samba-mirror/source3/modules/vfs_shadow_copy2.c

/*
 * Third attempt at a shadow copy module
 *
 * Copyright (C) Andrew Tridgell   2007 (portions taken from shadow_copy2)
 * Copyright (C) Ed Plese          2009
 * Copyright (C) Volker Lendecke   2011
 * Copyright (C) Christian Ambach  2011
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*

  This is a 3rd implemetation of a shadow copy module for exposing
  snapshots to windows clients as shadow copies. This version has the
  following features:

     1) you don't need to populate your shares with symlinks to the
     snapshots. This can be very important when you have thousands of
     shares, or use [homes]

     2) the inode number of the files is altered so it is different
     from the original. This allows the 'restore' button to work
     without a sharing violation

     3) shadow copy results can be sorted before being sent to the
     client.  This is beneficial for filesystems that don't read
     directories alphabetically (the default unix).

     4) vanity naming for snapshots. Snapshots can be named in any
     format compatible with str[fp]time conversions.

     5) time stamps in snapshot names can be represented in localtime
     rather than UTC.

  Module options:

      shadow:snapdir = <directory where snapshots are kept>

      This is the directory containing the @GMT-* snapshot directories. If it is an absolute
      path it is used as-is. If it is a relative path, then it is taken relative to the mount
      point of the filesystem that the root of this share is on

      shadow:basedir = <base directory that snapshots are from>

      This is an optional parameter that specifies the directory that
      the snapshots are relative to. It defaults to the filesystem
      mount point

      shadow:fixinodes = yes/no

      If you enable shadow:fixinodes then this module will modify the
      apparent inode number of files in the snapshot directories using
      a hash of the files path. This is needed for snapshot systems
      where the snapshots have the same device:inode number as the
      original files (such as happens with GPFS snapshots). If you
      don't set this option then the 'restore' button in the shadow
      copy UI will fail with a sharing violation.

      shadow:sort = asc/desc, or not specified for unsorted (default)

      This is an optional parameter that specifies that the shadow
      copy directories should be sorted before sending them to the
      client.  This can be beneficial as unix filesystems are usually
      not listed alphabetically sorted.  If enabled, you typically
      want to specify descending order.

      shadow:format = <format specification for snapshot names>

      This is an optional parameter that specifies the format
      specification for the naming of snapshots.  The format must
      be compatible with the conversion specifications recognized
      by str[fp]time.  The default value is "@GMT-%Y.%m.%d-%H.%M.%S".

      shadow:localtime = yes/no (default is no)

      This is an optional parameter that indicates whether the
      snapshot names are in UTC/GMT or the local time.


  The following command would generate a correctly formatted directory name
  for use with the default parameters:
     date -u +@GMT-%Y.%m.%d-%H.%M.%S
 */

#include "includes.h"
#include "system/filesys.h"
#include "include/ntioctl.h"
#include "smbd/proto.h"
#include <ccan/hash/hash.h>
#include "util_tdb.h"

#define GMT_NAME_LEN 24 /* length of a @GMT- name */
#define GMT_FORMAT "@GMT-%Y.%m.%d-%H.%M.%S"

static bool shadow_copy2_find_slashes(TALLOC_CTX *mem_ctx, const char *str,
				      size_t **poffsets,
				      unsigned *pnum_offsets)
{
	unsigned num_offsets;
	size_t *offsets;
	const char *p;

	num_offsets = 0;

	p = str;
	while ((p = strchr(p, '/')) != NULL) {
		num_offsets += 1;
		p += 1;
	}

	offsets = talloc_array(mem_ctx, size_t, num_offsets);
	if (offsets == NULL) {
		return false;
	}

	p = str;
	num_offsets = 0;
	while ((p = strchr(p, '/')) != NULL) {
		offsets[num_offsets] = p-str;
		num_offsets += 1;
		p += 1;
	}

	*poffsets = offsets;
	*pnum_offsets = num_offsets;
	return true;
}

static char *shadow_copy2_insert_string(TALLOC_CTX *mem_ctx,
					struct vfs_handle_struct *handle,
					time_t snapshot)
{
	struct tm snap_tm;
	fstring gmt;
	size_t gmt_len;

	if (localtime_r(&snapshot, &snap_tm) == 0) {
		DEBUG(10, ("gmtime_r failed\n"));
		return NULL;
	}
	gmt_len = strftime(gmt, sizeof(gmt),
			   lp_parm_const_string(SNUM(handle->conn), "shadow",
						"format", GMT_FORMAT),
			   &snap_tm);
	if (gmt_len == 0) {
		DEBUG(10, ("strftime failed\n"));
		return NULL;
	}
	return talloc_asprintf(talloc_tos(), "/%s/%s",
			       lp_parm_const_string(
				       SNUM(handle->conn), "shadow", "snapdir",
				       ".snapshots"),
			       gmt);
}

static bool shadow_copy2_strip_snapshot(TALLOC_CTX *mem_ctx,
					struct vfs_handle_struct *handle,
					const char *name,
					time_t *ptimestamp,
					char **pstripped)
{
	struct tm tm;
	time_t timestamp;
	const char *p;
	char *q;
	char *stripped;
	size_t rest_len, dst_len;

