/// <summary>
/// Return true if the path points to a junction. These are distinct
/// from symlinks.
/// </summary>
/// <returns></returns>
public bool IsJunction()
{
ReparsePoint rep;
return(ReparsePoint.TryCreate(PurePath.ToString(), out rep) &&
rep.Tag == ReparsePoint.TagType.JunctionPoint);
}
/// <inheritdoc/>
public override bool IsSymlink()
{
ReparsePoint rep;
return(ReparsePoint.TryCreate(PurePath.ToString(), out rep) &&
rep.Tag == ReparsePoint.TagType.SymbolicLink);
}
/// <summary>
/// Takes a full path to a reparse point and finds the target.
/// </summary>
/// <param name="path">Full path of the reparse point</param>
/// <param name="link"></param>
public static bool TryCreate(string path, out ReparsePoint link)
{
Debug.Assert(!string.IsNullOrEmpty(path) && path.Length > 2 && path[1] == ':' && path[2] == '\\');
var tag = TagType.None;
string normalizedTarget;
// Apparently we need to have backup privileges
IntPtr token;
TOKEN_PRIVILEGES tokenPrivileges = new TOKEN_PRIVILEGES
{
Privileges = new LUID_AND_ATTRIBUTES[1]
};
bool success = OpenProcessToken(
GetCurrentProcess(), TOKEN_ADJUST_PRIVILEGES, out token);
if (!success)
{
link = null;
return false;
}
success = LookupPrivilegeValue(
null, SE_BACKUP_NAME, out tokenPrivileges.Privileges[0].Luid);
if (!success)
{
link = null;
return false;
}
tokenPrivileges.PrivilegeCount = 1;
tokenPrivileges.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;
success = AdjustTokenPrivileges(token, false, ref tokenPrivileges, Marshal.SizeOf(tokenPrivileges), IntPtr.Zero, IntPtr.Zero);
CloseHandle(token);
if (!success)
{
link = null;
return false;
}
// Open the file and get its handle
IntPtr handle = CreateFile(path, FileAccess.Read, FileShare.None, 0, FileMode.Open, FILE_FLAG_OPEN_REPARSE_POINT | FILE_FLAG_BACKUP_SEMANTICS, IntPtr.Zero);
if (handle.ToInt32() < 0)
{
link = null;
return false;
}
REPARSE_DATA_BUFFER buffer;
// Make up the control code - see CTL_CODE on ntddk.h
const uint controlCode = (FILE_DEVICE_FILE_SYSTEM << 16) | (FILE_ANY_ACCESS << 14) | (FSCTL_GET_REPARSE_POINT << 2) | METHOD_BUFFERED;
uint bytesReturned;
success = DeviceIoControl(handle, controlCode, IntPtr.Zero, 0, out buffer, MAXIMUM_REPARSE_DATA_BUFFER_SIZE, out bytesReturned, IntPtr.Zero);
if (!success)
{
link = null;
return false;
}
string subsString = "";
string printString = "";
// Note that according to http://wesnerm.blogs.com/net_undocumented/2006/10/symbolic_links_.html
// Symbolic links store relative paths, while junctions use absolute paths
// however, they can in fact be either, and may or may not have a leading \.
