1 /* ----------------------------------------------------------------------- *
3 * Copyright 1998-2008 H. Peter Anvin - All Rights Reserved
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation, Inc., 53 Temple Place Ste 330,
8 * Boston MA 02111-1307, USA; either version 2 of the License, or
9 * (at your option) any later version; incorporated herein by reference.
11 * ----------------------------------------------------------------------- */
14 * syslinux.c - Linux installer program for SYSLINUX
16 * This is Linux-specific by now.
18 * This is an alternate version of the installer which doesn't require
19 * mtools, but requires root privilege.
23 * If DO_DIRECT_MOUNT is 0, call mount(8)
24 * If DO_DIRECT_MOUNT is 1, call mount(2)
27 # define DO_DIRECT_MOUNT 1
29 # define DO_DIRECT_MOUNT 0 /* glibc has broken losetup ioctls */
33 #define _XOPEN_SOURCE 500 /* For pread() pwrite() */
34 #define _FILE_OFFSET_BITS 64
45 #include <sys/types.h>
47 #include <sys/mount.h>
49 #include <sys/ioctl.h>
50 #include <linux/fs.h> /* FIGETBSZ, FIBMAP */
51 #include <linux/msdos_fs.h> /* FAT_IOCTL_SET_ATTRIBUTES, SECTOR_* */
52 #ifndef FAT_IOCTL_SET_ATTRIBUTES
53 # define FAT_IOCTL_SET_ATTRIBUTES _IOW('r', 0x11, uint32_t)
58 # define _PATH_MOUNT "/bin/mount"
61 # define _PATH_UMOUNT "/bin/umount"
64 # define _PATH_TMP "/tmp/"
70 # include <linux/loop.h>
73 const char *program; /* Name of program */
74 const char *device; /* Device to install to */
76 char *mntpath = NULL; /* Path on which to mount */
77 off_t filesystem_offset = 0; /* Filesystem offset */
79 int loop_fd = -1; /* Loop device */
82 void __attribute__ ((noreturn)) usage(void)
84 fprintf(stderr, "Usage: %s [-sfr][-d directory][-o offset] device\n",
89 void __attribute__ ((noreturn)) die(const char *msg)
91 fprintf(stderr, "%s: %s\n", program, msg);
95 ioctl(loop_fd, LOOP_CLR_FD, 0); /* Free loop device */
108 * read/write wrapper functions
110 ssize_t xpread(int fd, void *buf, size_t count, off_t offset)
112 char *bufp = (char *)buf;
117 rv = pread(fd, bufp, count, offset);
120 } else if (rv == -1) {
121 if (errno == EINTR) {
124 die(strerror(errno));
137 ssize_t xpwrite(int fd, const void *buf, size_t count, off_t offset)
139 const char *bufp = (const char *)buf;
144 rv = pwrite(fd, bufp, count, offset);
147 } else if (rv == -1) {
148 if (errno == EINTR) {
151 die(strerror(errno));
165 * Create a block map for ldlinux.sys
167 int make_block_map(uint32_t * sectors, int len, int dev_fd, int fd)
170 int blocksize, nblock, block;
175 if (ioctl(fd, FIGETBSZ, &blocksize) < 0)
176 die("ioctl FIGETBSZ failed");
178 blocksize >>= SECTOR_BITS; /* sectors/block */
183 if (ioctl(fd, FIBMAP, &block) < 0)
184 die("ioctl FIBMAP failed");
186 for (i = 0; i < blocksize; i++) {
190 *sectors++ = (block * blocksize) + i;
192 len -= (1 << SECTOR_BITS);
202 int do_mount(int dev_fd, int *cookie, const char *mntpath, const char *fstype)
208 if (fstat(dev_fd, &st) < 0)
213 if (!S_ISBLK(st.st_mode)) {
214 /* It's file, need to mount it loopback */
216 struct loop_info64 loopinfo;
219 for (n = 0; loop_fd < 0; n++) {
220 snprintf(devfdname, sizeof devfdname, "/dev/loop%u", n);
221 loop_fd = open(devfdname, O_RDWR);
222 if (loop_fd < 0 && errno == ENOENT) {
223 die("no available loopback device!");
225 if (ioctl(loop_fd, LOOP_SET_FD, (void *)dev_fd)) {
229 die("cannot set up loopback device");
234 if (ioctl(loop_fd, LOOP_GET_STATUS64, &loopinfo) ||
235 (loopinfo.lo_offset = filesystem_offset,
236 ioctl(loop_fd, LOOP_SET_STATUS64, &loopinfo)))
237 die("cannot set up loopback device");
242 snprintf(devfdname, sizeof devfdname, "/proc/%lu/fd/%d",
243 (unsigned long)mypid, dev_fd);
247 return mount(devfdname, mntpath, fstype,
248 MS_NOEXEC | MS_NOSUID, "umask=077,quiet");
252 char devfdname[128], mnt_opts[128];
256 snprintf(devfdname, sizeof devfdname, "/proc/%lu/fd/%d",
257 (unsigned long)mypid, dev_fd);
263 if (!S_ISBLK(st.st_mode)) {
264 snprintf(mnt_opts, sizeof mnt_opts,
265 "rw,nodev,noexec,loop,offset=%llu,umask=077,quiet",
266 (unsigned long long)filesystem_offset);
268 snprintf(mnt_opts, sizeof mnt_opts,
269 "rw,nodev,noexec,umask=077,quiet");
271 execl(_PATH_MOUNT, _PATH_MOUNT, "-t", fstype, "-o", mnt_opts,
272 devfdname, mntpath, NULL);
273 _exit(255); /* execl failed */
276 w = waitpid(f, &status, 0);
277 return (w != f || status) ? -1 : 0;
285 void do_umount(const char *mntpath, int cookie)
288 int loop_fd = cookie;
290 if (umount2(mntpath, 0))
291 die("could not umount path");
294 ioctl(loop_fd, LOOP_CLR_FD, 0); /* Free loop device */
308 execl(_PATH_UMOUNT, _PATH_UMOUNT, mntpath, NULL);
311 w = waitpid(f, &status, 0);
312 if (w != f || status) {
318 int main(int argc, char *argv[])
320 static unsigned char sectbuf[SECTOR_SIZE];
322 const unsigned char *cdp;
328 char *ldlinux_name, **argp, *opt;
329 const char *subdir = NULL;
330 uint32_t sectors[65]; /* 65 is maximum possible */
335 int force = 0; /* -f (force) option */
336 int stupid = 0; /* -s (stupid) option */
337 int raid_mode = 0; /* -r (RAID) option */
339 (void)argc; /* Unused */
348 for (argp = argv + 1; *argp; argp++) {
357 } else if (*opt == 'r') {
359 } else if (*opt == 'f') {
360 force = 1; /* Force install */
361 } else if (*opt == 'd' && argp[1]) {
363 } else if (*opt == 'o' && argp[1]) {
365 filesystem_offset = (off_t) strtoull(*++argp, NULL, 0);
382 * First make sure we can open the device at all, and that we have
383 * read/write permission.
