Progressing with assembly stores + shared libraries

Author: grendello

tools/apput/src/ApplicationAssembly/ApplicationAssembly.cs

@@ -13,12 +13,12 @@ public class ApplicationAssembly : IAspect
 	public ulong Size           { get; private set; }
 	public bool IgnoreOnLoad    { get; private set; }
 
-	public static IAspect LoadAspect (Stream stream, string? description)
+	public static IAspect LoadAspect (Stream stream, IAspectState state, string? description)
 	{
 		throw new NotImplementedException ();
 	}
 
-	public static bool ProbeAspect (Stream stream, string? description)
+	public static IAspectState ProbeAspect (Stream stream, string? description)
 	{
 		throw new NotImplementedException ();
 	}

tools/apput/src/AssemblyStore/AssemblyStore.cs

@@ -18,46 +18,78 @@ public class AssemblyStore : IAspect
 	public AndroidTargetArch Architecture { get; private set; } = AndroidTargetArch.None;
 	public ulong NumberOfAssemblies => (ulong)(Assemblies?.Count ?? 0);
 
-	public static IAspect LoadAspect (Stream stream, string? description)
+	public static IAspect LoadAspect (Stream stream, IAspectState state, string? description)
 	{
+		var storeState = state as AssemblyStoreAspectState;
 		throw new NotImplementedException ();
 	}
 
-	public static bool ProbeAspect (Stream stream, string? description)
+	public static IAspectState ProbeAspect (Stream stream, string? description)
 	{
-		// TODO: check if it's an ELF .so and extract the payload, if necessary
+		Stream? storeStream = null;
 
+		try {
+			IAspectState state = SharedLibrary.ProbeAspect (stream, description);
+			if (!state.Success) {
+				return DoProbeAspect (stream, description);
+			}
+
+			var library = (SharedLibrary)SharedLibrary.LoadAspect (stream, state, description);
+			if (!library.HasAndroidPayload) {
+				Log.Debug ($"AssemblyStore: stream ('{description}') is an ELF shared library, without payload");
+				return new BasicAspectState (false);
+			}
+			Log.Debug ($"AssemblyStore: stream ('{description}') is an ELF shared library with .NET for Android payload section");
+			storeStream = library.OpenAndroidPayload ();
+			return DoProbeAspect (storeStream, description);
+		} finally {
+			storeStream?.Dispose ();
+		}
+	}
+
+	// We return `BasicAspectState` instance for all failures, since there's no extra information we can
+	// pass on.
+	static IAspectState DoProbeAspect (Stream storeStream, string? description)
+	{
 		// All assembly store files are at least 8 bytes long - space taken up by
 		// the magic number + store version.
-		if (stream.Length < MinimumStoreSize) {
+		if (storeStream.Length < MinimumStoreSize) {
 			Log.Debug ($"AssemblyStore: stream ('{description}') isn't long enough. Need at least {MinimumStoreSize} bytes");
-			return false;
+			return new BasicAspectState (false);
 		}
 
-		stream.Seek (0, SeekOrigin.Begin);
-		using var reader = new BinaryReader (stream, Encoding.UTF8, leaveOpen: true);
+		storeStream.Seek (0, SeekOrigin.Begin);
+		using var reader = new BinaryReader (storeStream, Encoding.UTF8, leaveOpen: true);
 		uint magic = reader.ReadUInt32 ();
 		if (magic != MagicNumber) {
 			Log.Debug ($"AssemblyStore: stream ('{description}') doesn't have the correct signature.");
-			return false;
+			return new BasicAspectState (false);
 		}
 
 		uint version = reader.ReadUInt32 ();
 
 		// We currently support version 3. Main store version is kept in the lower 16 bits of the version word
 		uint mainVersion = version & 0xFFFF;
+		FormatBase? validator = null;
+
 		switch (mainVersion) {
+			case 2:
+				validator = new Format_V2 (storeStream, description);
+				break;
+
 			case 3:
-				return ValidateFormatVersion3 (stream, description);
+				validator = new Format_V3 (storeStream, description);
+				break;
 
 			default:
 				Log.Debug ($"AssemblyStore: unsupported store version: {mainVersion}");
-				return false;
+				return new BasicAspectState (false);
 		}
-	}
 
