mount.c

/* vi: set sw=4 ts=4: */
/*
 * Mini mount implementation for busybox
 *
 * Copyright (C) 1995, 1996 by Bruce Perens <bruce@pixar.com>.
 *
 * 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; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 * 3/21/1999	Charles P. Wright <cpwright@cpwright.com>
 *		searches through fstab when -a is passed
 *		will try mounting stuff with all fses when passed -t auto
 *
 * 1999-04-17	Dave Cinege...Rewrote -t auto. Fixed ro mtab.
 *
 * 1999-10-07	Erik Andersen <andersen@lineo.com>, <andersee@debian.org>.
 *              Rewrite of a lot of code. Removed mtab usage (I plan on
 *              putting it back as a compile-time option some time), 
 *              major adjustments to option parsing, and some serious 
 *              dieting all around.
 *
 * 1999-11-06	mtab suppport is back - andersee
 *
 * 2000-01-12   Ben Collins <bcollins@debian.org>, Borrowed utils-linux's
 *              mount to add loop support.
 *
 * 2000-04-30	Dave Cinege <dcinege@psychosis.com>
 *		Rewrote fstab while loop and lower mount section. Can now do
 *		single mounts from fstab. Can override fstab options for single
 *		mount. Common mount_one call for single mounts and 'all'. Fixed
 *		mtab updating and stale entries. Removed 'remount' default. 
 *	
 */

#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <mntent.h>
#include <ctype.h>
#if defined BB_FEATURE_USE_DEVPS_PATCH
#include <linux/devmtab.h> /* For Erik's nifty devmtab device driver */
#endif
#include "busybox.h"

enum {
	MS_MGC_VAL = 0xc0ed0000, /* Magic number indicatng "new" flags */
	MS_RDONLY = 1,      /* Mount read-only */
	MS_NOSUID = 2,      /* Ignore suid and sgid bits */
	MS_NODEV = 4,      /* Disallow access to device special files */
	MS_NOEXEC = 8,      /* Disallow program execution */
	MS_SYNCHRONOUS = 16,      /* Writes are synced at once */
	MS_REMOUNT = 32,      /* Alter flags of a mounted FS */
	MS_MANDLOCK = 64,      /* Allow mandatory locks on an FS */
	S_QUOTA = 128,     /* Quota initialized for file/directory/symlink */
	S_APPEND = 256,     /* Append-only file */
	S_IMMUTABLE = 512,     /* Immutable file */
	MS_NOATIME = 1024,    /* Do not update access times. */
	MS_NODIRATIME = 2048,    /* Do not update directory access times */
};


#if defined BB_FEATURE_MOUNT_LOOP
#include <fcntl.h>
#include <sys/ioctl.h>
static int use_loop = FALSE;
#endif

extern int mount (__const char *__special_file, __const char *__dir,
			__const char *__fstype, unsigned long int __rwflag,
			__const void *__data);
extern int umount (__const char *__special_file);
extern int umount2 (__const char *__special_file, int __flags);

#include <sys/syscall.h>
#include <linux/unistd.h>
static int sysfs( int option, unsigned int fs_index, char * buf);
_syscall3(int, sysfs, int, option, unsigned int, fs_index, char *, buf);


extern const char mtab_file[];	/* Defined in utility.c */

struct mount_options {
	const char *name;
	unsigned long and;
	unsigned long or;
};

static const struct mount_options mount_options[] = {
	{"async", ~MS_SYNCHRONOUS, 0},
	{"atime", ~0, ~MS_NOATIME},
	{"defaults", ~0, 0},
	{"dev", ~MS_NODEV, 0},
	{"diratime", ~0, ~MS_NODIRATIME},
	{"exec", ~MS_NOEXEC, 0},
	{"noatime", ~0, MS_NOATIME},
	{"nodev", ~0, MS_NODEV},
	{"nodiratime", ~0, MS_NODIRATIME},
	{"noexec", ~0, MS_NOEXEC},
	{"nosuid", ~0, MS_NOSUID},
	{"remount", ~0, MS_REMOUNT},
	{"ro", ~0, MS_RDONLY},
	{"rw", ~MS_RDONLY, 0},
	{"suid", ~MS_NOSUID, 0},
	{"sync", ~0, MS_SYNCHRONOUS},
	{0, 0, 0}
};

static int
do_mount(char *specialfile, char *dir, char *filesystemtype,
		 long flags, void *string_flags, int useMtab, int fakeIt,
		 char *mtab_opts)
{
	int status = 0;
#if defined BB_FEATURE_MOUNT_LOOP
	char *lofile = NULL;
#endif

	if (fakeIt == FALSE)
	{
#if defined BB_FEATURE_MOUNT_LOOP
		if (use_loop==TRUE) {
			int loro = flags & MS_RDONLY;
			
			lofile = specialfile;

			specialfile = find_unused_loop_device();
			if (specialfile == NULL) {
				error_msg_and_die("Could not find a spare loop device");
			}
			if (set_loop(specialfile, lofile, 0, &loro)) {
				error_msg_and_die("Could not setup loop device");
			}
			if (!(flags & MS_RDONLY) && loro) {	/* loop is ro, but wanted rw */
				error_msg("WARNING: loop device is read-only");
				flags &= ~MS_RDONLY;
			}
		}
#endif
		status = mount(specialfile, dir, filesystemtype, flags, string_flags);
		if (errno == EROFS) {
			error_msg("%s is write-protected, mounting read-only", specialfile);
			status = mount(specialfile, dir, filesystemtype, flags |= MS_RDONLY, string_flags);
		}
	}


