VfsAssemblyDirectory.cs

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/*
  Copyright (C) 2007-2011 Jeroen Frijters
 
  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.
 
  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:
 
  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
 
  Jeroen Frijters
  jeroen@frijters.net
  
*/
using System;
using System.Collections.Concurrent;
using System.Linq;
using System.Reflection;
using System.Text;
 
namespace IKVM.Runtime.Vfs
{
 
    internal sealed class VfsAssemblyDirectory : VfsDirectory
    {
 
        readonly ConcurrentDictionary<Assembly, VfsDirectory> directories = new ConcurrentDictionary<Assembly, VfsDirectory>();
 
        public VfsAssemblyDirectory(VfsContext context) :
            base(context)
        {
 
        }
 
        AssemblyName ParseDirectoryName(string directoryName)
        {
            try
            {
                var assemblyName = new AssemblyName();
                var sb = new ValueStringBuilder();
                var part = 0;
                for (var i = 0; i <= directoryName.Length; i++)
                {
                    if (i == directoryName.Length || directoryName[i] == '_')
                    {
                        if (i < directoryName.Length - 1 && directoryName[i + 1] == '!')
                        {
                            sb.Append('_');
                            i++;
                        }
                        else if (i == directoryName.Length || directoryName[i + 1] == '_')
                        {
                            switch (part++)
                            {
                                case 0:
                                    assemblyName.Name = sb.ToString();
                                    break;
                                case 1:
                                    assemblyName.Version = Version.Parse(sb.ToString());
                                    break;
                                case 2:
                                    assemblyName.SetPublicKeyToken(StringToByteArray(sb.ToString()));
                                    break;
                                case 3:
                                    assemblyName.CultureName = sb.ToString();
                                    break;
                                case 4:
                                    return null;
                            }
 
                            sb.Length = 0;
                            i++;
                        }
                        else
                        {
                            int start = i + 1;
                            int end = start;
                            while ('0' <= directoryName[end] && directoryName[end] <= '9')
                                end++;
 
#if NETFRAMEWORK
                            if (directoryName[end] != '_' || !int.TryParse(directoryName.Substring(start, end - start), out int repeatCount))
#else
                            if (directoryName[end] != '_' || !int.TryParse(directoryName.AsSpan(start, end - start), out int repeatCount))
#endif
                                return null;
 
                            sb.Append('_', repeatCount);
                            i = end;
                        }
                    }
                    else
                    {
                        sb.Append(directoryName[i]);
                    }
                }
 
                return assemblyName;
            }
            catch
            {
                return null;
            }
        }
 
        public override VfsEntry GetEntry(string name)
        {
            // search for a directory by MVID
            if (Guid.TryParse(name, out var guid))
            {
                foreach (var assemblyName in Context.GetAssemblyNames())
                    if (Context.GetAssembly(assemblyName) is Assembly assembly)
                        if (assembly.ManifestModule.ModuleVersionId == guid && assembly.IsDynamic == false)
                            return directories.GetOrAdd(assembly, CreateAssemblyDirectory);
 
                return null;
            }
            else
            {
                // search for a directory for the given full name
                var assemblyName = ParseDirectoryName(name);
                if (assemblyName != null)
                {
                    var assembly = Context.GetAssembly(assemblyName);
                    if (assembly != null && assembly.IsDynamic == false && name == VfsTable.GetAssemblyDirectoryName(Context, assembly))
                        return directories.GetOrAdd(assembly, CreateAssemblyDirectory);
                }
 
                return null;
            }
        }
 
        VfsDirectory CreateAssemblyDirectory(Assembly assembly)
        {
            var d = new VfsEntryDirectory(Context);
            d.AddEntry("resources", new VfsAssemblyResourceDirectory(Context, assembly));
            d.AddEntry("classes", new VfsAssemblyClassDirectory(Context, assembly, ""));
            return d;
        }
 
        public override string[] List()
        {
            return Array.Empty<string>();
        }
 
        byte[] StringToByteArray(string hex)
        {
            if (hex.Length % 2 == 1)
                throw new Exception("The binary key cannot have an odd number of digits");
 
            var arr = new byte[hex.Length >> 1];
            for (int i = 0; i < hex.Length >> 1; ++i)
                arr[i] = (byte)((GetHexVal(hex[i << 1]) << 4) + (GetHexVal(hex[(i << 1) + 1])));
 
            return arr;
 
            static int GetHexVal(char hex) => (int)hex - ((int)hex < 58 ? 48 : ((int)hex < 97 ? 55 : 87));
        }
 
    }
 
}