1 /* ----------------------------------------------------------------------- *
3 * Copyright 1998-2008 H. Peter Anvin - All Rights Reserved
4 * Copyright 2009 Intel Corporation; author: H. Peter Anvin
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation, Inc., 53 Temple Place Ste 330,
9 * Boston MA 02111-1307, USA; either version 2 of the License, or
10 * (at your option) any later version; incorporated herein by reference.
12 * ----------------------------------------------------------------------- */
17 * Install the extlinux boot block on an ext2/3 filesystem
20 #define _GNU_SOURCE /* Enable everything */
22 /* This is needed to deal with the kernel headers imported into glibc 3.3.3. */
36 #include <sys/ioctl.h>
38 #include <sys/types.h>
39 #include <sys/mount.h>
42 #include <linux/fd.h> /* Floppy geometry */
43 #include <linux/hdreg.h> /* Hard disk geometry */
44 #define statfs _kernel_statfs /* HACK to deal with broken 2.4 distros */
45 #include <linux/fs.h> /* FIGETBSZ, FIBMAP */
49 #include "../version.h"
53 # define dprintf printf
55 # define dprintf(...) ((void)0)
58 /* Global option handling */
62 /* These are the options we can set and their values */
71 .sectors = 0,.heads = 0,.raid_mode = 0,.stupid_mode = 0,.reset_adv =
74 static void __attribute__ ((noreturn)) usage(int rv)
77 "Usage: %s [options] directory\n"
78 " --install -i Install over the current bootsector\n"
79 " --update -U Update a previous EXTLINUX installation\n"
80 " --zip -z Force zipdrive geometry (-H 64 -S 32)\n"
81 " --sectors=# -S Force the number of sectors per track\n"
82 " --heads=# -H Force number of heads\n"
83 " --stupid -s Slow, safe and stupid mode\n"
84 " --raid -r Fall back to the next device on boot failure\n"
85 " --once=... -o Execute a command once upon boot\n"
86 " --clear-once -O Clear the boot-once command\n"
87 " --reset-adv Reset auxilliary data\n"
89 " Note: geometry is determined at boot time for devices which\n"
90 " are considered hard disks by the BIOS. Unfortunately, this is\n"
91 " not possible for devices which are considered floppy disks,\n"
92 " which includes zipdisks and LS-120 superfloppies.\n"
94 " The -z option is useful for USB devices which are considered\n"
95 " hard disks by some BIOSes and zipdrives by other BIOSes.\n",
106 static const struct option long_options[] = {
107 {"install", 0, NULL, 'i'},
108 {"update", 0, NULL, 'U'},
109 {"zipdrive", 0, NULL, 'z'},
110 {"sectors", 1, NULL, 'S'},
111 {"stupid", 0, NULL, 's'},
112 {"heads", 1, NULL, 'H'},
113 {"raid-mode", 0, NULL, 'r'},
114 {"version", 0, NULL, 'v'},
115 {"help", 0, NULL, 'h'},
116 {"once", 1, NULL, 'o'},
117 {"clear-once", 0, NULL, 'O'},
118 {"reset-adv", 0, NULL, OPT_RESET_ADV},
122 static const char short_options[] = "iUuzS:H:rvho:O";
124 #if defined(__linux__) && !defined(BLKGETSIZE64)
125 /* This takes a u64, but the size field says size_t. Someone screwed big. */
126 # define BLKGETSIZE64 _IOR(0x12,114,size_t)
129 #ifndef EXT2_SUPER_OFFSET
130 #define EXT2_SUPER_OFFSET 1024
138 extern unsigned char extlinux_bootsect[];
139 extern unsigned int extlinux_bootsect_len;
140 #define boot_block extlinux_bootsect
141 #define boot_block_len extlinux_bootsect_len
146 extern unsigned char extlinux_image[];
147 extern unsigned int extlinux_image_len;
