1 #ident "$Id: syslinux.c,v 1.7 2005/01/04 03:27:43 hpa Exp $"
2 /* ----------------------------------------------------------------------- *
4 * Copyright 1998-2005 H. Peter Anvin - All Rights Reserved
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 * ----------------------------------------------------------------------- */
15 * syslinux.c - Linux installer program for SYSLINUX
17 * This program ought to be portable. I hope so, at least.
19 * This is an alternate version of the installer which doesn't require
20 * mtools, but requires root privilege.
24 * If DO_DIRECT_MOUNT is 0, call mount(8)
25 * If DO_DIRECT_MOUNT is 1, call mount(2)
28 # define DO_DIRECT_MOUNT 1
30 # define DO_DIRECT_MOUNT 0 /* glibc has broken losetup ioctls */
34 #define _XOPEN_SOURCE 500 /* For pread() pwrite() */
35 #define _FILE_OFFSET_BITS 64
46 #include <sys/types.h>
48 #include <sys/mount.h>
55 # include <linux/loop.h>
61 # define _PATH_MOUNT "/bin/mount"
64 # define _PATH_UMOUNT "/bin/umount"
69 const char *program; /* Name of program */
70 const char *device; /* Device to install to */
72 char *mntpath = NULL; /* Path on which to mount */
73 off_t filesystem_offset = 0; /* Filesystem offset */
75 int loop_fd = -1; /* Loop device */
78 void __attribute__((noreturn)) usage(void)
80 fprintf(stderr, "Usage: %s [-sf] [-o offset] device\n", program);
84 void __attribute__((noreturn)) die(const char *msg)
86 fprintf(stderr, "%s: %s\n", program, msg);
89 if ( loop_fd != -1 ) {
90 ioctl(loop_fd, LOOP_CLR_FD, 0); /* Free loop device */
103 * read/write wrapper functions
105 ssize_t xpread(int fd, void *buf, size_t count, off_t offset)
107 char *bufp = (char *)buf;
112 rv = pread(fd, bufp, count, offset);
115 } else if ( rv == -1 ) {
116 if ( errno == EINTR ) {
119 die(strerror(errno));
132 ssize_t xpwrite(int fd, const void *buf, size_t count, off_t offset)
134 const char *bufp = (const char *)buf;
139 rv = pwrite(fd, bufp, count, offset);
142 } else if ( rv == -1 ) {
143 if ( errno == EINTR ) {
146 die(strerror(errno));
160 * Version of the read function suitable for libfat
162 int libfat_xpread(intptr_t pp, void *buf, size_t secsize, libfat_sector_t sector)
164 off_t offset = (off_t)sector * secsize + filesystem_offset;
165 return xpread(pp, buf, secsize, offset);
168 int main(int argc, char *argv[])
170 static unsigned char sectbuf[512];
172 const unsigned char *cdp;
179 char mntname[64], devfdname[64];
180 char *ldlinux_name, **argp, *opt;
181 int force = 0; /* -f (force) option */
182 struct libfat_filesystem *fs;
183 struct libfat_direntry dentry;
184 libfat_sector_t s, *secp, sectors[65]; /* 65 is maximum possible */
185 int32_t ldlinux_cluster;
189 (void)argc; /* Unused */
198 for ( argp = argv+1 ; *argp ; argp++ ) {
199 if ( **argp == '-' ) {
206 syslinux_make_stupid(); /* Use "safe, slow and stupid" code */
207 } else if ( *opt == 'f' ) {
208 force = 1; /* Force install */
209 } else if ( *opt == 'o' && argp[1] ) {
210 filesystem_offset = (off_t)strtoull(*++argp, NULL, 0); /* Byte offset */
227 * First make sure we can open the device at all, and that we have
228 * read/write permission.
230 dev_fd = open(device, O_RDWR);
231 if ( dev_fd < 0 || fstat(dev_fd, &st) < 0 ) {
236 if ( !force && !S_ISBLK(st.st_mode) && !S_ISREG(st.st_mode) ) {
237 die("not a block device or regular file (use -f to override)");
240 if ( !force && filesystem_offset && !S_ISREG(st.st_mode) ) {
241 die("not a regular file and an offset specified (use -f to override)");
244 xpread(dev_fd, sectbuf, 512, filesystem_offset);
248 * Check to see that what we got was indeed an MS-DOS boot sector/superblock
250 if( (errmsg = syslinux_check_bootsect(sectbuf)) ) {
251 fprintf(stderr, "%s: %s\n", device, errmsg);
256 * Now mount the device.
259 die("This program needs root privilege");
265 /* We're root or at least setuid.
