/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
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 * CDDL HEADER END
 */

/*
 * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright 2014 Nexenta Systems, Inc.  All rights reserved.
 */

#include <synch.h>
#include <pthread.h>
#include <unistd.h>
#include <string.h>
#include <strings.h>
#include <sys/errno.h>
#include <libzfs.h>

#include <smbsrv/libsmb.h>
#include <smbsrv/libsmbns.h>
#include <smbsrv/libmlsvc.h>
#include <smbsrv/smbinfo.h>
#include "smbd.h"

/*
 * This file supports three basic functions that all use the
 * the zfs_iter_snapshots function to get the snapshot info
 * from ZFS.  If the filesystem is not ZFS, the an error is sent
 * to the caller (door functions in this case) with the count of
 * zero in the case of smbd_vss_get_count.  Each function
 * is expecting a path that is the root of the dataset.
 * The basic idea is to define a structure for the data and
 * an iterator function that will be called for every snapshot
 * in the dataset that was opened.  The iterator function gets
 * a zfs_handle_t(that needs to be closed) for the snapshot
 * and a pointer to the structure of data defined passed to it.
 * If the iterator function returns a non-zero value, no more
 * snapshots will be processed.  There is no guarantee in the
 * order in which the snapshots are processed.
 *
 * The structure of this file is:
 * Three structures that are used between the iterator functions
 * and "main" functions
 * The 3 "main" functions
 * Support functions
 * The 3 iterator functions
 */

/*
 * The maximum number of snapshots returned per request.
 */
#define	SMBD_VSS_SNAPSHOT_MAX	725

static void smbd_vss_time2gmttoken(time_t time, char *gmttoken);
static int smbd_vss_cmp_time(const void *a, const void *b);
static int smbd_vss_iterate_count(zfs_handle_t *zhp, void *data);
static int smbd_vss_iterate_get_uint64_date(zfs_handle_t *zhp, void *data);
static int smbd_vss_iterate_map_gmttoken(zfs_handle_t *zhp, void *data);

typedef struct smbd_vss_count {
	int vc_count;
} smbd_vss_count_t;

/*
 * gd_count how many @GMT tokens are expected
 * gd_return_count how many @GMT tokens are being returned
 * gd_gmt_array array of the @GMT token with max size of gd_count
 */
typedef struct smbd_vss_get_uint64_date {
	int gd_count;
	int gd_return_count;
	uint64_t *gd_gmt_array;
} smbd_vss_get_uint64_date_t;

typedef struct smbd_vss_map_gmttoken {
	time_t mg_snaptime;
	char *mg_snapname;
} smbd_vss_map_gmttoken_t;


/*
 * path - path of the dataset
 * count - return value of the number of snapshots for the dataset
 */
int
smbd_vss_get_count(const char *path, uint32_t *count)
{
	char dataset[MAXPATHLEN];
	libzfs_handle_t *libhd;
	zfs_handle_t *zfshd;
	smbd_vss_count_t vss_count;

	bzero(&vss_count, sizeof (smbd_vss_count_t));
	*count = 0;

	if (smb_getdataset(path, dataset, MAXPATHLEN) != 0)
		return (-1);

	if ((libhd = libzfs_init()) == NULL)
		return (-1);

	if ((zfshd = zfs_open(libhd, dataset, ZFS_TYPE_DATASET)) == NULL) {
		libzfs_fini(libhd);
		return (-1);
	}

	(void) zfs_iter_snapshots(zfshd, smbd_vss_iterate_count,
	    (void *)&vss_count);

	if (vss_count.vc_count > SMBD_VSS_SNAPSHOT_MAX)
		vss_count.vc_count = SMBD_VSS_SNAPSHOT_MAX;

	*count = vss_count.vc_count;
	zfs_close(zfshd);
	libzfs_fini(libhd);
	return (0);
}