	p = strstr_m(name, "@GMT-");
	if (p == NULL) {
		goto no_snapshot;
	}
	if ((p > name) && (p[-1] != '/')) {
		goto no_snapshot;
	}
	q = strptime(p, GMT_FORMAT, &tm);
	if (q == NULL) {
		goto no_snapshot;
	}
	tm.tm_isdst = -1;
	timestamp = mktime(&tm);
	if (timestamp == (time_t)-1) {
		goto no_snapshot;
	}
	if ((p == name) && (q[0] == '\0')) {
		if (pstripped != NULL) {
			stripped = talloc_strdup(mem_ctx, "");
			if (stripped == NULL) {
				return false;
			}
			*pstripped = stripped;
		}
		*ptimestamp = timestamp;
		return true;
	}
	if (q[0] != '/') {
		goto no_snapshot;
	}
	q += 1;

	rest_len = strlen(q);
	dst_len = (p-name) + rest_len;

	if (lp_parm_bool(SNUM(handle->conn), "shadow", "snapdirseverywhere",
			 false)) {
		char *insert;
		bool have_insert;
		insert = shadow_copy2_insert_string(talloc_tos(), handle,
						    timestamp);
		if (insert == NULL) {
			errno = ENOMEM;
			return false;
		}

		have_insert = (strstr(name, insert+1) != NULL);
		TALLOC_FREE(insert);
		if (have_insert) {
			goto no_snapshot;
		}
	}

	if (pstripped != NULL) {
		stripped = talloc_array(mem_ctx, char, dst_len+1);
		if (stripped == NULL) {
			errno = ENOMEM;
			return false;
		}
		if (p > name) {
			memcpy(stripped, name, p-name);
		}
		if (rest_len > 0) {
			memcpy(stripped + (p-name), q, rest_len);
		}
		stripped[dst_len] = '\0';
		*pstripped = stripped;
	}
	*ptimestamp = timestamp;
	return true;
no_snapshot:
	*ptimestamp = 0;
	return true;
}

static char *shadow_copy2_find_mount_point(TALLOC_CTX *mem_ctx,
					   vfs_handle_struct *handle)
{
	char *path = talloc_strdup(mem_ctx, handle->conn->connectpath);
	dev_t dev;
	struct stat st;
	char *p;

	if (stat(path, &st) != 0) {
		talloc_free(path);
		return NULL;
	}

	dev = st.st_dev;

	while ((p = strrchr(path, '/')) && p > path) {
		*p = 0;
		if (stat(path, &st) != 0) {
			talloc_free(path);
			return NULL;
		}
		if (st.st_dev != dev) {
			*p = '/';
			break;
		}
	}

	return path;
}

static char *shadow_copy2_convert(TALLOC_CTX *mem_ctx,
				  struct vfs_handle_struct *handle,
				  const char *name, time_t timestamp)
{
	struct smb_filename converted_fname;
	char *result = NULL;
	size_t *slashes = NULL;
	unsigned num_slashes;
	char *path = NULL;
	size_t pathlen;
	char *insert = NULL;
	char *converted = NULL;
	size_t insertlen;
	int i, saved_errno;
	size_t min_offset;

	path = talloc_asprintf(mem_ctx, "%s/%s", handle->conn->connectpath,
			       name);
	if (path == NULL) {
		errno = ENOMEM;
		goto fail;
	}
	pathlen = talloc_get_size(path)-1;

	DEBUG(10, ("converting %s\n", path));

	if (!shadow_copy2_find_slashes(talloc_tos(), path,
				       &slashes, &num_slashes)) {
		goto fail;
	}
	insert = shadow_copy2_insert_string(talloc_tos(), handle, timestamp);
	if (insert == NULL) {
		goto fail;
	}
	insertlen = talloc_get_size(insert)-1;
	converted = talloc_array(mem_ctx, char, pathlen + insertlen + 1);
	if (converted == NULL) {
		goto fail;
	}

	if (path[pathlen-1] != '/') {
		/*
		 * Append a fake slash to find the snapshot root
		 */
		size_t *tmp;
		tmp = talloc_realloc(talloc_tos(), slashes,
				     size_t, num_slashes+1);
		if (tmp == NULL) {
			goto fail;
		}
		slashes = tmp;
		slashes[num_slashes] = pathlen;
		num_slashes += 1;
	}

	min_offset = 0;

	if (!lp_parm_bool(SNUM(handle->conn), "shadow", "crossmountpoints",
			  false)) {
		char *mount_point;

		mount_point = shadow_copy2_find_mount_point(talloc_tos(),
							    handle);
		if (mount_point == NULL) {
			goto fail;
		}
		min_offset = strlen(mount_point);
		TALLOC_FREE(mount_point);
	}

	memcpy(converted, path, pathlen+1);
	converted[pathlen+insertlen] = '\0';

	ZERO_STRUCT(converted_fname);
	converted_fname.base_name = converted;

	for (i = num_slashes-1; i>=0; i--) {
		int ret;
		size_t offset;

		offset = slashes[i];

		if (offset < min_offset) {
			errno = ENOENT;
			goto fail;
		}

		memcpy(converted+offset, insert, insertlen);

		offset += insertlen;
		memcpy(converted+offset, path + slashes[i],
		       pathlen - slashes[i]);

		ret = SMB_VFS_NEXT_LSTAT(handle, &converted_fname);

		DEBUG(10, ("Trying %s: %d (%s)\n", converted,
			   ret, ret == 0 ? "ok" : strerror(errno)));
		if (ret == 0) {
			/* success */
			break;
		}
		if (errno == ENOTDIR) {
			/*
			 * This is a valid condition: We appended the
			 * .snaphots/@GMT.. to a file name. Just try
			 * with the upper levels.
			 */
			continue;
		}
		if (errno != ENOENT) {
			/* Other problem than "not found" */
			goto fail;
		}
	}

	if (i >= 0) {
		/*
		 * Found something
		 */
		DEBUG(10, ("Found %s\n", converted));
		result = converted;
		converted = NULL;
	} else {
		errno = ENOENT;
	}
fail:
	saved_errno = errno;
	TALLOC_FREE(converted);
	TALLOC_FREE(insert);
	TALLOC_FREE(slashes);
	TALLOC_FREE(path);
	errno = saved_errno;
	return result;
}

