/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1980, 1986, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#define _WANT_P_OSREL
#include <sys/param.h>
#include <sys/file.h>
#include <sys/mount.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <sys/uio.h>
#include <sys/disklabel.h>

#include <ufs/ufs/dinode.h>
#include <ufs/ffs/fs.h>

#include <err.h>
#include <errno.h>
#include <fstab.h>
#include <grp.h>
#include <inttypes.h>
#include <mntopts.h>
#include <paths.h>
#include <stdint.h>
#include <string.h>
#include <time.h>

#include "fsck.h"

static int  restarts;
static char snapname[BUFSIZ];   /* when doing snapshots, the name of the file */

static void usage(void) __dead2;
static intmax_t argtoimax(int flag, const char *req, const char *str, int base);
static int checkfilesys(char *filesys);
static int setup_bkgrdchk(struct statfs *mntp, int sbrdfailed, char **filesys);

int
main(int argc, char *argv[])
{
        int ch;
        struct rlimit rlimit;
        struct itimerval itimerval;
        int fsret;
        int ret = 0;

        sync();
        skipclean = 1;
        inoopt = 0;
        while ((ch = getopt(argc, argv, "b:Bc:CdEfFm:npRrSyZz")) != -1) {
                switch (ch) {
                case 'b':
                        skipclean = 0;
                        bflag = argtoimax('b', "number", optarg, 10);
                        printf("Alternate super block location: %jd\n", bflag);
                        break;

                case 'B':
                        bkgrdflag = 1;
                        break;

                case 'c':
                        skipclean = 0;
                        cvtlevel = argtoimax('c', "conversion level", optarg,
                            10);
                        if (cvtlevel < 3)
                                errx(EEXIT, "cannot do level %d conversion",
                                    cvtlevel);
                        break;

                case 'd':
                        debug++;
                        break;

                case 'E':
                        Eflag++;
                        break;

                case 'f':
                        skipclean = 0;
                        break;

                case 'F':
                        bkgrdcheck = 1;
                        break;

                case 'm':
                        lfmode = argtoimax('m', "mode", optarg, 8);
                        if (lfmode &~ 07777)
                                errx(EEXIT, "bad mode to -m: %o", lfmode);
                        printf("** lost+found creation mode %o\n", lfmode);
                        break;

                case 'n':
                        nflag++;
                        yflag = 0;
                        break;

                case 'p':
                        preen++;
                        /*FALLTHROUGH*/

                case 'C':
                        ckclean++;
                        break;

                case 'R':
                        wantrestart = 1;
                        break;
                case 'r':
                        inoopt++;
                        break;

                case 'S':
                        surrender = 1;
                        break;

                case 'y':
                        yflag++;
                        nflag = 0;
                        break;

                case 'Z':
                        Zflag++;
                        break;

                case 'z':
                        zflag++;
                        break;

                default:
                        usage();
                }
        }
        argc -= optind;
        argv += optind;

        if (!argc)
                usage();

        if (bkgrdflag && cvtlevel > 0) {
                pfatal("CANNOT CONVERT A SNAPSHOT\n");
                exit(EEXIT);
        }

        if (signal(SIGINT, SIG_IGN) != SIG_IGN)
                (void)signal(SIGINT, catch);
        if (ckclean)
                (void)signal(SIGQUIT, catchquit);
        signal(SIGINFO, infohandler);
        if (bkgrdflag) {
                signal(SIGALRM, alarmhandler);
                itimerval.it_interval.tv_sec = 5;
                itimerval.it_interval.tv_usec = 0;
                itimerval.it_value.tv_sec = 5;
                itimerval.it_value.tv_usec = 0;
                setitimer(ITIMER_REAL, &itimerval, NULL);
        }
        /*
         * Push up our allowed memory limit so we can cope
         * with huge file systems.
         */
        if (getrlimit(RLIMIT_DATA, &rlimit) == 0) {
                rlimit.rlim_cur = rlimit.rlim_max;
                (void)setrlimit(RLIMIT_DATA, &rlimit);
        }
        while (argc > 0) {
                if ((fsret = checkfilesys(*argv)) == ERESTART)
                        continue;
                ret |= fsret;
                argc--;
                argv++;
        }

        if (returntosingle)
                ret = 2;
        exit(ret);
}

static intmax_t
argtoimax(int flag, const char *req, const char *str, int base)
{
        char *cp;
        intmax_t ret;

        ret = strtoimax(str, &cp, base);
        if (cp == str || *cp)
                errx(EEXIT, "-%c flag requires a %s", flag, req);
        return (ret);
}

