extlinux installer.

2 files changed, 587 insertions, 0 deletions

diff --git a/extlinux/Makefile b/extlinux/Makefile
new file mode 100644
index 00000000..3358f5af
--- /dev/null
+++ b/extlinux/Makefile
@@ -0,0 +1,40 @@
+CC	 = gcc
+OPTFLAGS = -g -Os
+INCLUDES = -I. -I.. -I../libfat
+CFLAGS	 = -W -Wall -Wno-sign-compare -D_FILE_OFFSET_BITS=64 $(OPTFLAGS) $(INCLUDES)
+LDFLAGS	 = -s
+
+SRCS     = extlinux.c ../extlinux_bss_bin.c ../extlinux_sys_bin.c
+OBJS	 = $(patsubst %.c,%.o,$(notdir $(SRCS)))
+
+.SUFFIXES: .c .o .i .s .S
+
+VPATH = .:..
+
+all: installer
+
+tidy:
+	-rm -f *.o *.i *.s *.a .*.d
+
+clean: tidy
+	-rm -f extlinux
+
+spotless: clean
+	-rm -f *~
+
+installer: extlinux
+
+extlinux: $(OBJS)
+	$(CC) $(LDFLAGS) -o $@ $^
+
+%.o: %.c
+	$(CC) -Wp,-MT,$@,-MMD,.$@.d $(CFLAGS) -c -o $@ $<
+%.i: %.c
+	$(CC) $(CFLAGS) -E -o $@ $<
+%.s: %.c
+	$(CC) $(CFLAGS) -S -o $@ $<
+
+-include .*.d
+
+
+
diff --git a/extlinux/extlinux.c b/extlinux/extlinux.c
new file mode 100644
index 00000000..56641556
--- /dev/null
+++ b/extlinux/extlinux.c
@@ -0,0 +1,547 @@
+#ident "$Id$"
+/* ----------------------------------------------------------------------- *
+ *   
+ *   Copyright 1998-2004 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 <alloca.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <mntent.h>
+#include <stdlib.h>
+#include <string.h>
+#include <inttypes.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include <linux/ext2_fs.h>
+#include <linux/fd.h>		/* Floppy geometry */
+#include <linux/hdreg.h>	/* Hard disk geometry */
+#include <linux/fs.h>		/* FIGETBSZ, FIBMAP */
+
+#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);
+}
+
+/*
+ * pread() and pwrite() augmented with retry on short access or EINTR.
+ */
+ssize_t xpread(int fd, void *buf, size_t count, off_t offset)
+{
+  ssize_t rv;
+  ssize_t done = 0;
+
+  while ( count ) {
+    rv = pread(fd, buf, count, offset);
+    if ( rv == 0 ) {
+      die("short read");
+    } else if ( rv == -1 ) {
+      if ( errno == EINTR ) {
+	continue;
+      } else {
+	perror(program);
+	exit(1);
+      }
+    } else {
+      offset += rv;
+      done += rv;
+      count -= rv;
+    }
+  }
+
+  return done;
+}
+
+ssize_t xpwrite(int fd, void *buf, size_t count, off_t offset)
+{
+  ssize_t rv;
+  ssize_t done = 0;
+
+  while ( count ) {
+    rv = pwrite(fd, buf, count, offset);
+    if ( rv == 0 ) {
+      die("short write");
+    } else if ( rv == -1 ) {
+      if ( errno == EINTR ) {
+	continue;
+      } else {
+	perror(program);
+	exit(1);
+      }
+    } else {
+      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++;
+    printf("querying block %u\n", blk);
+    if ( ioctl(fd, FIBMAP, &blk) )
+      return -1;
+
+    blk *= blksize;
+    for ( i = 0 ; i < blksize ; i++ ) {
+      if ( !nsectors )
+	return 0;
+
+      printf("Sector: %10u\n", blk);
+      *sectors++ = blk++;
+      nsectors--;
+    }
+  }
+
+  return 0;
+}
+
+/*
+ * Query the device geometry and put it into the boot sector.
+ * Map the file and put the map in the boot sector and file.
+ * Stick the "current directory" inode number into the file.