148 #define boot_image extlinux_image
149 #define boot_image_len extlinux_image_len
152 * Common abort function
154 void __attribute__ ((noreturn)) die(const char *msg)
161 * read/write wrapper functions
163 ssize_t xpread(int fd, void *buf, size_t count, off_t offset)
165 char *bufp = (char *)buf;
170 rv = pread(fd, bufp, count, offset);
173 } else if (rv == -1) {
174 if (errno == EINTR) {
177 die(strerror(errno));
190 ssize_t xpwrite(int fd, const void *buf, size_t count, off_t offset)
192 const char *bufp = (const char *)buf;
197 rv = pwrite(fd, bufp, count, offset);
200 } else if (rv == -1) {
201 if (errno == EINTR) {
204 die(strerror(errno));
220 int sectmap(int fd, uint32_t * sectors, int nsectors)
222 unsigned int blksize, blk, nblk;
226 if (ioctl(fd, FIGETBSZ, &blksize))
229 /* Number of sectors per block */
230 blksize >>= SECTOR_SHIFT;
236 dprintf("querying block %u\n", blk);
237 if (ioctl(fd, FIBMAP, &blk))
241 for (i = 0; i < blksize; i++) {
245 dprintf("Sector: %10u\n", blk);
255 * Get the size of a block device
257 uint64_t get_size(int devfd)
264 if (!ioctl(devfd, BLKGETSIZE64, &bytes))
267 if (!ioctl(devfd, BLKGETSIZE, §s))
268 return (uint64_t) sects << 9;
269 else if (!fstat(devfd, &st) && st.st_size)
276 * Get device geometry and partition offset
278 struct geometry_table {
280 struct hd_geometry g;
283 /* Standard floppy disk geometries, plus LS-120. Zipdisk geometry
284 (x/64/32) is the final fallback. I don't know what LS-240 has
285 as its geometry, since I don't have one and don't know anyone that does,
286 and Google wasn't helpful... */
287 static const struct geometry_table standard_geometries[] = {
288 {360 * 1024, {2, 9, 40, 0}},
289 {720 * 1024, {2, 9, 80, 0}},
290 {1200 * 1024, {2, 15, 80, 0}},
291 {1440 * 1024, {2, 18, 80, 0}},
292 {1680 * 1024, {2, 21, 80, 0}},
293 {1722 * 1024, {2, 21, 80, 0}},
294 {2880 * 1024, {2, 36, 80, 0}},
295 {3840 * 1024, {2, 48, 80, 0}},
296 {123264 * 1024, {8, 32, 963, 0}}, /* LS120 */
300 int get_geometry(int devfd, uint64_t totalbytes, struct hd_geometry *geo)
302 struct floppy_struct fd_str;
303 const struct geometry_table *gp;
305 memset(geo, 0, sizeof *geo);
307 if (!ioctl(devfd, HDIO_GETGEO, &geo)) {
309 } else if (!ioctl(devfd, FDGETPRM, &fd_str)) {
310 geo->heads = fd_str.head;
311 geo->sectors = fd_str.sect;
312 geo->cylinders = fd_str.track;
317 /* Didn't work. Let's see if this is one of the standard geometries */
318 for (gp = standard_geometries; gp->bytes; gp++) {
319 if (gp->bytes == totalbytes) {
320 memcpy(geo, &gp->g, sizeof *geo);
325 /* Didn't work either... assign a geometry of 64 heads, 32 sectors; this is
326 what zipdisks use, so this would help if someone has a USB key that
327 they're booting in USB-ZIP mode. */
329 geo->heads = opt.heads ? : 64;
330 geo->sectors = opt.sectors ? : 32;
331 geo->cylinders = totalbytes / (geo->heads * geo->sectors << SECTOR_SHIFT);
334 if (!opt.sectors && !opt.heads)
336 "Warning: unable to obtain device geometry (defaulting to %d heads, %d sectors)\n"
337 " (on hard disks, this is usually harmless.)\n",
338 geo->heads, geo->sectors);
344 * Query the device geometry and put it into the boot sector.
345 * Map the file and put the map in the boot sector and file.
346 * Stick the "current directory" inode number into the file.
