summaryrefslogtreecommitdiff
path: root/src/StardewModdingAPI/Framework/ModAssemblyLoader.cs
blob: bde23e3bead3e99bc630a5356b579663b78cb6a0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
using System;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Security.Cryptography;
using Mono.Cecil;
using StardewModdingAPI.Framework.AssemblyRewriting;

namespace StardewModdingAPI.Framework
{
    /// <summary>Preprocesses and loads mod assemblies.</summary>
    internal class ModAssemblyLoader
    {
        /*********
        ** Properties
        *********/
        /// <summary>The directory in which to cache data.</summary>
        private readonly string CacheDirPath;

        /// <summary>Encapsulates monitoring and logging for a given module.</summary>
        private readonly IMonitor Monitor;


        /*********
        ** Public methods
        *********/
        /// <summary>Construct an instance.</summary>
        /// <param name="cacheDirPath">The cache directory.</param>
        /// <param name="targetPlatform">The current game platform.</param>
        /// <param name="monitor">Encapsulates monitoring and logging for a given module.</param>
        public ModAssemblyLoader(string cacheDirPath, Platform targetPlatform, IMonitor monitor)
        {
            this.CacheDirPath = cacheDirPath;
            this.Monitor = monitor;
        }

        /// <summary>Preprocess an assembly and cache the modified version.</summary>
        /// <param name="assemblyPath">The assembly file path.</param>
        public void ProcessAssembly(string assemblyPath)
        {
            // read assembly data
            byte[] assemblyBytes = File.ReadAllBytes(assemblyPath);
            byte[] hash = MD5.Create().ComputeHash(assemblyBytes);

            // check cache
            CachePaths cachePaths = this.GetCacheInfo(assemblyPath);
            bool canUseCache = File.Exists(cachePaths.Assembly) && File.Exists(cachePaths.Hash) && hash.SequenceEqual(File.ReadAllBytes(cachePaths.Hash));

            // process assembly if not cached
            if (!canUseCache)
            {
                this.Monitor.Log($"Preprocessing new assembly {assemblyPath}...");

                // read assembly definition
                AssemblyDefinition definition;
                using (Stream readStream = new MemoryStream(assemblyBytes))
                    definition = AssemblyDefinition.ReadAssembly(readStream);

                // write cache
                using (MemoryStream outStream = new MemoryStream())
                {
                    definition.Write(outStream);
                    byte[] outBytes = outStream.ToArray();
                    Directory.CreateDirectory(cachePaths.Directory);
                    File.WriteAllBytes(cachePaths.Assembly, outBytes);
                    File.WriteAllBytes(cachePaths.Hash, hash);
                }
            }
        }

        /// <summary>Load a preprocessed assembly.</summary>
        /// <param name="assemblyPath">The assembly file path.</param>
        public Assembly LoadCachedAssembly(string assemblyPath)
        {
            CachePaths cachePaths = this.GetCacheInfo(assemblyPath);
            if (!File.Exists(cachePaths.Assembly))
                throw new InvalidOperationException($"The assembly {assemblyPath} doesn't exist in the preprocessed cache.");
            return Assembly.UnsafeLoadFrom(cachePaths.Assembly);
        }


        /*********
        ** Private methods
        *********/
        /// <summary>Get the cache details for an assembly.</summary>
        /// <param name="assemblyPath">The assembly file path.</param>
        private CachePaths GetCacheInfo(string assemblyPath)
        {
            string key = Path.GetFileNameWithoutExtension(assemblyPath);
            string dirPath = Path.Combine(this.CacheDirPath, new DirectoryInfo(Path.GetDirectoryName(assemblyPath)).Name);
            string cacheAssemblyPath = Path.Combine(dirPath, $"{key}.dll");
            string cacheHashPath = Path.Combine(dirPath, $"{key}.hash");
            return new CachePaths(dirPath, cacheAssemblyPath, cacheHashPath);
        }
    }
}