File.Copy no longer respects FileShare.None on Linux/Mac in 5.0 #31429
Description
Found this taking a new runtime into dotnet/sdk test run environment, as one of our tests started failing on Linux/Mac.
Program.cs
using System;
using System.IO;
class Program
{
static void Main()
{
File.WriteAllText("x", "x");
File.WriteAllText("y", "y");
using (var stream = new FileStream("y", FileMode.Open, FileAccess.Read, FileShare.None))
{
File.Copy("x", "y", overwrite: true);
}
Console.WriteLine("Success");
}
}Repro.csproj
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<OutputType>Exe</OutputType>
<TargetFrameworks>netcoreapp3.0;netcoreapp5.0</TargetFrameworks>
</PropertyGroup>
</Project>Repro steps
- dotnet run -f netcoreapp3.0
- dotnet run -f netcoreapp5.0
Expected result
Both 3.0 and 5.0 fail with IOExceptions
Actual result
Only 3.0 fails, 5.0 succeeds unexpectedly
3.0 (fails as expected)
Unhandled exception. System.IO.IOException: The process cannot access the file '/home/nicholg/src/sdk/q/y' because it is being used by another process.
at System.IO.FileStream.Init(FileMode mode, FileShare share, String originalPath)
at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options)
at System.IO.FileSystem.CopyFile(String sourceFullPath, String destFullPath, Boolean overwrite)
at System.IO.File.Copy(String sourceFileName, String destFileName, Boolean overwrite)
at Program.Main()
5.0 (succeeds unexpectedly)
Success