/*
 * Check the specified file system.
 */
/* ARGSUSED */
static int
checkfilesys(char *filesys)
{
        ufs2_daddr_t n_ffree, n_bfree;
        struct dups *dp;
        struct statfs *mntp;
        intmax_t blks, files;
        size_t size;
        int sbreadfailed, ofsmodified;

        fsutilinit();
        fsckinit();

        cdevname = filesys;
        if (debug && ckclean)
                pwarn("starting\n");
        /*
         * Make best effort to get the disk name. Check first to see
         * if it is listed among the mounted file systems. Failing that
         * check to see if it is listed in /etc/fstab.
         */
        mntp = getmntpoint(filesys);
        if (mntp != NULL)
                filesys = mntp->f_mntfromname;
        else
                filesys = blockcheck(filesys);
        /*
         * If -F flag specified, check to see whether a background check
         * is possible and needed. If possible and needed, exit with
         * status zero. Otherwise exit with status non-zero. A non-zero
         * exit status will cause a foreground check to be run.
         */
        sblock_init();
        sbreadfailed = 0;
        if (openfilesys(filesys) == 0 || readsb() == 0)
                sbreadfailed = 1;
        if (bkgrdcheck) {
                if (sbreadfailed)
                        exit(3);        /* Cannot read superblock */
                if ((sblock.fs_flags & FS_NEEDSFSCK) == FS_NEEDSFSCK)
                        exit(4);        /* Earlier background failed */
                if ((sblock.fs_flags & FS_SUJ) == FS_SUJ) {
                        maxino = sblock.fs_ncg * sblock.fs_ipg;
                        maxfsblock = sblock.fs_size;
                        bufinit();
                        preen = 1;
                        if (suj_check(filesys) == 0)
                                exit(4); /* Journal good, run it now */
                }
                if ((sblock.fs_flags & FS_DOSOFTDEP) == 0)
                        exit(5);        /* Not running soft updates */
                size = MIBSIZE;
                if (sysctlnametomib("vfs.ffs.adjrefcnt", adjrefcnt, &size) < 0)
                        exit(6);        /* Lacks kernel support */
                if ((mntp == NULL && sblock.fs_clean == 1) ||
                    (mntp != NULL && (sblock.fs_flags & FS_UNCLEAN) == 0))
                        exit(7);        /* Filesystem clean, report it now */
                exit(0);
        }
        if (ckclean && skipclean) {
                /*
                 * If file system is gjournaled, check it here.
                 */
                if (sbreadfailed)
                        exit(3);        /* Cannot read superblock */
                if (bkgrdflag == 0 &&
                    (nflag || (fswritefd = open(filesys, O_WRONLY)) < 0)) {
                        fswritefd = -1;
                        if (preen)
                                pfatal("NO WRITE ACCESS");
                        printf(" (NO WRITE)");
                }
                if ((sblock.fs_flags & FS_GJOURNAL) != 0) {
                        if (sblock.fs_clean == 1) {
                                pwarn("FILE SYSTEM CLEAN; SKIPPING CHECKS\n");
                                exit(0);
                        }
                        if ((sblock.fs_flags &
                            (FS_UNCLEAN | FS_NEEDSFSCK)) == 0) {
                                bufinit();
                                gjournal_check(filesys);
                                if (chkdoreload(mntp, pwarn) == 0)
                                        exit(0);
                                exit(4);
                        } else {
                                pfatal("FULL FSCK NEEDED, CANNOT RUN FAST "
                                    "FSCK\n");
                        }
                }
                close(fswritefd);
                fswritefd = -1;
        }
        if (bkgrdflag) {
                switch (setup_bkgrdchk(mntp, sbreadfailed, &filesys)) {
                case -1: /* filesystem clean */
                        goto clean;
                case 0: /* cannot do background, give up */
                        exit(EEXIT);
                case 1: /* doing background check, preen rules apply */
                        preen = 1;
                        break;
                }
        }