/*
  modify a sbuf return to ensure that inodes in the shadow directory
  are different from those in the main directory
 */
static void convert_sbuf(vfs_handle_struct *handle, const char *fname,
			 SMB_STRUCT_STAT *sbuf)
{
	if (lp_parm_bool(SNUM(handle->conn), "shadow", "fixinodes", False)) {
		/* some snapshot systems, like GPFS, return the name
		   device:inode for the snapshot files as the current
		   files. That breaks the 'restore' button in the shadow copy
		   GUI, as the client gets a sharing violation.

		   This is a crude way of allowing both files to be
		   open at once. It has a slight chance of inode
		   number collision, but I can't see a better approach
		   without significant VFS changes
		*/
		uint32_t shash;

		shash = hash(fname, strlen(fname), 0) & 0xFF000000;
		if (shash == 0) {
			shash = 1;
		}
		sbuf->st_ex_ino ^= shash;
	}
}

static SMB_STRUCT_DIR *shadow_copy2_opendir(vfs_handle_struct *handle,
					    const char *fname,
					    const char *mask,
					    uint32 attr)
{
	time_t timestamp;
	char *stripped;
	SMB_STRUCT_DIR *ret;
	int saved_errno;
	char *conv;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, fname,
					 &timestamp, &stripped)) {
		return NULL;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_OPENDIR(handle, fname, mask, attr);
	}
	conv = shadow_copy2_convert(talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);
	if (conv == NULL) {
		return NULL;
	}
	ret = SMB_VFS_NEXT_OPENDIR(handle, conv, mask, attr);
	saved_errno = errno;
	TALLOC_FREE(conv);
	errno = saved_errno;
	return ret;
}

static int shadow_copy2_rename(vfs_handle_struct *handle,
			       const struct smb_filename *smb_fname_src,
			       const struct smb_filename *smb_fname_dst)
{
	time_t timestamp_src, timestamp_dst;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle,
					 smb_fname_src->base_name,
					 &timestamp_src, NULL)) {
		return -1;
	}
	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle,
					 smb_fname_dst->base_name,
					 &timestamp_dst, NULL)) {
		return -1;
	}
	if (timestamp_src != 0) {
		errno = EXDEV;
		return -1;
	}
	if (timestamp_dst != 0) {
		errno = EROFS;
		return -1;
	}
	return SMB_VFS_NEXT_RENAME(handle, smb_fname_src, smb_fname_dst);
}

static int shadow_copy2_symlink(vfs_handle_struct *handle,
				const char *oldname, const char *newname)
{
	time_t timestamp_old, timestamp_new;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, oldname,
					 &timestamp_old, NULL)) {
		return -1;
	}
	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, newname,
					 &timestamp_new, NULL)) {
		return -1;
	}
	if ((timestamp_old != 0) || (timestamp_new != 0)) {
		errno = EROFS;
		return -1;
	}
	return SMB_VFS_NEXT_SYMLINK(handle, oldname, newname);
}

static int shadow_copy2_link(vfs_handle_struct *handle,
			     const char *oldname, const char *newname)
{
	time_t timestamp_old, timestamp_new;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, oldname,
					 &timestamp_old, NULL)) {
		return -1;
	}
	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, newname,
					 &timestamp_new, NULL)) {
		return -1;
	}
	if ((timestamp_old != 0) || (timestamp_new != 0)) {
		errno = EROFS;
		return -1;
	}
	return SMB_VFS_NEXT_LINK(handle, oldname, newname);
}

static int shadow_copy2_stat(vfs_handle_struct *handle,
			     struct smb_filename *smb_fname)
{
	time_t timestamp;
	char *stripped, *tmp;
	int ret, saved_errno;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle,
					 smb_fname->base_name,
					 &timestamp, &stripped)) {
		return -1;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_STAT(handle, smb_fname);
	}

	tmp = smb_fname->base_name;
	smb_fname->base_name = shadow_copy2_convert(
		talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);

	if (smb_fname->base_name == NULL) {
		smb_fname->base_name = tmp;
		return -1;
	}

	ret = SMB_VFS_NEXT_STAT(handle, smb_fname);
	saved_errno = errno;

	TALLOC_FREE(smb_fname->base_name);
	smb_fname->base_name = tmp;

	if (ret == 0) {
		convert_sbuf(handle, smb_fname->base_name, &smb_fname->st);
	}
	errno = saved_errno;
	return ret;
}

static int shadow_copy2_lstat(vfs_handle_struct *handle,
			      struct smb_filename *smb_fname)
{
	time_t timestamp;
	char *stripped, *tmp;
	int ret, saved_errno;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle,
					 smb_fname->base_name,
					 &timestamp, &stripped)) {
		return -1;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_LSTAT(handle, smb_fname);
	}

	tmp = smb_fname->base_name;
	smb_fname->base_name = shadow_copy2_convert(
		talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);

	if (smb_fname->base_name == NULL) {
		smb_fname->base_name = tmp;
		return -1;
	}

	ret = SMB_VFS_NEXT_LSTAT(handle, smb_fname);
	saved_errno = errno;