+ */
+void
+patch_file_and_bootblock(int fd, int dirfd)
+{
+  struct stat dirst;
+  struct hd_geometry   hd_geo;
+  struct floppy_struct fd_str;
+  uint16_t heads, cylinders;
+  uint32_t sectors, offset;
+  uint32_t *sectp;
+  int nsect;
+  unsigned char *p, *patcharea;
+  int i, dw;
+  uint32_t csum;
+
+  if ( ioctl(fd, HDIO_GETGEO, &hd_geo) == 0 ) {
+    heads     = hd_geo.heads;
+    sectors   = hd_geo.sectors;
+    cylinders = hd_geo.cylinders;
+    offset    = hd_geo.start;
+  } else if ( ioctl(fd, FDGETPRM, &fd_str) == 0 ) {
+    heads     = fd_str.head;
+    sectors   = fd_str.sect;
+    cylinders = fd_str.track;
+    offset    = 0;
+  } else {
+    fprintf(stderr, "Warning: unable to obtain device geometry (may or may not work)\n");
+    heads = sectors = cylinders = offset = 0;
+  }
+
+  if ( fstat(dirfd, &dirst) ) {
+    perror("fstat dirfd");
+    exit(255);			/* This should never happen */
+  }
+
+  /* Patch this into a fake FAT superblock.  This isn't because
+     FAT is a good format in any way, it's because it lets the
+     early bootstrap share code with the FAT version. */
+  printf("cyl = %u, heads = %u, sect = %u\n", cylinders, heads, sectors);
+
+  set_16(boot_block+bsBytesPerSec, 512);
+  set_16(boot_block+bsSecPerTrack, sectors);
+  set_16(boot_block+bsHeads, heads);
+  set_32(boot_block+bsHiddenSecs, offset);
+
+  /* Construct the boot file */
+
+  printf("directory inode = %lu\n", (unsigned long) dirst.st_ino);
+  nsect = (boot_image_len+SECTOR_SIZE-1) >> SECTOR_SHIFT;
+  sectp = alloca(sizeof(uint32_t)*nsect);
+  if ( sectmap(fd, sectp, nsect) ) {
+    perror("bmap");
+    exit(1);
+  }
+
+  /* First sector need pointer in boot sector */
+  set_32(boot_block+0x1F8, *sectp++);
+  nsect--;
+  
+  /* Search for LDLINUX_MAGIC to find the patch area */
+  for ( p = boot_image ; get_32(p) != LDLINUX_MAGIC ; p += 4 );
+  patcharea = p+8;
+  
+  /* Set up the totals */
+  dw = boot_image_len >> 2; /* COMPLETE dwords! */
+  set_16(patcharea, dw);
+  set_16(patcharea+2, nsect);	/* Does not include the first sector! */
+  set_32(patcharea+8, dirst.st_ino); /* "Current" directory */
+  
+  /* Set the sector pointers */
+  p = patcharea+12;
+  
+  memset(p, 0, 64*4);
+  while ( nsect-- ) {
+    set_32(p, *sectp++);
+    p += 4;
+  }
+  
+  /* Now produce a checksum */
+  set_32(patcharea+4, 0);
+
+  csum = LDLINUX_MAGIC;
+  for ( i = 0, p = boot_image ; i < dw ; i++, p += 4 )
+    csum -= get_32(p);		/* Negative checksum */
+  
+  set_32(patcharea+4, csum);
+}
+
+/*
+ * Install the boot block on the specified device.
+ * Must be run AFTER install_file()!
+ */
+int
+install_bootblock(int fd, char *device)
+{
+  struct ext2_super_block sb;
+
+  if ( xpread(fd, &sb, sizeof sb, EXT2_SUPER_OFFSET) != sizeof sb ) {
+    perror("reading superblock");
+    return 1;
+  }
+
+  if ( sb.s_magic != EXT2_SUPER_MAGIC ) {
+    fprintf(stderr, "no ext2/ext3 superblock found on %s\n", device);
+    return 1;
+  }
+  
+  if ( xpwrite(fd, boot_block, boot_block_len, 0) != boot_block_len ) {
+    perror("writing bootblock");
+    return 1;
+  }
+
+  return 0;
+}
+
+int
+install_file(char *path, struct stat *rst)
+{
+  char *file;
+  int fd = -1, dirfd = -1, flags;
+  struct stat st;
+
+  asprintf(&file, "%s%sextlinux.sys",
+	   path,
+	   path[0] && path[strlen(path)-1] == '/' ? "" : "/");
+  if ( !file ) {
+    perror(program);
+    return 1;