385 dev_fd = open(device, O_RDWR);
386 if (dev_fd < 0 || fstat(dev_fd, &st) < 0) {
391 if (!S_ISBLK(st.st_mode) && !S_ISREG(st.st_mode) && !S_ISCHR(st.st_mode)) {
392 die("not a device or regular file");
395 if (filesystem_offset && S_ISBLK(st.st_mode)) {
396 die("can't combine an offset with a block device");
399 xpread(dev_fd, sectbuf, SECTOR_SIZE, filesystem_offset);
403 * Check to see that what we got was indeed an MS-DOS boot sector/superblock
405 if ((errmsg = syslinux_check_bootsect(sectbuf))) {
406 fprintf(stderr, "%s: %s\n", device, errmsg);
411 * Now mount the device.
414 die("This program needs root privilege");
420 /* We're root or at least setuid.
421 Make a temp dir and pass all the gunky options to mount. */
423 if (chdir(_PATH_TMP)) {
427 #define TMP_MODE (S_IXUSR|S_IWUSR|S_IXGRP|S_IWGRP|S_IWOTH|S_IXOTH|S_ISVTX)
429 if (stat(".", &dst) || !S_ISDIR(dst.st_mode) ||
430 (dst.st_mode & TMP_MODE) != TMP_MODE) {
431 die("possibly unsafe " _PATH_TMP " permissions");
435 snprintf(mntname, sizeof mntname, "syslinux.mnt.%lu.%d",
436 (unsigned long)mypid, i);
438 if (lstat(mntname, &dst) != -1 || errno != ENOENT)
441 rv = mkdir(mntname, 0000);
444 if (errno == EEXIST || errno == EINTR)
450 if (lstat(mntname, &dst) || dst.st_mode != (S_IFDIR | 0000) ||
452 die("someone is trying to symlink race us!");
454 break; /* OK, got something... */
460 if (do_mount(dev_fd, &mnt_cookie, mntpath, "vfat") &&
461 do_mount(dev_fd, &mnt_cookie, mntpath, "msdos")) {
466 ldlinux_name = alloca(strlen(mntpath) + 14 +
467 (subdir ? strlen(subdir) + 2 : 0));
473 sprintf(ldlinux_name, "%s%s%s//ldlinux.sys",
474 mntpath, subdir ? "//" : "", subdir ? subdir : "");
476 if ((fd = open(ldlinux_name, O_RDONLY)) >= 0) {
477 uint32_t zero_attr = 0;
478 ioctl(fd, FAT_IOCTL_SET_ATTRIBUTES, &zero_attr);
482 unlink(ldlinux_name);
483 fd = open(ldlinux_name, O_WRONLY | O_CREAT | O_TRUNC, 0444);
490 cdp = syslinux_ldlinux;
491 left = syslinux_ldlinux_len;
493 nb = write(fd, cdp, left);
494 if (nb == -1 && errno == EINTR)
511 uint32_t attr = 0x07; /* Hidden+System+Readonly */
512 ioctl(fd, FAT_IOCTL_SET_ATTRIBUTES, &attr);
516 * Create a block map.
518 nsectors = make_block_map(sectors, syslinux_ldlinux_len, dev_fd, fd);
524 do_umount(mntpath, mnt_cookie);
532 * Patch ldlinux.sys and the boot sector
534 syslinux_patch(sectors, nsectors, stupid, raid_mode);
537 * Write the now-patched first sector of ldlinux.sys
539 xpwrite(dev_fd, syslinux_ldlinux, SECTOR_SIZE,
540 filesystem_offset + ((off_t) sectors[0] << SECTOR_BITS));
543 * To finish up, write the boot sector
546 /* Read the superblock again since it might have changed while mounted */
547 xpread(dev_fd, sectbuf, SECTOR_SIZE, filesystem_offset);
549 /* Copy the syslinux code into the boot sector */
550 syslinux_make_bootsect(sectbuf);
552 /* Write new boot sector */
553 xpwrite(dev_fd, sectbuf, SECTOR_SIZE, filesystem_offset);