        switch (setup(filesys)) {
        case 0:
                if (preen)
                        pfatal("CAN'T CHECK FILE SYSTEM.");
                return (EEXIT);
        case -1:
        clean:
                pwarn("clean, %ld free ", (long)(sblock.fs_cstotal.cs_nffree +
                    sblock.fs_frag * sblock.fs_cstotal.cs_nbfree));
                printf("(%jd frags, %jd blocks, %.1f%% fragmentation)\n",
                    (intmax_t)sblock.fs_cstotal.cs_nffree,
                    (intmax_t)sblock.fs_cstotal.cs_nbfree,
                    sblock.fs_cstotal.cs_nffree * 100.0 / sblock.fs_dsize);
                return (0);
        }
        /*
         * Determine if we can and should do journal recovery.
         */
        if (bkgrdflag == 0 && (sblock.fs_flags & FS_SUJ) == FS_SUJ) {
                if ((sblock.fs_flags & FS_NEEDSFSCK) != FS_NEEDSFSCK &&
                    skipclean) {
                        sujrecovery = 1;
                        if (suj_check(filesys) == 0) {
                                pwarn("\n**** FILE SYSTEM MARKED CLEAN ****\n");
                                if (chkdoreload(mntp, pwarn) == 0)
                                        exit(0);
                                exit(4);
                        }
                        sujrecovery = 0;
                        pwarn("Skipping journal, "
                            "falling through to full fsck\n");
                }
                if (fswritefd != -1) {
                        /*
                         * Write the superblock so we don't try to recover the
                         * journal on another pass. If this is the only change
                         * to the filesystem, we do not want it to be called
                         * out as modified.
                         */
                        sblock.fs_mtime = time(NULL);
                        sbdirty();
                        ofsmodified = fsmodified;
                        flush(fswritefd, &sblk);
                        fsmodified = ofsmodified;
                }
        }
        /*
         * If the filesystem was run on an old kernel that did not
         * support check hashes, clear the check-hash flags so that
         * we do not try to verify them.
         */
        if ((sblock.fs_flags & FS_METACKHASH) == 0)
                sblock.fs_metackhash = 0;
        /*
         * If we are running on a kernel that can provide check hashes
         * that are not yet enabled for the filesystem and we are
         * running manually without the -y flag, offer to add any
         * supported check hashes that are not already enabled.
         */
        ckhashadd = 0;
        if (preen == 0 && yflag == 0 && sblock.fs_magic != FS_UFS1_MAGIC &&
            fswritefd != -1 && getosreldate() >= P_OSREL_CK_CYLGRP) {
                if ((sblock.fs_metackhash & CK_CYLGRP) == 0 &&
                    reply("ADD CYLINDER GROUP CHECK-HASH PROTECTION") != 0) {
                        ckhashadd |= CK_CYLGRP;
                        sblock.fs_metackhash |= CK_CYLGRP;
                }
                if ((sblock.fs_metackhash & CK_SUPERBLOCK) == 0 &&
                    getosreldate() >= P_OSREL_CK_SUPERBLOCK &&
                    reply("ADD SUPERBLOCK CHECK-HASH PROTECTION") != 0) {
                        ckhashadd |= CK_SUPERBLOCK;
                        sblock.fs_metackhash |= CK_SUPERBLOCK;
                }
                if ((sblock.fs_metackhash & CK_INODE) == 0 &&
                    getosreldate() >= P_OSREL_CK_INODE &&
                    reply("ADD INODE CHECK-HASH PROTECTION") != 0) {
                        ckhashadd |= CK_INODE;
                        sblock.fs_metackhash |= CK_INODE;
                }
#ifdef notyet
                if ((sblock.fs_metackhash & CK_INDIR) == 0 &&
                    getosreldate() >= P_OSREL_CK_INDIR &&
                    reply("ADD INDIRECT BLOCK CHECK-HASH PROTECTION") != 0) {
                        ckhashadd |= CK_INDIR;
                        sblock.fs_metackhash |= CK_INDIR;
                }
                if ((sblock.fs_metackhash & CK_DIR) == 0 &&
                    getosreldate() >= P_OSREL_CK_DIR &&
                    reply("ADD DIRECTORY CHECK-HASH PROTECTION") != 0) {
                        ckhashadd |= CK_DIR;
                        sblock.fs_metackhash |= CK_DIR;
                }
#endif /* notyet */
                if (ckhashadd != 0) {
                        sblock.fs_flags |= FS_METACKHASH;
                        sbdirty();
                }
        }
        /*
         * Cleared if any questions answered no. Used to decide if
         * the superblock should be marked clean.
         */
        resolved = 1;
        /*
         * 1: scan inodes tallying blocks used
         */
        if (preen == 0 || debug) {
                printf("** Last Mounted on %s\n", sblock.fs_fsmnt);
                if (mntp != NULL && mntp->f_flags & MNT_ROOTFS)
                        printf("** Root file system\n");
                printf("** Phase 1 - Check Blocks and Sizes\n");
        }
        clock_gettime(CLOCK_REALTIME_PRECISE, &startprog);
        pass1();
        IOstats("Pass1");

