Handle Mutex creation exceptions

src/Microsoft.AspNetCore.Razor.Tools/ServerCommand.cs

@@ -34,37 +34,51 @@ namespace Microsoft.AspNetCore.Razor.Tools
         protected override Task<int> ExecuteCoreAsync()
         {
             // Make sure there's only one server with the same identity at a time.
-            using (var mutex = new Mutex(initiallyOwned: true, name: MutexName.GetServerMutexName(Pipe.Value()), createdNew: out var holdsMutex))
+            var serverMutexName = MutexName.GetServerMutexName(Pipe.Value());
+            Mutex serverMutex = null;
+            var holdsMutex = false;
+
+            try
             {
-                if (!holdsMutex)
+                serverMutex = new Mutex(initiallyOwned: true, name: serverMutexName, createdNew: out holdsMutex);
+            }
+            catch (Exception ex)
+            {
+                // The Mutex constructor can throw in certain cases. One specific example is docker containers
+                // where the /tmp directory is restricted. In those cases there is no reliable way to execute
+                // the server and we need to fall back to the command line.
+                // Example: https://github.com/dotnet/roslyn/issues/24124
+
+                Error.Write($"Server mutex creation failed. {ex.Message}");
+
+                return Task.FromResult(-1);
+            }
+
+            if (!holdsMutex)
+            {
+                // Another server is running, just exit.
+                Error.Write("Another server already running...");
+                return Task.FromResult(1);
+            }
+
+            try
+            {
+                TimeSpan? keepAlive = null;
+                if (KeepAlive.HasValue() && int.TryParse(KeepAlive.Value(), out var result))
                 {
-                    // Another server is running, just exit.
+                    // Keep alive times are specified in seconds
-                    Error.Write("Another server already running...");
+                    keepAlive = TimeSpan.FromSeconds(result);
-                    return Task.FromResult(1);
                 }
 
-                try
+                var host = ConnectionHost.Create(Pipe.Value());
-                {
-                    TimeSpan? keepAlive = null;
-                    if (KeepAlive.HasValue())
-                    {
-                        var value = KeepAlive.Value();
-                        if (int.TryParse(value, out var result))
-                        {
-                            // Keep alive times are specified in seconds
-                            keepAlive = TimeSpan.FromSeconds(result);
-                        }
-                    }
 
-                    var host = ConnectionHost.Create(Pipe.Value());
+                var compilerHost = CompilerHost.Create();
-
+                ExecuteServerCore(host, compilerHost, Cancelled, eventBus: null, keepAlive: keepAlive);
-                    var compilerHost = CompilerHost.Create();
+            }
-                    ExecuteServerCore(host, compilerHost, Cancelled, eventBus: null, keepAlive: keepAlive);
+            finally
-                }
+            {
-                finally
+                serverMutex.ReleaseMutex();
-                {
+                serverMutex.Dispose();
-                    mutex.ReleaseMutex();
-                }
             }
 
             return Task.FromResult(0);

src/Microsoft.AspNetCore.Razor.Tools/ServerProtocol/ServerConnection.cs

@@ -23,13 +23,21 @@ namespace Microsoft.AspNetCore.Razor.Tools
 
         public static bool WasServerMutexOpen(string mutexName)
         {
-            var open = Mutex.TryOpenExisting(mutexName, out var mutex);
+            Mutex mutex = null;
-            if (open)
+            var open = false;
+            try
             {
-                mutex.Dispose();
+                open = Mutex.TryOpenExisting(mutexName, out mutex);
-                return true;
             }
-            return false;
+            catch
+            {
+                // In the case an exception occured trying to open the Mutex then
+                // the assumption is that it's not open.
+            }
+
+            mutex?.Dispose();
+
+            return open;
         }
 