266 Make a temp dir and pass all the gunky options to mount. */
268 if ( chdir("/tmp") ) {
273 #define TMP_MODE (S_IXUSR|S_IWUSR|S_IXGRP|S_IWGRP|S_IWOTH|S_IXOTH|S_ISVTX)
275 if ( stat(".", &dst) || !S_ISDIR(dst.st_mode) ||
276 (dst.st_mode & TMP_MODE) != TMP_MODE ) {
277 die("possibly unsafe /tmp permissions");
280 for ( i = 0 ; ; i++ ) {
281 snprintf(mntname, sizeof mntname, "syslinux.mnt.%lu.%d",
282 (unsigned long)mypid, i);
284 if ( lstat(mntname, &dst) != -1 || errno != ENOENT )
287 rv = mkdir(mntname, 0000);
290 if ( errno == EEXIST || errno == EINTR )
296 if ( lstat(mntname, &dst) || dst.st_mode != (S_IFDIR|0000) ||
298 die("someone is trying to symlink race us!");
300 break; /* OK, got something... */
306 if ( S_ISREG(st.st_mode) ) {
307 /* It's file, need to mount it loopback */
309 struct loop_info64 loopinfo;
311 for ( n = 0 ; loop_fd < 0 ; n++ ) {
312 snprintf(devfdname, sizeof devfdname, "/dev/loop%u", n);
313 loop_fd = open(devfdname, O_RDWR);
314 if ( loop_fd < 0 && errno == ENOENT ) {
315 die("no available loopback device!");
317 if ( ioctl(loop_fd, LOOP_SET_FD, (void *)dev_fd) ) {
318 close(loop_fd); loop_fd = -1;
319 if ( errno != EBUSY )
320 die("cannot set up loopback device");
325 if ( ioctl(loop_fd, LOOP_GET_STATUS64, &loopinfo) ||
326 (loopinfo.lo_offset = filesystem_offset,
327 ioctl(loop_fd, LOOP_SET_STATUS64, &loopinfo)) )
328 die("cannot set up loopback device");
331 snprintf(devfdname, sizeof devfdname, "/proc/%lu/fd/%d",
332 (unsigned long)mypid, dev_fd);
335 if ( mount(devfdname, mntpath, "msdos",
336 MS_NOEXEC|MS_NOSUID, "umask=077,quiet") )
337 die("could not mount filesystem");
341 snprintf(devfdname, sizeof devfdname, "/proc/%lu/fd/%d",
342 (unsigned long)mypid, dev_fd);
349 } else if ( f == 0 ) {
351 if ( S_ISREG(st.st_mode) ) {
352 snprintf(mnt_opts, sizeof mnt_opts, "rw,nodev,noexec,loop,offset=%llu,umask=077,quiet",
353 (unsigned long long)filesystem_offset);
355 snprintf(mnt_opts, sizeof mnt_opts, "rw,nodev,noexec,umask=077,quiet");
357 execl(_PATH_MOUNT, _PATH_MOUNT, "-t", "msdos", "-o", mnt_opts,\
358 devfdname, mntpath, NULL);
359 _exit(255); /* execl failed */
362 w = waitpid(f, &status, 0);
363 if ( w != f || status ) {
365 exit(1); /* Mount failed */
371 ldlinux_name = alloca(strlen(mntpath)+13);
372 if ( !ldlinux_name ) {
377 sprintf(ldlinux_name, "%s/ldlinux.sys", mntpath);
379 unlink(ldlinux_name);
380 fd = open(ldlinux_name, O_WRONLY|O_CREAT|O_TRUNC, 0444);
387 cdp = syslinux_ldlinux;
388 left = syslinux_ldlinux_len;
390 nb = write(fd, cdp, left);
391 if ( nb == -1 && errno == EINTR )
393 else if ( nb <= 0 ) {
404 * I don't understand why I need this. Does the DOS filesystems
405 * not honour the mode passed to open()?
416 if ( umount2(mntpath, 0) )
417 die("could not umount path");
419 if ( loop_fd != -1 ) {
420 ioctl(loop_fd, LOOP_CLR_FD, 0); /* Free loop device */
431 } else if ( f == 0 ) {
432 execl(_PATH_UMOUNT, _PATH_UMOUNT, mntpath, NULL);
435 w = waitpid(f, &status, 0);
436 if ( w != f || status ) {
449 * Now, use libfat to create a block map. This probably
450 * should be changed to use ioctl(...,FIBMAP,...) since
451 * this is supposed to be a simple, privileged version
454 fs = libfat_open(libfat_xpread, dev_fd);
455 ldlinux_cluster = libfat_searchdir(fs, 0, "LDLINUX SYS", &dentry);
458 s = libfat_clustertosector(fs, ldlinux_cluster);
459 while ( s && nsectors < 65 ) {
462 s = libfat_nextsector(fs, s);
467 * Patch ldlinux.sys and the boot sector
469 syslinux_patch(sectors, nsectors);
472 * Write the now-patched first sector of ldlinux.sys
474 xpwrite(dev_fd, syslinux_ldlinux, 512, filesystem_offset + ((off_t)sectors[0] << 9));
477 * Patch the root directory to set attributes to
478 * HIDDEN|SYSTEM|READONLY
481 const unsigned char attrib = 0x07;
482 xpwrite(dev_fd, &attrib, 1, ((off_t)dentry.sector << 9)+dentry.offset+11);
486 * To finish up, write the boot sector
489 /* Read the superblock again since it might have changed while mounted */
490 xpread(dev_fd, sectbuf, 512, filesystem_offset);
492 /* Copy the syslinux code into the boot sector */
493 syslinux_make_bootsect(sectbuf);
495 /* Write new boot sector */
496 xpwrite(dev_fd, sectbuf, 512, filesystem_offset);