Fix crash when user home directory cannot be determined.

Currently, dotnet will crash with an `ArgumentNullException` if `USERPROFILE`
(Windows) or `HOME` (macOS and Linux) is not set in the environment.  This
is because there is a missing null check after retrieving the environment
variable's value.  Additionally, if either variable is set to an empty string,
a `.dotnet` directory is created in the current directory where dotnet is being
run.

This commit fixes this by printing a graceful error informing the user the home
directory could not be determined and to set `DOTNET_CLI_HOME` to the directory
to use.  This variable will be respected before `USERPROFILE` or `HOME`. It is
likely that CI environments where `HOME` is not set can use `DOTNET_CLI_HOME`
to specify a local temporary location; by using this variable rather than
setting `HOME`, it is guaranteed to only affect dotnet.

It was discussed that we should perhaps fallback to some temporary location if
the home directory could not be determined, but NuGet currently requires `HOME`
to be set to work.  Because of this, it was decided that we should just handle
this case gracefully and provide a way for users to override the home directory
without relying on `USERPROFILE`/`HOME` entirely.

Closes #8053.

src/Microsoft.DotNet.Cli.Utils/Properties/AssemblyInfo.cs

@@ -7,6 +7,7 @@ using System.Runtime.CompilerServices;
 [assembly: AssemblyMetadataAttribute("Serviceable", "True")]
 [assembly: InternalsVisibleTo("dotnet, PublicKey=0024000004800000940000000602000000240000525341310004000001000100f33a29044fa9d740c9b3213a93e57c84b472c84e0b8a0e1ae48e67a9f8f6de9d5f7f3d52ac23e48ac51801f1dc950abe901da34d2a9e3baadb141a17c77ef3c565dd5ee5054b91cf63bb3c6ab83f72ab3aafe93d0fc3c2348b764fafb0b1c0733de51459aeab46580384bf9d74c4e28164b7cde247f891ba07891c9d872ad2bb")]
 [assembly: InternalsVisibleTo("dotnet.Tests, PublicKey=0024000004800000940000000602000000240000525341310004000001000100f33a29044fa9d740c9b3213a93e57c84b472c84e0b8a0e1ae48e67a9f8f6de9d5f7f3d52ac23e48ac51801f1dc950abe901da34d2a9e3baadb141a17c77ef3c565dd5ee5054b91cf63bb3c6ab83f72ab3aafe93d0fc3c2348b764fafb0b1c0733de51459aeab46580384bf9d74c4e28164b7cde247f891ba07891c9d872ad2bb")]
+[assembly: InternalsVisibleTo("Microsoft.DotNet.Configurer, PublicKey=0024000004800000940000000602000000240000525341310004000001000100f33a29044fa9d740c9b3213a93e57c84b472c84e0b8a0e1ae48e67a9f8f6de9d5f7f3d52ac23e48ac51801f1dc950abe901da34d2a9e3baadb141a17c77ef3c565dd5ee5054b91cf63bb3c6ab83f72ab3aafe93d0fc3c2348b764fafb0b1c0733de51459aeab46580384bf9d74c4e28164b7cde247f891ba07891c9d872ad2bb")]
 [assembly: InternalsVisibleTo("Microsoft.DotNet.Tools.Test, PublicKey=0024000004800000940000000602000000240000525341310004000001000100f33a29044fa9d740c9b3213a93e57c84b472c84e0b8a0e1ae48e67a9f8f6de9d5f7f3d52ac23e48ac51801f1dc950abe901da34d2a9e3baadb141a17c77ef3c565dd5ee5054b91cf63bb3c6ab83f72ab3aafe93d0fc3c2348b764fafb0b1c0733de51459aeab46580384bf9d74c4e28164b7cde247f891ba07891c9d872ad2bb")]
 [assembly: InternalsVisibleTo("Microsoft.DotNet.Cli.Utils.Tests, PublicKey=0024000004800000940000000602000000240000525341310004000001000100f33a29044fa9d740c9b3213a93e57c84b472c84e0b8a0e1ae48e67a9f8f6de9d5f7f3d52ac23e48ac51801f1dc950abe901da34d2a9e3baadb141a17c77ef3c565dd5ee5054b91cf63bb3c6ab83f72ab3aafe93d0fc3c2348b764fafb0b1c0733de51459aeab46580384bf9d74c4e28164b7cde247f891ba07891c9d872ad2bb")]
 [assembly: InternalsVisibleTo("Microsoft.DotNet.TestFramework, PublicKey=0024000004800000940000000602000000240000525341310004000001000100f33a29044fa9d740c9b3213a93e57c84b472c84e0b8a0e1ae48e67a9f8f6de9d5f7f3d52ac23e48ac51801f1dc950abe901da34d2a9e3baadb141a17c77ef3c565dd5ee5054b91cf63bb3c6ab83f72ab3aafe93d0fc3c2348b764fafb0b1c0733de51459aeab46580384bf9d74c4e28164b7cde247f891ba07891c9d872ad2bb")]

