/* vi: set sw=4 ts=4: */
/*
 * pfsck --- A generic, parallelizing front-end for the fsck program.
 * It will automatically try to run fsck programs in parallel if the
 * devices are on separate spindles.  It is based on the same ideas as
 * the generic front end for fsck by David Engel and Fred van Kempen,
 * but it has been completely rewritten from scratch to support
 * parallel execution.
 *
 * Written by Theodore Ts'o, <tytso@mit.edu>
 *
 * Miquel van Smoorenburg (miquels@drinkel.ow.org) 20-Oct-1994:
 *   o Changed -t fstype to behave like with mount when -A (all file
 *     systems) or -M (like mount) is specified.
 *   o fsck looks if it can find the fsck.type program to decide
 *     if it should ignore the fs type. This way more fsck programs
 *     can be added without changing this front-end.
 *   o -R flag skip root file system.
 *
 * Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
 *      2001, 2002, 2003, 2004, 2005 by  Theodore Ts'o.
 *
 * %Begin-Header%
 * This file may be redistributed under the terms of the GNU Public
 * License.
 * %End-Header%
 */

#include <sys/types.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <limits.h>
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <time.h>
#include <stdlib.h>
#include <errno.h>
#include <paths.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>

#include "fsck.h"
#include "blkid/blkid.h"

#include "e2fsbb.h"

#include "libbb.h"

#ifndef _PATH_MNTTAB
#define _PATH_MNTTAB    "/etc/fstab"
#endif

/*
 * fsck.h
 */

#ifndef DEFAULT_FSTYPE
#define DEFAULT_FSTYPE	"ext2"
#endif

#define MAX_DEVICES 32
#define MAX_ARGS 32

/*
 * Internal structure for mount tabel entries.
 */

struct fs_info {
	char  *device;
	char  *mountpt;
	char  *type;
	char  *opts;
	int   freq;
	int   passno;
	int   flags;
	struct fs_info *next;
};

#define FLAG_DONE 1
#define FLAG_PROGRESS 2

/*
 * Structure to allow exit codes to be stored
 */
struct fsck_instance {
	int	pid;
	int	flags;
	int	exit_status;
	time_t	start_time;
	char *	prog;
	char *	type;
	char *	device;
	char *	base_device;
	struct fsck_instance *next;
};

/*
 * base_device.c
 *
 * Return the "base device" given a particular device; this is used to
 * assure that we only fsck one partition on a particular drive at any
 * one time.  Otherwise, the disk heads will be seeking all over the
 * place.  If the base device cannot be determined, return NULL.
 *
 * The base_device() function returns an allocated string which must
 * be freed.
 *
 */


#ifdef CONFIG_FEATURE_DEVFS
/*
 * Required for the uber-silly devfs /dev/ide/host1/bus2/target3/lun3
 * pathames.
 */
static const char *const devfs_hier[] = {
	"host", "bus", "target", "lun", 0
};
#endif

static char *base_device(const char *device)
{
	char *str, *cp;
#ifdef CONFIG_FEATURE_DEVFS
	const char *const *hier;
	const char *disk;
	int len;
#endif

	cp = str = xstrdup(device);

	/* Skip over /dev/; if it's not present, give up. */
	if (strncmp(cp, "/dev/", 5) != 0)
		goto errout;
	cp += 5;

	/*
	 * For md devices, we treat them all as if they were all
	 * on one disk, since we don't know how to parallelize them.
	 */
	if (cp[0] == 'm' && cp[1] == 'd') {
		*(cp+2) = 0;
		return str;
	}

	/* Handle DAC 960 devices */
	if (strncmp(cp, "rd/", 3) == 0) {
		cp += 3;
		if (cp[0] != 'c' || cp[2] != 'd' ||
		    !isdigit(cp[1]) || !isdigit(cp[3]))
			goto errout;
		*(cp+4) = 0;
		return str;
	}

	/* Now let's handle /dev/hd* and /dev/sd* devices.... */
	if ((cp[0] == 'h' || cp[0] == 's') && (cp[1] == 'd')) {
		cp += 2;
		/* If there's a single number after /dev/hd, skip it */
		if (isdigit(*cp))
			cp++;
		/* What follows must be an alpha char, or give up */
		if (!isalpha(*cp))
			goto errout;
		*(cp + 1) = 0;
		return str;
	}