        /*
         * 1b: locate first references to duplicates, if any
         */
        if (duplist) {
                if (preen || usedsoftdep)
                        pfatal("INTERNAL ERROR: DUPS WITH %s%s%s",
                            preen ? "-p" : "",
                            (preen && usedsoftdep) ? " AND " : "",
                            usedsoftdep ? "SOFTUPDATES" : "");
                if (preen == 0 || debug)
                        printf("** Phase 1b - Rescan For More DUPS\n");
                pass1b();
                IOstats("Pass1b");
        }

        /*
         * 2: traverse directories from root to mark all connected directories
         */
        if (preen == 0 || debug)
                printf("** Phase 2 - Check Pathnames\n");
        pass2();
        IOstats("Pass2");

        /*
         * 3: scan inodes looking for disconnected directories
         */
        if (preen == 0 || debug)
                printf("** Phase 3 - Check Connectivity\n");
        pass3();
        IOstats("Pass3");

        /*
         * 4: scan inodes looking for disconnected files; check reference counts
         */
        if (preen == 0 || debug)
                printf("** Phase 4 - Check Reference Counts\n");
        pass4();
        IOstats("Pass4");

        /*
         * 5: check and repair resource counts in cylinder groups
         */
        if (preen == 0 || debug)
                printf("** Phase 5 - Check Cyl groups\n");
        snapflush(std_checkblkavail);
        if (cgheader_corrupt) {
                printf("PHASE 5 SKIPPED DUE TO CORRUPT CYLINDER GROUP "
                    "HEADER(S)\n\n");
        } else {
                pass5();
                IOstats("Pass5");
        }

        /*
         * print out summary statistics
         */
        n_ffree = sblock.fs_cstotal.cs_nffree;
        n_bfree = sblock.fs_cstotal.cs_nbfree;
        files = maxino - UFS_ROOTINO - sblock.fs_cstotal.cs_nifree - n_files;
        blks = n_blks +
            sblock.fs_ncg * (cgdmin(&sblock, 0) - cgsblock(&sblock, 0));
        blks += cgsblock(&sblock, 0) - cgbase(&sblock, 0);
        blks += howmany(sblock.fs_cssize, sblock.fs_fsize);
        blks = maxfsblock - (n_ffree + sblock.fs_frag * n_bfree) - blks;
        if (bkgrdflag && (files > 0 || blks > 0)) {
                countdirs = sblock.fs_cstotal.cs_ndir - countdirs;
                pwarn("Reclaimed: %ld directories, %jd files, %jd fragments\n",
                    countdirs, files - countdirs, blks);
        }
        pwarn("%ld files, %jd used, %ju free ",
            (long)n_files, (intmax_t)n_blks,
            (uintmax_t)n_ffree + sblock.fs_frag * n_bfree);
        printf("(%ju frags, %ju blocks, %.1f%% fragmentation)\n",
            (uintmax_t)n_ffree, (uintmax_t)n_bfree,
            n_ffree * 100.0 / sblock.fs_dsize);
        if (debug) {
                if (files < 0)
                        printf("%jd inodes missing\n", -files);
                if (blks < 0)
                        printf("%jd blocks missing\n", -blks);
                if (duplist != NULL) {
                        printf("The following duplicate blocks remain:");
                        for (dp = duplist; dp; dp = dp->next)
                                printf(" %jd,", (intmax_t)dp->dup);
                        printf("\n");
                }
        }
        duplist = (struct dups *)0;
        muldup = (struct dups *)0;
        inocleanup();
        if (fsmodified) {
                sblock.fs_time = time(NULL);
                sbdirty();
        }
        if (cvtlevel && (sblk.b_flags & B_DIRTY) != 0) {
                /*
                 * Write out the duplicate super blocks
                 */
                if (sbput(fswritefd, &sblock, sblock.fs_ncg) == 0)
                        fsmodified = 1;
        }
        if (rerun)
                resolved = 0;