src/Microsoft.DotNet.Configurer/CliFolderPathCalculator.cs

@@ -4,12 +4,14 @@
 using System;
 using System.IO;
 using System.Runtime.InteropServices;
+using Microsoft.DotNet.Cli.Utils;
 using NuGet.Common;
 
 namespace Microsoft.DotNet.Configurer
 {
     public static class CliFolderPathCalculator
     {
+        public const string DotnetHomeVariableName = "DOTNET_CLI_HOME";
         private const string DotnetProfileDirectoryName = ".dotnet";
         private const string ToolsShimFolderName = "tools";
 
@@ -21,23 +23,36 @@ namespace Microsoft.DotNet.Configurer
 
         public static string ToolsPackagePath => ToolPackageFolderPathCalculator.GetToolPackageFolderPath(ToolsShimPath);
 
-        public static BashPathUnderHomeDirectory ToolsShimPathInUnix
+        public static BashPathUnderHomeDirectory ToolsShimPathInUnix =>
+            new BashPathUnderHomeDirectory(
+                DotnetHomePath,
+                Path.Combine(DotnetProfileDirectoryName, ToolsShimFolderName));
+
+        public static string DotnetUserProfileFolderPath =>
+            Path.Combine(DotnetHomePath, DotnetProfileDirectoryName);
+
+        public static string PlatformHomeVariableName =>
+            RuntimeInformation.IsOSPlatform(OSPlatform.Windows) ? "USERPROFILE" : "HOME";
+
+        public static string DotnetHomePath
         {
             get
             {
-                return new BashPathUnderHomeDirectory(Environment.GetEnvironmentVariable("HOME"),
+                var home = Environment.GetEnvironmentVariable(DotnetHomeVariableName);
-                    Path.Combine(DotnetProfileDirectoryName, ToolsShimFolderName));
+                if (string.IsNullOrEmpty(home))
-            }
+                {
-        }
+                    home = Environment.GetEnvironmentVariable(PlatformHomeVariableName);
+                    if (string.IsNullOrEmpty(home))
+                    {
+                        throw new ConfigurationException(
+                            string.Format(
+                                LocalizableStrings.FailedToDetermineUserHomeDirectory,
+                                DotnetHomeVariableName))
+                            .DisplayAsError();
+                    }
+                }
 
-        public static string DotnetUserProfileFolderPath
+                return home;
-        {
-            get
-            {
-                string profileDir = Environment.GetEnvironmentVariable(
-                    RuntimeInformation.IsOSPlatform(OSPlatform.Windows) ? "USERPROFILE" : "HOME");
-
-                return Path.Combine(profileDir, DotnetProfileDirectoryName);
             }
         }
 

src/Microsoft.DotNet.Configurer/ConfigurationException.cs

@@ -0,0 +1,22 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
+
+namespace Microsoft.DotNet.Configurer
+{
+    internal class ConfigurationException : Exception
+    {
+        public ConfigurationException()
+        {
+        }
+
+        public ConfigurationException(string message) : base(message)
+        {
+        }
+
+        public ConfigurationException(string message, Exception innerException) : base(message, innerException)
+        {
+        }
+    }
+}

src/Microsoft.DotNet.Configurer/LocalizableStrings.resx

@@ -154,4 +154,7 @@ Successfully installed the ASP.NET Core HTTPS Development Certificate.
 To trust the certificate run 'dotnet dev-certs https --trust' (Windows and macOS only). For establishing trust on other platforms refer to the platform specific documentation.
 For more information on configuring HTTPS see https://go.microsoft.com/fwlink/?linkid=848054.</value>
   </data>
+  <data name="FailedToDetermineUserHomeDirectory" xml:space="preserve">
+    <value>The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</value>
+  </data>
 </root>

src/Microsoft.DotNet.Configurer/Microsoft.DotNet.Configurer.csproj

@@ -17,6 +17,7 @@
   </ItemGroup>
 
   <ItemGroup>
+    <PackageReference Include="NETStandard.Library" Version="2.0.0" />
     <PackageReference Include="NuGet.Common" Version="$(NuGetCommonPackageVersion)" />
     <PackageReference Include="NuGet.Configuration" Version="$(NuGetConfigurationPackageVersion)" />
     <PackageReference Include="Microsoft.DotNet.Archive" Version="$(MicrosoftDotNetArchivePackageVersion)" />