#ifdef CONFIG_FEATURE_DEVFS
	/* Now let's handle devfs (ugh) names */
	len = 0;
	if (strncmp(cp, "ide/", 4) == 0)
		len = 4;
	if (strncmp(cp, "scsi/", 5) == 0)
		len = 5;
	if (len) {
		cp += len;
		/*
		 * Now we proceed down the expected devfs hierarchy.
		 * i.e., .../host1/bus2/target3/lun4/...
		 * If we don't find the expected token, followed by
		 * some number of digits at each level, abort.
		 */
		for (hier = devfs_hier; *hier; hier++) {
			len = strlen(*hier);
			if (strncmp(cp, *hier, len) != 0)
				goto errout;
			cp += len;
			while (*cp != '/' && *cp != 0) {
				if (!isdigit(*cp))
					goto errout;
				cp++;
			}
			cp++;
		}
		*(cp - 1) = 0;
		return str;
	}

	/* Now handle devfs /dev/disc or /dev/disk names */
	disk = 0;
	if (strncmp(cp, "discs/", 6) == 0)
		disk = "disc";
	else if (strncmp(cp, "disks/", 6) == 0)
		disk = "disk";
	if (disk) {
		cp += 6;
		if (strncmp(cp, disk, 4) != 0)
			goto errout;
		cp += 4;
		while (*cp != '/' && *cp != 0) {
			if (!isdigit(*cp))
				goto errout;
			cp++;
		}
		*cp = 0;
		return str;
	}
#endif

errout:
	free(str);
	return NULL;
}


static const char *const ignored_types[] = {
	"ignore",
	"iso9660",
	"nfs",
	"proc",
	"sw",
	"swap",
	"tmpfs",
	"devpts",
	NULL
};

static const char *const really_wanted[] = {
	"minix",
	"ext2",
	"ext3",
	"jfs",
	"reiserfs",
	"xiafs",
	"xfs",
	NULL
};

#define BASE_MD "/dev/md"

/*
 * Global variables for options
 */
static char *devices[MAX_DEVICES];
static char *args[MAX_ARGS];
static int num_devices, num_args;

static int verbose;
static int doall;
static int noexecute;
static int serialize;
static int skip_root;
static int like_mount;
static int notitle;
static int parallel_root;
static int progress;
static int progress_fd;
static int force_all_parallel;
static int num_running;
static int max_running;
static volatile int cancel_requested;
static int kill_sent;
static char *fstype;
static struct fs_info *filesys_info, *filesys_last;
static struct fsck_instance *instance_list;
static char *fsck_path;
static blkid_cache cache;

static char *string_copy(const char *s)
{
	char    *ret;

	if (!s)
		return 0;
	ret = strdup(s);
	return ret;
}

static int string_to_int(const char *s)
{
	long l;
	char *p;

	l = strtol(s, &p, 0);
	if (*p || l == LONG_MIN || l == LONG_MAX || l < 0 || l > INT_MAX)
		return -1;
	else
		return (int) l;
}

static char *skip_over_blank(char *cp)
{
	while (*cp && isspace(*cp))
		cp++;
	return cp;
}

static char *skip_over_word(char *cp)
{
	while (*cp && !isspace(*cp))
		cp++;
	return cp;
}

static void strip_line(char *line)
{
	char    *p;

	while (*line) {
		p = line + strlen(line) - 1;
		if ((*p == '\n') || (*p == '\r'))
			*p = 0;
		else
			break;
	}
}

static char *parse_word(char **buf)
{
	char *word, *next;

	word = *buf;
	if (*word == 0)
		return 0;

	word = skip_over_blank(word);
	next = skip_over_word(word);
	if (*next)
		*next++ = 0;
	*buf = next;
	return word;
}

static void parse_escape(char *word)
{
	char    *q, c;
	const char *p;

	if (!word)
		return;

	for (p = q = word; *p; q++) {
		c = *p++;
		if (c != '\\') {
			*q = c;
		} else {
			*q = bb_process_escape_sequence(&p);
		}
	}
	*q = 0;
}

static void free_instance(struct fsck_instance *i)
{
	if (i->prog)
		free(i->prog);
	if (i->device)
		free(i->device);
	if (i->base_device)
		free(i->base_device);
	free(i);
}

static struct fs_info *create_fs_device(const char *device, const char *mntpnt,
					const char *type, const char *opts,
					int freq, int passno)
{
	struct fs_info *fs;

	if (!(fs = malloc(sizeof(struct fs_info))))
		return NULL;

	fs->device = string_copy(device);
	fs->mountpt = string_copy(mntpnt);
	fs->type = string_copy(type);
	fs->opts = string_copy(opts ? opts : "");
	fs->freq = freq;
	fs->passno = passno;
	fs->flags = 0;
	fs->next = NULL;

	if (!filesys_info)
		filesys_info = fs;
	else
		filesys_last->next = fs;
	filesys_last = fs;

	return fs;
}


static int parse_fstab_line(char *line, struct fs_info **ret_fs)
{
	char    *dev, *device, *mntpnt, *type, *opts, *freq, *passno, *cp;
	struct fs_info *fs;