	/* If the mount was sucessful, do anything needed, then return TRUE */
	if (status == 0 || fakeIt==TRUE) {

#if defined BB_MTAB
		if (useMtab == TRUE) {
			erase_mtab(specialfile);	// Clean any stale entries
			write_mtab(specialfile, dir, filesystemtype, flags, mtab_opts);
		}
#endif
		return (TRUE);
	}

	/* Bummer.  mount failed.  Clean up */
#if defined BB_FEATURE_MOUNT_LOOP
	if (lofile != NULL) {
		del_loop(specialfile);
	}
#endif

	if (errno == EPERM) {
		error_msg_and_die("permission denied. Are you root?");
	}

	return (FALSE);
}



/* Seperate standard mount options from the nonstandard string options */
static void
parse_mount_options(char *options, int *flags, char *strflags)
{
	while (options) {
		int gotone = FALSE;
		char *comma = strchr(options, ',');
		const struct mount_options *f = mount_options;

		if (comma)
			*comma = '\0';

		while (f->name != 0) {
			if (strcasecmp(f->name, options) == 0) {

				*flags &= f->and;
				*flags |= f->or;
				gotone = TRUE;
				break;
			}
			f++;
		}
#if defined BB_FEATURE_MOUNT_LOOP
		if (gotone == FALSE && !strcasecmp("loop", options)) {	/* loop device support */
			use_loop = TRUE;
			gotone = TRUE;
		}
#endif
		if (*strflags && strflags != '\0' && gotone == FALSE) {
			char *temp = strflags;

			temp += strlen(strflags);
			*temp++ = ',';
			*temp++ = '\0';
		}
		if (gotone == FALSE)
			strcat(strflags, options);
		if (comma) {
			*comma = ',';
			options = ++comma;
		} else {
			break;
		}
	}
}

static int
mount_one(char *blockDevice, char *directory, char *filesystemType,
		  unsigned long flags, char *string_flags, int useMtab, int fakeIt,
		  char *mtab_opts, int whineOnErrors)
{
	int status = 0;

	if (strcmp(filesystemType, "auto") == 0) {
		static const char *strings[] = { "tmpfs", "shm", "proc", "ramfs", "devpts", 0 };
		const char** nodevfss;
		const int num_of_filesystems = sysfs(3, 0, 0);
		char buf[255];
		int i=0;

		filesystemType=buf;

		while(i < num_of_filesystems) {
			sysfs(2, i++, filesystemType);
			for (nodevfss = strings; *nodevfss; nodevfss++) {
				if (!strcmp(filesystemType, *nodevfss)) {
					break;
				}
			}
			if (!*nodevfss) {
				status = do_mount(blockDevice, directory, filesystemType,
					flags | MS_MGC_VAL, string_flags,
					useMtab, fakeIt, mtab_opts);
				if (status == TRUE)
					break;
			}
		}
	} else {
		status = do_mount(blockDevice, directory, filesystemType,
				flags | MS_MGC_VAL, string_flags, useMtab,
				fakeIt, mtab_opts);
	}

	if (status == FALSE) {
		if (whineOnErrors == TRUE) {
			perror_msg("Mounting %s on %s failed", blockDevice, directory);
		}
		return (FALSE);
	}
	return (TRUE);
}

extern int mount_main(int argc, char **argv)
{
	char string_flags_buf[1024] = "";
	char *string_flags = string_flags_buf;
	char *extra_opts = string_flags_buf;
	int flags = 0;
	char *filesystemType = "auto";
	char *device = NULL;
	char *directory = NULL;
	int all = FALSE;
	int fakeIt = FALSE;
	int useMtab = TRUE;
	int i;
	int rc = EXIT_FAILURE;
	int fstabmount = FALSE;	

#if defined BB_FEATURE_USE_DEVPS_PATCH
	if (argc == 1) {
		int fd, i, numfilesystems;
		char device[] = "/dev/mtab";
		struct k_mntent *mntentlist;

		/* open device */ 
		fd = open(device, O_RDONLY);
		if (fd < 0)
			perror_msg_and_die("open failed for `%s'", device);

		/* How many mounted filesystems?  We need to know to 
		 * allocate enough space for later... */
		numfilesystems = ioctl (fd, DEVMTAB_COUNT_MOUNTS);
		if (numfilesystems<0)
			perror_msg_and_die( "\nDEVMTAB_COUNT_MOUNTS");
		mntentlist = (struct k_mntent *) xcalloc ( numfilesystems, sizeof(struct k_mntent));
		
