--- /dev/null
+#ident "$Id$"
+/* ----------------------------------------------------------------------- *
+ *
+ * Copyright 1998-2003 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., 675 Mass Ave, Cambridge MA 02139,
+ * USA; either version 2 of the License, or (at your option) any later
+ * version; incorporated herein by reference.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * syslinux.c - Linux installer program for SYSLINUX
+ *
+ * This program ought to be portable. I hope so, at least.
+ *
+ * This is an alternate version of the installer which doesn't require
+ * mtools, but requires root privilege.
+ */
+
+#define _XOPEN_SOURCE 500 /* Required on glibc 2.x */
+#define _BSD_SOURCE
+#include <alloca.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <mntent.h>
+#include <paths.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+#include "syslinux.h"
+
+#ifndef _PATH_MOUNT
+#define _PATH_MOUNT "/bin/mount"
+#endif
+
+#ifndef _PATH_UMOUNT
+#define _PATH_UMOUNT "/bin/umount"
+#endif
+
+char *program; /* Name of program */
+char *device; /* Device to install to */
+uid_t ruid; /* Real uid */
+uid_t euid; /* Initial euid */
+pid_t mypid;
+
+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,
+ bsDriveNumber = 0x24,
+ bsReserved1 = 0x25,
+ bsBootSignature = 0x26,
+ bsVolumeID = 0x27,
+ bsVolumeLabel = 0x2b,
+ bsFileSysType = 0x36,
+ bsCode = 0x3e,
+ bsSignature = 0x1fe
+};
+
+/*
+ * Access functions for littleendian numbers, possibly misaligned.
+ */
+static u_int16_t get_16(unsigned char *p)
+{
+ return (u_int16_t)p[0] + ((u_int16_t)p[1] << 8);
+}
+
+static u_int32_t get_32(unsigned char *p)
+{
+ return (u_int32_t)p[0] + ((u_int32_t)p[1] << 8) +
+ ((u_int32_t)p[2] << 16) + ((u_int32_t)p[3] << 24);
+}
+
+#if 0 /* Not needed */
+static void set_16(unsigned char *p, u_int16_t v)
+{
+ p[0] = (v & 0xff);
+ p[1] = ((v >> 8) & 0xff);
+}
+
+static void set_32(unsigned char *p, u_int32_t v)
+{
+ p[0] = (v & 0xff);
+ p[1] = ((v >> 8) & 0xff);
+ p[2] = ((v >> 16) & 0xff);
+ p[3] = ((v >> 24) & 0xff);
+}
+#endif
+
+void usage(void)
+{
+ fprintf(stderr, "Usage: %s [-sf] [-o offset] device\n", program);
+ exit(1);
+}
+
+/*
+ * read/write wrapper functions
+ */
+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 ) {
+ fprintf(stderr, "%s: short read\n", program);
+ exit(1);
+ } 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 ) {
+ fprintf(stderr, "%s: short write\n", program);
+ exit(1);
+ } else if ( rv == -1 ) {
+ if ( errno == EINTR ) {
+ continue;
+ } else {
+ perror(program);
+ exit(1);
+ }
+ } else {
+ offset += rv;
+ done += rv;
+ count -= rv;
+ }
+ }
+
+ return done;
+}
+
+int main(int argc, char *argv[])
+{
+ static unsigned char sectbuf[512];
+ unsigned char *dp;
+ const unsigned char *cdp;
+ int dev_fd, fd;
+ struct stat st;
+ int nb, left, veryold;
+ unsigned int sectors, clusters;
+ int err = 0;
+ pid_t f, w;
+ int status;
+ char *mntpath = NULL, mntname[64], devfdname[64];
+ char *ldlinux_name, **argp, *opt;
+ int my_umask;
+ int force = 0; /* -f (force) option */
+ off_t offset = 0; /* -o (offset) option */
+
+ ruid = getuid();
+ euid = geteuid();
+ mypid = getpid();
+
+ if ( !euid )
+ setreuid(-1, ruid); /* Run as regular user until we need it */
+
+ program = argv[0];
+
+ device = NULL;
+
+ for ( argp = argv+1 ; *argp ; argp++ ) {
+ if ( **argp == '-' ) {
+ opt = *argp + 1;
+ if ( !*opt )
+ usage();
+
+ while ( *opt ) {
+ if ( *opt == 's' ) {
+ syslinux_make_stupid(); /* Use "safe, slow and stupid" code */
+ } else if ( *opt == 'f' ) {
+ force = 1; /* Force install */
+ } else if ( *opt == 'o' && argp[1] ) {
+ offset = strtoul(*++argp, NULL, 0); /* Byte offset */
+ } else {
+ usage();
+ }
+ opt++;
+ }
+ } else {
+ if ( device )
+ usage();
+ device = *argp;
+ }
+ }
+
+ if ( !device )
+ usage();
+
+ /*
+ * First make sure we can open the device at all, and that we have
+ * read/write permission.