	*ret_fs = 0;
	strip_line(line);
	if ((cp = strchr(line, '#')))
		*cp = 0;        /* Ignore everything after the comment char */
	cp = line;

	device = parse_word(&cp);
	mntpnt = parse_word(&cp);
	type = parse_word(&cp);
	opts = parse_word(&cp);
	freq = parse_word(&cp);
	passno = parse_word(&cp);

	if (!device)
		return 0;       /* Allow blank lines */

	if (!mntpnt || !type)
		return -1;

	parse_escape(device);
	parse_escape(mntpnt);
	parse_escape(type);
	parse_escape(opts);
	parse_escape(freq);
	parse_escape(passno);

	dev = blkid_get_devname(cache, device, NULL);
	if (dev)
		device = dev;

	if (strchr(type, ','))
		type = 0;

	fs = create_fs_device(device, mntpnt, type ? type : "auto", opts,
			      freq ? atoi(freq) : -1,
			      passno ? atoi(passno) : -1);
	if (dev)
		free(dev);

	if (!fs)
		return -1;
	*ret_fs = fs;
	return 0;
}

static void interpret_type(struct fs_info *fs)
{
	char    *t;

	if (strcmp(fs->type, "auto") != 0)
		return;
	t = blkid_get_tag_value(cache, "TYPE", fs->device);
	if (t) {
		free(fs->type);
		fs->type = t;
	}
}

/*
 * Load the filesystem database from /etc/fstab
 */
static void load_fs_info(const char *filename)
{
	FILE    *f;
	char    buf[1024];
	int     lineno = 0;
	int     old_fstab = 1;
	struct fs_info *fs;

	if ((f = fopen_or_warn(filename, "r")) == NULL) {
		return;
	}
	while (!feof(f)) {
		lineno++;
		if (!fgets(buf, sizeof(buf), f))
			break;
		buf[sizeof(buf)-1] = 0;
		if (parse_fstab_line(buf, &fs) < 0) {
			bb_error_msg("WARNING: bad format "
				"on line %d of %s\n", lineno, filename);
			continue;
		}
		if (!fs)
			continue;
		if (fs->passno < 0)
			fs->passno = 0;
		else
			old_fstab = 0;
	}

	fclose(f);

	if (old_fstab) {
		fputs("\007\007\007"
		"WARNING: Your /etc/fstab does not contain the fsck passno\n"
		"       field.  I will kludge around things for you, but you\n"
		"       should fix your /etc/fstab file as soon as you can.\n\n", stderr);

		for (fs = filesys_info; fs; fs = fs->next) {
			fs->passno = 1;
		}
	}
}

/* Lookup filesys in /etc/fstab and return the corresponding entry. */
static struct fs_info *lookup(char *filesys)
{
	struct fs_info *fs;

	/* No filesys name given. */
	if (filesys == NULL)
		return NULL;

	for (fs = filesys_info; fs; fs = fs->next) {
		if (!strcmp(filesys, fs->device) ||
		    (fs->mountpt && !strcmp(filesys, fs->mountpt)))
			break;
	}

	return fs;
}

/* Find fsck program for a given fs type. */
static char *find_fsck(char *type)
{
  char *s;
  const char *tpl;
  char *p = string_copy(fsck_path);
  struct stat st;

  /* Are we looking for a program or just a type? */
  tpl = (strncmp(type, "fsck.", 5) ? "%s/fsck.%s" : "%s/%s");

  for(s = strtok(p, ":"); s; s = strtok(NULL, ":")) {
	s = xasprintf(tpl, s, type);
	if (stat(s, &st) == 0) break;
	free(s);
  }
  free(p);
  return s;
}

static int progress_active(void)
{
	struct fsck_instance *inst;

	for (inst = instance_list; inst; inst = inst->next) {
		if (inst->flags & FLAG_DONE)
			continue;
		if (inst->flags & FLAG_PROGRESS)
			return 1;
	}
	return 0;
}

