internal static bool IsDotNetCoreAppHost(string filename, [NotNullWhen(true)] out string?dllFilename)
{
// We detect the apphost.exe like so:
// - must have an exe extension
// - must be a PE file and an EXE (DLL bit cleared)
// - must not have .NET metadata
// - must have a file with the same name but a dll extension
// - this dll file must be a PE file and have .NET metadata
// .NET Core 1.x: the apphost is a renamed dotnet.exe and it assumes (unless overridden
// on the command line) that the managed dll is apphostname with a dll extension.
// .NET Core 2.x-3.x: the relative path of the managed dll is part of the exe, patched
// by an MSBuild task. Max utf8 string length is 1024 bytes. It's currently not possible
// to override this path so it should be identical to apphostname with a dll extension,
// unless someone patched the apphost exe (eg. dnSpy).
// Windows apphosts have an .exe extension. Don't call Path.ChangeExtension() unless it's guaranteed
// to have an .exe extension, eg. 'some.file' => 'some.file.dll', not 'some.dll'
if (filename.EndsWith(".exe", StringComparison.OrdinalIgnoreCase))
{
dllFilename = Path.ChangeExtension(filename, ".dll");
}
else if (!filename.EndsWith(".dll", StringComparison.OrdinalIgnoreCase))
{
dllFilename = filename + ".dll";
}
else
{
dllFilename = null;
return(false);
}
if (!File.Exists(dllFilename))
{
return(false);
}
if (PortableExecutableFileHelpers.IsPE(filename, out bool isExe, out bool hasDotNetMetadata) && (!isExe || hasDotNetMetadata))
{
return(false);
}
if (!PortableExecutableFileHelpers.IsPE(dllFilename, out _, out hasDotNetMetadata) || !hasDotNetMetadata)
{
return(false);
}
return(true);
}
internal static bool TryGetAppHostEmbeddedDotNetDllPath(string apphostFilename, out bool couldBeAppHost, [NotNullWhen(true)] out string?dotNetDllPath)
{
dotNetDllPath = null;
couldBeAppHost = false;
if (!File.Exists(apphostFilename))
{
return(false);
}
if (PortableExecutableFileHelpers.IsPE(apphostFilename, out _, out var hasDotNetMetadata) && hasDotNetMetadata)
{
return(false);
}
try {
var data = ReadBytes(apphostFilename, MaxAppHostExeSize);
if (GetOffset(data, AppHostExeUnpatchedSignature) >= 0)
{
couldBeAppHost = true;
return(false);
}
if (GetOffset(data, AppHostExeSignature) < 0)
{
return(false);
}
couldBeAppHost = true;
if (!ExeUtils.TryGetTextSectionInfo(new BinaryReader(new MemoryStream(data)), out _, out _))
{
return(false);
}
var basePath = Path.GetDirectoryName(apphostFilename) !;
foreach (var info in GetAppHostInfos(data))
{
if (!TryGetUtf8StringZ(data, (int)info.RelPathOffset, AppHostInfo.MaxAppHostRelPathLength, out var relPath))
{
continue;
}
if (relPath == AppHostExeUnpatched)
{
continue;
}
string dotnetFile;
try {
dotnetFile = Path.Combine(basePath, relPath);
}
catch (ArgumentException) {
continue;
}
if (!PortableExecutableFileHelpers.IsPE(dotnetFile, out _, out hasDotNetMetadata))
{
continue;
}
if (!hasDotNetMetadata)
{
continue;
}
dotNetDllPath = dotnetFile;
return(true);
}
}
catch (IOException) {
}
return(false);
}