/*
 * path - is the path of the dataset
 * count - is the maxium number of GMT tokens allowed to be returned
 * return_count - is how many should be returned
 * num_gmttokens - how many gmttokens in gmttokenp (0 if error)
 * gmttokenp - array of @GMT tokens (even if zero, elements still need
 * to be freed)
 */

void
smbd_vss_get_snapshots(const char *path, uint32_t count,
    uint32_t *return_count, uint32_t *num_gmttokens, char **gmttokenp)
{
	char dataset[MAXPATHLEN];
	libzfs_handle_t *libhd;
	zfs_handle_t *zfshd;
	smbd_vss_get_uint64_date_t vss_uint64_date;
	int i;
	uint64_t *timep;

	*return_count = 0;
	*num_gmttokens = 0;

	if (count == 0)
		return;

	if (count > SMBD_VSS_SNAPSHOT_MAX)
		count = SMBD_VSS_SNAPSHOT_MAX;

	vss_uint64_date.gd_count = count;
	vss_uint64_date.gd_return_count = 0;
	vss_uint64_date.gd_gmt_array = malloc(count * sizeof (uint64_t));
	if (vss_uint64_date.gd_gmt_array == NULL)
		return;

	if (smb_getdataset(path, dataset, MAXPATHLEN) != 0) {
		free(vss_uint64_date.gd_gmt_array);
		return;
	}

	if ((libhd = libzfs_init()) == NULL) {
		free(vss_uint64_date.gd_gmt_array);
		return;
	}

	if ((zfshd = zfs_open(libhd, dataset, ZFS_TYPE_DATASET)) == NULL) {
		free(vss_uint64_date.gd_gmt_array);
		libzfs_fini(libhd);
		return;
	}

	(void) zfs_iter_snapshots(zfshd, smbd_vss_iterate_get_uint64_date,
	    (void *)&vss_uint64_date);

	*num_gmttokens = vss_uint64_date.gd_return_count;
	*return_count = vss_uint64_date.gd_return_count;

	/*
	 * Sort the list since neither zfs nor the client sorts it.
	 */
	qsort((char *)vss_uint64_date.gd_gmt_array,
	    vss_uint64_date.gd_return_count,
	    sizeof (uint64_t), smbd_vss_cmp_time);

	timep = vss_uint64_date.gd_gmt_array;

	for (i = 0; i < vss_uint64_date.gd_return_count; i++) {
		*gmttokenp = malloc(SMB_VSS_GMT_SIZE);

		if (*gmttokenp)
			smbd_vss_time2gmttoken(*timep, *gmttokenp);
		else
			vss_uint64_date.gd_return_count = 0;

		timep++;
		gmttokenp++;
	}

	free(vss_uint64_date.gd_gmt_array);
	zfs_close(zfshd);
	libzfs_fini(libhd);
}

static const char
smbd_vss_gmttoken_fmt[] = "@GMT-%Y.%m.%d-%H.%M.%S";

/*
 * path - path of the dataset for the operation
 * gmttoken - the @GMT token to be looked up
 * toktime - time_t used if gmttoken == NULL
 * snapname - the snapshot name to be returned [MAXPATHLEN]
 *
 * Here we are going to get the snapshot name from the @GMT token
 * The snapname returned by ZFS is : <dataset name>@<snapshot name>
 * So we are going to make sure there is the @ symbol in
 * the right place and then just return the snapshot name
 */
int
smbd_vss_map_gmttoken(const char *path, char *gmttoken, time_t toktime,
	char *snapname)
{
	char dataset[MAXPATHLEN];
	libzfs_handle_t *libhd;
	zfs_handle_t *zfshd;
	smbd_vss_map_gmttoken_t vss_map_gmttoken;
	char *zsnap;
	const char *lsnap;
	struct tm tm;

	if (gmttoken != NULL && *gmttoken == '@' &&
	    strptime(gmttoken, smbd_vss_gmttoken_fmt, &tm) != NULL) {
		toktime = timegm(&tm);
	}

	vss_map_gmttoken.mg_snaptime = toktime;
	vss_map_gmttoken.mg_snapname = snapname;
	*snapname = '\0';

	if (smb_getdataset(path, dataset, MAXPATHLEN) != 0)
		return (-1);

	if ((libhd = libzfs_init()) == NULL)
		return (-1);

	if ((zfshd = zfs_open(libhd, dataset, ZFS_TYPE_DATASET)) == NULL) {
		libzfs_fini(libhd);
		return (-1);
	}