348 void patch_file_and_bootblock(int fd, int dirfd, int devfd)
351 struct hd_geometry geo;
353 uint64_t totalbytes, totalsectors;
356 struct boot_sector *bs;
357 struct patch_area *patcharea;
361 if (fstat(dirfd, &dirst)) {
362 perror("fstat dirfd");
363 exit(255); /* This should never happen */
366 totalbytes = get_size(devfd);
367 get_geometry(devfd, totalbytes, &geo);
370 geo.heads = opt.heads;
372 geo.sectors = opt.sectors;
374 /* Patch this into a fake FAT superblock. This isn't because
375 FAT is a good format in any way, it's because it lets the
376 early bootstrap share code with the FAT version. */
377 dprintf("heads = %u, sect = %u\n", geo.heads, geo.sectors);
379 bs = (struct boot_sector *)boot_block;
381 totalsectors = totalbytes >> SECTOR_SHIFT;
382 if (totalsectors >= 65536) {
383 set_16(&bs->bsSectors, 0);
385 set_16(&bs->bsSectors, totalsectors);
387 set_32(&bs->bsHugeSectors, totalsectors);
389 set_16(&bs->bsBytesPerSec, SECTOR_SIZE);
390 set_16(&bs->bsSecPerTrack, geo.sectors);
391 set_16(&bs->bsHeads, geo.heads);
392 set_32(&bs->bsHiddenSecs, geo.start);
394 /* If we're in RAID mode then patch the appropriate instruction;
395 either way write the proper boot signature */
396 i = get_16(&bs->bsSignature);
398 set_16((uint16_t *) (boot_block + i), 0x18CD); /* INT 18h */
400 set_16(&bs->bsSignature, 0xAA55);
402 /* Construct the boot file */
404 dprintf("directory inode = %lu\n", (unsigned long)dirst.st_ino);
405 nsect = (boot_image_len + SECTOR_SIZE - 1) >> SECTOR_SHIFT;
406 nsect += 2; /* Two sectors for the ADV */
407 sectp = alloca(sizeof(uint32_t) * nsect);
408 if (sectmap(fd, sectp, nsect)) {
413 /* First sector need pointer in boot sector */
414 set_32(&bs->NextSector, *sectp++);
418 set_16(&bs->MaxTransfer, 1);
420 /* Search for LDLINUX_MAGIC to find the patch area */
421 for (wp = (uint32_t *) boot_image; get_32(wp) != LDLINUX_MAGIC; wp++) ;
422 patcharea = (struct patch_area *)wp;
424 /* Set up the totals */
425 dw = boot_image_len >> 2; /* COMPLETE dwords, excluding ADV */
426 set_16(&patcharea->data_sectors, nsect - 2); /* -2 for the ADVs */
427 set_16(&patcharea->adv_sectors, 2);
428 set_32(&patcharea->dwords, dw);
429 set_32(&patcharea->currentdir, dirst.st_ino);
431 /* Set the sector pointers */
432 wp = (uint32_t *) ((char *)boot_image + get_16(&patcharea->secptroffset));
433 nptrs = get_16(&patcharea->secptrcnt);
435 memset(wp, 0, nptrs * 4);
437 set_32(wp++, *sectp++);
439 /* Now produce a checksum */
440 set_32(&patcharea->checksum, 0);
442 csum = LDLINUX_MAGIC;
443 for (i = 0, wp = (uint32_t *) boot_image; i < dw; i++, wp++)
444 csum -= get_32(wp); /* Negative checksum */
446 set_32(&patcharea->checksum, csum);
450 * Read the ADV from an existing instance, or initialize if invalid.
451 * Returns -1 on fatal errors, 0 if ADV is okay, and 1 if no valid
454 int read_adv(const char *path)
461 asprintf(&file, "%s%sextlinux.sys",
462 path, path[0] && path[strlen(path) - 1] == '/' ? "" : "/");
469 fd = open(file, O_RDONLY);
471 if (errno != ENOENT) {
474 syslinux_reset_adv(syslinux_adv);
476 } else if (fstat(fd, &st)) {
478 } else if (st.st_size < 2 * ADV_SIZE) {
479 /* Too small to be useful */
480 syslinux_reset_adv(syslinux_adv);
481 err = 0; /* Nothing to read... */
482 } else if (xpread(fd, syslinux_adv, 2 * ADV_SIZE,
483 st.st_size - 2 * ADV_SIZE) != 2 * ADV_SIZE) {
486 /* We got it... maybe? */
487 err = syslinux_validate_adv(syslinux_adv) ? 1 : 0;
502 * Update the ADV in an existing installation.