	TALLOC_FREE(smb_fname->base_name);
	smb_fname->base_name = tmp;

	if (ret == 0) {
		convert_sbuf(handle, smb_fname->base_name, &smb_fname->st);
	}
	errno = saved_errno;
	return ret;
}

static int shadow_copy2_fstat(vfs_handle_struct *handle, files_struct *fsp,
			      SMB_STRUCT_STAT *sbuf)
{
	time_t timestamp;
	int ret;

	ret = SMB_VFS_NEXT_FSTAT(handle, fsp, sbuf);
	if (ret == -1) {
		return ret;
	}
	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle,
					 fsp->fsp_name->base_name,
					 &timestamp, NULL)) {
		return 0;
	}
	if (timestamp != 0) {
		convert_sbuf(handle, fsp->fsp_name->base_name, sbuf);
	}
	return 0;
}

static int shadow_copy2_open(vfs_handle_struct *handle,
			     struct smb_filename *smb_fname, files_struct *fsp,
			     int flags, mode_t mode)
{
	time_t timestamp;
	char *stripped, *tmp;
	int ret, saved_errno;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle,
					 smb_fname->base_name,
					 &timestamp, &stripped)) {
		return -1;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_OPEN(handle, smb_fname, fsp, flags, mode);
	}

	tmp = smb_fname->base_name;
	smb_fname->base_name = shadow_copy2_convert(
		talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);

	if (smb_fname->base_name == NULL) {
		smb_fname->base_name = tmp;
		return -1;
	}

	ret = SMB_VFS_NEXT_OPEN(handle, smb_fname, fsp, flags, mode);
	saved_errno = errno;

	TALLOC_FREE(smb_fname->base_name);
	smb_fname->base_name = tmp;

	errno = saved_errno;
	return ret;
}

static int shadow_copy2_unlink(vfs_handle_struct *handle,
			       const struct smb_filename *smb_fname)
{
	time_t timestamp;
	char *stripped;
	int ret, saved_errno;
	struct smb_filename *conv;
	NTSTATUS status;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle,
					 smb_fname->base_name,
					 &timestamp, &stripped)) {
		return -1;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_UNLINK(handle, smb_fname);
	}
	status = copy_smb_filename(talloc_tos(), smb_fname, &conv);
	if (!NT_STATUS_IS_OK(status)) {
		errno = ENOMEM;
		return -1;
	}
	conv->base_name = shadow_copy2_convert(
		conv, handle, stripped, timestamp);
	TALLOC_FREE(stripped);
	if (conv->base_name == NULL) {
		return -1;
	}
	ret = SMB_VFS_NEXT_UNLINK(handle, conv);
	saved_errno = errno;
	TALLOC_FREE(conv);
	errno = saved_errno;
	return ret;
}

static int shadow_copy2_chmod(vfs_handle_struct *handle, const char *fname,
			      mode_t mode)
{
	time_t timestamp;
	char *stripped;
	int ret, saved_errno;
	char *conv;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, fname,
					 &timestamp, &stripped)) {
		return -1;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_CHMOD(handle, fname, mode);
	}
	conv = shadow_copy2_convert(talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);
	if (conv == NULL) {
		return -1;
	}
	ret = SMB_VFS_NEXT_CHMOD(handle, conv, mode);
	saved_errno = errno;
	TALLOC_FREE(conv);
	errno = saved_errno;
	return ret;
}

static int shadow_copy2_chown(vfs_handle_struct *handle, const char *fname,
			      uid_t uid, gid_t gid)
{
	time_t timestamp;
	char *stripped;
	int ret, saved_errno;
	char *conv;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, fname,
					 &timestamp, &stripped)) {
		return -1;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_CHOWN(handle, fname, uid, gid);
	}
	conv = shadow_copy2_convert(talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);
	if (conv == NULL) {
		return -1;
	}
	ret = SMB_VFS_NEXT_CHOWN(handle, conv, uid, gid);
	saved_errno = errno;
	TALLOC_FREE(conv);
	errno = saved_errno;
	return ret;
}

static int shadow_copy2_chdir(vfs_handle_struct *handle,
			      const char *fname)
{
	time_t timestamp;
	char *stripped;
	int ret, saved_errno;
	char *conv;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, fname,
					 &timestamp, &stripped)) {
		return -1;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_CHDIR(handle, fname);
	}
	conv = shadow_copy2_convert(talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);
	if (conv == NULL) {
		return -1;
	}
	ret = SMB_VFS_NEXT_CHDIR(handle, conv);
	saved_errno = errno;
	TALLOC_FREE(conv);
	errno = saved_errno;
	return ret;
}

static int shadow_copy2_ntimes(vfs_handle_struct *handle,
			       const struct smb_filename *smb_fname,
			       struct smb_file_time *ft)
{
	time_t timestamp;
	char *stripped;
	int ret, saved_errno;
	struct smb_filename *conv;
	NTSTATUS status;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle,
					 smb_fname->base_name,
					 &timestamp, &stripped)) {
		return -1;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_NTIMES(handle, smb_fname, ft);
	}
	status = copy_smb_filename(talloc_tos(), smb_fname, &conv);
	if (!NT_STATUS_IS_OK(status)) {
		errno = ENOMEM;
		return -1;
	}
	conv->base_name = shadow_copy2_convert(
		conv, handle, stripped, timestamp);
	TALLOC_FREE(stripped);
	if (conv->base_name == NULL) {
		return -1;
	}
	ret = SMB_VFS_NEXT_NTIMES(handle, conv, ft);
	saved_errno = errno;
	TALLOC_FREE(conv);
	errno = saved_errno;
	return ret;
}