	(void) zfs_iter_snapshots(zfshd, smbd_vss_iterate_map_gmttoken,
	    (void *)&vss_map_gmttoken);

	/* compare the zfs snapshot name and the local snap name */
	zsnap = snapname;
	lsnap = dataset;
	while ((*lsnap != '\0') && (*zsnap != '\0') && (*lsnap == *zsnap)) {
		zsnap++;
		lsnap++;
	}

	/* Now we should be passed the dataset name */
	if ((*zsnap == '@') && (*lsnap == '\0')) {
		zsnap++;
		(void) strlcpy(snapname, zsnap, MAXPATHLEN);
	} else {
		*snapname = '\0';
	}

	zfs_close(zfshd);
	libzfs_fini(libhd);
	return (0);
}

static void
smbd_vss_time2gmttoken(time_t time, char *gmttoken)
{
	struct tm t;

	(void) gmtime_r(&time, &t);

	(void) strftime(gmttoken, SMB_VSS_GMT_SIZE,
	    smbd_vss_gmttoken_fmt, &t);
}

static int
smbd_vss_cmp_time(const void *a, const void *b)
{
	if (*(uint64_t *)a < *(uint64_t *)b)
		return (1);
	if (*(uint64_t *)a == *(uint64_t *)b)
		return (0);
	return (-1);
}

/*
 * ZFS snapshot iterator to count snapshots.
 * Note: libzfs expects us to close the handle.
 * Return 0 to continue iterating or non-zreo to terminate the iteration.
 */
static int
smbd_vss_iterate_count(zfs_handle_t *zhp, void *data)
{
	smbd_vss_count_t *vss_data = data;

	if (vss_data->vc_count < SMBD_VSS_SNAPSHOT_MAX) {
		vss_data->vc_count++;
		zfs_close(zhp);
		return (0);
	}

	zfs_close(zhp);
	return (-1);
}

/*
 * ZFS snapshot iterator to get snapshot creation time.
 * Note: libzfs expects us to close the handle.
 * Return 0 to continue iterating or non-zreo to terminate the iteration.
 */
static int
smbd_vss_iterate_get_uint64_date(zfs_handle_t *zhp, void *data)
{
	smbd_vss_get_uint64_date_t *vss_data = data;
	int count;

	count = vss_data->gd_return_count;

	if (count < vss_data->gd_count) {
		vss_data->gd_gmt_array[count] =
		    zfs_prop_get_int(zhp, ZFS_PROP_CREATION);
		vss_data->gd_return_count++;
		zfs_close(zhp);
		return (0);
	}

	zfs_close(zhp);
	return (-1);
}

/*
 * ZFS snapshot iterator to map a snapshot creation time to a token.
 * Note: libzfs expects us to close the handle.
 * Return 0 to continue iterating or non-zreo to terminate the iteration.
 */
static int
smbd_vss_iterate_map_gmttoken(zfs_handle_t *zhp, void *data)
{
	smbd_vss_map_gmttoken_t *vss_data = data;
	time_t time;

	time = (time_t)zfs_prop_get_int(zhp, ZFS_PROP_CREATION);
	if (time == vss_data->mg_snaptime) {
		(void) strlcpy(vss_data->mg_snapname, zfs_get_name(zhp),
		    MAXPATHLEN);

		/* we found a match, do not process anymore snapshots */
		zfs_close(zhp);
		return (-1);
	}

	zfs_close(zhp);
	return (0);
}