-	static bool ValidateFormatVersion3 (Stream stream, string? description)
-	{
-		return true;
+		if (validator == null) {
+			throw new InvalidOperationException ("Internal error: validator should never be null here");
+		}
+
+		return validator.Validate ();
 	}
 }

tools/apput/src/AssemblyStore/AssemblyStoreAspectState.cs

@@ -0,0 +1,13 @@
+using System.Collections.Generic;
+
+namespace ApplicationUtility;
+
+class AssemblyStoreAspectState : BasicAspectState
+{
+	public AssemblyStoreHeader Header { get; }
+	public AssemblyStoreIndex Index { get; }
+
+	public AssemblyStoreAspectState (bool success)
+		: base (success)
+	{}
+}

tools/apput/src/AssemblyStore/AssemblyStoreIndex.cs

@@ -0,0 +1,5 @@
+using ApplicationUtility;
+
+class AssemblyStoreIndex
+{
+}

tools/apput/src/AssemblyStore/FormatBase.cs

@@ -0,0 +1,17 @@
+using System.IO;
+
+namespace ApplicationUtility;
+
+abstract class FormatBase
+{
+	protected Stream StoreStream { get; }
+	protected string? Description { get; }
+
+	protected FormatBase (Stream storeStream, string? description)
+	{
+		this.StoreStream = storeStream;
+		this.Description = description;
+	}
+
+	public abstract IAspectState Validate ();
+}

tools/apput/src/AssemblyStore/Format_V2.cs

@@ -0,0 +1,16 @@
+using System;
+using System.IO;
+
+namespace ApplicationUtility;
+
+class Format_V2 : FormatBase
+{
+	public Format_V2 (Stream storeStream, string? description)
+		: base (storeStream, description)
+	{}
+
+	public override IAspectState Validate ()
+	{
+		throw new NotImplementedException ();
+	}
+}

tools/apput/src/AssemblyStore/Format_V3.cs

@@ -1,5 +1,17 @@
+using System.IO;
+
 namespace ApplicationUtility;
 
-class Format_V3
+class Format_V3 : FormatBase
 {
+	public Format_V3 (Stream storeStream, string? description)
+		: base (storeStream, description)
+	{}
+
+	public override IAspectState Validate ()
+	{
+		// TODO: validate that the store has correct format and populate the state below accordingly
+		//       to save time later.
+		return new AssemblyStoreAspectState (true);
+	}
 }

tools/apput/src/Common/BasicAspectState.cs

@@ -0,0 +1,11 @@
+namespace ApplicationUtility;
+
+class BasicAspectState : IAspectState
+{
+	public bool Success { get; }
+
+	public BasicAspectState (bool success)
+	{
+		Success = success;
+	}
+}

tools/apput/src/Common/IAspect.cs

@@ -23,12 +23,12 @@ public interface IAspect
 	/// `false` otherwise. The <paramref name="description"/> parameter can be anything that makes
 	/// sense for the given aspect (e.g. a file name).
 	/// </summary>
-	static bool ProbeAspect (Stream stream, string? description = null) => throw new NotImplementedException ();
+	static IAspectState ProbeAspect (Stream stream, string? description = null) => throw new NotImplementedException ();
 
 	/// <summary>
 	/// Load the aspect and return instance of a class implementing support for it.
 	/// The <paramref name="description"/> parameter can be anything that makes
 	/// sense for the given aspect (e.g. a file name).
 	/// </summary>
-	static IAspect LoadAspect (Stream stream, string? description = null) => throw new NotImplementedException ();
+	static IAspect LoadAspect (Stream stream, IAspectState state, string? description = null) => throw new NotImplementedException ();
 }

tools/apput/src/Common/IAspectState.cs

@@ -0,0 +1,15 @@
+namespace ApplicationUtility;
+
+/// <summary>
+/// An empty interface which can be used by the aspect detection mechanism to
+/// preserve some state between <see cref="IAspect.ProbeAspect"/> and
+/// <see cref="IAspect.LoadAspect"/> calls, to optimize resource usage.
+/// </summary>
+public interface IAspectState
+{
+	/// <summary>
+	/// Indicates that whatever method returned instance of this interface, the operation was
+	/// successful if `true`.
+	/// </summary>
+	bool Success { get; }
+}