9.0.6 - Self Contained on a \\server\share\directory no longer executes

[tenbaset]

Description

SDK 9.0.6 has an issue where a Self Contained deployment to a network share no longer works, the process ends immediately with result code (0x80008083); irrespective of using a mapped drive letter or a \\unc path. Copying the same files to a local drive and executing there works correctly.

Worked under previous 9.0.5

Reproduction Steps

1. Build simple "hello world!" exe file
2. Publish it to a folder on a network share.
3. Attempt to run it. Observe nothing happens!

Example pubxml:

<?xml version="1.0" encoding="utf-8"?>
<!-- https://go.microsoft.com/fwlink/?LinkID=208121. -->
<Project>
  <PropertyGroup>
    <Configuration>Release</Configuration>
    <Platform>Any CPU</Platform>
    <PublishDir>\\server.domain.local\share\Software\dummy</PublishDir>
    <PublishProtocol>FileSystem</PublishProtocol>
    <_TargetId>Folder</_TargetId>
    <TargetFramework>net9.0</TargetFramework>
    <RuntimeIdentifier>win-x64</RuntimeIdentifier>
    <SelfContained>true</SelfContained>
    <PublishSingleFile>false</PublishSingleFile>
    <PublishReadyToRun>false</PublishReadyToRun>
    <PublishTrimmed>false</PublishTrimmed>
  </PropertyGroup>
</Project>

Expected behavior

When running \\server.domain.local\share\Software\dummy\consoleapp1.exe, expect program executes (e.g., output Hello World!)

Actual behavior

Program ends with no output.

Regression?

Worked in previous SDK 9.0.5.

Known Workarounds

• Previous SDK
• Copying files locally first

Configuration

• .Net SDK 9.0.6
• Self-contained deployment, not single-file
• Windows 11 x64
• Believe it is specific to Windows

Other information

Comparing the code tagged 9.0.6 and 9.0.5, this may be related to the (new) calls to is_path_rooted. The C++ "pal::is_path_rooted" (in the Windows implementation) only checks that the second character is a colon, which doesn't work when the path is a \\unc\share path!

I suggest updating is_path_rooted to permit paths that start with \\ as well (it seems mapped drive letters are translated into \\unc representations earlier in the process-startup, verified by using native debugger), but I'm unsure of any wider ramifications of that change.

[dotnet-policy-service]

Tagging subscribers to this area: @vitek-karas, @agocke, @VSadov
See info in area-owners.md if you want to be subscribed.

[WolfgangHG]

Attached is a small NET8 winforms sample. It contains a file "deploy.bat" inside, which calls "dotnet publish".
LaunchFailureSample.zip

To reproduce the issue: after executing "deploy.bat", launch the app using the UNC path. E.g. if the project is placed in "c:\temp", use the path \\mycomputer\c$\Temp\LaunchFailureSample\bin\Release\net8.0-windows\win-x64\publish\LaunchFailureSample.exe.

I added a "global.json" to control the version of .NET SDK and found this matrix:

{
  "sdk": {
    //Works:
    //"version": "9.0.300",
    //Fails:
    //"version": "9.0.205",
    //Fails:
    "version": "9.0.301",
    //Fails:
    //"version": "8.0.117",
    //Works:
    //"version": "8.0.204",
    //Fails:
    //"version": "8.0.314",
    //Fails:
    //"version": "8.0.411",
    "rollForward": "disable"
  }
}

If seems to fail for SDKs that contain runtime 9.0.6, but works for 9.0.5 (as the author of this issue wrote).

The problem also applies to .NET8 SDKs, probably since runtime 8.0.17. I tested some SDKs that were installed on my machine, but the versioning is rather irritating ;-). The one that works (8.0.204) seems to be for runtime 8.0.4

[jkotas]

cc @elinor-fung @agocke

Looks like a regression introduced by 214743e .

Does

runtime/src/native/corehost/hostmisc/pal.windows.cpp

Lines 660 to 663 in 0eb2b0a

	bool pal::is_path_rooted(const string_t& path)
	{
	return path.length() >= 2 && path[1] == L':';
	}

need to take UNC paths into account?

[jkotas]

The managed implementation that handles all corner-cases is at

runtime/src/libraries/Common/src/System/IO/PathInternal.Windows.cs

Lines 250 to 274 in 0eb2b0a

	internal static bool IsPartiallyQualified(ReadOnlySpan<char> path)
	{
	if (path.Length < 2)
	{
	// It isn't fixed, it must be relative. There is no way to specify a fixed
	// path with one character (or less).
	return true;
	}
	if (IsDirectorySeparator(path[0]))
	{
	// There is no valid way to specify a relative path with two initial slashes or
	// \? as ? isn't valid for drive relative paths and \??\ is equivalent to \\?\
	return !(path[1] == '?' || IsDirectorySeparator(path[1]));
	}
	// The only way to specify a fixed path that doesn't begin with two slashes
	// is the drive, colon, slash format- i.e. C:\
	return !((path.Length >= 3)
	&& (path[1] == VolumeSeparatorChar)
	&& IsDirectorySeparator(path[2])
	// To match old behavior we'll check the drive character for validity as the path is technically
	// not qualified if you don't have a valid drive. "=:\" is the "=" file's default data stream.
	&& IsValidDriveChar(path[0]));
	}