static int shadow_copy2_readlink(vfs_handle_struct *handle,
				 const char *fname, char *buf, size_t bufsiz)
{
	time_t timestamp;
	char *stripped;
	int ret, saved_errno;
	char *conv;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, fname,
					 &timestamp, &stripped)) {
		return -1;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_READLINK(handle, fname, buf, bufsiz);
	}
	conv = shadow_copy2_convert(talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);
	if (conv == NULL) {
		return -1;
	}
	ret = SMB_VFS_NEXT_READLINK(handle, conv, buf, bufsiz);
	saved_errno = errno;
	TALLOC_FREE(conv);
	errno = saved_errno;
	return ret;
}

static int shadow_copy2_mknod(vfs_handle_struct *handle,
			      const char *fname, mode_t mode, SMB_DEV_T dev)
{
	time_t timestamp;
	char *stripped;
	int ret, saved_errno;
	char *conv;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, fname,
					 &timestamp, &stripped)) {
		return -1;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_MKNOD(handle, fname, mode, dev);
	}
	conv = shadow_copy2_convert(talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);
	if (conv == NULL) {
		return -1;
	}
	ret = SMB_VFS_NEXT_MKNOD(handle, conv, mode, dev);
	saved_errno = errno;
	TALLOC_FREE(conv);
	errno = saved_errno;
	return ret;
}

static char *shadow_copy2_realpath(vfs_handle_struct *handle,
				   const char *fname)
{
	time_t timestamp;
	char *stripped = NULL;
	char *tmp = NULL;
	char *result = NULL;
	char *inserted = NULL;
	char *inserted_to, *inserted_end;
	int saved_errno;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, fname,
					 &timestamp, &stripped)) {
		goto done;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_REALPATH(handle, fname);
	}

	tmp = shadow_copy2_convert(talloc_tos(), handle, stripped, timestamp);
	if (tmp == NULL) {
		goto done;
	}

	result = SMB_VFS_NEXT_REALPATH(handle, tmp);
	if (result == NULL) {
		goto done;
	}

	/*
	 * Take away what we've inserted. This removes the @GMT-thingy
	 * completely, but will give a path under the share root.
	 */
	inserted = shadow_copy2_insert_string(talloc_tos(), handle, timestamp);
	if (inserted == NULL) {
		goto done;
	}
	inserted_to = strstr_m(result, inserted);
	if (inserted_to == NULL) {
		DEBUG(2, ("SMB_VFS_NEXT_REALPATH removed %s\n", inserted));
		goto done;
	}
	inserted_end = inserted_to + talloc_get_size(inserted) - 1;
	memmove(inserted_to, inserted_end, strlen(inserted_end)+1);

done:
	saved_errno = errno;
	TALLOC_FREE(inserted);
	TALLOC_FREE(tmp);
	TALLOC_FREE(stripped);
	errno = saved_errno;
	return result;
}

static char *have_snapdir(struct vfs_handle_struct *handle,
			  const char *path)
{
	struct smb_filename smb_fname;
	int ret;

	ZERO_STRUCT(smb_fname);
	smb_fname.base_name = talloc_asprintf(
		talloc_tos(), "%s/%s", path,
		lp_parm_const_string(SNUM(handle->conn), "shadow", "snapdir",
				     ".snapshots"));
	if (smb_fname.base_name == NULL) {
		return NULL;
	}

	ret = SMB_VFS_NEXT_STAT(handle, &smb_fname);
	if ((ret == 0) && (S_ISDIR(smb_fname.st.st_ex_mode))) {
		return smb_fname.base_name;
	}
	TALLOC_FREE(smb_fname.base_name);
	return NULL;
}

static char *shadow_copy2_find_snapdir(TALLOC_CTX *mem_ctx,
				       struct vfs_handle_struct *handle,
				       struct smb_filename *smb_fname)
{
	char *path, *p;
	char *snapdir;

	path = talloc_asprintf(mem_ctx, "%s/%s",
			       handle->conn->connectpath,
			       smb_fname->base_name);
	if (path == NULL) {
		return NULL;
	}

	snapdir = have_snapdir(handle, path);
	if (snapdir != NULL) {
		TALLOC_FREE(path);
		return snapdir;
	}

	while ((p = strrchr(path, '/')) && (p > path)) {

		p[0] = '\0';

		snapdir = have_snapdir(handle, path);
		if (snapdir != NULL) {
			TALLOC_FREE(path);
			return snapdir;
		}
	}
	TALLOC_FREE(path);
	return NULL;
}

static bool shadow_copy2_snapshot_to_gmt(TALLOC_CTX *mem_ctx,
					 vfs_handle_struct *handle,
					 const char *name,
					 char *gmt, size_t gmt_len)
{
	struct tm timestamp;
	time_t timestamp_t;
	const char *fmt;

	fmt = lp_parm_const_string(SNUM(handle->conn), "shadow",
				   "format", GMT_FORMAT);

	ZERO_STRUCT(timestamp);
	if (strptime(name, fmt, &timestamp) == NULL) {
		DEBUG(10, ("shadow_copy2_snapshot_to_gmt: no match %s: %s\n",
			   fmt, name));
		return false;
	}

	DEBUG(10, ("shadow_copy2_snapshot_to_gmt: match %s: %s\n", fmt, name));

	if (lp_parm_bool(SNUM(handle->conn), "shadow", "localtime", false)) {
		timestamp.tm_isdst = -1;
		timestamp_t = mktime(&timestamp);
		gmtime_r(&timestamp_t, &timestamp);
	}
	strftime(gmt, gmt_len, GMT_FORMAT, &timestamp);
	return true;
}

static int shadow_copy2_label_cmp_asc(const void *x, const void *y)
{
	return strncmp((const char *)x, (const char *)y, sizeof(SHADOW_COPY_LABEL));
}

static int shadow_copy2_label_cmp_desc(const void *x, const void *y)
{
	return -strncmp((const char *)x, (const char *)y, sizeof(SHADOW_COPY_LABEL));
}