+ */
+ dev_fd = open(device, O_RDWR);
+ if ( dev_fd < 0 || fstat(dev_fd, &st) < 0 ) {
+ perror(device);
+ exit(1);
+ }
+
+ if ( !force && !S_ISBLK(st.st_mode) && !S_ISREG(st.st_mode) ) {
+ fprintf(stderr, "%s: not a block device or regular file (use -f to override)\n", device);
+ exit(1);
+ }
+
+ if ( !force && offset != 0 && !S_ISREG(st.st_mode) ) {
+ fprintf(stderr, "%s: not a regular file and an offset specified (use -f to override)\n", device);
+ exit(1);
+ }
+
+ if ( lseek(dev_fd, offset, SEEK_SET) != offset ) {
+ if ( !(force && errno == EBADF) ) {
+ fprintf(stderr, "%s: seek error", device);
+ exit(1);
+ }
+ }
+
+ xpread(dev_fd, sectbuf, 512, offset);
+ fsync(dev_fd);
+
+ /*
+ * Check to see that what we got was indeed an MS-DOS boot sector/superblock
+ */
+
+ if ( sectbuf[bsBootSignature] == 0x29 ) {
+ /* It's DOS, and it has all the new nice fields */
+
+ veryold = 0;
+
+ sectors = get_16(sectbuf+bsSectors);
+ sectors = sectors ? sectors : get_32(sectbuf+bsHugeSectors);
+ clusters = sectors / sectbuf[bsSecPerClust];
+
+ if ( !memcmp(sectbuf+bsFileSysType, "FAT12 ", 8) ) {
+ if ( clusters > 4086 ) {
+ fprintf(stderr, "%s: ERROR: FAT12 but claims more than 4086 clusters\n",
+ device);
+ exit(1);
+ }
+ } else if ( !memcmp(sectbuf+bsFileSysType, "FAT16 ", 8) ) {
+ if ( clusters <= 4086 ) {
+ fprintf(stderr, "%s: ERROR: FAT16 but claims less than 4086 clusters\n",
+ device);
+ exit(1);
+ }
+ } else if ( !memcmp(sectbuf+bsFileSysType, "FAT ", 8) ) {
+ /* OS/2 sets up the filesystem as just `FAT'. */
+ } else {
+ fprintf(stderr, "%s: filesystem type \"%8.8s\" not supported\n",
+ device, sectbuf+bsFileSysType);
+ exit(1);
+ }
+ } else {
+ veryold = 1;
+
+ if ( sectbuf[bsSecPerClust] & (sectbuf[bsSecPerClust] - 1) ||
+ sectbuf[bsSecPerClust] == 0 ) {
+ fprintf(stderr, "%s: This doesn't look like a FAT filesystem\n",
+ device);
+ }
+
+ sectors = get_16(sectbuf+bsSectors);
+ sectors = sectors ? sectors : get_32(sectbuf+bsHugeSectors);
+ clusters = sectors / sectbuf[bsSecPerClust];
+ }
+
+ if ( get_16(sectbuf+bsBytesPerSec) != 512 ) {
+ fprintf(stderr, "%s: Sector sizes other than 512 not supported\n",
+ device);
+ exit(1);
+ }
+ if ( sectbuf[bsSecPerClust] > 32 ) {
+ fprintf(stderr, "%s: Cluster sizes larger than 16K not supported\n",
+ device);
+ }
+
+ /*
+ * Now mount the device.
+ */
+ if ( euid ) {
+ fprintf(stderr, "%s: This program needs root privilege\n", program);
+ exit(1);
+ } else {
+ int i = 0;
+ struct stat dst;
+ int rv;
+
+ /* We're root or at least setuid.