         /// <summary>
@@ -129,44 +137,63 @@ namespace Microsoft.AspNetCore.Razor.Tools
             var timeoutExistingProcess = timeoutOverride ?? TimeOutMsExistingProcess;
             var clientMutexName = MutexName.GetClientMutexName(pipeName);
             Task<Client> pipeTask = null;
-            using (var clientMutex = new Mutex(initiallyOwned: true, name: clientMutexName, createdNew: out var holdsMutex))
+
+            Mutex clientMutex = null;
+            var holdsMutex = false;
+
+            try
             {
                 try
                 {
-                    if (!holdsMutex)
+                    clientMutex = new Mutex(initiallyOwned: true, name: clientMutexName, createdNew: out holdsMutex);
-                    {
-                        try
-                        {
-                            holdsMutex = clientMutex.WaitOne(timeoutNewProcess);
-
-                            if (!holdsMutex)
-                            {
-                                return new RejectedServerResponse();
-                            }
-                        }
-                        catch (AbandonedMutexException)
-                        {
-                            holdsMutex = true;
-                        }
-                    }
-
-                    // Check for an already running server
-                    var serverMutexName = MutexName.GetServerMutexName(pipeName);
-                    var wasServerRunning = WasServerMutexOpen(serverMutexName);
-                    var timeout = wasServerRunning ? timeoutExistingProcess : timeoutNewProcess;
-
-                    if (wasServerRunning || tryCreateServerFunc(clientDir, pipeName, debug))
-                    {
-                        pipeTask = Client.ConnectAsync(pipeName, TimeSpan.FromMilliseconds(timeout), cancellationToken);
-                    }
                 }
-                finally
+                catch (Exception ex)
                 {
-                    if (holdsMutex)
+                    // The Mutex constructor can throw in certain cases. One specific example is docker containers
+                    // where the /tmp directory is restricted. In those cases there is no reliable way to execute
+                    // the server and we need to fall back to the command line.
+                    // Example: https://github.com/dotnet/roslyn/issues/24124
+
+                    ServerLogger.LogException(ex, "Client mutex creation failed.");
+
+                    return new RejectedServerResponse();
+                }
+
+                if (!holdsMutex)
+                {
+                    try
                     {
-                        clientMutex.ReleaseMutex();
+                        holdsMutex = clientMutex.WaitOne(timeoutNewProcess);
+
+                        if (!holdsMutex)
+                        {
+                            return new RejectedServerResponse();
+                        }
+                    }
+                    catch (AbandonedMutexException)
+                    {
+                        holdsMutex = true;
                     }
                 }
+
+                // Check for an already running server
+                var serverMutexName = MutexName.GetServerMutexName(pipeName);
+                var wasServerRunning = WasServerMutexOpen(serverMutexName);
+                var timeout = wasServerRunning ? timeoutExistingProcess : timeoutNewProcess;
+
+                if (wasServerRunning || tryCreateServerFunc(clientDir, pipeName, debug))
+                {
+                    pipeTask = Client.ConnectAsync(pipeName, TimeSpan.FromMilliseconds(timeout), cancellationToken);
+                }
+            }
+            finally
+            {
+                if (holdsMutex)
+                {
+                    clientMutex?.ReleaseMutex();
+                }
+
+                clientMutex?.Dispose();
             }
 
             if (pipeTask != null)

test/Microsoft.AspNetCore.Razor.Design.Test/IntegrationTests/BuildServerIntegrationTest.cs

@@ -103,5 +103,35 @@ namespace Microsoft.AspNetCore.Razor.Design.IntegrationTests
             Assert.FileExists(result, IntermediateOutputPath, "SimpleMvc.dll");
             Assert.FileDoesNotExist(result, IntermediateOutputPath, "SimpleMvc.Views.dll");
         }
+
+        [Fact]
+        [InitializeTestProject("SimpleMvc")]
+        public async Task Build_ServerConnectionMutexCreationFails_FallsBackToInProcessRzc()
+        {
+            // Use a pipe name longer that 260 characters to make the Mutex constructor throw.
+            var pipeName = new string('P', 261);
+            var result = await DotnetMSBuild(
+                "Build",
+                "/p:_RazorForceBuildServer=true",
+                buildServerPipeName: pipeName);
+
+            // We expect this to fail because we don't allow it to fallback to in process execution.
+            Assert.BuildFailed(result);
+            Assert.FileDoesNotExist(result, IntermediateOutputPath, "SimpleMvc.Views.dll");
+
+            // Try to build again without forcing it to run on build server.
+            result = await DotnetMSBuild(
+                "Build",
+                "/p:_RazorForceBuildServer=false",
+                buildServerPipeName: pipeName);
+
+            Assert.BuildPassed(result);
+
+            Assert.FileExists(result, IntermediateOutputPath, "SimpleMvc.dll");
+            Assert.FileExists(result, IntermediateOutputPath, "SimpleMvc.Views.dll");
+
+            // Note: We don't need to handle server clean up here because it will fail before
+            // it reaches server creation part.
+        }
     }
 }

test/Microsoft.AspNetCore.Razor.Design.Test/IntegrationTests/MSBuildIntegrationTestBase.cs

@@ -58,6 +58,7 @@ namespace Microsoft.AspNetCore.Razor.Design.IntegrationTests
             bool suppressRestore = false,
             bool suppressTimeout = false,
             bool suppressBuildServer = false,
+            string buildServerPipeName = null,
             MSBuildProcessKind msBuildProcessKind = MSBuildProcessKind.Dotnet)
         {
             var timeout = suppressTimeout ? (TimeSpan?)Timeout.InfiniteTimeSpan : null;
@@ -70,7 +71,7 @@ namespace Microsoft.AspNetCore.Razor.Design.IntegrationTests
 
             if (!suppressBuildServer)
             {
-                buildArgumentList.Add($"/p:_RazorBuildServerPipeName={BuildServer.PipeName}");
+                buildArgumentList.Add($"/p:_RazorBuildServerPipeName={buildServerPipeName ?? BuildServer.PipeName}");
             }
 
             buildArgumentList.Add($"/t:{target} /p:Configuration={Configuration} {args}");