2022-06-19 16:57:44 -06:00

93 lines
3.1 KiB
C#

using Newtonsoft.Json;
using System;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
namespace FileManager
{
public class LongPath
{
//https://docs.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation?tabs=cmd
public const int MaxDirectoryLength = MaxPathLength - 13;
public const int MaxPathLength = short.MaxValue;
public const int MaxFilenameLength = 255;
private const int MAX_PATH = 260;
private const string LONG_PATH_PREFIX = "\\\\?\\";
private static readonly StringBuilder longPathBuffer = new(MaxPathLength);
public string Path { get; init; }
public override string ToString() => Path;
public static implicit operator LongPath(string path)
{
if (path is null) return null;
//File I/O functions in the Windows API convert "/" to "\" as part of converting
//the name to an NT-style name, except when using the "\\?\" prefix
path = path.Replace(System.IO.Path.AltDirectorySeparatorChar, System.IO.Path.DirectorySeparatorChar);
if (path.StartsWith(LONG_PATH_PREFIX))
return new LongPath { Path = path };
else if ((path.Length > 2 && path[1] == ':') || path.StartsWith("UNC\\"))
return new LongPath { Path = LONG_PATH_PREFIX + path };
else if (path.StartsWith("\\\\"))
//The "\\?\" prefix can also be used with paths constructed according to the
//universal naming convention (UNC). To specify such a path using UNC, use
//the "\\?\UNC\" prefix.
return new LongPath { Path = LONG_PATH_PREFIX + "UNC\\" + path.Substring(2) };
else
{
//These prefixes are not used as part of the path itself. They indicate that
//the path should be passed to the system with minimal modification, which
//means that you cannot use forward slashes to represent path separators, or
//a period to represent the current directory, or double dots to represent the
//parent directory. Because you cannot use the "\\?\" prefix with a relative
//path, relative paths are always limited to a total of MAX_PATH characters.
if (path.Length > MAX_PATH)
throw new System.IO.PathTooLongException();
return new LongPath { Path = path };
}
}
public static implicit operator string(LongPath path) => path?.Path ?? null;
[JsonIgnore]
public string ShortPathName
{
get
{
if (Path is null) return null;
GetShortPathName(Path, longPathBuffer, MAX_PATH);
return longPathBuffer.ToString();
}
}
[JsonIgnore]
public string LongPathName
{
get
{
if (Path is null) return null;
GetLongPathName(Path, longPathBuffer, MaxPathLength);
return longPathBuffer.ToString();
}
}
[JsonIgnore]
public string PathWithoutPrefix
=> Path?.StartsWith(LONG_PATH_PREFIX) == true ?
Path.Remove(0, LONG_PATH_PREFIX.Length) :
Path;
[DllImport("kernel32.dll", CharSet = CharSet.Unicode)]
private static extern int GetShortPathName(string path, StringBuilder shortPath, int shortPathLength);
[DllImport("kernel32.dll", CharSet = CharSet.Unicode)]
private static extern int GetLongPathName(string lpszShortPath, StringBuilder lpszLongPath, int cchBuffer);
}
}