/*
  sort the shadow copy data in ascending or descending order
 */
static void shadow_copy2_sort_data(vfs_handle_struct *handle,
				   struct shadow_copy_data *shadow_copy2_data)
{
	int (*cmpfunc)(const void *, const void *);
	const char *sort;

	sort = lp_parm_const_string(SNUM(handle->conn), "shadow",
				    "sort", NULL);
	if (sort == NULL) {
		return;
	}

	if (strcmp(sort, "asc") == 0) {
		cmpfunc = shadow_copy2_label_cmp_asc;
	} else if (strcmp(sort, "desc") == 0) {
		cmpfunc = shadow_copy2_label_cmp_desc;
	} else {
		return;
	}

	if (shadow_copy2_data && shadow_copy2_data->num_volumes > 0 &&
	    shadow_copy2_data->labels)
	{
		TYPESAFE_QSORT(shadow_copy2_data->labels,
			       shadow_copy2_data->num_volumes,
			       cmpfunc);
	}

	return;
}

static int shadow_copy2_get_shadow_copy_data(
	vfs_handle_struct *handle, files_struct *fsp,
	struct shadow_copy_data *shadow_copy2_data,
	bool labels)
{
	SMB_STRUCT_DIR *p;
	const char *snapdir;
	struct dirent *d;
	TALLOC_CTX *tmp_ctx = talloc_stackframe();

	snapdir = shadow_copy2_find_snapdir(tmp_ctx, handle, fsp->fsp_name);
	if (snapdir == NULL) {
		DEBUG(0,("shadow:snapdir not found for %s in get_shadow_copy_data\n",
			 handle->conn->connectpath));
		errno = EINVAL;
		talloc_free(tmp_ctx);
		return -1;
	}

	p = SMB_VFS_NEXT_OPENDIR(handle, snapdir, NULL, 0);

	if (!p) {
		DEBUG(2,("shadow_copy2: SMB_VFS_NEXT_OPENDIR() failed for '%s'"
			 " - %s\n", snapdir, strerror(errno)));
		talloc_free(tmp_ctx);
		errno = ENOSYS;
		return -1;
	}

	shadow_copy2_data->num_volumes = 0;
	shadow_copy2_data->labels      = NULL;

	while ((d = SMB_VFS_NEXT_READDIR(handle, p, NULL))) {
		char snapshot[GMT_NAME_LEN+1];
		SHADOW_COPY_LABEL *tlabels;

		/*
		 * ignore names not of the right form in the snapshot
		 * directory
		 */
		if (!shadow_copy2_snapshot_to_gmt(
			    tmp_ctx, handle, d->d_name,
			    snapshot, sizeof(snapshot))) {

			DEBUG(6, ("shadow_copy2_get_shadow_copy_data: "
				  "ignoring %s\n", d->d_name));
			continue;
		}
		DEBUG(6,("shadow_copy2_get_shadow_copy_data: %s -> %s\n",
			 d->d_name, snapshot));

		if (!labels) {
			/* the caller doesn't want the labels */
			shadow_copy2_data->num_volumes++;
			continue;
		}

		tlabels = talloc_realloc(shadow_copy2_data,
					 shadow_copy2_data->labels,
					 SHADOW_COPY_LABEL,
					 shadow_copy2_data->num_volumes+1);
		if (tlabels == NULL) {
			DEBUG(0,("shadow_copy2: out of memory\n"));
			SMB_VFS_NEXT_CLOSEDIR(handle, p);
			talloc_free(tmp_ctx);
			return -1;
		}

		strlcpy(tlabels[shadow_copy2_data->num_volumes], snapshot,
			sizeof(*tlabels));

		shadow_copy2_data->num_volumes++;
		shadow_copy2_data->labels = tlabels;
	}

	SMB_VFS_NEXT_CLOSEDIR(handle,p);

	shadow_copy2_sort_data(handle, shadow_copy2_data);

	talloc_free(tmp_ctx);
	return 0;
}

static NTSTATUS shadow_copy2_fget_nt_acl(vfs_handle_struct *handle,
					struct files_struct *fsp,
					uint32 security_info,
					struct security_descriptor **ppdesc)
{
	time_t timestamp;
	char *stripped;
	NTSTATUS status;
	char *conv;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle,
					 fsp->fsp_name->base_name,
					 &timestamp, &stripped)) {
		return map_nt_error_from_unix(errno);
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_FGET_NT_ACL(handle, fsp, security_info,
						ppdesc);
	}
	conv = shadow_copy2_convert(talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);
	if (conv == NULL) {
		return map_nt_error_from_unix(errno);
	}
	status = SMB_VFS_NEXT_GET_NT_ACL(handle, conv, security_info, ppdesc);
	TALLOC_FREE(conv);
	return status;
}

static NTSTATUS shadow_copy2_get_nt_acl(vfs_handle_struct *handle,
					const char *fname,
					uint32 security_info,
					struct security_descriptor **ppdesc)
{
	time_t timestamp;
	char *stripped;
	NTSTATUS status;
	char *conv;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, fname,
					 &timestamp, &stripped)) {
		return map_nt_error_from_unix(errno);
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_GET_NT_ACL(handle, fname, security_info,
					       ppdesc);
	}
	conv = shadow_copy2_convert(talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);
	if (conv == NULL) {
		return map_nt_error_from_unix(errno);
	}
	status = SMB_VFS_NEXT_GET_NT_ACL(handle, conv, security_info, ppdesc);
	TALLOC_FREE(conv);
	return status;
}