/*
 * Execute a particular fsck program, and link it into the list of
 * child processes we are waiting for.
 */
static int execute(const char *type, const char *device, const char *mntpt,
		   int interactive)
{
	char *s, *argv[80];
	char *prog;
	int  argc, i;
	struct fsck_instance *inst, *p;
	pid_t   pid;

	inst = malloc(sizeof(struct fsck_instance));
	if (!inst)
		return ENOMEM;
	memset(inst, 0, sizeof(struct fsck_instance));

	prog = xasprintf("fsck.%s", type);
	argv[0] = prog;
	argc = 1;

	for (i=0; i <num_args; i++)
		argv[argc++] = string_copy(args[i]);

	if (progress && !progress_active()) {
		if ((strcmp(type, "ext2") == 0) ||
		    (strcmp(type, "ext3") == 0)) {
			char tmp[80];
			snprintf(tmp, 80, "-C%d", progress_fd);
			argv[argc++] = string_copy(tmp);
			inst->flags |= FLAG_PROGRESS;
		}
	}

	argv[argc++] = string_copy(device);
	argv[argc] = 0;

	s = find_fsck(prog);
	if (s == NULL) {
		bb_error_msg("%s: not found", prog);
		return ENOENT;
	}

	if (verbose || noexecute) {
		printf("[%s (%d) -- %s] ", s, num_running,
		       mntpt ? mntpt : device);
		for (i=0; i < argc; i++)
			printf("%s ", argv[i]);
		bb_putchar('\n');
	}

	/* Fork and execute the correct program. */
	if (noexecute)
		pid = -1;
	else if ((pid = fork()) < 0) {
		perror("fork");
		return errno;
	} else if (pid == 0) {
		if (!interactive)
			close(0);
		(void) execv(s, argv);
		bb_simple_perror_msg_and_die(argv[0]);
	}

	for (i = 1; i < argc; i++)
		free(argv[i]);

	free(s);
	inst->pid = pid;
	inst->prog = prog;
	inst->type = string_copy(type);
	inst->device = string_copy(device);
	inst->base_device = base_device(device);
	inst->start_time = time(0);
	inst->next = NULL;

	/*
	 * Find the end of the list, so we add the instance on at the end.
	 */
	for (p = instance_list; p && p->next; p = p->next);

	if (p)
		p->next = inst;
	else
		instance_list = inst;

	return 0;
}

/*
 * Send a signal to all outstanding fsck child processes
 */
static int kill_all(int signum)
{
	struct fsck_instance *inst;
	int     n = 0;

	for (inst = instance_list; inst; inst = inst->next) {
		if (inst->flags & FLAG_DONE)
			continue;
		kill(inst->pid, signum);
		n++;
	}
	return n;
}

/*
 * Wait for one child process to exit; when it does, unlink it from
 * the list of executing child processes, and return it.
 */
static struct fsck_instance *wait_one(int flags)
{
	int     status;
	int     sig;
	struct fsck_instance *inst, *inst2, *prev;
	pid_t   pid;

	if (!instance_list)
		return NULL;

	if (noexecute) {
		inst = instance_list;
		prev = 0;
#ifdef RANDOM_DEBUG
		while (inst->next && (random() & 1)) {
			prev = inst;
			inst = inst->next;
		}
#endif
		inst->exit_status = 0;
		goto ret_inst;
	}

	/*
	 * gcc -Wall fails saving throw against stupidity
	 * (inst and prev are thought to be uninitialized variables)
	 */
	inst = prev = NULL;

	do {
		pid = waitpid(-1, &status, flags);
		if (cancel_requested && !kill_sent) {
			kill_all(SIGTERM);
			kill_sent++;
		}
		if ((pid == 0) && (flags & WNOHANG))
			return NULL;
		if (pid < 0) {
			if ((errno == EINTR) || (errno == EAGAIN))
				continue;
			if (errno == ECHILD) {
				bb_error_msg("wait: no more child process?!?");
				return NULL;
			}
			perror("wait");
			continue;
		}
		for (prev = 0, inst = instance_list;
		     inst;
		     prev = inst, inst = inst->next) {
			if (inst->pid == pid)
				break;
		}
	} while (!inst);

