System.IO.FileNotFoundException 在 Blazor wasm 中使用 CSharpScript 时

Question

我正在尝试在 Blazor wasm 应用程序中使用 CSharpScript，使用简单的 EvaluateAsync 进行测试：

var result = await CSharpScript.EvaluateAsync<int>("1 + 1");

投掷：System.IO.FileNotFoundException: Could not find file "/mscorlib.dll"

我正在使用 Blazor wasm 3.2.0-preview3.20168.3

编辑：这是 index.razor 中的完整代码：

@code{
    protected override async Task OnInitializedAsync()
    {
        await base.OnInitializedAsync();
        Console.WriteLine("Initializing...");
        var result = await CSharpScript.EvaluateAsync<int>("1 + 1");
    }
}

这是控制台输出：

Initializing...
blazor.webassembly.js:1 crit: Microsoft.AspNetCore.Components.WebAssembly.Rendering.WebAssemblyRenderer[100]
      Unhandled exception rendering component: Could not find file "/mscorlib.dll"
System.IO.FileNotFoundException: Could not find file "/mscorlib.dll"
File name: '/mscorlib.dll'
  at System.IO.FileStream..ctor (System.String path, System.IO.FileMode mode, System.IO.FileAccess access, System.IO.FileShare share, System.Int32 bufferSize, System.Boolean anonymous, System.IO.FileOptions options) <0x3ba83f8 + 0x002b4> in <filename unknown>:0 
  at System.IO.FileStream..ctor (System.String path, System.IO.FileMode mode, System.IO.FileAccess access, System.IO.FileShare share) <0x3b987a0 + 0x0001c> in <filename unknown>:0 
  at System.IO.File.OpenRead (System.String path) <0x3b986d0 + 0x0000a> in <filename unknown>:0 
  at Roslyn.Utilities.FileUtilities.OpenFileStream (System.String path) [0x0001c] in /_/src/Compilers/Core/Portable/FileSystem/FileUtilities.cs:416 
  at Microsoft.CodeAnalysis.MetadataReference.CreateFromAssemblyInternal (System.Reflection.Assembly assembly, Microsoft.CodeAnalysis.MetadataReferenceProperties properties, Microsoft.CodeAnalysis.DocumentationProvider documentation) [0x0005a] in /_/src/Compilers/Core/Portable/MetadataReference/MetadataReference.cs:329 
  at Microsoft.CodeAnalysis.MetadataReference.CreateFromAssemblyInternal (System.Reflection.Assembly assembly) [0x00000] in /_/src/Compilers/Core/Portable/MetadataReference/MetadataReference.cs:271 
  at Microsoft.CodeAnalysis.Scripting.Script.GetReferencesForCompilation (Microsoft.CodeAnalysis.CommonMessageProvider messageProvider, Microsoft.CodeAnalysis.DiagnosticBag diagnostics, Microsoft.CodeAnalysis.MetadataReference languageRuntimeReferenceOpt) [0x0001a] in /_/src/Scripting/Core/Script.cs:252 
  at Microsoft.CodeAnalysis.CSharp.Scripting.CSharpScriptCompiler.CreateSubmission (Microsoft.CodeAnalysis.Scripting.Script script) [0x00021] in /_/src/Scripting/CSharp/CSharpScriptCompiler.cs:40 
  at Microsoft.CodeAnalysis.Scripting.Script.GetCompilation () [0x00008] in /_/src/Scripting/Core/Script.cs:144 
  at Microsoft.CodeAnalysis.Scripting.Script`1[T].GetExecutor (System.Threading.CancellationToken cancellationToken) [0x00008] in /_/src/Scripting/Core/Script.cs:361 
  at Microsoft.CodeAnalysis.Scripting.Script`1[T].RunAsync (System.Object globals, System.Func`2[T,TResult] catchException, System.Threading.CancellationToken cancellationToken) [0x0001b] in /_/src/Scripting/Core/Script.cs:465 
  at Microsoft.CodeAnalysis.Scripting.Script`1[T].RunAsync (System.Object globals, System.Threading.CancellationToken cancellationToken) [0x00000] in /_/src/Scripting/Core/Script.cs:439 
  at Microsoft.CodeAnalysis.CSharp.Scripting.CSharpScript.RunAsync[T] (System.String code, Microsoft.CodeAnalysis.Scripting.ScriptOptions options, System.Object globals, System.Type globalsType, System.Threading.CancellationToken cancellationToken) [0x00000] in /_/src/Scripting/CSharp/CSharpScript.cs:93 
  at Microsoft.CodeAnalysis.CSharp.Scripting.CSharpScript.EvaluateAsync[T] (System.String code, Microsoft.CodeAnalysis.Scripting.ScriptOptions options, System.Object globals, System.Type globalsType, System.Threading.CancellationToken cancellationToken) [0x00000] in /_/src/Scripting/CSharp/CSharpScript.cs:123 
  at ScriptPlayground.Pages.Index.OnInitializedAsync () [0x0008a] in C:\Users\sarma\source\repos\ScriptPlayground\Pages\Index.razor:17 
  at Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync () <0x36de968 + 0x0013a> in <filename unknown>:0