static int shadow_copy2_mkdir(vfs_handle_struct *handle,
			      const char *fname, mode_t mode)
{
	time_t timestamp;
	char *stripped;
	int ret, saved_errno;
	char *conv;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, fname,
					 &timestamp, &stripped)) {
		return -1;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_MKDIR(handle, fname, mode);
	}
	conv = shadow_copy2_convert(talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);
	if (conv == NULL) {
		return -1;
	}
	ret = SMB_VFS_NEXT_MKDIR(handle, conv, mode);
	saved_errno = errno;
	TALLOC_FREE(conv);
	errno = saved_errno;
	return ret;
}

static int shadow_copy2_rmdir(vfs_handle_struct *handle, const char *fname)
{
	time_t timestamp;
	char *stripped;
	int ret, saved_errno;
	char *conv;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, fname,
					 &timestamp, &stripped)) {
		return -1;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_RMDIR(handle, fname);
	}
	conv = shadow_copy2_convert(talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);
	if (conv == NULL) {
		return -1;
	}
	ret = SMB_VFS_NEXT_RMDIR(handle, conv);
	saved_errno = errno;
	TALLOC_FREE(conv);
	errno = saved_errno;
	return ret;
}

static int shadow_copy2_chflags(vfs_handle_struct *handle, const char *fname,
				unsigned int flags)
{
	time_t timestamp;
	char *stripped;
	int ret, saved_errno;
	char *conv;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, fname,
					 &timestamp, &stripped)) {
		return -1;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_CHFLAGS(handle, fname, flags);
	}
	conv = shadow_copy2_convert(talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);
	if (conv == NULL) {
		return -1;
	}
	ret = SMB_VFS_NEXT_CHFLAGS(handle, conv, flags);
	saved_errno = errno;
	TALLOC_FREE(conv);
	errno = saved_errno;
	return ret;
}

static ssize_t shadow_copy2_getxattr(vfs_handle_struct *handle,
				     const char *fname, const char *aname,
				     void *value, size_t size)
{
	time_t timestamp;
	char *stripped;
	ssize_t ret;
	int saved_errno;
	char *conv;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, fname,
					 &timestamp, &stripped)) {
		return -1;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_GETXATTR(handle, fname, aname, value,
					     size);
	}
	conv = shadow_copy2_convert(talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);
	if (conv == NULL) {
		return -1;
	}
	ret = SMB_VFS_NEXT_GETXATTR(handle, conv, aname, value, size);
	saved_errno = errno;
	TALLOC_FREE(conv);
	errno = saved_errno;
	return ret;
}

static ssize_t shadow_copy2_lgetxattr(vfs_handle_struct *handle,
				      const char *fname, const char *aname,
				      void *value, size_t size)
{
	time_t timestamp;
	char *stripped;
	ssize_t ret;
	int saved_errno;
	char *conv;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, fname,
					 &timestamp, &stripped)) {
		return -1;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_LGETXATTR(handle, fname, aname, value,
					      size);
	}
	conv = shadow_copy2_convert(talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);
	if (conv == NULL) {
		return -1;
	}
	ret = SMB_VFS_NEXT_LGETXATTR(handle, conv, aname, value, size);
	saved_errno = errno;
	TALLOC_FREE(conv);
	errno = saved_errno;
	return ret;
}

static ssize_t shadow_copy2_listxattr(struct vfs_handle_struct *handle,
				      const char *fname,
				      char *list, size_t size)
{
	time_t timestamp;
	char *stripped;
	ssize_t ret;
	int saved_errno;
	char *conv;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, fname,
					 &timestamp, &stripped)) {
		return -1;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_LISTXATTR(handle, fname, list, size);
	}
	conv = shadow_copy2_convert(talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);
	if (conv == NULL) {
		return -1;
	}
	ret = SMB_VFS_NEXT_LISTXATTR(handle, conv, list, size);
	saved_errno = errno;
	TALLOC_FREE(conv);
	errno = saved_errno;
	return ret;
}

static int shadow_copy2_removexattr(vfs_handle_struct *handle,
				    const char *fname, const char *aname)
{
	time_t timestamp;
	char *stripped;
	int ret, saved_errno;
	char *conv;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, fname,
					 &timestamp, &stripped)) {
		return -1;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_REMOVEXATTR(handle, fname, aname);
	}
	conv = shadow_copy2_convert(talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);
	if (conv == NULL) {
		return -1;
	}
	ret = SMB_VFS_NEXT_REMOVEXATTR(handle, conv, aname);
	saved_errno = errno;
	TALLOC_FREE(conv);
	errno = saved_errno;
	return ret;
}

static int shadow_copy2_lremovexattr(vfs_handle_struct *handle,
				     const char *fname, const char *aname)
{
	time_t timestamp;
	char *stripped;
	int ret, saved_errno;
	char *conv;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, fname,
					 &timestamp, &stripped)) {
		return -1;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_LREMOVEXATTR(handle, fname, aname);
	}
	conv = shadow_copy2_convert(talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);
	if (conv == NULL) {
		return -1;
	}
	ret = SMB_VFS_NEXT_LREMOVEXATTR(handle, conv, aname);
	saved_errno = errno;
	TALLOC_FREE(conv);
	errno = saved_errno;
	return ret;
}

