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jbevain / cecil

Cecil is a library to inspect, modify and create .NET programs and libraries.
MIT License
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Resolve `.dll` before `.exe` #949

Closed mrvoorhe closed 2 months ago

mrvoorhe commented 2 months ago

In the .NET world, executable assemblies have a Foo.exe and Foo.dll file. Foo.exe is not a managed assembly and attempting to load it will cause

System.BadImageFormatException: Format of the executable (.exe) or library (.dll) is invalid.
   at Mono.Cecil.PE.ImageReader.ReadOptionalHeaders(UInt16& subsystem, UInt16& dll_characteristics) in C:\UnitySrc\dev\il2cpp-18\external\cecil\Mono.Cecil.PE\ImageReader.cs:line 198
   at Mono.Cecil.PE.ImageReader.ReadImage() in C:\UnitySrc\dev\il2cpp-18\external\cecil\Mono.Cecil.PE\ImageReader.cs:line 86
   at Mono.Cecil.PE.ImageReader.ReadImage(Disposable`1 stream, String file_name) in C:\UnitySrc\dev\il2cpp-18\external\cecil\Mono.Cecil.PE\ImageReader.cs:line 766
   at Mono.Cecil.ModuleDefinition.ReadModule(Disposable`1 stream, String fileName, ReaderParameters parameters) in C:\UnitySrc\dev\il2cpp-18\external\cecil\Mono.Cecil\ModuleDefinition.cs:line 1141
   at Mono.Cecil.ModuleDefinition.ReadModule(String fileName, ReaderParameters parameters) in C:\UnitySrc\dev\il2cpp-18\external\cecil\Mono.Cecil\ModuleDefinition.cs:line 1110
   at Mono.Cecil.AssemblyDefinition.ReadAssembly(String fileName, ReaderParameters parameters) in C:\UnitySrc\dev\il2cpp-18\external\cecil\Mono.Cecil\AssemblyDefinition.cs:line 132

By attempting to locate .dll files before .exe this problem can be avoided.

For context, I hit this in one of our resolvers while attempting to resolve all of the dependencies of an executable that referenced another executable. I fixed our resolver the same way but noticed BaseAssemblyResolver had the same behavior we had so I thought I'd upstream the change.