+  }
+
+  dirfd = open(path, O_RDONLY|O_DIRECTORY);
+  if ( dirfd < 0 ) {
+    perror(path);
+    goto bail;
+  }
+    
+  fd = open(file, O_RDONLY);
+  if ( fd < 0 ) {
+    if ( errno != ENOENT ) {
+      perror(file);
+      goto bail;
+    }
+  } else {
+    /* If file exist, remove the immutable flag and set u+w mode */
+    if ( !ioctl(fd, EXT2_IOC_GETFLAGS, &flags) ) {
+      flags &= ~EXT2_IMMUTABLE_FL;
+      ioctl(fd, EXT2_IOC_SETFLAGS, &flags);
+    }
+    if ( !fstat(fd, &st) ) {
+      fchmod(fd, st.st_mode | S_IWUSR);
+    }
+  }
+  close(fd);
+
+  fd = open(file, O_WRONLY|O_TRUNC|O_CREAT, S_IRUSR|S_IRGRP|S_IROTH);
+  if ( fd < 0 ) {
+    perror(file);
+    goto bail;
+  }
+  
+  /* Write it the first time */
+  if ( xpwrite(fd, boot_image, boot_image_len, 0) != boot_image_len ) {
+    fprintf(stderr, "%s: write failure on %s\n", program, file);
+    goto bail;
+  }
+
+  /* Map the file, and patch the initial sector accordingly */
+  patch_file_and_bootblock(fd, dirfd);
+  patch_file_and_bootblock(fd, dirfd);
+
+  /* Write it again - this relies on the file being overwritten in place! */
+  if ( xpwrite(fd, boot_image, boot_image_len, 0) != boot_image_len ) {
+    fprintf(stderr, "%s: write failure on %s\n", program, file);
+    goto bail;
+  }
+
+  /* Attempt to set immutable flag and remove all write access */
+  /* Only set immutable flag if file is owned by root */
+  if ( !fstat(fd, &st) ) {
+    fchmod(fd, st.st_mode & (S_IRUSR|S_IRGRP|S_IROTH));
+    if ( st.st_uid == 0 && !ioctl(fd, EXT2_IOC_GETFLAGS, &flags) ) {
+      flags |= EXT2_IMMUTABLE_FL;
+      ioctl(fd, EXT2_IOC_SETFLAGS, &flags);
+    }
+  }
+
+  if ( fstat(fd, rst) ) {
+    perror(file);
+    goto bail;
+  }
+
+  close(dirfd);
+  close(fd);
+  return 0;
+
+ bail:
+  if ( dirfd >= 0 )
+    close(dirfd);
+  if ( fd >= 0 )
+    close(fd);
+
+  return 1;
+}
+
+int
+install_loader(char *path)
+{
+  struct stat st, dst, fst;
+  struct mntent *mnt;
+  int devfd, rv;
+  FILE *mtab;
+
+  if ( stat(path, &st) || !S_ISDIR(st.st_mode) ) {
+    fprintf(stderr, "%s: Not a directory: %s\n", program, path);
+    return 1;
+  }
+  
+  if ( !(mtab = setmntent("/etc/mtab", "r")) ) {
+    fprintf(stderr, "%s: cannot open /etc/mtab\n", program);
+    return 1;
+  }
+
+  devfd = -1;
+  while ( (mnt = getmntent(mtab)) ) {
+    if ( (!strcmp(mnt->mnt_type, "ext2") ||
+	  !strcmp(mnt->mnt_type, "ext3")) &&
+	 !stat(mnt->mnt_fsname, &dst) &&
+	 dst.st_rdev == st.st_dev ) {
+      fprintf(stderr, "%s is device %s\n", path, mnt->mnt_fsname);
+      if ( (devfd = open(mnt->mnt_fsname, O_RDWR|O_SYNC)) < 0 ) {
+	fprintf(stderr, "%s: cannot open device %s\n", program, mnt->mnt_fsname);
+	return 1;
+      }
+      break;
+    }
+  }
+
+  if ( devfd < 0 ) {
+    fprintf(stderr, "%s: cannot find device for path %s", program, path);
+    return 1;
+  }
+
+  install_file(path, &fst);
+
+  if ( fst.st_dev != st.st_dev ) {
+    fprintf(stderr, "%s: file system changed under us - aborting!\n",
+	    program);
+    return 1;
+  }
+
+  sync();
+  rv = install_bootblock(devfd, mnt->mnt_fsname);
+  close(devfd);
+  sync();
+
+  endmntent(mtab);
+
+  if ( rv ) return rv;
+
+  return 0;
+}
+
+int
+main(int argc, char *argv[])
+{
+  program = argv[0];
+
+  if ( argc != 2 ) {
+    fprintf(stderr, "Usage: %s directory\n", program);
+    exit(1);
+  }
+
+  return install_loader(argv[1]);
+}