504 int write_adv(const char *path)
506 unsigned char advtmp[2 * ADV_SIZE];
513 asprintf(&file, "%s%sextlinux.sys",
514 path, path[0] && path[strlen(path) - 1] == '/' ? "" : "/");
521 fd = open(file, O_RDONLY);
524 } else if (fstat(fd, &st)) {
526 } else if (st.st_size < 2 * ADV_SIZE) {
527 /* Too small to be useful */
529 } else if (xpread(fd, advtmp, 2 * ADV_SIZE,
530 st.st_size - 2 * ADV_SIZE) != 2 * ADV_SIZE) {
533 /* We got it... maybe? */
534 err = syslinux_validate_adv(advtmp) ? -2 : 0;
536 /* Got a good one, write our own ADV here */
537 if (!ioctl(fd, EXT2_IOC_GETFLAGS, &flags)) {
538 nflags = flags & ~EXT2_IMMUTABLE_FL;
540 ioctl(fd, EXT2_IOC_SETFLAGS, &nflags);
542 if (!(st.st_mode & S_IWUSR))
543 fchmod(fd, st.st_mode | S_IWUSR);
545 /* Need to re-open read-write */
547 fd = open(file, O_RDWR | O_SYNC);
550 } else if (fstat(fd, &xst) || xst.st_ino != st.st_ino ||
551 xst.st_dev != st.st_dev || xst.st_size != st.st_size) {
552 fprintf(stderr, "%s: race condition on write\n", file);
555 /* Write our own version ... */
556 if (xpwrite(fd, syslinux_adv, 2 * ADV_SIZE,
557 st.st_size - 2 * ADV_SIZE) != 2 * ADV_SIZE) {
563 if (!(st.st_mode & S_IWUSR))
564 fchmod(fd, st.st_mode);
567 ioctl(fd, EXT2_IOC_SETFLAGS, &flags);
572 fprintf(stderr, "%s: cannot write auxilliary data (need --update)?\n",
586 * Make any user-specified ADV modifications
593 if (syslinux_setadv(ADV_BOOTONCE, strlen(opt.set_once), opt.set_once)) {
594 fprintf(stderr, "%s: not enough space for boot-once command\n",
604 * Install the boot block on the specified device.
605 * Must be run AFTER install_file()!
607 int install_bootblock(int fd, const char *device)
609 struct ext2_super_block sb;
611 if (xpread(fd, &sb, sizeof sb, EXT2_SUPER_OFFSET) != sizeof sb) {
612 perror("reading superblock");
616 if (sb.s_magic != EXT2_SUPER_MAGIC) {
617 fprintf(stderr, "no ext2/ext3 superblock found on %s\n", device);
621 if (xpwrite(fd, boot_block, boot_block_len, 0) != boot_block_len) {
622 perror("writing bootblock");
629 int install_file(const char *path, int devfd, struct stat *rst)
632 int fd = -1, dirfd = -1, flags;
635 asprintf(&file, "%s%sextlinux.sys",
636 path, path[0] && path[strlen(path) - 1] == '/' ? "" : "/");
642 dirfd = open(path, O_RDONLY | O_DIRECTORY);
648 fd = open(file, O_RDONLY);
650 if (errno != ENOENT) {
655 /* If file exist, remove the immutable flag and set u+w mode */
656 if (!ioctl(fd, EXT2_IOC_GETFLAGS, &flags)) {
657 flags &= ~EXT2_IMMUTABLE_FL;
658 ioctl(fd, EXT2_IOC_SETFLAGS, &flags);
660 if (!fstat(fd, &st)) {
661 fchmod(fd, st.st_mode | S_IWUSR);
666 fd = open(file, O_WRONLY | O_TRUNC | O_CREAT | O_SYNC,
667 S_IRUSR | S_IRGRP | S_IROTH);
673 /* Write it the first time */
674 if (xpwrite(fd, boot_image, boot_image_len, 0) != boot_image_len ||
675 xpwrite(fd, syslinux_adv, 2 * ADV_SIZE,
676 boot_image_len) != 2 * ADV_SIZE) {
677 fprintf(stderr, "%s: write failure on %s\n", program, file);
681 /* Map the file, and patch the initial sector accordingly */
682 patch_file_and_bootblock(fd, dirfd, devfd);
684 /* Write the first sector again - this relies on the file being
685 overwritten in place! */
686 if (xpwrite(fd, boot_image, SECTOR_SIZE, 0) != SECTOR_SIZE) {
687 fprintf(stderr, "%s: write failure on %s\n", program, file);
691 /* Attempt to set immutable flag and remove all write access */
692 /* Only set immutable flag if file is owned by root */
693 if (!fstat(fd, &st)) {
694 fchmod(fd, st.st_mode & (S_IRUSR | S_IRGRP | S_IROTH));
695 if (st.st_uid == 0 && !ioctl(fd, EXT2_IOC_GETFLAGS, &flags)) {
696 flags |= EXT2_IMMUTABLE_FL;
697 ioctl(fd, EXT2_IOC_SETFLAGS, &flags);
701 if (fstat(fd, rst)) {
719 /* EXTLINUX installs the string 'EXTLINUX' at offset 3 in the boot
720 sector; this is consistent with FAT filesystems. */
721 int already_installed(int devfd)
725 xpread(devfd, buffer, 8, 3);
726 return !memcmp(buffer, "EXTLINUX", 8);
730 static char devname_buf[64];
732 static void device_cleanup(void)
738 /* Verify that a device fd and a pathname agree.
