/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1994
 *      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.
 */

#include <sys/param.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/uio.h>

#include <err.h>
#include <errno.h>
#include <mntopts.h>
#include <paths.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int getmnt_silent = 0;

void
getmntopts(const char *options, const struct mntopt *m0, int *flagp,
        int *altflagp)
{
        const struct mntopt *m;
        int negative, len;
        char *opt, *optbuf, *p;
        int *thisflagp;

        /* Copy option string, since it is about to be torn asunder... */
        if ((optbuf = strdup(options)) == NULL)
                err(1, NULL);

        for (opt = optbuf; (opt = strtok(opt, ",")) != NULL; opt = NULL) {
                /* Check for "no" prefix. */
                if (opt[0] == 'n' && opt[1] == 'o') {
                        negative = 1;
                        opt += 2;
                } else
                        negative = 0;

                /*
                 * for options with assignments in them (ie. quotas)
                 * ignore the assignment as it's handled elsewhere
                 */
                p = strchr(opt, '=');
                if (p != NULL)
                         *++p = '\0';

                /* Scan option table. */
                for (m = m0; m->m_option != NULL; ++m) {
                        len = strlen(m->m_option);
                        if (strncasecmp(opt, m->m_option, len) == 0)
                                if (opt[len] == '\0' || opt[len] == '=')
                                        break;
                }

                /* Save flag, or fail if option is not recognized. */
                if (m->m_option) {
                        thisflagp = m->m_altloc ? altflagp : flagp;
                        if (negative == m->m_inverse)
                                *thisflagp |= m->m_flag;
                        else
                                *thisflagp &= ~m->m_flag;
                } else if (!getmnt_silent) {
                        errx(1, "-o %s: option not supported", opt);
                }
        }

        free(optbuf);
}

void
rmslashes(char *rrpin, char *rrpout)
{
        char *rrpoutstart;

        *rrpout = *rrpin;
        for (rrpoutstart = rrpout; *rrpin != '\0'; *rrpout++ = *rrpin++) {

                /* skip all double slashes */
                while (*rrpin == '/' && *(rrpin + 1) == '/')
                         rrpin++;
        }

        /* remove trailing slash if necessary */
        if (rrpout - rrpoutstart > 1 && *(rrpout - 1) == '/')
                *(rrpout - 1) = '\0';
        else
                *rrpout = '\0';
}

int
checkpath(const char *path, char *resolved)
{
        struct stat sb;

        if (realpath(path, resolved) == NULL || stat(resolved, &sb) != 0)
                return (1);
        if (!S_ISDIR(sb.st_mode)) {
                errno = ENOTDIR;
                return (1);
        }
        return (0);
}

int
checkpath_allow_file(const char *path, char *resolved)
{
        struct stat sb;

        if (realpath(path, resolved) == NULL || stat(resolved, &sb) != 0)
                return (1);
        if (!S_ISDIR(sb.st_mode) && !S_ISREG(sb.st_mode)) {
                errno = ENOTDIR;
                return (1);
        }
        return (0);
}

static char *
prependdevtopath(const char *path, char *buf, u_long buflen)
{
        u_long len;

        if ((len = strlen(_PATH_DEV) + strlen(path) + 1) > buflen)
                return NULL;
        strncpy(buf, _PATH_DEV, len);
        strncat(buf, path, len - sizeof(_PATH_DEV));
        return (buf);
}

/*
 * Get the mount point information for name. Name may be mount point name
 * or device name (with or without /dev/ preprended).
 */
struct statfs *
getmntpoint(const char *name)
{
        struct stat devstat, mntdevstat;
        char *devname;
        struct statfs *mntbuf, *statfsp;
        int i, len, isdev, mntsize, mntfromnamesize;
        char device[sizeof(_PATH_DEV) - 1 + MNAMELEN];
        u_long devlen;