	if (WIFEXITED(status))
		status = WEXITSTATUS(status);
	else if (WIFSIGNALED(status)) {
		sig = WTERMSIG(status);
		if (sig == SIGINT) {
			status = EXIT_UNCORRECTED;
		} else {
			printf("Warning... %s for device %s exited "
			       "with signal %d.\n",
			       inst->prog, inst->device, sig);
			status = EXIT_ERROR;
		}
	} else {
		printf("%s %s: status is %x, should never happen.\n",
		       inst->prog, inst->device, status);
		status = EXIT_ERROR;
	}
	inst->exit_status = status;
	if (progress && (inst->flags & FLAG_PROGRESS) &&
	    !progress_active()) {
		for (inst2 = instance_list; inst2; inst2 = inst2->next) {
			if (inst2->flags & FLAG_DONE)
				continue;
			if (strcmp(inst2->type, "ext2") &&
			    strcmp(inst2->type, "ext3"))
				continue;
			/*
			 * If we've just started the fsck, wait a tiny
			 * bit before sending the kill, to give it
			 * time to set up the signal handler
			 */
			if (inst2->start_time < time(0)+2) {
				if (fork() == 0) {
					sleep(1);
					kill(inst2->pid, SIGUSR1);
					exit(0);
				}
			} else
				kill(inst2->pid, SIGUSR1);
			inst2->flags |= FLAG_PROGRESS;
			break;
		}
	}
ret_inst:
	if (prev)
		prev->next = inst->next;
	else
		instance_list = inst->next;
	if (verbose > 1)
		printf("Finished with %s (exit status %d)\n",
		       inst->device, inst->exit_status);
	num_running--;
	return inst;
}

#define FLAG_WAIT_ALL           0
#define FLAG_WAIT_ATLEAST_ONE   1
/*
 * Wait until all executing child processes have exited; return the
 * logical OR of all of their exit code values.
 */
static int wait_many(int flags)
{
	struct fsck_instance *inst;
	int     global_status = 0;
	int     wait_flags = 0;

	while ((inst = wait_one(wait_flags))) {
		global_status |= inst->exit_status;
		free_instance(inst);
#ifdef RANDOM_DEBUG
		if (noexecute && (flags & WNOHANG) && !(random() % 3))
			break;
#endif
		if (flags & FLAG_WAIT_ATLEAST_ONE)
			wait_flags = WNOHANG;
	}
	return global_status;
}

/*
 * Run the fsck program on a particular device
 *
 * If the type is specified using -t, and it isn't prefixed with "no"
 * (as in "noext2") and only one filesystem type is specified, then
 * use that type regardless of what is specified in /etc/fstab.
 *
 * If the type isn't specified by the user, then use either the type
 * specified in /etc/fstab, or DEFAULT_FSTYPE.
 */
static void fsck_device(struct fs_info *fs, int interactive)
{
	const char *type;
	int retval;

	interpret_type(fs);

	if (strcmp(fs->type, "auto") != 0)
		type = fs->type;
	else if (fstype && strncmp(fstype, "no", 2) &&
	    strncmp(fstype, "opts=", 5) && strncmp(fstype, "loop", 4) &&
	    !strchr(fstype, ','))
		type = fstype;
	else
		type = DEFAULT_FSTYPE;

	num_running++;
	retval = execute(type, fs->device, fs->mountpt, interactive);
	if (retval) {
		bb_error_msg("error %d while executing fsck.%s for %s",
						retval, type, fs->device);
		num_running--;
	}
}


/*
 * Deal with the fsck -t argument.
 */
struct fs_type_compile {
	char **list;
	int *type;
	int  negate;
} fs_type_compiled;

#define FS_TYPE_NORMAL  0
#define FS_TYPE_OPT     1
#define FS_TYPE_NEGOPT  2

static const char fs_type_syntax_error[] =
"Either all or none of the filesystem types passed to -t must be prefixed\n"
   "with 'no' or '!'.";

static void compile_fs_type(char *fs_type, struct fs_type_compile *cmp)
{
	char    *cp, *list, *s;
	int     num = 2;
	int     negate, first_negate = 1;

	if (fs_type) {
		for (cp=fs_type; *cp; cp++) {
			if (*cp == ',')
				num++;
		}
	}

	cmp->list = xzalloc(num * sizeof(char *));
	cmp->type = xzalloc(num * sizeof(int));
	cmp->negate = 0;

	if (!fs_type)
		return;

