Snapshot.cs



#region Copyright Notice
/*
 * AlphaVSS Sample Code
 * Written by Jay Miller
 * 
 * This code is hereby released into the public domain, This applies
 * worldwide.
 */
#endregion

using System;
using Alphaleonis.Win32.Vss;

namespace FolderSync
{
    /// <summary>
    /// Utility class to manage the snapshot's contents and ID.
    /// </summary>
    class Snapshot : IDisposable
    {
        /// <summary>A reference to the VSS context.</summary>
        IVssBackupComponents _backup;

        /// <summary>Metadata about this object's snapshot.</summary>
        VssSnapshotProperties _props;

        /// <summary>Identifier for the overall shadow copy.</summary>
        Guid _set_id;

        /// <summary>Identifier for our single snapshot volume.</summary>
        Guid _snap_id;

        /// <summary>
        /// Initializes a snapshot.  We save the GUID of this snap in order to
        /// refer to it elsewhere in the class.
        /// </summary>
        /// <param name="backup">A VssBackupComponents implementation for the current OS.</param>
        public Snapshot(IVssBackupComponents backup)
        {
            _backup = backup;
            _set_id = backup.StartSnapshotSet();
        }

        /// <summary>
        /// Dispose of the shadow copies created by this instance.
        /// </summary>
        public void Dispose()
        {
            try { Delete(); } catch { }
        }

        /// <summary>
        /// Adds a volume to the current snapshot.
        /// </summary>
        /// <param name="volumeName">Name of the volume to add (eg. "C:\").</param>
        /// <remarks>
        /// Note the IsVolumeSupported check prior to adding each volume.
        /// </remarks>
        public void AddVolume(string volumeName)
        {
            if (volumeName.StartsWith(@"\\?\"))     //roland: IsVolumeSupported does not like \\?\ paths
                volumeName = volumeName.Substring(4);

            if (!volumeName.EndsWith(@"\"))     //roland: IsVolumeSupported requires \ at the end
                volumeName += @"\";

            if (_backup.IsVolumeSupported(volumeName))
            //if (true)
                _snap_id = _backup.AddToSnapshotSet(volumeName);
            else
                throw new VssVolumeNotSupportedException(volumeName);
        }

        /// <summary>
        /// Create the actual snapshot.  This process can take around 10s.
        /// </summary>
        public void Copy()
        {
            _backup.DoSnapshotSet();
        }

        /// <summary>
        /// Remove all snapshots.
        /// </summary>
        public void Delete()
        {
            _backup.DeleteSnapshotSet(_set_id, false);
        }

        /// <summary>
        /// Gets the string that identifies the root of this snapshot.
        /// </summary>
        public string Root
        {
            get
            {
                if (_props == null)
                    _props = _backup.GetSnapshotProperties(_snap_id);
                return _props.SnapshotDeviceObject;
            }
        }
    }
}