        devlen = sizeof(device);
        /*
         * Note that stat(NULL, &statbuf) returns -1 (EBADF) which will
         * cause us to return NULL if prependdevtopath() returns NULL.
         */
        if (stat(name, &devstat) != 0 &&
            (name[0] != '/' &&
             stat(prependdevtopath(name, device, devlen), &devstat) != 0))
                return (NULL);
        if (S_ISCHR(devstat.st_mode) || S_ISBLK(devstat.st_mode))
                isdev = 1;
        else
                isdev = 0;
        mntsize = getmntinfo(&mntbuf, MNT_NOWAIT);
        mntfromnamesize = sizeof(statfsp->f_mntfromname);
        for (i = 0; i < mntsize; i++) {
                statfsp = &mntbuf[i];
                if (isdev == 0) {
                        if (strcmp(name, statfsp->f_mntonname))
                                continue;
                        return (statfsp);
                }
                devname = statfsp->f_mntfromname;
                if (*devname == '/') {
                        if (stat(devname, &mntdevstat) != 0)
                                continue;
                } else {
                        devname = prependdevtopath(devname, device, devlen);
                        if (devname == NULL ||
                            (len = strlen(devname)) > mntfromnamesize)
                                continue;
                        if (stat(devname, &mntdevstat) != 0)
                                continue;
                        strncpy(statfsp->f_mntfromname, devname, len);
                }
                if (S_ISCHR(mntdevstat.st_mode) &&
                    mntdevstat.st_rdev == devstat.st_rdev)
                        return (statfsp);
        }
        return (NULL);
}

/*
 * If possible reload a mounted filesystem.
 * When prtmsg != NULL print a warning if a reload is attempted, but fails.
 * Return 0 on success, 1 on failure.
 */
int
chkdoreload(struct statfs *mntp,
        void (*prtmsg)(const char *, ...) __printflike(1,2))
{
        struct iovec *iov;
        int iovlen, error;
        char errmsg[255];

        /*
         * If the filesystem is not mounted it does not need to be reloaded.
         * If it is mounted for writing, then it could not have been opened
         * for writing by a utility, so does not need to be reloaded.
         */
        if (mntp == NULL || (mntp->f_flags & MNT_RDONLY) == 0)
                return (0);

        /*
         * We modified a mounted file system.  Do a mount update on
         * it so we can continue using it as safely as possible.
         */
        iov = NULL;
        iovlen = 0;
        errmsg[0] = '\0';
        build_iovec(&iov, &iovlen, "fstype", __DECONST(void *, "ffs"), 4);
        build_iovec(&iov, &iovlen, "from", mntp->f_mntfromname, (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, "reload", NULL, 0);
        /*
         * XX: We need the following line until we clean up
         * nmount parsing of root mounts and NFS root mounts.
         */
        build_iovec(&iov, &iovlen, "ro", NULL, 0);
        error = nmount(iov, iovlen, mntp->f_flags);
        free_iovec(&iov, &iovlen);
        if (error == 0)
                return (0);
        if (prtmsg != NULL)
                prtmsg("mount reload of '%s' failed: %s %s\n\n",
                    mntp->f_mntonname, strerror(errno), errmsg);
        return (1);
}

void
build_iovec(struct iovec **iov, int *iovlen, const char *name, void *val,
            size_t len)
{
        int i;

        if (*iovlen < 0)
                return;
        i = *iovlen;
        *iov = realloc(*iov, sizeof **iov * (i + 2));
        if (*iov == NULL) {
                *iovlen = -1;
                return;
        }
        (*iov)[i].iov_base = strdup(name);
        (*iov)[i].iov_len = strlen(name) + 1;
        i++;
        (*iov)[i].iov_base = val;
        if (len == (size_t)-1) {
                if (val != NULL)
                        len = strlen(val) + 1;
                else
                        len = 0;
        }
        (*iov)[i].iov_len = (int)len;
        *iovlen = ++i;
}

/*
 * This function is needed for compatibility with parameters
 * which used to use the mount_argf() command for the old mount() syscall.
 */
void
build_iovec_argf(struct iovec **iov, int *iovlen, const char *name,
    const char *fmt, ...)
{
        va_list ap;
        char val[255] = { 0 };

        va_start(ap, fmt);
        vsnprintf(val, sizeof(val), fmt, ap);
        va_end(ap);
        build_iovec(iov, iovlen, name, strdup(val), (size_t)-1);
}

/*
 * Free the iovec and reset to NULL with zero length.  Useful for calling
 * nmount in a loop.
 */
void
free_iovec(struct iovec **iov, int *iovlen)
{
        int i;

        for (i = 0; i < *iovlen; i += 2)
                free((*iov)[i].iov_base);
        free(*iov);
}