739 Return 0 on valid, -1 on error. */
740 static int validate_device(const char *path, int devfd)
742 struct stat pst, dst;
744 if (stat(path, &pst) || fstat(devfd, &dst))
747 return (pst.st_dev == dst.st_rdev) ? 0 : -1;
751 static const char *find_device(const char *mtab_file, dev_t dev)
756 const char *devname = NULL;
758 mtab = setmntent(mtab_file, "r");
762 while ((mnt = getmntent(mtab))) {
763 if ((!strcmp(mnt->mnt_type, "ext2") ||
764 !strcmp(mnt->mnt_type, "ext3")) &&
765 !stat(mnt->mnt_fsname, &dst) && dst.st_rdev == dev) {
766 devname = strdup(mnt->mnt_fsname);
776 int install_loader(const char *path, int update_only)
780 const char *devname = NULL;
783 if (stat(path, &st) || !S_ISDIR(st.st_mode)) {
784 fprintf(stderr, "%s: Not a directory: %s\n", program, path);
788 if (statfs(path, &sfs)) {
789 fprintf(stderr, "%s: statfs %s: %s\n", program, path, strerror(errno));
793 if (sfs.f_type != EXT2_SUPER_MAGIC) {
794 fprintf(stderr, "%s: not an ext2/ext3 filesystem: %s\n", program, path);
802 /* klibc doesn't have getmntent and friends; instead, just create
803 a new device with the appropriate device type */
804 snprintf(devname_buf, sizeof devname_buf, "/tmp/dev-%u:%u",
805 major(st.st_dev), minor(st.st_dev));
807 if (mknod(devname_buf, S_IFBLK | 0600, st.st_dev)) {
808 fprintf(stderr, "%s: cannot create device %s\n", program, devname);
812 atexit(device_cleanup); /* unlink the device node on exit */
813 devname = devname_buf;
817 devname = find_device("/proc/mounts", st.st_dev);
819 /* Didn't find it in /proc/mounts, try /etc/mtab */
820 devname = find_device("/etc/mtab", st.st_dev);
823 fprintf(stderr, "%s: cannot find device for path %s\n", program, path);
827 fprintf(stderr, "%s is device %s\n", path, devname);
830 if ((devfd = open(devname, O_RDWR | O_SYNC)) < 0) {
831 fprintf(stderr, "%s: cannot open device %s\n", program, devname);
835 /* Verify that the device we opened is the device intended */
836 if (validate_device(path, devfd)) {
837 fprintf(stderr, "%s: path %s doesn't match device %s\n",
838 program, path, devname);
842 if (update_only && !already_installed(devfd)) {
843 fprintf(stderr, "%s: no previous extlinux boot sector found\n",
848 /* Read a pre-existing ADV, if already installed */
850 syslinux_reset_adv(syslinux_adv);
851 else if (read_adv(path) < 0)
854 if (modify_adv() < 0)
857 /* Install extlinux.sys */
858 if (install_file(path, devfd, &fst))
861 if (fst.st_dev != st.st_dev) {
862 fprintf(stderr, "%s: file system changed under us - aborting!\n",
868 rv = install_bootblock(devfd, devname);
876 * Modify the ADV of an existing installation
878 int modify_existing_adv(const char *path)
881 syslinux_reset_adv(syslinux_adv);
882 else if (read_adv(path) < 0)
885 if (modify_adv() < 0)
888 if (write_adv(path) < 0)
894 int main(int argc, char *argv[])
897 const char *directory;
898 int update_only = -1;
902 while ((o = getopt_long(argc, argv, short_options,
903 long_options, NULL)) != EOF) {
910 opt.sectors = strtoul(optarg, NULL, 0);
911 if (opt.sectors < 1 || opt.sectors > 63) {
913 "%s: invalid number of sectors: %u (must be 1-63)\n",
914 program, opt.sectors);
919 opt.heads = strtoul(optarg, NULL, 0);
920 if (opt.heads < 1 || opt.heads > 256) {
922 "%s: invalid number of heads: %u (must be 1-256)\n",
944 opt.set_once = optarg;
953 fputs("extlinux " VERSION_STR
954 " Copyright 1994-" YEAR_STR " H. Peter Anvin \n", stderr);
961 directory = argv[optind];
966 if (update_only == -1) {
967 if (opt.reset_adv || opt.set_once) {
968 return modify_existing_adv(directory);
974 return install_loader(directory, update_only);