Debug.Assert(buffer.ReparseTag == IO_REPARSE_TAG_SYMLINK || buffer.ReparseTag == IO_REPARSE_TAG_MOUNT_POINT,
"Unrecognised reparse tag"); // We only recognise these two
if (buffer.ReparseTag == IO_REPARSE_TAG_SYMLINK)
{
// for some reason symlinks seem to have an extra two characters on the front
subsString = new string(buffer.ReparseTarget, (buffer.SubsNameOffset / 2 + 2), buffer.SubsNameLength / 2);
printString = new string(buffer.ReparseTarget, (buffer.PrintNameOffset / 2 + 2), buffer.PrintNameLength / 2);
tag = TagType.SymbolicLink;
}
else if (buffer.ReparseTag == IO_REPARSE_TAG_MOUNT_POINT)
{
// This could be a junction or a mounted drive - a mounted drive starts with "\\??\\Volume"
subsString = new string(buffer.ReparseTarget, buffer.SubsNameOffset/2, buffer.SubsNameLength/2);
printString = new string(buffer.ReparseTarget, buffer.PrintNameOffset / 2, buffer.PrintNameLength / 2);
tag = subsString.StartsWith(@"\??\Volume") ? TagType.MountPoint : TagType.JunctionPoint;
}
Debug.Assert(!(string.IsNullOrEmpty(subsString) && string.IsNullOrEmpty(printString)), "Failed to retrieve parse point");
// the printstring should give us what we want
if (!string.IsNullOrEmpty(printString))
{
normalizedTarget = printString;
}
else
{
// if not we can use the substring with a bit of tweaking
normalizedTarget = subsString;
Debug.Assert(normalizedTarget.Length > 2, "Target string too short");
Debug.Assert(
(normalizedTarget.StartsWith(@"\??\") && (normalizedTarget[5] == ':' || normalizedTarget.StartsWith(@"\??\Volume")) ||
(!normalizedTarget.StartsWith(@"\??\") && normalizedTarget[1] != ':')),
"Malformed subsString");
// Junction points must be absolute
Debug.Assert(
buffer.ReparseTag == IO_REPARSE_TAG_SYMLINK ||
normalizedTarget.StartsWith(@"\??\Volume") ||
normalizedTarget[1] == ':' ||
normalizedTarget.StartsWith(@"\??\") && normalizedTarget[5] == ':',
"Relative junction point");
if (normalizedTarget.StartsWith(@"\??\"))
{
normalizedTarget = normalizedTarget.Substring(4);
}
}
var target = normalizedTarget;
// Symlinks can be relative.
if (buffer.ReparseTag == IO_REPARSE_TAG_SYMLINK && (normalizedTarget.Length < 2 || normalizedTarget[1] != ':'))
{
// it's relative, we need to tack it onto the path
if (normalizedTarget[0] == '\\')
{
normalizedTarget = normalizedTarget.Substring(1);
}
if (path.EndsWith(@"\"))
{
path = path.Substring(0, path.Length - 1);
}
// Need to take the symlink name off the path
normalizedTarget = path.Substring(0, path.LastIndexOf('\\')) + @"\" + normalizedTarget;
// Note that if the symlink target path contains any ..s these are not normalised but returned as is.
}
// Remove any final slash for consistency
if (normalizedTarget.EndsWith("\\"))
{
normalizedTarget = normalizedTarget.Substring(0, normalizedTarget.Length-1);
}
CloseHandle(handle);
link = new ReparsePoint
{
_normalizedTarget = normalizedTarget,
Target = target,
Tag = tag
};
return true;
}
/// <summary>
/// Takes a full path to a reparse point and finds the target.
/// </summary>
/// <param name="path">Full path of the reparse point</param>
/// <param name="link"></param>
public static bool TryCreate(string path, out ReparsePoint link)
{
Debug.Assert(!string.IsNullOrEmpty(path) && path.Length > 2 && path[1] == ':' && path[2] == '\\');
var tag = TagType.None;
string normalizedTarget;
// Apparently we need to have backup privileges
IntPtr token;
TOKEN_PRIVILEGES tokenPrivileges = new TOKEN_PRIVILEGES
{
Privileges = new LUID_AND_ATTRIBUTES[1]
};
bool success = OpenProcessToken(
GetCurrentProcess(), TOKEN_ADJUST_PRIVILEGES, out token);
if (!success)
{
link = null;
return(false);
}
success = LookupPrivilegeValue(
null, SE_BACKUP_NAME, out tokenPrivileges.Privileges[0].Luid);
if (!success)
{
link = null;
return(false);
}
tokenPrivileges.PrivilegeCount = 1;
tokenPrivileges.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;
success = AdjustTokenPrivileges(token, false, ref tokenPrivileges, Marshal.SizeOf(tokenPrivileges), IntPtr.Zero, IntPtr.Zero);
CloseHandle(token);
if (!success)
{
link = null;
return(false);
}
// Open the file and get its handle
IntPtr handle = CreateFile(path, FileAccess.Read, FileShare.None, 0, FileMode.Open, FILE_FLAG_OPEN_REPARSE_POINT | FILE_FLAG_BACKUP_SEMANTICS, IntPtr.Zero);
if (handle.ToInt32() < 0)
{
link = null;
return(false);
}
REPARSE_DATA_BUFFER buffer;
// Make up the control code - see CTL_CODE on ntddk.h
const uint controlCode = (FILE_DEVICE_FILE_SYSTEM << 16) | (FILE_ANY_ACCESS << 14) | (FSCTL_GET_REPARSE_POINT << 2) | METHOD_BUFFERED;
uint bytesReturned;
success = DeviceIoControl(handle, controlCode, IntPtr.Zero, 0, out buffer, MAXIMUM_REPARSE_DATA_BUFFER_SIZE, out bytesReturned, IntPtr.Zero);
if (!success)
{
link = null;
return(false);
}
string subsString = "";
string printString = "";
// Note that according to http://wesnerm.blogs.com/net_undocumented/2006/10/symbolic_links_.html
// Symbolic links store relative paths, while junctions use absolute paths
// however, they can in fact be either, and may or may not have a leading \.