src/Microsoft.DotNet.Configurer/xlf/LocalizableStrings.cs.xlf

@@ -71,6 +71,11 @@ Pokud chcete certifikátu důvěřovat (platí jenom pro Windows a macOS), nains
 Další informace o konfiguraci protokolu HTTPS najdete na webu https://go.microsoft.com/fwlink/?linkid=848054.</target>
         <note />
       </trans-unit>
+      <trans-unit id="FailedToDetermineUserHomeDirectory">
+        <source>The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</source>
+        <target state="new">The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Microsoft.DotNet.Configurer/xlf/LocalizableStrings.de.xlf

@@ -71,6 +71,11 @@ Um dem Zertifikat zu vertrauen (nur Windows und macOS), installieren Sie zuerst
 Weitere Informationen zur Konfiguration von HTTPS finden Sie unter https://go.microsoft.com/fwlink/?linkid=848054.</target>
         <note />
       </trans-unit>
+      <trans-unit id="FailedToDetermineUserHomeDirectory">
+        <source>The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</source>
+        <target state="new">The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Microsoft.DotNet.Configurer/xlf/LocalizableStrings.es.xlf

@@ -70,6 +70,11 @@ Para confiar en el certificado (solo Windows y macOS), instale primero la herram
 Para obtener más información sobre la configuración HTTPS, vea https://go.microsoft.com/fwlink/?linkid=848054.</target>
         <note />
       </trans-unit>
+      <trans-unit id="FailedToDetermineUserHomeDirectory">
+        <source>The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</source>
+        <target state="new">The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Microsoft.DotNet.Configurer/xlf/LocalizableStrings.fr.xlf

@@ -71,6 +71,11 @@ Pour approuver le certificat (Windows et macOS uniquement), installez d'abord l'
 Pour plus d'informations sur la configuration du protocole HTTPS, consultez https://go.microsoft.com/fwlink/?linkid=848054.</target>
         <note />
       </trans-unit>
+      <trans-unit id="FailedToDetermineUserHomeDirectory">
+        <source>The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</source>
+        <target state="new">The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Microsoft.DotNet.Configurer/xlf/LocalizableStrings.it.xlf

@@ -71,6 +71,11 @@ Per considerare attendibile il certificato (solo Windows e macOS), installare pr
 Per altre informazioni sulla configurazione di HTTPS, vedere https://go.microsoft.com/fwlink/?linkid=848054.</target>
         <note />
       </trans-unit>
+      <trans-unit id="FailedToDetermineUserHomeDirectory">
+        <source>The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</source>
+        <target state="new">The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Microsoft.DotNet.Configurer/xlf/LocalizableStrings.ja.xlf

@@ -71,6 +71,11 @@ ASP.NET Core HTTPS 開発証明書が正常にインストールされました
 HTTPS を構成する方法の詳細については、https://go.microsoft.com/fwlink/?linkid=848054 をご覧ください。</target>
         <note />
       </trans-unit>
+      <trans-unit id="FailedToDetermineUserHomeDirectory">
+        <source>The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</source>
+        <target state="new">The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Microsoft.DotNet.Configurer/xlf/LocalizableStrings.ko.xlf

@@ -71,6 +71,11 @@ ASP.NET Core HTTPS 개발 인증서를 설치했습니다.
 HTTPS 구성에 대한 자세한 내용은 https://go.microsoft.com/fwlink/?linkid=848054를 참조하세요.</target>
         <note />
       </trans-unit>
+      <trans-unit id="FailedToDetermineUserHomeDirectory">
+        <source>The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</source>
+        <target state="new">The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Microsoft.DotNet.Configurer/xlf/LocalizableStrings.pl.xlf

@@ -71,6 +71,11 @@ Aby ufać temu certyfikatowi (dotyczy tylko systemów Windows i macOS), najpierw
 Aby uzyskać więcej informacji dotyczących konfigurowania protokołu HTTPS, zobacz https://go.microsoft.com/fwlink/?linkid=848054.</target>
         <note />
       </trans-unit>
+      <trans-unit id="FailedToDetermineUserHomeDirectory">
+        <source>The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</source>
+        <target state="new">The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Microsoft.DotNet.Configurer/xlf/LocalizableStrings.pt-BR.xlf

@@ -71,6 +71,11 @@ Para confiar no certificado (apenas Windows e macOS), primeiramente instale a fe
 Para saber mais sobre a configuração de HTTPS, acesse https://go.microsoft.com/fwlink/?linkid=848054.</target>
         <note />
       </trans-unit>
+      <trans-unit id="FailedToDetermineUserHomeDirectory">
+        <source>The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</source>
+        <target state="new">The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Microsoft.DotNet.Configurer/xlf/LocalizableStrings.ru.xlf

