/*
 * Copyright (c) 2017 Kyle J. Kneitinger <kyle@kneit.in>
 * Copyright (c) 2018 Kyle Evans <kevans@FreeBSD.org>
 * Copyright (c) 2019 Wes Maag <wes@jwmaag.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <sys/cdefs.h>
#include <sys/mntent.h>

#include "be.h"
#include "be_impl.h"

#define LIBBE_MOUNT_PREFIX      "be_mount."

struct be_mountcheck_info {
        const char *path;
        char *name;
};

struct be_mount_info {
        libbe_handle_t *lbh;
        const char *be;
        const char *mountpoint;
        int mntflags;
        int deepmount;
        int depth;
};

static int
be_mountcheck_cb(zfs_handle_t *zfs_hdl, void *data)
{
        struct be_mountcheck_info *info;
        char *mountpoint;

        if (data == NULL)
                return (1);
        info = (struct be_mountcheck_info *)data;
        if (!zfs_is_mounted(zfs_hdl, &mountpoint))
                return (0);
        if (strcmp(mountpoint, info->path) == 0) {
                info->name = strdup(zfs_get_name(zfs_hdl));
                free(mountpoint);
                return (1);
        }
        free(mountpoint);
        return (0);
}

/*
 * Called from be_mount, uses the given zfs_handle and attempts to
 * mount it at the passed mountpoint. If the deepmount flag is set, continue
 * calling the function for each child dataset.
 */
static int
be_mount_iter(zfs_handle_t *zfs_hdl, void *data)
{
        int err;
        char *mountpoint;
        char tmp[BE_MAXPATHLEN], zfs_mnt[BE_MAXPATHLEN];
        struct be_mount_info *info;

        info = (struct be_mount_info *)data;

        if (zfs_is_mounted(zfs_hdl, &mountpoint)) {
                free(mountpoint);
                return (0);
        }

        /*
         * canmount and mountpoint are both ignored for the BE dataset, because
         * the rest of the system (kernel and loader) will effectively do the
         * same.
         */
        if (info->depth == 0) {
                snprintf(tmp, BE_MAXPATHLEN, "%s", info->mountpoint);
        } else {
                if (zfs_prop_get_int(zfs_hdl, ZFS_PROP_CANMOUNT) ==
                    ZFS_CANMOUNT_OFF)
                        return (0);

                if (zfs_prop_get(zfs_hdl, ZFS_PROP_MOUNTPOINT, zfs_mnt,
                    BE_MAXPATHLEN, NULL, NULL, 0, 1))
                        return (1);

                /*
                 * We've encountered mountpoint=none at some intermediate
                 * dataset (e.g. zroot/var) that will have children that may
                 * need to be mounted.  Skip mounting it, but iterate through
                 * the children.
                 */
                if (strcmp("none", zfs_mnt) == 0)
                        goto skipmount;

                mountpoint = be_mountpoint_augmented(info->lbh, zfs_mnt);
                snprintf(tmp, BE_MAXPATHLEN, "%s%s", info->mountpoint,
                    mountpoint);
        }

        if ((err = zfs_mount_at(zfs_hdl, NULL, info->mntflags, tmp)) != 0) {
                switch (errno) {
                case ENAMETOOLONG:
                        return (set_error(info->lbh, BE_ERR_PATHLEN));
                case ELOOP:
                case ENOENT:
                case ENOTDIR:
                        return (set_error(info->lbh, BE_ERR_BADPATH));
                case EPERM:
                        return (set_error(info->lbh, BE_ERR_PERMS));
                case EBUSY:
                        return (set_error(info->lbh, BE_ERR_PATHBUSY));
                default:
                        return (set_error(info->lbh, BE_ERR_UNKNOWN));
                }
        }

        if (!info->deepmount)
                return (0);

skipmount:
        ++info->depth;
        err = zfs_iter_filesystems(zfs_hdl, be_mount_iter, info);
        --info->depth;
        return (err);
}


static int
be_umount_iter(zfs_handle_t *zfs_hdl, void *data)
{

        int err;
        char *mountpoint;
        struct be_mount_info *info;

        info = (struct be_mount_info *)data;

        ++info->depth;
        if((err = zfs_iter_filesystems(zfs_hdl, be_umount_iter, info)) != 0) {
                return (err);
        }
        --info->depth;

        if (!zfs_is_mounted(zfs_hdl, &mountpoint)) {
                return (0);
        }

        if (info->depth == 0 && info->mountpoint == NULL)
                info->mountpoint = mountpoint;
        else
                free(mountpoint);

        if (zfs_unmount(zfs_hdl, NULL, info->mntflags) != 0) {
                switch (errno) {
                case ENAMETOOLONG:
                        return (set_error(info->lbh, BE_ERR_PATHLEN));
                case ELOOP:
                case ENOENT:
                case ENOTDIR:
                        return (set_error(info->lbh, BE_ERR_BADPATH));
                case EPERM:
                        return (set_error(info->lbh, BE_ERR_PERMS));
                case EBUSY:
                        return (set_error(info->lbh, BE_ERR_PATHBUSY));
                default:
                        return (set_error(info->lbh, BE_ERR_UNKNOWN));
                }
        }
        return (0);
}