        /*
         * Check to see if the file system is mounted read-write.
         */
        if (bkgrdflag == 0 && mntp != NULL && (mntp->f_flags & MNT_RDONLY) == 0)
                resolved = 0;
        ckfini(resolved);

        if (fsmodified && !preen)
                printf("\n***** FILE SYSTEM WAS MODIFIED *****\n");
        if (rerun) {
                if (wantrestart && (restarts++ < 10) &&
                    (preen || reply("RESTART")))
                        return (ERESTART);
                printf("\n***** PLEASE RERUN FSCK *****\n");
        }
        if (chkdoreload(mntp, pwarn) != 0) {
                if (!fsmodified)
                        return (0);
                if (!preen)
                        printf("\n***** REBOOT NOW *****\n");
                sync();
                return (4);
        }
        return (rerun ? ERERUN : 0);
}

/*
 * If we are to do a background check:
 *      Get the mount point information of the file system
 *      If already clean, return -1
 *      Check that kernel supports background fsck
 *      Find or create the snapshot directory
 *      Create the snapshot file
 *      Open snapshot
 *      If anything fails print reason and return 0 which exits
 */
static int
setup_bkgrdchk(struct statfs *mntp, int sbreadfailed, char **filesys)
{
        struct stat snapdir;
        struct group *grp;
        struct iovec *iov;
        char errmsg[255];
        int iovlen;
        size_t size;

