File size: 5,352 Bytes
8c763fb | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 | // Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.
#nullable enable
using System;
using System.Buffers;
using System.ComponentModel;
using System.Management.Automation;
using System.Runtime.InteropServices;
internal static partial class Interop
{
internal static partial class Windows
{
[LibraryImport(PinvokeDllNames.QueryDosDeviceDllName, EntryPoint = "QueryDosDeviceW", StringMarshalling = StringMarshalling.Utf16, SetLastError = true)]
internal static partial int QueryDosDevice(Span<char> lpDeviceName, Span<char> lpTargetPath, uint ucchMax);
internal static string GetDosDeviceForNetworkPath(char deviceName)
{
// By default buffer size is set to 300 which would generally be sufficient in most of the cases.
const int StartLength =
#if DEBUG
// In debug, validate ArrayPool growth.
1;
#else
300;
#endif
Span<char> buffer = stackalloc char[StartLength + 1];
Span<char> fullDeviceName = [deviceName, ':', '\0'];
char[]? rentedArray = null;
try
{
while (true)
{
uint length = (uint)buffer.Length;
int retValue = QueryDosDevice(fullDeviceName, buffer, length);
if (retValue > 0)
{
if (buffer.StartsWith("\\??\\"))
{
// QueryDosDevice always return array of NULL-terminating strings with additional final NULL
// so the buffer has always two NULL-s on end.
//
// "\\??\\UNC\\localhost\\c$\\tmp\0\0" -> "UNC\\localhost\\c$\\tmp\0\0"
Span<char> res = buffer.Slice(4);
if (res.StartsWith("UNC"))
{
// -> "C\\localhost\\c$\\tmp\0\0" -> "\\\\localhost\\c$\\tmp"
//
// We need to take only first null-terminated string as QueryDosDevice() docs say.
int i = 3;
for (; i < res.Length; i++)
{
if (res[i] == '\0')
{
break;
}
}
Diagnostics.Assert(i < res.Length, "Broken QueryDosDevice() buffer.");
res = res.Slice(2, i);
res[0] = '\\';
// If we want always to have terminating slash -> "\\\\localhost\\c$\\tmp\\"
// res = res.Slice(2, retValue - 3);
// res[0] = '\\';
// res[^1] = '\\';
}
// else if (res[^3] == ':')
// {
// Diagnostics.Assert(false, "Really it is a dead code since GetDosDevice() is called only if PSDrive.DriveType == DriveType.Network");
// // The substed path is the root path of a drive. For example: subst Y: C:\
// // -> "C:\0\0" -> "C:\"
// res = res.Slice(0, retValue - 1);
// res[^1] = '\\';
// }
else
{
throw new Exception("GetDosDeviceForNetworkPath() can be called only if PSDrive.DriveType == DriveType.Network.");
}
return res.ToString();
}
else
{
Diagnostics.Assert(false, "Really it is a dead code since GetDosDevice() is called only if PSDrive.DriveType == DriveType.Network");
// The drive name is not a substed path, then we return the root path of the drive
// "C:\0" -> "C:\\"
fullDeviceName[^1] = '\\';
return fullDeviceName.ToString();
}
}
const int ERROR_INSUFFICIENT_BUFFER = 122;
int errorCode = Marshal.GetLastPInvokeError();
if (errorCode != ERROR_INSUFFICIENT_BUFFER)
{
throw new Win32Exception((int)errorCode);
}
char[]? toReturn = rentedArray;
buffer = rentedArray = ArrayPool<char>.Shared.Rent(buffer.Length * 2);
if (toReturn is not null)
{
ArrayPool<char>.Shared.Return(toReturn);
}
}
}
finally
{
if (rentedArray is not null)
{
ArrayPool<char>.Shared.Return(rentedArray);
}
}
}
}
}
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