Debug.Assert(buffer.ReparseTag == IO_REPARSE_TAG_SYMLINK || buffer.ReparseTag == IO_REPARSE_TAG_MOUNT_POINT,
"Unrecognised reparse tag"); // We only recognise these two
if (buffer.ReparseTag == IO_REPARSE_TAG_SYMLINK)
{
// for some reason symlinks seem to have an extra two characters on the front
subsString = new string(buffer.ReparseTarget, (buffer.SubsNameOffset / 2 + 2), buffer.SubsNameLength / 2);
printString = new string(buffer.ReparseTarget, (buffer.PrintNameOffset / 2 + 2), buffer.PrintNameLength / 2);
tag = TagType.SymbolicLink;
}
else if (buffer.ReparseTag == IO_REPARSE_TAG_MOUNT_POINT)
{
// This could be a junction or a mounted drive - a mounted drive starts with "\\??\\Volume"
subsString = new string(buffer.ReparseTarget, buffer.SubsNameOffset / 2, buffer.SubsNameLength / 2);
printString = new string(buffer.ReparseTarget, buffer.PrintNameOffset / 2, buffer.PrintNameLength / 2);
tag = subsString.StartsWith(@"\??\Volume") ? TagType.MountPoint : TagType.JunctionPoint;
}
Debug.Assert(!(string.IsNullOrEmpty(subsString) && string.IsNullOrEmpty(printString)), "Failed to retrieve parse point");
// the printstring should give us what we want
if (!string.IsNullOrEmpty(printString))
{
normalizedTarget = printString;
}
else
{
// if not we can use the substring with a bit of tweaking
normalizedTarget = subsString;
Debug.Assert(normalizedTarget.Length > 2, "Target string too short");
Debug.Assert(
(normalizedTarget.StartsWith(@"\??\") && (normalizedTarget[5] == ':' || normalizedTarget.StartsWith(@"\??\Volume")) ||
(!normalizedTarget.StartsWith(@"\??\") && normalizedTarget[1] != ':')),
"Malformed subsString");
// Junction points must be absolute
Debug.Assert(
buffer.ReparseTag == IO_REPARSE_TAG_SYMLINK ||
normalizedTarget.StartsWith(@"\??\Volume") ||
normalizedTarget[1] == ':' ||
normalizedTarget.StartsWith(@"\??\") && normalizedTarget[5] == ':',
"Relative junction point");
if (normalizedTarget.StartsWith(@"\??\"))
{
normalizedTarget = normalizedTarget.Substring(4);
}
}
var target = normalizedTarget;
// Symlinks can be relative.
if (buffer.ReparseTag == IO_REPARSE_TAG_SYMLINK && (normalizedTarget.Length < 2 || normalizedTarget[1] != ':'))
{
// it's relative, we need to tack it onto the path
if (normalizedTarget[0] == '\\')
{
normalizedTarget = normalizedTarget.Substring(1);
}
if (path.EndsWith(@"\"))
{
path = path.Substring(0, path.Length - 1);
}
// Need to take the symlink name off the path
normalizedTarget = path.Substring(0, path.LastIndexOf('\\')) + @"\" + normalizedTarget;
// Note that if the symlink target path contains any ..s these are not normalised but returned as is.
}
// Remove any final slash for consistency
if (normalizedTarget.EndsWith("\\"))
{
normalizedTarget = normalizedTarget.Substring(0, normalizedTarget.Length - 1);
}
CloseHandle(handle);
link = new ReparsePoint
{
_normalizedTarget = normalizedTarget,
Target = target,
Tag = tag
};
return(true);
}