        /* Get the mount point information of the file system */
        if (mntp == NULL) {
                pwarn("NOT MOUNTED, CANNOT RUN IN BACKGROUND\n");
                return (0);
        }
        if ((mntp->f_flags & MNT_RDONLY) != 0) {
                pwarn("MOUNTED READ-ONLY, CANNOT RUN IN BACKGROUND\n");
                return (0);
        }
        if ((mntp->f_flags & MNT_SOFTDEP) == 0) {
                pwarn("NOT USING SOFT UPDATES, CANNOT RUN IN BACKGROUND\n");
                return (0);
        }
        if (sbreadfailed) {
                pwarn("SUPERBLOCK READ FAILED, CANNOT RUN IN BACKGROUND\n");
                return (0);
        }
        if ((sblock.fs_flags & FS_NEEDSFSCK) != 0) {
                pwarn("FULL FSCK NEEDED, CANNOT RUN IN BACKGROUND\n");
                return (0);
        }
        if (skipclean && ckclean &&
           (sblock.fs_flags & (FS_UNCLEAN|FS_NEEDSFSCK)) == 0) {
                /*
                 * file system is clean;
                 * skip snapshot and report it clean
                 */
                pwarn("FILE SYSTEM CLEAN; SKIPPING CHECKS\n");
                return (-1);
        }
        /* Check that kernel supports background fsck */
        size = MIBSIZE;
        if (sysctlnametomib("vfs.ffs.adjrefcnt", adjrefcnt, &size) < 0||
            sysctlnametomib("vfs.ffs.adjblkcnt", adjblkcnt, &size) < 0||
            sysctlnametomib("vfs.ffs.setsize", setsize, &size) < 0 ||
            sysctlnametomib("vfs.ffs.freefiles", freefiles, &size) < 0||
            sysctlnametomib("vfs.ffs.freedirs", freedirs, &size) < 0 ||
            sysctlnametomib("vfs.ffs.freeblks", freeblks, &size) < 0) {
                pwarn("KERNEL LACKS BACKGROUND FSCK SUPPORT\n");
                return (0);
        }
        /*
         * When kernel lacks runtime bgfsck superblock summary
         * adjustment functionality, it does not mean we can not
         * continue, as old kernels will recompute the summary at
         * mount time. However, it will be an unexpected softupdates
         * inconsistency if it turns out that the summary is still
         * incorrect. Set a flag so subsequent operation can know this.
         */
        bkgrdsumadj = 1;
        if (sysctlnametomib("vfs.ffs.adjndir", adjndir, &size) < 0 ||
           sysctlnametomib("vfs.ffs.adjnbfree", adjnbfree, &size) < 0 ||
           sysctlnametomib("vfs.ffs.adjnifree", adjnifree, &size) < 0 ||
           sysctlnametomib("vfs.ffs.adjnffree", adjnffree, &size) < 0 ||
           sysctlnametomib("vfs.ffs.adjnumclusters", adjnumclusters,
           &size) < 0) {
                bkgrdsumadj = 0;
                pwarn("KERNEL LACKS RUNTIME SUPERBLOCK SUMMARY ADJUSTMENT "
                    "SUPPORT\n");
        }
        /* Find or create the snapshot directory */
        snprintf(snapname, sizeof snapname, "%s/.snap", mntp->f_mntonname);
        if (stat(snapname, &snapdir) < 0) {
                if (errno != ENOENT) {
                        pwarn("CANNOT FIND SNAPSHOT DIRECTORY %s: %s, CANNOT "
                            "RUN IN BACKGROUND\n", snapname, strerror(errno));
                        return (0);
                }
                if ((grp = getgrnam("operator")) == NULL ||
                           mkdir(snapname, 0770) < 0 ||
                           chown(snapname, -1, grp->gr_gid) < 0 ||
                           chmod(snapname, 0770) < 0) {
                        pwarn("CANNOT CREATE SNAPSHOT DIRECTORY %s: %s, "
                            "CANNOT RUN IN BACKGROUND\n", snapname,
                            strerror(errno));
                        return (0);
                }
        } else if (!S_ISDIR(snapdir.st_mode)) {
                pwarn("%s IS NOT A DIRECTORY, CANNOT RUN IN BACKGROUND\n",
                    snapname);
                return (0);
        }
        /* Create the snapshot file */
        iov = NULL;
        iovlen = 0;
        errmsg[0] = '\0';
        snprintf(snapname, sizeof snapname, "%s/.snap/fsck_snapshot",
            mntp->f_mntonname);
        build_iovec(&iov, &iovlen, "fstype", "ffs", 4);
        build_iovec(&iov, &iovlen, "from", snapname, (size_t)-1);
        build_iovec(&iov, &iovlen, "fspath", mntp->f_mntonname, (size_t)-1);
        build_iovec(&iov, &iovlen, "errmsg", errmsg, sizeof(errmsg));
        build_iovec(&iov, &iovlen, "update", NULL, 0);
        build_iovec(&iov, &iovlen, "snapshot", NULL, 0);
        /* Create snapshot, removing old snapshot if it exists */
        while (nmount(iov, iovlen, mntp->f_flags) < 0) {
                if (errno == EEXIST && unlink(snapname) == 0)
                        continue;
                pwarn("CANNOT CREATE SNAPSHOT %s: %s %s\n", snapname,
                    strerror(errno), errmsg);
                return (0);
        }
        /* Open snapshot */
        if (openfilesys(snapname) == 0) {
                unlink(snapname);
                pwarn("CANNOT OPEN SNAPSHOT %s: %s, CANNOT RUN IN "
                    "BACKGROUND\n", snapname, strerror(errno));
                return (0);
        }
        /* Immediately unlink snapshot so that it will be deleted when closed */
        unlink(snapname);
        free(sblock.fs_csp);
        free(sblock.fs_si);
        if (readsb() == 0) {
                pwarn("CANNOT READ SNAPSHOT SUPERBLOCK\n");
                return (0);
        }
        *filesys = snapname;
        cmd.version = FFS_CMD_VERSION;
        cmd.handle = fsreadfd;
        return (1);
}

static void
usage(void)
{
        (void) fprintf(stderr,
"usage: %s [-BCdEFfnpRrSyZ] [-b block] [-c level] [-m mode] filesystem ...\n",
            getprogname());
        exit(1);
}

void
infohandler(int sig __unused)
{
        got_siginfo = 1;
}

void
alarmhandler(int sig __unused)
{
        got_sigalarm = 1;
}