系统.在Blazor wasm中使用CSharpScript时出现IO.FileNotFoundException

Question

我正试图在Blazor-wasm应用程序中使用CSharpScript，用一个简单的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-预览3.20168.3

编辑：以下是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:UserssarmasourcereposScriptPlaygroundPagesIndex.razor:17 
at Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync () <0x36de968 + 0x0013a> in <filename unknown>:0

编辑2：在深入研究这个问题后，我们在Script.cs:中追踪到了这些行

/// <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，这都将在编译时调用，MetadataReference.CreateFromAssemblyInternal尝试从磁盘加载文件。因此，从磁盘加载程序集似乎是硬编码到该过程中的。我们正在寻找一种干净的方式来克服这一点。

我们已经成功地使用HttpClient:从流加载程序集

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

但只要CSharpScript在从磁盘编译期间加载另一组程序集，这就无关紧要了

Answer 1

不幸的是，CsharpScriptAPI的构建依赖于在本地文件系统上查找程序集。如果你深入挖掘MetadataReference.CreateFromStream源代码，你会发现罪魁祸首是对File.OpenRead()的调用

我花了一些时间研究API的任何可能的可扩展性，其中可以提供一种替代的程序集解析策略。在ScriptOptions中有一条通过提供自定义MetaDataReferenceResolver的路径，但是您发现的线路的烘焙

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

有效地创建了对文件系统的硬依赖，这扼杀了这个想法。

mscorlib的解析如上所述，但所有其他组件都使用Options.MetaDataReferences列表。为什么我不知道。。。。

作为一个纯粹的黑客，我甚至在捕获对File.OpenRead()的调用并从HttpClient返回我自己的stream时遇到了漏洞。注入在桌面进程中起作用，但wasm中出现了问题。最后，我也放弃了，转而采用这种方法或这种方法。

这是对任何感兴趣的人的试用破解。

//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-