Fix race conditions introduced by parallelisation

.gitignore

@@ -111,3 +111,4 @@ Protobuild.FunctionalTests/TestData/PackageUnifiedNuGetLocalInstallNoDedup/TestI
 Protobuild.FunctionalTests/TestData/ExtractXSLTWorks/Build/NuGetPlatformMappings.xml
 Protobuild.FunctionalTests/TestData/SafeResolveDefaultsWithoutFeatureSet/Package/Test.txt
 Protobuild.FunctionalTests/TestData/ModuleInfoGetsUpgraded/xunit/
+.vs/

Protobuild.Internal/BuildResources/ResourceProvider.cs

@@ -136,7 +136,7 @@ private Stream LoadOverriddableResource(ResourceType resourceType, Language lang
                     if (File.Exists(path))
                     {
                         loadHash = "path:" + path;
-                        source = File.Open(path, FileMode.Open);
+                        source = File.Open(path, FileMode.Open, FileAccess.Read, FileShare.Read);
                         break;
                     }
                 }

Protobuild.Internal/Core/ModuleExecution.cs

@@ -7,6 +7,8 @@ namespace Protobuild
 {
     internal class ModuleExecution : IModuleExecution
     {
+        private static object _selfWorkingDirectoryLock = new object();
+
         public Tuple<int, string, string> RunProtobuild(ModuleInfo module, string args, bool capture = false)
         {
             var invokeInline = false;
@@ -23,35 +25,41 @@ public Tuple<int, string, string> RunProtobuild(ModuleInfo module, string args,
                 var ourBuffer = new RedirectableBuffer();
                 RedirectableConsole.TargetBuffer = ourBuffer;
                 var needsEndSelfInvoke = true;
-                var old = Environment.CurrentDirectory;
-                try
+                lock (_selfWorkingDirectoryLock)
                 {
-                    Environment.CurrentDirectory = module.Path;
-                    var exitCode = ExecEnvironment.InvokeSelf(args.SplitCommandLine().ToArray());
-                    RedirectableConsole.TargetBuffer = oldBuffer;
-                    needsEndSelfInvoke = false;
-                    if (capture)
-                    {
-                        return new Tuple<int, string, string>(
-                            exitCode,
-                            ourBuffer.Stdout,
-                            ourBuffer.Stderr);
-                    }
-                    else
+                    var oldLock = _selfWorkingDirectoryLock;
+                    _selfWorkingDirectoryLock = new object();
+                    var old = Environment.CurrentDirectory;
+                    try
                     {
-                        return new Tuple<int, string, string>(
-                            exitCode,
-                            string.Empty,
-                            string.Empty);
+                        Environment.CurrentDirectory = module.Path;
+                        var exitCode = ExecEnvironment.InvokeSelf(args.SplitCommandLine().ToArray());
+                        RedirectableConsole.TargetBuffer = oldBuffer;
+                        needsEndSelfInvoke = false;
+                        if (capture)
+                        {
+                            return new Tuple<int, string, string>(
+                                exitCode,
+                                ourBuffer.Stdout,
+                                ourBuffer.Stderr);
+                        }
+                        else
+                        {
+                            return new Tuple<int, string, string>(
+                                exitCode,
+                                string.Empty,
+                                string.Empty);
+                        }
                     }
-                }
-                finally
-                {
-                    if (needsEndSelfInvoke)
+                    finally
                     {
-                        RedirectableConsole.TargetBuffer = oldBuffer;
+                        if (needsEndSelfInvoke)
+                        {
+                            RedirectableConsole.TargetBuffer = oldBuffer;
+                        }
+                        Environment.CurrentDirectory = old;
+                        _selfWorkingDirectoryLock = oldLock;
                     }
-                    Environment.CurrentDirectory = old;
                 }
             }
 

Protobuild.Internal/ExecEnvironment.cs

@@ -26,6 +26,7 @@ public static class ExecEnvironment
         /// </summary>
         public static bool DoNotWrapExecutionInTry = false;
 
+        [ThreadStatic]
         private static int _selfInvokeCounter = 0;
 
         /// <summary>