/*
 * usage
 */
int
be_mounted_at(libbe_handle_t *lbh, const char *path, nvlist_t *details)
{
        char be[BE_MAXPATHLEN];
        zfs_handle_t *root_hdl;
        struct be_mountcheck_info info;
        prop_data_t propinfo;

        bzero(&be, BE_MAXPATHLEN);
        if ((root_hdl = zfs_open(lbh->lzh, lbh->root,
            ZFS_TYPE_FILESYSTEM)) == NULL)
                return (BE_ERR_ZFSOPEN);

        info.path = path;
        info.name = NULL;
        zfs_iter_filesystems(root_hdl, be_mountcheck_cb, &info);
        zfs_close(root_hdl);

        if (info.name != NULL) {
                if (details != NULL) {
                        if ((root_hdl = zfs_open(lbh->lzh, info.name,
                            ZFS_TYPE_FILESYSTEM)) == NULL) {
                                free(info.name);
                                return (BE_ERR_ZFSOPEN);
                        }

                        propinfo.lbh = lbh;
                        propinfo.list = details;
                        propinfo.single_object = false;
                        propinfo.bootonce = NULL;
                        prop_list_builder_cb(root_hdl, &propinfo);
                        zfs_close(root_hdl);
                }
                free(info.name);
                return (0);
        }
        return (1);
}

/*
 * usage
 */
int
be_mount(libbe_handle_t *lbh, const char *bootenv, const char *mountpoint,
    int flags, char *result_loc)
{
        char be[BE_MAXPATHLEN];
        char mnt_temp[BE_MAXPATHLEN];
        int mntflags, mntdeep;
        int err;
        struct be_mount_info info;
        zfs_handle_t *zhdl;

        if ((err = be_root_concat(lbh, bootenv, be)) != 0)
                return (set_error(lbh, err));

        if ((err = be_exists(lbh, bootenv)) != 0)
                return (set_error(lbh, err));

        if (is_mounted(lbh->lzh, be, NULL))
                return (set_error(lbh, BE_ERR_MOUNTED));

        mntdeep = (flags & BE_MNT_DEEP) ? 1 : 0;
        mntflags = (flags & BE_MNT_FORCE) ? MNT_FORCE : 0;

        /* Create mountpoint if it is not specified */
        if (mountpoint == NULL) {
                const char *tmpdir;

                tmpdir = getenv("TMPDIR");
                if (tmpdir == NULL)
                        tmpdir = _PATH_TMP;

                if (snprintf(mnt_temp, sizeof(mnt_temp), "%s%s%sXXXX", tmpdir,
                    tmpdir[strlen(tmpdir) - 1] == '/' ? "" : "/",
                     LIBBE_MOUNT_PREFIX) >= (int)sizeof(mnt_temp))
                        return (set_error(lbh, BE_ERR_PATHLEN));

                if (mkdtemp(mnt_temp) == NULL)
                        return (set_error(lbh, BE_ERR_IO));
        }

        if ((zhdl = zfs_open(lbh->lzh, be, ZFS_TYPE_FILESYSTEM)) == NULL)
                return (set_error(lbh, BE_ERR_ZFSOPEN));

        info.lbh = lbh;
        info.be = be;
        info.mountpoint = (mountpoint == NULL) ? mnt_temp : mountpoint;
        info.mntflags = mntflags;
        info.deepmount = mntdeep;
        info.depth = 0;

        if((err = be_mount_iter(zhdl, &info) != 0)) {
                zfs_close(zhdl);
                return (err);
        }
        zfs_close(zhdl);

        if (result_loc != NULL)
                strlcpy(result_loc, mountpoint == NULL ? mnt_temp : mountpoint,
                    BE_MAXPATHLEN);

        return (BE_ERR_SUCCESS);
}

/*
 * usage
 */
int
be_unmount(libbe_handle_t *lbh, const char *bootenv, int flags)
{
        int err;
        char be[BE_MAXPATHLEN];
        zfs_handle_t *root_hdl;
        struct be_mount_info info;

        if ((err = be_root_concat(lbh, bootenv, be)) != 0)
                return (set_error(lbh, err));

        if ((root_hdl = zfs_open(lbh->lzh, be, ZFS_TYPE_FILESYSTEM)) == NULL)
                return (set_error(lbh, BE_ERR_ZFSOPEN));

        info.lbh = lbh;
        info.be = be;
        info.mountpoint = NULL;
        info.mntflags = (flags & BE_MNT_FORCE) ? MS_FORCE : 0;
        info.depth = 0;

        if ((err = be_umount_iter(root_hdl, &info)) != 0) {
                free(__DECONST(char *, info.mountpoint));
                zfs_close(root_hdl);
                return (err);
        }

        /*
         * We'll attempt to remove the directory if we created it on a
         * best-effort basis.  rmdir(2) failure will not be reported.
         */
        if (info.mountpoint != NULL) {
                const char *mdir;

                mdir = strrchr(info.mountpoint, '/');
                if (mdir == NULL)
                        mdir = info.mountpoint;
                else
                        mdir++;

                if (strncmp(mdir, LIBBE_MOUNT_PREFIX,
                    sizeof(LIBBE_MOUNT_PREFIX) - 1) == 0) {
                        (void)rmdir(info.mountpoint);
                }
        }

        free(__DECONST(char *, info.mountpoint));

        zfs_close(root_hdl);
        return (BE_ERR_SUCCESS);
}

/*
 * This function will blow away the input buffer as needed if we're discovered
 * to be looking at a root-mount.  If the mountpoint is naturally beyond the
 * root, however, the buffer may be left intact and a pointer to the section
 * past altroot will be returned instead for the caller's perusal.
 */
char *
be_mountpoint_augmented(libbe_handle_t *lbh, char *mountpoint)
{

        if (lbh->altroot_len == 0)
                return (mountpoint);
        if (mountpoint == NULL || *mountpoint == '\0')
                return (mountpoint);

        if (mountpoint[lbh->altroot_len] == '\0') {
                *(mountpoint + 1) = '\0';
                return (mountpoint);
        } else
                return (mountpoint + lbh->altroot_len);
}