS:H:vh";



#if defined(__linux__) && !defined(BLKGETSIZE64)
/* This takes a u64, but the size field says size_t.  Someone screwed big. */
# define BLKGETSIZE64 _IOR(0x12,114,size_t)
#endif

#define LDLINUX_MAGIC	0x3eb202fe

enum bs_offsets {
  bsJump            = 0x00,
  bsOemName         = 0x03,
  bsBytesPerSec     = 0x0b,
  bsSecPerClust     = 0x0d,
  bsResSectors      = 0x0e,
  bsFATs            = 0x10,
  bsRootDirEnts     = 0x11,
  bsSectors         = 0x13,
  bsMedia           = 0x15,
  bsFATsecs         = 0x16,
  bsSecPerTrack     = 0x18,
  bsHeads           = 0x1a,
  bsHiddenSecs      = 0x1c,
  bsHugeSectors     = 0x20,

  /* FAT12/16 only */
  bs16DriveNumber   = 0x24,
  bs16Reserved1     = 0x25,
  bs16BootSignature = 0x26,
  bs16VolumeID      = 0x27,
  bs16VolumeLabel   = 0x2b,
  bs16FileSysType   = 0x36,
  bs16Code          = 0x3e,

  /* FAT32 only */
  bs32FATSz32       = 36,
  bs32ExtFlags      = 40,
  bs32FSVer         = 42,
  bs32RootClus      = 44,
  bs32FSInfo        = 48,
  bs32BkBootSec     = 50,
  bs32Reserved      = 52,
  bs32DriveNumber   = 64,
  bs32Reserved1     = 65,
  bs32BootSignature = 66,
  bs32VolumeID      = 67,
  bs32VolumeLabel   = 71,
  bs32FileSysType   = 82,
  bs32Code          = 90,
  
  bsSignature     = 0x1fe
};

#define bsHead      bsJump
#define bsHeadLen   (bsOemName-bsHead)
#define bsCode	    bs32Code	/* The common safe choice */
#define bsCodeLen   (bsSignature-bs32Code)

/*
 * Access functions for littleendian numbers, possibly misaligned.
 */
static inline uint8_t get_8(const unsigned char *p)
{
  return *(const uint8_t *)p;
}

static inline uint16_t get_16(const unsigned char *p)
{
#if defined(__i386__) || defined(__x86_64__)
  /* Littleendian and unaligned-capable */
  return *(const uint16_t *)p;
#else
  return (uint16_t)p[0] + ((uint16_t)p[1] << 8);
#endif
}

static inline uint32_t get_32(const unsigned char *p)
{
#if defined(__i386__) || defined(__x86_64__)
  /* Littleendian and unaligned-capable */
  return *(const uint32_t *)p;
#else
  return (uint32_t)p[0] + ((uint32_t)p[1] << 8) +
    ((uint32_t)p[2] << 16) + ((uint32_t)p[3] << 24);
#endif
}

static inline void set_16(unsigned char *p, uint16_t v)
{
#if defined(__i386__) || defined(__x86_64__)
  /* Littleendian and unaligned-capable */
  *(uint16_t *)p = v;
#else
  p[0] = (v & 0xff);
  p[1] = ((v >> 8) & 0xff);
#endif
}

static inline void set_32(unsigned char *p, uint32_t v)
{
#if defined(__i386__) || defined(__x86_64__)
  /* Littleendian and unaligned-capable */
  *(uint32_t *)p = v;
#else
  p[0] = (v & 0xff);
  p[1] = ((v >> 8) & 0xff);
  p[2] = ((v >> 16) & 0xff);
  p[3] = ((v >> 24) & 0xff);
#endif
}

#ifndef EXT2_SUPER_OFFSET
#define EXT2_SUPER_OFFSET 1024
#endif

#define SECTOR_SHIFT	9	/* 512-byte sectors */
#define SECTOR_SIZE	(1 << SECTOR_SHIFT)

const char *program;

/*
 * Boot block
 */
extern unsigned char extlinux_bootsect[];
extern unsigned int  extlinux_bootsect_len;
#define boot_block	extlinux_bootsect
#define boot_block_len  extlinux_bootsect_len