		/* Grab the list of mounted filesystems */
		if (ioctl (fd, DEVMTAB_GET_MOUNTS, mntentlist)<0)
			perror_msg_and_die( "\nDEVMTAB_GET_MOUNTS");

		for( i = 0 ; i < numfilesystems ; i++) {
			printf( "%s %s %s %s %d %d\n", mntentlist[i].mnt_fsname,
					mntentlist[i].mnt_dir, mntentlist[i].mnt_type, 
					mntentlist[i].mnt_opts, mntentlist[i].mnt_freq, 
					mntentlist[i].mnt_passno);
		}
#ifdef BB_FEATURE_CLEAN_UP
		/* Don't bother to close files or free memory.  Exit 
		 * does that automagically, so we can save a few bytes */
		free( mntentlist);
		close(fd);
#endif
		return EXIT_SUCCESS;
	}
#else
	if (argc == 1) {
		FILE *mountTable = setmntent(mtab_file, "r");

		if (mountTable) {
			struct mntent *m;

			while ((m = getmntent(mountTable)) != 0) {
				char *blockDevice = m->mnt_fsname;
				if (strcmp(blockDevice, "/dev/root") == 0) {
					find_real_root_device_name( blockDevice);
				}
				printf("%s on %s type %s (%s)\n", blockDevice, m->mnt_dir,
					   m->mnt_type, m->mnt_opts);
			}
			endmntent(mountTable);
		} else {
			perror_msg_and_die("%s", mtab_file);
		}
		return EXIT_SUCCESS;
	}
#endif

	/* Parse options */
	i = --argc;
	argv++;
	while (i > 0 && **argv) {
		if (**argv == '-') {
			char *opt = *argv;

			while (i > 0 && *++opt)
				switch (*opt) {
				case 'o':
					if (--i == 0) {
						goto goodbye;
					}
					parse_mount_options(*(++argv), &flags, string_flags);
					break;
				case 'r':
					flags |= MS_RDONLY;
					break;
				case 't':
					if (--i == 0) {
						goto goodbye;
					}
					filesystemType = *(++argv);
					break;
				case 'w':
					flags &= ~MS_RDONLY;
					break;
				case 'a':
					all = TRUE;
					break;
				case 'f':
					fakeIt = TRUE;
					break;
#ifdef BB_MTAB
				case 'n':
					useMtab = FALSE;
					break;
#endif
				case 'v':
					break; /* ignore -v */
				case 'h':
				case '-':
					goto goodbye;
				}
		} else {
			if (device == NULL)
				device = *argv;
			else if (directory == NULL)
				directory = *argv;
			else {
				goto goodbye;
			}
		}
		i--;
		argv++;
	}

	if (all == TRUE || directory == NULL) {
		struct mntent *m;
		FILE *f = setmntent("/etc/fstab", "r");
		fstabmount = TRUE;

		if (f == NULL)
			perror_msg_and_die( "\nCannot read /etc/fstab");

		while ((m = getmntent(f)) != NULL) {
			if (all == FALSE && directory == NULL && (
				(strcmp(device, m->mnt_fsname) != 0) &&
				(strcmp(device, m->mnt_dir) != 0) ) ) {
				continue;
			}
			
			if (all == TRUE && (				// If we're mounting 'all'
				(strstr(m->mnt_opts, "noauto")) ||	// and the file system isn't noauto,
				(strstr(m->mnt_type, "swap")) ||	// and isn't swap or nfs, then mount it
				(strstr(m->mnt_type, "nfs")) ) ) {
				continue;
			}
			
			if (all == TRUE || flags == 0) {	// Allow single mount to override fstab flags
				flags = 0;
				*string_flags = '\0';
				parse_mount_options(m->mnt_opts, &flags, string_flags);
			}
			
			device = strdup(m->mnt_fsname);
			directory = strdup(m->mnt_dir);
			filesystemType = strdup(m->mnt_type);
singlemount:			
			string_flags = strdup(string_flags);
			rc = EXIT_SUCCESS;
#ifdef BB_NFSMOUNT
			if (strchr(device, ':') != NULL)
				filesystemType = "nfs";
			if (strcmp(filesystemType, "nfs") == 0) {
				if (nfsmount (device, directory, &flags, &extra_opts,
							&string_flags, 1)) {
					perror_msg("nfsmount failed");
					rc = EXIT_FAILURE;
				}
			}
#endif
			if (!mount_one(device, directory, filesystemType, flags,
					string_flags, useMtab, fakeIt, extra_opts, TRUE))
				rc = EXIT_FAILURE;
				
			if (all == FALSE)
				break;
		}
		if (fstabmount == TRUE)
			endmntent(f);
			
		if (all == FALSE && fstabmount == TRUE && directory == NULL)
			fprintf(stderr, "Can't find %s in /etc/fstab\n", device);
	
		return rc;
	}
	
	goto singlemount;
	
goodbye:
	show_usage();
}