README.md

NCode.ReparsePoints

This library provides an API to create and inspect Win32 file and folder reparse points such as hard links, junctions (aka soft links), and symbolic links.

Link Types

• Hard Link
• Junction (also known as Soft Link)
• Symbolic Link

Hard Link

Technically speaking a Hard Link is not really a Reparse Point on Win32 systems. Instead they are a type of file pointer supported since Windows XP and Server 2003.

• Files only
• Supported since:
  • Windows XP
  • Windows Server 2003
• Must be on same volume
• Must be on same computer
• No special privileges required (other than file security)

See MSDN for more information.

Junction

• Directories only
• Supported since:
  • Windows XP
  • Windows Server 2003
• Resolved by server (vs client)
• Can be on different volume
• Must be on same computer
• No special privileges required (other than folder security)

See MSDN for more information.

Symbolic Link

• Files or Directories
• Supported since:
  • Windows Vista
  • Windows Server 2008
• Resolved by client (vs server)
• Can be on different volume
• Can be on different computer
• Requires the SeCreateSymbolicLinkPrivilege right:
  • Administrator accounts has this right by default, but they must be running as elevated.
  • Non-administrator accounts need to be added to Local Security Policy.

See MSDN for more information.

Example Usage

using NCode.ReparsePoints;
internal static class Program
{
	private static void Main()
	{
	    var provider = ReparsePointFactory.Provider;
	    provider.CreateLink("D:\NewJunction", "C:\SourceDir", LinkType.Junction);
	
	    var link = provider.GetLink("D:\NewJunction");
	    Console.WriteLine("Type: {0}", link.Type);
	    Console.WriteLine("Target: {0}", link.Target);
	}
}

Interface

/// <summary>
/// Represents the type of reparse point such as a hard link, junction (aka
/// soft link), or symbolic link.
/// </summary>
[Serializable]
public enum LinkType
{
	/// <summary>
	/// Represents an unknown reparse point type.
	/// </summary>
	Unknown = 0,

	/// <summary>
	/// Represents a file <c>hard link</c>.
	/// </summary>
	/// <remarks>
	/// Technically not a reparse point.
	/// </remarks>
	HardLink,

	/// <summary>
	/// Represents a directory <c>junction</c> (aka soft link).
	/// </summary>
	Junction,

	/// <summary>
	/// Represents a <c>symbolic link</c> to either a file or folder.
	/// </summary>
	/// <remarks>
	/// In order to create symbolic links, the current user must either be an
	/// administrator running with elevated privileges or a non-admin user that
	/// has the SeCreateSymbolicLinkPrivilege right in local security policy.
	/// </remarks>
	Symbolic
}

/// <summary>
/// Contains the methods to create and inspect win32 file and folder reparse
/// points such as hard links, junctions (aka soft links), and symbolic links.
/// </summary>
/// <remarks>
/// Technically speaking, hard links are not reparse points but this library
/// supports them too.
/// </remarks>
public interface IReparsePointProvider
{
	/// <summary>
	/// Given a path, determines the type of reparse point.
	/// </summary>
	/// <param name="path">The path to inspect.</param>
	/// <returns>A <see cref="LinkType"/> enumeration.</returns>
	LinkType GetLinkType(string path);

	/// <summary>
	/// Given a path, returns the information about a reparse point.
	/// </summary>
	/// <param name="path">The path to inspect.</param>
	/// <returns>A <see cref="ReparseLink"/> that contains the information
	/// about a reparse point.</returns>
	ReparseLink GetLink(string path);

	/// <summary>
	/// Creates a new reparse point such as a hard link, junction (aka soft
	/// link), or symoblic link.
	/// </summary>
	/// <remarks>
	/// In order to create symbolic links, the current user must either be an
	/// administrator running with elevated privileges or a non-admin user that
	/// has the SeCreateSymbolicLinkPrivilege right in local security policy.
	/// </remarks>
	/// <param name="path">The path of reparse point to create.</param>
	/// <param name="target">The target for the reparse point.</param>
	/// <param name="type">A <see cref="LinkType"/> enumeration that specifies
	/// the type of reparse point to create.</param>
	void CreateLink(string path, string target, LinkType type);
}

/// <summary>
/// Contains the information about a reparse point.
/// </summary>
public struct ReparseLink
{
	/// <summary>
	/// Contains the <see cref="FileAttributes"/> of a reparse point.
	/// </summary>
	public FileAttributes Attributes { get; set; }

	/// <summary>
	/// Contains the <see cref="LinkType"/> of a reparse point.
	/// </summary>
	public LinkType Type { get; set; }

	/// <summary>
	/// Contains the target of a reparse point.
	/// </summary>
	/// <remarks>
	/// The target for a hard link cannot be determined so this member will
	/// always be <c>null</c> for hard links.
	/// </remarks>
	public string Target { get; set; }
}