编辑 2：在深入研究该问题后，我们将其追溯到 Script.cs:

中的这些行

/// <summary>
/// Gets the references that need to be assigned to the compilation.
/// This can be different than the list of references defined by the <see cref="ScriptOptions"/> instance.
/// </summary>
internal ImmutableArray<MetadataReference> GetReferencesForCompilation(
    CommonMessageProvider messageProvider,
    DiagnosticBag diagnostics,
    MetadataReference languageRuntimeReferenceOpt = null)
{
    var resolver = Options.MetadataResolver;
    var references = ArrayBuilder<MetadataReference>.GetInstance();
    try
    {
        if (Previous == null)
        {
            var corLib = MetadataReference.CreateFromAssemblyInternal(typeof(object).GetTypeInfo().Assembly);
            references.Add(corLib);

无论我们传递什么选项，编译时都会调用它，MetadataReference.CreateFromAssemblyInternal 尝试从磁盘加载文件。因此，从磁盘加载程序集似乎已硬编码到该过程中。我们正在寻找一种干净的方法来覆盖它。

我们已经成功地使用 HttpClient 从流中加载程序集：

foreach (var assembly in AppDomain.CurrentDomain.GetAssemblies())
{
    var name = assembly.GetName().Name + ".dll";
    references.Add(
        MetadataReference.CreateFromStream(
            await this.HttpClient.GetStreamAsync("/_framework/_bin/" + name)));
}

但这并不重要，只要 CSharpScript 在从磁盘编译期间加载另一组程序集

Answer 1

不幸的是，CsharpScript API 的构建依赖于在本地文件系统上查找程序集。如果你在 MetadataReference.CreateFromStream 源代码中挖掘得足够深，你会发现罪魁祸首是对 File.OpenRead()

的调用

我自己花了一些时间研究 API 的任何可能的可扩展性，其中可以提供替代的程序集解析策略。在 ScriptOptions 中有一个自定义 MetaDataReferenceResolver 的路径，但是你找到的行的烘烤

 var corLib = MetadataReference.CreateFromAssemblyInternal(typeof(object).GetTypeInfo().Assembly);

有效地创建了对文件系统的硬依赖，从而扼杀了这个想法。

mscorlib 的解析是通过上面的方式完成的，但是所有其他程序集都使用 Options.MetaDataReferences 列表。为什么我不知道....

作为一个纯粹的 hack，我什至在捕获对 File.OpenRead() 的调用并从 HttpClient 返回我自己的 stream 方面遇到了困难。注入在桌面进程中有效，但在 wasm 中出现了问题。最后我也放弃了支持滚动替代方案，例如 this approach or this one.

这是供感兴趣的人使用的试用版。

    //Using the Pose library https://github.com/tonerdo/pose
    var client = new HttpClient() { BaseAddress = new Uri(navigationManager.BaseUri) };
    Shim fileShim = Shim.Replace(() => System.IO.File.OpenRead(Is.A<string>())).With(delegate (string assembly)
    {
        var fs = new System.IO.FileStream(assembly, System.IO.FileMode.Open);
        client.GetStreamAsync($"_framework/_bin/{assembly}").Result.CopyTo(fs);
        return fs;
    });

    PoseContext.Isolate(() => Text = CSharpScript.EvaluateAsync<string>("hello").Result, fileShim);

HTH

System.IO.FileNotFoundException 在 Blazor wasm 中使用 CSharpScript 时

System.IO.FileNotFoundException when using CSharpScript in Blazor wasm

c#

.net-core

blazor

csharpscript

blazor-client-side