System.IO.Directory.CreateTempSubdirectory(String prefix) fails with Success exception in wasi-wasm build

[dbaeumer]

Description

Calling System.IO.Directory.CreateTempSubdirectory(String prefix) fails with an exception in a wasi-wasm build

Reproduction Steps

• .Net version 8.0.100-rc.1.23455.8
• tempDir.csproj

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <RuntimeIdentifier>wasi-wasm</RuntimeIdentifier>
    <OutputType>Exe</OutputType>
    <PublishTrimmed>true</PublishTrimmed>
    <WasmSingleFileBundle>true</WasmSingleFileBundle>
  </PropertyGroup>
</Project>

• Program.cs

using System;
using System.IO;
using System.Text;

Console.WriteLine("Hello, Wasi Console!");

using (var writer = File.Create("/tmp/test.txt")) {
	writer.Write(Encoding.UTF8.GetBytes("Hello World!"));
}

var dir = Directory.CreateTempSubdirectory();
Console.WriteLine("Created temp dir: " + dir.FullName);

• dotnet build
• create a tmp directory in the workspace directory
• wasmtime 12.0.2
• run wasmtime run --mapdir /::. --env TMPDIR=/tmp obj/Debug/net8.0/wasi-wasm/wasm/for-build/tempDir.wasm

Expected behavior

Creating the temp directory works

Actual behavior

System.IO.IOException: Success
   at Interop.ThrowExceptionForIoErrno(ErrorInfo errorInfo, String path, Boolean isDirError)
   at Interop.ThrowIOExceptionForLastError()
   at System.IO.Directory.CreateTempSubdirectoryCore(String prefix)
   at System.IO.Directory.CreateTempSubdirectory(String prefix)
   at Program.<Main>$(String[] args)

The write to the file happened successful.

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

Tagging subscribers to this area: @dotnet/area-system-io
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

Calling System.IO.Directory.CreateTempSubdirectory(String prefix) fails with an exception in a wasi-wasm build

Reproduction Steps

• .Net version 8.0.100-rc.1.23455.8
• tempDir.csproj

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <RuntimeIdentifier>wasi-wasm</RuntimeIdentifier>
    <OutputType>Exe</OutputType>
    <PublishTrimmed>true</PublishTrimmed>
    <WasmSingleFileBundle>true</WasmSingleFileBundle>
  </PropertyGroup>
</Project>

• Program.cs

using System;
using System.IO;
using System.Text;

Console.WriteLine("Hello, Wasi Console!");

using (var writer = File.Create("/tmp/test.txt")) {
	writer.Write(Encoding.UTF8.GetBytes("Hello World!"));
}

var dir = Directory.CreateTempSubdirectory();
Console.WriteLine("Created temp dir: " + dir.FullName);

• dotnet build
• create a tmp directory in the workspace directory
• wasmtime 12.0.2
• run wasmtime run --mapdir /::. --env TMPDIR=/tmp obj/Debug/net8.0/wasi-wasm/wasm/for-build/tempDir.wasm

Expected behavior

Creating the temp directory works

Actual behavior

System.IO.IOException: Success
   at Interop.ThrowExceptionForIoErrno(ErrorInfo errorInfo, String path, Boolean isDirError)
   at Interop.ThrowIOExceptionForLastError()
   at System.IO.Directory.CreateTempSubdirectoryCore(String prefix)
   at System.IO.Directory.CreateTempSubdirectory(String prefix)
   at Program.<Main>$(String[] args)

The write to the file happened successful.

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

Author:	dbaeumer
Assignees:	-
Labels:	area-System.IO
Milestone:	-

Tagging subscribers to 'arch-wasm': @lewing
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

Calling System.IO.Directory.CreateTempSubdirectory(String prefix) fails with an exception in a wasi-wasm build

Reproduction Steps

• .Net version 8.0.100-rc.1.23455.8
• tempDir.csproj

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <RuntimeIdentifier>wasi-wasm</RuntimeIdentifier>
    <OutputType>Exe</OutputType>
    <PublishTrimmed>true</PublishTrimmed>
    <WasmSingleFileBundle>true</WasmSingleFileBundle>
  </PropertyGroup>
</Project>

• Program.cs

using System;
using System.IO;
using System.Text;

Console.WriteLine("Hello, Wasi Console!");

using (var writer = File.Create("/tmp/test.txt")) {
	writer.Write(Encoding.UTF8.GetBytes("Hello World!"));
}

var dir = Directory.CreateTempSubdirectory();
Console.WriteLine("Created temp dir: " + dir.FullName);

• dotnet build
• create a tmp directory in the workspace directory
• wasmtime 12.0.2
• run wasmtime run --mapdir /::. --env TMPDIR=/tmp obj/Debug/net8.0/wasi-wasm/wasm/for-build/tempDir.wasm

Expected behavior

Creating the temp directory works

Actual behavior

System.IO.IOException: Success
   at Interop.ThrowExceptionForIoErrno(ErrorInfo errorInfo, String path, Boolean isDirError)
   at Interop.ThrowIOExceptionForLastError()
   at System.IO.Directory.CreateTempSubdirectoryCore(String prefix)
   at System.IO.Directory.CreateTempSubdirectory(String prefix)
   at Program.<Main>$(String[] args)

The write to the file happened successful.

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

Author:	dbaeumer
Assignees:	-
Labels:	arch-wasm, area-System.IO, untriaged, os-wasi
Milestone:	-

[dbaeumer]

I can create a directory as well using the following code

var dirOne = Directory.CreateDirectory("/tmp/dirOne");
Console.WriteLine("Created dir: " + dirOne.FullName);

[pavelsavara]

Could be related #81210 and WebAssembly/wasi-libc#414

[dbaeumer]

@pavelsavara I executed the WASM file on the VS Code WASI host implementation which offers nice tracing of host calls. The Directory.CreateTempSubdirectory() call doesn't result in any host calls, so I guess this fails inside some C# code and is falsely reported as a exception with an errno. There aren't any fd_readdir calls either before.

What I did notice as well is that the wasm code does tons of clock_time_get(id: monotonic, precision: 1) calls.

[pavelsavara]

See

runtime/src/native/libs/System.Native/pal_io.c

Lines 850 to 852 in 32c3355

	#else /* TARGET_WASI */
	return NULL;
	#endif /* TARGET_WASI */

https://github.com/WebAssembly/wasi-libc/blob/ce2f157d46e04f323edf93f02c8f60069d88df96/libc-top-half/musl/include/stdlib.h#L118-L122

[dbaeumer]

Any reason why we couldn't implement that in C# for WASI. I can understand why we can't use libc since they hardcode /tmp but Python on wasm-wasi has support for this since they come with their own mkdtemp implementation.

[pavelsavara]

That's what #81210 wants I think.

It would be also good to do that for emscripten build.

Because the idea of generating randomness out of timer + checking if there is file system conflict is very ugly.
We had issues with that already because of the granularity of browser timer used.

https://github.com/emscripten-core/emscripten/blob/813a727fa77b3596c75a6d62b2fdb87365f9d75a/system/lib/libc/musl/src/temp/mkdtemp.c#L16-L19

https://github.com/emscripten-core/emscripten/blob/813a727fa77b3596c75a6d62b2fdb87365f9d75a/system/lib/libc/musl/src/temp/__randname.c#L13-L14

PR welcome.

[adamsitnik]

It reminds me of