From 443bb02eeaf6a67692fff922485abc52e2fbbd63 Mon Sep 17 00:00:00 2001
From: Victor XField <vxfield@outlook.com>
Date: Mon, 28 Dec 2020 22:06:59 -0800
Subject: [PATCH] Fix the check on SDK versions (allow greater versions, block
 lesser versions) Fix console output event handling (need too hook the event
 before starting the process, and allow the process to exit before we receive
 the events) Fix to not required the base path to be present to return the
 full list of SDKs.

---
 src/MSBuildLocator/DotNetSdkLocationHelper.cs | 62 +++++++++----------
 1 file changed, 31 insertions(+), 31 deletions(-)

diff --git a/src/MSBuildLocator/DotNetSdkLocationHelper.cs b/src/MSBuildLocator/DotNetSdkLocationHelper.cs
index 415fab3e..b92ff76b 100644
--- a/src/MSBuildLocator/DotNetSdkLocationHelper.cs
+++ b/src/MSBuildLocator/DotNetSdkLocationHelper.cs
@@ -49,13 +49,13 @@ public static VisualStudioInstance GetInstance(string dotNetSdkPath)
             {
                 return null;
             }
-            
+
             // Components of the SDK often have dependencies on the runtime they shipped with, including that several tasks that shipped
             // in the .NET 5 SDK rely on the .NET 5.0 runtime. Assuming the runtime that shipped with a particular SDK has the same version,
             // this ensures that we don't choose an SDK that doesn't work with the runtime of the chosen application. This is not guaranteed
             // to always work but should work for now.
-            if (major > Environment.Version.Major ||
-                (major == Environment.Version.Major && minor > Environment.Version.Minor))
+            if (major < Environment.Version.Major ||
+                (major == Environment.Version.Major && minor < Environment.Version.Minor))
             {
                 return null;
             }
@@ -82,22 +82,34 @@ private static IEnumerable<string> GetDotNetBasePaths(string workingDirectory)
             const string DOTNET_CLI_UI_LANGUAGE = nameof(DOTNET_CLI_UI_LANGUAGE);
             
             Process process;
+            var lines = new List<string>();
             try
             {
-                var startInfo = new ProcessStartInfo("dotnet", "--info")
+                process = new Process()
                 {
-                    WorkingDirectory = workingDirectory,
-                    CreateNoWindow = true,
-                    UseShellExecute = false,
-                    RedirectStandardOutput = true,
-                    RedirectStandardError = true
+                    StartInfo = new ProcessStartInfo("dotnet", "--info")
+                    {
+                        WorkingDirectory = workingDirectory,
+                        CreateNoWindow = true,
+                        UseShellExecute = false,
+                        RedirectStandardOutput = true,
+                        RedirectStandardError = true
+                    }
                 };
 
                 // Ensure that we set the DOTNET_CLI_UI_LANGUAGE environment variable to "en-US" before
                 // running 'dotnet --info'. Otherwise, we may get localized results.
-                startInfo.EnvironmentVariables[DOTNET_CLI_UI_LANGUAGE] = "en-US";
+                process.StartInfo.EnvironmentVariables[DOTNET_CLI_UI_LANGUAGE] = "en-US";
 
-                process = Process.Start(startInfo);
+                process.OutputDataReceived += (_, e) =>
+                {
+                    if (!string.IsNullOrWhiteSpace(e.Data))
+                    {
+                        lines.Add(e.Data);
+                    }
+                };
+
+                process.Start();
             }
             catch
             {
@@ -105,20 +117,6 @@ private static IEnumerable<string> GetDotNetBasePaths(string workingDirectory)
                 yield break;
             }
 
-            if (process.HasExited)
-            {
-                yield break;
-            }
-
-            var lines = new List<string>();
-            process.OutputDataReceived += (_, e) =>
-            {
-                if (!string.IsNullOrWhiteSpace(e.Data))
-                {
-                    lines.Add(e.Data);
-                }
-            };
-
             process.BeginOutputReadLine();
 
             process.WaitForExit();
@@ -126,14 +124,16 @@ private static IEnumerable<string> GetDotNetBasePaths(string workingDirectory)
             var outputString = string.Join(Environment.NewLine, lines);
 
             var matched = DotNetBasePathRegex.Match(outputString);
-            if (!matched.Success)
+            // We return the version in use at the front of the list in order to ensure
+            // FirstOrDefault always returns the version in use.
+            // The BasePath might not be found if the required version (via global.json)
+            // is not installed. In that case, we can still iterate to the other SDKs installed
+            string basePath = null;
+            if (matched.Success)
             {
-                yield break; 
+                basePath = matched.Groups[1].Value.Trim();
+                yield return basePath; 
             }
-            
-            var basePath = matched.Groups[1].Value.Trim();
-
-            yield return basePath; // We return the version in use at the front of the list in order to ensure FirstOrDefault always returns the version in use.
 
             var lineSdkIndex = lines.FindIndex(line => line.Contains("SDKs installed"));