	list = string_copy(fs_type);
	num = 0;
	s = strtok(list, ",");
	while(s) {
		negate = 0;
		if (strncmp(s, "no", 2) == 0) {
			s += 2;
			negate = 1;
		} else if (*s == '!') {
			s++;
			negate = 1;
		}
		if (strcmp(s, "loop") == 0)
			/* loop is really short-hand for opts=loop */
			goto loop_special_case;
		else if (strncmp(s, "opts=", 5) == 0) {
			s += 5;
		loop_special_case:
			cmp->type[num] = negate ? FS_TYPE_NEGOPT : FS_TYPE_OPT;
		} else {
			if (first_negate) {
				cmp->negate = negate;
				first_negate = 0;
			}
			if ((negate && !cmp->negate) ||
			    (!negate && cmp->negate)) {
				bb_error_msg_and_die("%s", fs_type_syntax_error);
			}
		}
		cmp->list[num++] = string_copy(s);
		s = strtok(NULL, ",");
	}
	free(list);
}

/*
 * This function returns true if a particular option appears in a
 * comma-delimited options list
 */
static int opt_in_list(char *opt, char *optlist)
{
	char    *list, *s;

	if (!optlist)
		return 0;
	list = string_copy(optlist);

	s = strtok(list, ",");
	while(s) {
		if (strcmp(s, opt) == 0) {
			free(list);
			return 1;
		}
		s = strtok(NULL, ",");
	}
	free(list);
	return 0;
}

/* See if the filesystem matches the criteria given by the -t option */
static int fs_match(struct fs_info *fs, struct fs_type_compile *cmp)
{
	int n, ret = 0, checked_type = 0;
	char *cp;

	if (cmp->list == 0 || cmp->list[0] == 0)
		return 1;

	for (n=0; (cp = cmp->list[n]); n++) {
		switch (cmp->type[n]) {
		case FS_TYPE_NORMAL:
			checked_type++;
			if (strcmp(cp, fs->type) == 0) {
				ret = 1;
			}
			break;
		case FS_TYPE_NEGOPT:
			if (opt_in_list(cp, fs->opts))
				return 0;
			break;
		case FS_TYPE_OPT:
			if (!opt_in_list(cp, fs->opts))
				return 0;
			break;
		}
	}
	if (checked_type == 0)
		return 1;
	return (cmp->negate ? !ret : ret);
}

/* Check if we should ignore this filesystem. */
static int ignore(struct fs_info *fs)
{
	int wanted;
	char *s;

	/*
	 * If the pass number is 0, ignore it.
	 */
	if (fs->passno == 0)
		return 1;

	interpret_type(fs);

	/*
	 * If a specific fstype is specified, and it doesn't match,
	 * ignore it.
	 */
	if (!fs_match(fs, &fs_type_compiled)) return 1;

	/* Are we ignoring this type? */
	if (index_in_str_array(ignored_types, fs->type) >= 0)
		return 1;

	/* Do we really really want to check this fs? */
	wanted = index_in_str_array(really_wanted, fs->type) >= 0;

	/* See if the <fsck.fs> program is available. */
	s = find_fsck(fs->type);
	if (s == NULL) {
		if (wanted)
			bb_error_msg("cannot check %s: fsck.%s not found",
				fs->device, fs->type);
		return 1;
	}
	free(s);

	/* We can and want to check this file system type. */
	return 0;
}

/*
 * Returns TRUE if a partition on the same disk is already being
 * checked.
 */
static int device_already_active(char *device)
{
	struct fsck_instance *inst;
	char *base;

	if (force_all_parallel)
		return 0;

#ifdef BASE_MD
	/* Don't check a soft raid disk with any other disk */
	if (instance_list &&
	    (!strncmp(instance_list->device, BASE_MD, sizeof(BASE_MD)-1) ||
	     !strncmp(device, BASE_MD, sizeof(BASE_MD)-1)))
		return 1;
#endif

	base = base_device(device);
	/*
	 * If we don't know the base device, assume that the device is
	 * already active if there are any fsck instances running.
	 */
	if (!base)
		return (instance_list != 0);
	for (inst = instance_list; inst; inst = inst->next) {
		if (!inst->base_device || !strcmp(base, inst->base_device)) {
			free(base);
			return 1;
		}
	}
	free(base);
	return 0;
}

/* Check all file systems, using the /etc/fstab table. */
static int check_all(void)
{
	struct fs_info *fs = NULL;
	int status = EXIT_OK;
	int not_done_yet = 1;
	int passno = 1;
	int pass_done;

	if (verbose)
		fputs("Checking all file systems.\n", stdout);