@@ -71,6 +71,11 @@ For more information on configuring HTTPS see https://go.microsoft.com/fwlink/?l
 Дополнительные сведения о настройке HTTPS: https://go.microsoft.com/fwlink/?linkid=848054.</target>
         <note />
       </trans-unit>
+      <trans-unit id="FailedToDetermineUserHomeDirectory">
+        <source>The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</source>
+        <target state="new">The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Microsoft.DotNet.Configurer/xlf/LocalizableStrings.tr.xlf

@@ -71,6 +71,11 @@ Sertifikaya güvenmek için (yalnızca Windows ve macOS) önce 'dotnet tool inst
 HTTPS yapılandırması hakkında daha fazla bilgi için bkz. https://go.microsoft.com/fwlink/?linkid=848054.</target>
         <note />
       </trans-unit>
+      <trans-unit id="FailedToDetermineUserHomeDirectory">
+        <source>The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</source>
+        <target state="new">The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Microsoft.DotNet.Configurer/xlf/LocalizableStrings.zh-Hans.xlf

@@ -71,6 +71,11 @@ For more information on configuring HTTPS see https://go.microsoft.com/fwlink/?l
 有关配置 HTTPS 的详细信息，请参阅 https://go.microsoft.com/fwlink/?linkid=848054。</target>
         <note />
       </trans-unit>
+      <trans-unit id="FailedToDetermineUserHomeDirectory">
+        <source>The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</source>
+        <target state="new">The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Microsoft.DotNet.Configurer/xlf/LocalizableStrings.zh-Hant.xlf

@@ -71,6 +71,11 @@ For more information on configuring HTTPS see https://go.microsoft.com/fwlink/?l
 如需如何設定 HTTPS 的詳細資訊，請參閱 https://go.microsoft.com/fwlink/?linkid=848054。</target>
         <note />
       </trans-unit>
+      <trans-unit id="FailedToDetermineUserHomeDirectory">
+        <source>The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</source>
+        <target state="new">The user's home directory could not be determined. Set the '{0}' environment variable to specify the directory to use.</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

test/dotnet.Tests/GivenThatDotNetRunsCommands.cs

@@ -5,9 +5,12 @@ using System;
 using System.IO;
 using FluentAssertions;
 using Microsoft.DotNet.Cli.Utils;
+using Microsoft.DotNet.Configurer;
 using Microsoft.DotNet.Tools.Test.Utilities;
 using Xunit;
 
+using LocalizableStrings = Microsoft.DotNet.Cli.Utils.LocalizableStrings;
+
 namespace Microsoft.DotNet.Tests
 {
     public class GivenThatDotNetRunsCommands : TestBase
@@ -32,5 +35,19 @@ namespace Microsoft.DotNet.Tests
                 .Should().Fail()
                      .And.HaveStdErrContaining(string.Format(LocalizableStrings.NoExecutableFoundMatchingCommand, "dotnet-crash"));
         }
+
+        [Theory]
+        [InlineData("")]
+        [InlineData(null)]
+        public void GivenAMissingHomeVariableItPrintsErrorMessage(string value)
+        {
+            new TestCommand("dotnet")
+                .WithEnvironmentVariable(CliFolderPathCalculator.PlatformHomeVariableName, value)
+                .ExecuteWithCapturedOutput("--help")
+                .Should()
+                .Fail()
+                .And
+                .HaveStdErrContaining(CliFolderPathCalculator.DotnetHomeVariableName);
+        }
     }
 }

test/dotnet.Tests/GivenThatIWantToManageMulticoreJIT.cs

@@ -59,20 +59,6 @@ namespace Microsoft.DotNet.Tests
                 .Should().BeFalse("Because multicore JIT is disabled");
         }
 
-        [Fact]
-        public void WhenTheProfileRootIsUndefinedThenDotnetDoesNotCrash()
-        {
-            var testDirectory = TestAssets.CreateTestDirectory();
-            var testStartTime = GetTruncatedDateTime();
-            
-            var optimizationProfileFilePath = GetOptimizationProfileFilePath(testDirectory.FullName);
-
-            new TestCommand("dotnet")
-                .WithUserProfileRoot("")
-                .ExecuteWithCapturedOutput("--help")
-                .Should().Pass();
-        }
-
         [Fact]
         public void WhenCliRepoBuildsThenDotnetWritesOptimizationDataToTheDefaultProfileRoot()
         {