+ Make a temp dir and pass all the gunky options to mount. */
+
+ if ( chdir("/tmp") ) {
+ perror(program);
+ exit(1);
+ }
+
+#define TMP_MODE (S_IXUSR|S_IWUSR|S_IXGRP|S_IWGRP|S_IWOTH|S_IXOTH|S_ISVTX)
+
+ if ( stat(".", &dst) || !S_ISDIR(dst.st_mode) ||
+ (dst.st_mode & TMP_MODE) != TMP_MODE ) {
+ fprintf(stderr, "%s: possibly unsafe /tmp permissions\n", program);
+ exit(1);
+ }
+
+ for ( i = 0 ; ; i++ ) {
+ snprintf(mntname, sizeof mntname, "syslinux.mnt.%lu.%d",
+ (unsigned long)mypid, i);
+
+ if ( lstat(mntname, &dst) != -1 || errno != ENOENT )
+ continue;
+
+ seteuid(0); /* *** BECOME ROOT *** */
+ rv = mkdir(mntname, 0000); /* AS ROOT */
+ seteuid(ruid);
+
+ if ( rv == -1 ) {
+ if ( errno == EEXIST || errno == EINTR )
+ continue;
+ perror(program);
+ exit(1);
+ }
+
+ if ( lstat(mntname, &dst) || dst.st_mode != (S_IFDIR|0000) ||
+ dst.st_uid != 0 ) {
+ fprintf(stderr, "%s: someone is trying to symlink race us!\n", program);
+ exit(1);
+ }
+ break; /* OK, got something... */
+ }
+
+ mntpath = mntname;
+
+ snprintf(devfdname, sizeof devfdname, "/proc/%lu/fd/%d",
+ (unsigned long)mypid, dev_fd);
+
+ f = fork();
+ if ( f < 0 ) {
+ perror(program);
+ rmdir(mntpath);
+ exit(1);
+ } else if ( f == 0 ) {
+ char mnt_opts[128];
+ seteuid(0); /* ***BECOME ROOT*** */
+ setuid(0);
+ if ( S_ISREG(st.st_mode) ) {
+ snprintf(mnt_opts, sizeof mnt_opts, "rw,nodev,noexec,loop,offset=%llu,umask=077,uid=%lu",
+ (unsigned long long)offset, (unsigned long)ruid);
+ } else {
+ snprintf(mnt_opts, sizeof mnt_opts, "rw,nodev,noexec,umask=077,uid=%lu",
+ (unsigned long)ruid);
+ }
+ execl(_PATH_MOUNT, _PATH_MOUNT, "-t", "msdos", "-o", mnt_opts,\
+ devfdname, mntpath, NULL);
+ _exit(255); /* execl failed */
+ }
+ }
+
+ w = waitpid(f, &status, 0);
+ if ( w != f || status ) {
+ if ( !euid )
+ rmdir(mntpath);
+ exit(1); /* Mount failed */
+ }
+
+ ldlinux_name = alloca(strlen(mntpath)+13);
+ if ( !ldlinux_name ) {
+ perror(program);
+ err = 1;
+ goto umount;
+ }
+ sprintf(ldlinux_name, "%s/ldlinux.sys", mntpath);
+
+ unlink(ldlinux_name);
+ fd = open(ldlinux_name, O_WRONLY|O_CREAT|O_TRUNC, 0444);
+ if ( fd < 0 ) {
+ perror(device);
+ err = 1;
+ goto umount;
+ }
+
+ cdp = syslinux_ldlinux;
+ left = syslinux_ldlinux_len;
+ while ( left ) {
+ nb = write(fd, cdp, left);
+ if ( nb == -1 && errno == EINTR )
+ continue;
+ else if ( nb <= 0 ) {
+ perror(device);
+ err = 1;
+ goto umount;
+ }
+
+ dp += nb;
+ left -= nb;
+ }
+
+ /*
+ * I don't understand why I need this. Does the DOS filesystems
+ * not honour the mode passed to open()?
+ */
+ my_umask = umask(0777);
+ umask(my_umask);
+ fchmod(fd, 0444 & ~my_umask);
+
+ close(fd);
+
+umount:
+ f = fork();
+ if ( f < 0 ) {
+ perror("fork");
+ exit(1);
+ } else if ( f == 0 ) {
+ seteuid(0); /* ***BECOME ROOT*** */
+ setuid(0);
+ execl(_PATH_UMOUNT, _PATH_UMOUNT, mntpath, NULL);
+ }
+
+ w = waitpid(f, &status, 0);
+ if ( w != f || status ) {
+ exit(1);
+ }
+
+ sync();
+
+ if ( !euid ) {
+ seteuid(0); /* *** BECOME ROOT *** */
+ rmdir(mntpath); /* AS ROOT */
+ seteuid(ruid);
+ }
+
+ if ( err )
+ exit(err);
+
+ /*
+ * To finish up, write the boot sector
+ */
+
+ /* Read the superblock again since it might have changed while mounted */
+ xpread(dev_fd, sectbuf, 512, offset);
+
+ /* Copy the syslinux code into the boot sector */
+ syslinux_make_bootsect(sectbuf);
+
+ /* Write new boot sector */
+ xpwrite(dev_fd, sectbuf, 512, offset);
+
+ close(dev_fd);
+ sync();
+
+ /* Done! */
+
+ return 0;
+}
projects / platform / upstream / syslinux.git / commitdiff