	/*
	 * Do an initial scan over the filesystem; mark filesystems
	 * which should be ignored as done, and resolve any "auto"
	 * filesystem types (done as a side-effect of calling ignore()).
	 */
	for (fs = filesys_info; fs; fs = fs->next) {
		if (ignore(fs))
			fs->flags |= FLAG_DONE;
	}

	/*
	 * Find and check the root filesystem.
	 */
	if (!parallel_root) {
		for (fs = filesys_info; fs; fs = fs->next) {
			if (LONE_CHAR(fs->mountpt, '/'))
				break;
		}
		if (fs) {
			if (!skip_root && !ignore(fs)) {
				fsck_device(fs, 1);
				status |= wait_many(FLAG_WAIT_ALL);
				if (status > EXIT_NONDESTRUCT)
					return status;
			}
			fs->flags |= FLAG_DONE;
		}
	}
	/*
	 * This is for the bone-headed user who enters the root
	 * filesystem twice.  Skip root will skep all root entries.
	 */
	if (skip_root)
		for (fs = filesys_info; fs; fs = fs->next)
			if (LONE_CHAR(fs->mountpt, '/'))
				fs->flags |= FLAG_DONE;

	while (not_done_yet) {
		not_done_yet = 0;
		pass_done = 1;

		for (fs = filesys_info; fs; fs = fs->next) {
			if (cancel_requested)
				break;
			if (fs->flags & FLAG_DONE)
				continue;
			/*
			 * If the filesystem's pass number is higher
			 * than the current pass number, then we don't
			 * do it yet.
			 */
			if (fs->passno > passno) {
				not_done_yet++;
				continue;
			}
			/*
			 * If a filesystem on a particular device has
			 * already been spawned, then we need to defer
			 * this to another pass.
			 */
			if (device_already_active(fs->device)) {
				pass_done = 0;
				continue;
			}
			/*
			 * Spawn off the fsck process
			 */
			fsck_device(fs, serialize);
			fs->flags |= FLAG_DONE;

			/*
			 * Only do one filesystem at a time, or if we
			 * have a limit on the number of fsck's extant
			 * at one time, apply that limit.
			 */
			if (serialize ||
			    (max_running && (num_running >= max_running))) {
				pass_done = 0;
				break;
			}
		}
		if (cancel_requested)
			break;
		if (verbose > 1)
			printf("--waiting-- (pass %d)\n", passno);
		status |= wait_many(pass_done ? FLAG_WAIT_ALL :
				    FLAG_WAIT_ATLEAST_ONE);
		if (pass_done) {
			if (verbose > 1)
				printf("----------------------------------\n");
			passno++;
		} else
			not_done_yet++;
	}
	if (cancel_requested && !kill_sent) {
		kill_all(SIGTERM);
		kill_sent++;
	}
	status |= wait_many(FLAG_WAIT_ATLEAST_ONE);
	return status;
}

static void signal_cancel(int sig FSCK_ATTR((unused)))
{
	cancel_requested++;
}

static void PRS(int argc, char **argv)
{
	int     i, j;
	char    *arg, *dev, *tmp = 0;
	char    options[128];
	int     opt = 0;
	int     opts_for_fsck = 0;
	struct sigaction        sa;

	/*
	 * Set up signal action
	 */
	memset(&sa, 0, sizeof(struct sigaction));
	sa.sa_handler = signal_cancel;
	sigaction(SIGINT, &sa, 0);
	sigaction(SIGTERM, &sa, 0);

	num_devices = 0;
	num_args = 0;
	instance_list = 0;