static int shadow_copy2_setxattr(struct vfs_handle_struct *handle,
				 const char *fname,
				 const char *aname, const void *value,
				 size_t size, int flags)
{
	time_t timestamp;
	char *stripped;
	ssize_t ret;
	int saved_errno;
	char *conv;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, fname,
					 &timestamp, &stripped)) {
		return -1;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_SETXATTR(handle, fname, aname, value, size,
					     flags);
	}
	conv = shadow_copy2_convert(talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);
	if (conv == NULL) {
		return -1;
	}
	ret = SMB_VFS_NEXT_SETXATTR(handle, conv, aname, value, size, flags);
	saved_errno = errno;
	TALLOC_FREE(conv);
	errno = saved_errno;
	return ret;
}

static int shadow_copy2_lsetxattr(struct vfs_handle_struct *handle,
				  const char *fname,
				  const char *aname, const void *value,
				  size_t size, int flags)
{
	time_t timestamp;
	char *stripped;
	ssize_t ret;
	int saved_errno;
	char *conv;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, fname,
					 &timestamp, &stripped)) {
		return -1;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_LSETXATTR(handle, fname, aname, value,
					      size, flags);
	}
	conv = shadow_copy2_convert(talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);
	if (conv == NULL) {
		return -1;
	}
	ret = SMB_VFS_NEXT_LSETXATTR(handle, conv, aname, value, size, flags);
	saved_errno = errno;
	TALLOC_FREE(conv);
	errno = saved_errno;
	return ret;
}

static int shadow_copy2_chmod_acl(vfs_handle_struct *handle,
				  const char *fname, mode_t mode)
{
	time_t timestamp;
	char *stripped;
	ssize_t ret;
	int saved_errno;
	char *conv;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, fname,
					 &timestamp, &stripped)) {
		return -1;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_CHMOD_ACL(handle, fname, mode);
	}
	conv = shadow_copy2_convert(talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);
	if (conv == NULL) {
		return -1;
	}
	ret = SMB_VFS_NEXT_CHMOD_ACL(handle, conv, mode);
	saved_errno = errno;
	TALLOC_FREE(conv);
	errno = saved_errno;
	return ret;
}

static int shadow_copy2_get_real_filename(struct vfs_handle_struct *handle,
					  const char *path,
					  const char *name,
					  TALLOC_CTX *mem_ctx,
					  char **found_name)
{
	time_t timestamp;
	char *stripped;
	ssize_t ret;
	int saved_errno;
	char *conv;

	if (!shadow_copy2_strip_snapshot(talloc_tos(), handle, path,
					 &timestamp, &stripped)) {
		return -1;
	}
	if (timestamp == 0) {
		return SMB_VFS_NEXT_GET_REAL_FILENAME(handle, path, name,
						      mem_ctx, found_name);
	}
	if (stripped[0] == '\0') {
		*found_name = talloc_strdup(mem_ctx, name);
		if (*found_name == NULL) {
			errno = ENOMEM;
			return -1;
		}
		return 0;
	}
	conv = shadow_copy2_convert(talloc_tos(), handle, stripped, timestamp);
	TALLOC_FREE(stripped);
	if (conv == NULL) {
		return -1;
	}
	ret = SMB_VFS_NEXT_GET_REAL_FILENAME(handle, conv, name,
					     mem_ctx, found_name);
	saved_errno = errno;
	TALLOC_FREE(conv);
	errno = saved_errno;
	return ret;
}


static struct vfs_fn_pointers vfs_shadow_copy2_fns = {
	.opendir_fn = shadow_copy2_opendir,
	.rename_fn = shadow_copy2_rename,
	.link_fn = shadow_copy2_link,
	.symlink_fn = shadow_copy2_symlink,
	.stat_fn = shadow_copy2_stat,
	.lstat_fn = shadow_copy2_lstat,
	.fstat_fn = shadow_copy2_fstat,
	.open_fn = shadow_copy2_open,
	.unlink_fn = shadow_copy2_unlink,
	.chmod_fn = shadow_copy2_chmod,
	.chown_fn = shadow_copy2_chown,
	.chdir_fn = shadow_copy2_chdir,
	.ntimes_fn = shadow_copy2_ntimes,
	.readlink_fn = shadow_copy2_readlink,
	.mknod_fn = shadow_copy2_mknod,
	.realpath_fn = shadow_copy2_realpath,
	.get_nt_acl_fn = shadow_copy2_get_nt_acl,
	.fget_nt_acl_fn = shadow_copy2_fget_nt_acl,
	.get_shadow_copy_data_fn = shadow_copy2_get_shadow_copy_data,
	.mkdir_fn = shadow_copy2_mkdir,
	.rmdir_fn = shadow_copy2_rmdir,
	.getxattr_fn = shadow_copy2_getxattr,
	.lgetxattr_fn = shadow_copy2_lgetxattr,
	.listxattr_fn = shadow_copy2_listxattr,
	.removexattr_fn = shadow_copy2_removexattr,
	.lremovexattr_fn = shadow_copy2_lremovexattr,
	.setxattr_fn = shadow_copy2_setxattr,
	.lsetxattr_fn = shadow_copy2_lsetxattr,
	.chmod_acl_fn = shadow_copy2_chmod_acl,
	.chflags_fn = shadow_copy2_chflags,
	.get_real_filename_fn = shadow_copy2_get_real_filename,
};

NTSTATUS vfs_shadow_copy2_init(void);
NTSTATUS vfs_shadow_copy2_init(void)
{
	return smb_register_vfs(SMB_VFS_INTERFACE_VERSION,
				"shadow_copy2", &vfs_shadow_copy2_fns);
}