From 4e5188817b669ef03e94b02bc7284c6dca6fa371 Mon Sep 17 00:00:00 2001
From: William Lee <wul@microsoft.com>
Date: Fri, 22 Dec 2017 12:47:33 -0800
Subject: [PATCH] Check null for env (#8286)

As you see, the implementation of the 3 OS to check PATH is different.
There is not too much to extract. And I tried to move the
"contains a folder path in env:path?" to a method. But that
method requires to pass in env:path, targetapath and path separator for
different OS. This method has low value. And people still must
remember to use this method. So I just added simple null check to the
place I used GetEnvPath.
---
 src/dotnet/ShellShim/LinuxEnvironmentPath.cs   | 11 +++++++++--
 src/dotnet/ShellShim/OsxEnvironmentPath.cs     | 13 +++++++++----
 src/dotnet/ShellShim/WindowsEnvironmentPath.cs | 16 +++++++++++++---
 3 files changed, 31 insertions(+), 9 deletions(-)

diff --git a/src/dotnet/ShellShim/LinuxEnvironmentPath.cs b/src/dotnet/ShellShim/LinuxEnvironmentPath.cs
index 2c9dc050e..05978edbe 100644
--- a/src/dotnet/ShellShim/LinuxEnvironmentPath.cs
+++ b/src/dotnet/ShellShim/LinuxEnvironmentPath.cs
@@ -48,8 +48,15 @@ namespace Microsoft.DotNet.ShellShim
 
         private bool PackageExecutablePathExists()
         {
-            return _environmentProvider
-                .GetEnvironmentVariable(PathName)
+            var environmentVariable = _environmentProvider
+                .GetEnvironmentVariable(PathName);
+
+            if (environmentVariable == null)
+            {
+                return false;
+            }
+
+            return environmentVariable
                 .Split(':').Contains(_packageExecutablePath.Path);
         }
 
diff --git a/src/dotnet/ShellShim/OsxEnvironmentPath.cs b/src/dotnet/ShellShim/OsxEnvironmentPath.cs
index e682d25d6..54ad814d9 100644
--- a/src/dotnet/ShellShim/OsxEnvironmentPath.cs
+++ b/src/dotnet/ShellShim/OsxEnvironmentPath.cs
@@ -49,10 +49,15 @@ namespace Microsoft.DotNet.ShellShim
 
         private bool PackageExecutablePathExists()
         {
-            return _environmentProvider.GetEnvironmentVariable(PathName).Split(':')
-                       .Contains(_packageExecutablePath.PathWithTilde) ||
-                   _environmentProvider.GetEnvironmentVariable(PathName).Split(':')
-                       .Contains(_packageExecutablePath.Path);
+            var environmentVariable = _environmentProvider.GetEnvironmentVariable(PathName);
+
+            if (environmentVariable == null)
+            {
+                return false;
+            }
+
+            return environmentVariable.Split(':').Contains(_packageExecutablePath.PathWithTilde)
+                || environmentVariable.Split(':').Contains(_packageExecutablePath.Path);
         }
 
         public void PrintAddPathInstructionIfPathDoesNotExist()
diff --git a/src/dotnet/ShellShim/WindowsEnvironmentPath.cs b/src/dotnet/ShellShim/WindowsEnvironmentPath.cs
index f6058079c..fe754df05 100644
--- a/src/dotnet/ShellShim/WindowsEnvironmentPath.cs
+++ b/src/dotnet/ShellShim/WindowsEnvironmentPath.cs
@@ -40,9 +40,19 @@ namespace Microsoft.DotNet.ShellShim
 
         private bool PackageExecutablePathExists()
         {
-            return Environment.GetEnvironmentVariable(PathName, EnvironmentVariableTarget.User).Split(';').Contains(_packageExecutablePath)
-             || Environment.GetEnvironmentVariable(PathName, EnvironmentVariableTarget.Machine).Split(';').Contains(_packageExecutablePath)
-             || Environment.GetEnvironmentVariable(PathName, EnvironmentVariableTarget.Process).Split(';').Contains(_packageExecutablePath);
+            return EnvironmentVariableConatinsPackageExecutablePath(Environment.GetEnvironmentVariable(PathName, EnvironmentVariableTarget.User))
+                || EnvironmentVariableConatinsPackageExecutablePath(Environment.GetEnvironmentVariable(PathName, EnvironmentVariableTarget.Machine))
+                || EnvironmentVariableConatinsPackageExecutablePath(Environment.GetEnvironmentVariable(PathName, EnvironmentVariableTarget.Process));
+        }
+
+        private bool EnvironmentVariableConatinsPackageExecutablePath(string environmentVariable)
+        {
+            if (environmentVariable == null)
+            {
+                return false;
+            }
+
+            return environmentVariable.Split(';').Contains(_packageExecutablePath);
         }
 
         public void PrintAddPathInstructionIfPathDoesNotExist()