	for (i=1; i < argc; i++) {
		arg = argv[i];
		if (!arg)
			continue;
		if ((arg[0] == '/' && !opts_for_fsck) || strchr(arg, '=')) {
			if (num_devices >= MAX_DEVICES) {
				bb_error_msg_and_die("too many devices");
			}
			dev = blkid_get_devname(cache, arg, NULL);
			if (!dev && strchr(arg, '=')) {
				/*
				 * Check to see if we failed because
				 * /proc/partitions isn't found.
				 */
				if (access("/proc/partitions", R_OK) < 0) {
					bb_perror_msg_and_die("cannot open /proc/partitions "
							"(is /proc mounted?)");
				}
				/*
				 * Check to see if this is because
				 * we're not running as root
				 */
				if (geteuid())
					bb_error_msg_and_die(
		"must be root to scan for matching filesystems: %s\n", arg);
				else
					bb_error_msg_and_die(
		"cannot find matching filesystem: %s", arg);
			}
			devices[num_devices++] = dev ? dev : string_copy(arg);
			continue;
		}
		if (arg[0] != '-' || opts_for_fsck) {
			if (num_args >= MAX_ARGS) {
				bb_error_msg_and_die("too many arguments");
			}
			args[num_args++] = string_copy(arg);
			continue;
		}
		for (j=1; arg[j]; j++) {
			if (opts_for_fsck) {
				options[++opt] = arg[j];
				continue;
			}
			switch (arg[j]) {
			case 'A':
				doall++;
				break;
			case 'C':
				progress++;
				if (arg[j+1]) {
					progress_fd = string_to_int(arg+j+1);
					if (progress_fd < 0)
						progress_fd = 0;
					else
						goto next_arg;
				} else if ((i+1) < argc
				 && argv[i+1][0] != '-') {
					progress_fd = string_to_int(argv[i]);
					if (progress_fd < 0)
						progress_fd = 0;
					else {
						goto next_arg;
						i++;
					}
				}
				break;
			case 'V':
				verbose++;
				break;
			case 'N':
				noexecute++;
				break;
			case 'R':
				skip_root++;
				break;
			case 'T':
				notitle++;
				break;
			case 'M':
				like_mount++;
				break;
			case 'P':
				parallel_root++;
				break;
			case 's':
				serialize++;
				break;
			case 't':
				tmp = 0;
				if (fstype)
					bb_show_usage();
				if (arg[j+1])
					tmp = arg+j+1;
				else if ((i+1) < argc)
					tmp = argv[++i];
				else
					bb_show_usage();
				fstype = string_copy(tmp);
				compile_fs_type(fstype, &fs_type_compiled);
				goto next_arg;
			case '-':
				opts_for_fsck++;
				break;
			case '?':
				bb_show_usage();
				break;
			default:
				options[++opt] = arg[j];
				break;
			}
		}
	next_arg:
		if (opt) {
			options[0] = '-';
			options[++opt] = '\0';
			if (num_args >= MAX_ARGS) {
				bb_error_msg("too many arguments");
			}
			args[num_args++] = string_copy(options);
			opt = 0;
		}
	}
	if (getenv("FSCK_FORCE_ALL_PARALLEL"))
		force_all_parallel++;
	if ((tmp = getenv("FSCK_MAX_INST")))
	    max_running = atoi(tmp);
}

int fsck_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int fsck_main(int argc, char **argv)
{
	int i, status = 0;
	int interactive = 0;
	const char *fstab;
	struct fs_info *fs;

	setvbuf(stdout, NULL, _IONBF, BUFSIZ);
	setvbuf(stderr, NULL, _IONBF, BUFSIZ);

	blkid_get_cache(&cache, NULL);
	PRS(argc, argv);

	if (!notitle)
		printf("fsck %s (%s)\n", E2FSPROGS_VERSION, E2FSPROGS_DATE);

	fstab = getenv("FSTAB_FILE");
	if (!fstab)
		fstab = _PATH_MNTTAB;
	load_fs_info(fstab);

	fsck_path = e2fs_set_sbin_path();

	if ((num_devices == 1) || (serialize))
		interactive = 1;

	/* If -A was specified ("check all"), do that! */
	if (doall)
		return check_all();

	if (num_devices == 0) {
		serialize++;
		interactive++;
		return check_all();
	}
	for (i = 0; i < num_devices; i++) {
		if (cancel_requested) {
			if (!kill_sent) {
				kill_all(SIGTERM);
				kill_sent++;
			}
			break;
		}
		fs = lookup(devices[i]);
		if (!fs) {
			fs = create_fs_device(devices[i], 0, "auto",
					      0, -1, -1);
			if (!fs)
				continue;
		}
		fsck_device(fs, interactive);
		if (serialize ||
		    (max_running && (num_running >= max_running))) {
			struct fsck_instance *inst;

			inst = wait_one(0);
			if (inst) {
				status |= inst->exit_status;
				free_instance(inst);
			}
			if (verbose > 1)
				printf("----------------------------------\n");
		}
	}
	status |= wait_many(FLAG_WAIT_ALL);
	blkid_put_cache(cache);
	return status;
}