/*
 * Image file
 */
extern unsigned char extlinux_image[];
extern unsigned int  extlinux_image_len;
#define boot_image	extlinux_image
#define boot_image_len  extlinux_image_len

/*
 * Common abort function
 */
void __attribute__((noreturn)) die(const char *msg)
{
  fputs(msg, stderr);
  exit(1);
}

/*
 * read/write wrapper functions
 */
ssize_t xpread(int fd, void *buf, size_t count, off_t offset)
{
  char *bufp = (char *)buf;
  ssize_t rv;
  ssize_t done = 0;

  while ( count ) {
    rv = pread(fd, bufp, count, offset);
    if ( rv == 0 ) {
      die("short read");
    } else if ( rv == -1 ) {
      if ( errno == EINTR ) {
	continue;
      } else {
	die(strerror(errno));
      }
    } else {
      bufp += rv;
      offset += rv;
      done += rv;
      count -= rv;
    }
  }

  return done;
}

ssize_t xpwrite(int fd, const void *buf, size_t count, off_t offset)
{
  const char *bufp = (const char *)buf;
  ssize_t rv;
  ssize_t done = 0;

  while ( count ) {
    rv = pwrite(fd, bufp, count, offset);
    if ( rv == 0 ) {
      die("short write");
    } else if ( rv == -1 ) {
      if ( errno == EINTR ) {
	continue;
      } else {
	die(strerror(errno));
      }
    } else {
      bufp += rv;
      offset += rv;
      done += rv;
      count -= rv;
    }
  }

  return done;
}

/*
 * Produce file map
 */
int
sectmap(int fd, uint32_t *sectors, int nsectors)
{
  unsigned int blksize, blk, nblk;
  unsigned int i;

  /* Get block size */
  if ( ioctl(fd, FIGETBSZ, &blksize) )
    return -1;

  /* Number of sectors per block */
  blksize >>= SECTOR_SHIFT;

  nblk = 0;
  while ( nsectors ) {
    
    blk = nblk++;
    dprintf("querying block %u\n", blk);
    if ( ioctl(fd, FIBMAP, &blk) )
      return -1;

    blk *= blksize;
    for ( i = 0 ; i < blksize ; i++ ) {
      if ( !nsectors )
	return 0;

      dprintf("Sector: %10u\n", blk);
      *sectors++ = blk++;
      nsectors--;
    }
  }

  return 0;
}

/*
 * Get the size of a block device
 */
uint64_t get_size(int devfd)
{
  uint64_t bytes;
  uint32_t sects;
  struct stat st;

#ifdef BLKGETSIZE64
  if ( !ioctl(devfd, BLKGETSIZE64, &bytes) )
    return bytes;
#endif
  if ( !ioctl(devfd, BLKGETSIZE, &sects) )
    return (uint64_t)sects << 9;
  else if ( !fstat(devfd, &st) && st.st_size )
    return st.st_size;
  else
    return 0;
}


/*
 * Get device geometry and partition offset
 */
struct geometry_table {
  uint64_t bytes;
  struct hd_geometry g;
};

/* Standard floppy disk geometries, plus LS-120.  Zipdisk geometry
   (x/64/32) is the final fallback.  I don't know what LS-240 has
   as its geometry, since I don't have one and don't know anyone that does,
   and Google wasn't helpful... */
static const struct geometry_table standard_geometries[] = {
  {    360*1024, {  2,  9,  40, 0 } },
  {    720*1024, {  2,  9,  80, 0 } },
  {   1200*1024, {  2, 15,  80, 0 } },
  {   1440*1024, {  2, 18,  80, 0 } },
  {   1680*1024, {  2, 21,  80, 0 } },
  {   1722*1024, {  2, 21,  80, 0 } },
  {   2880*1024, {  2, 36,  80, 0 } },
  {   3840*1024, {  2, 48,  80, 0 } },
  { 123264*1024, {  8, 32, 963, 0 } }, /* LS120 */
  { 0, {0,0,0,0} }
};

int
get_geometry(int devfd, uint64_t totalbytes, struct hd_geometry *geo)
{
  struct floppy_struct fd_str;
  const struct geometry_table *gp;

  memset(geo, 0, sizeof *geo);