Silence duplicate warnings about being unable to set console encoding.

In some versions of Unity (e.g 2019.1.11f1) it's not possible to set
the console encoding. This changes the CommandLine module to warn only
once when this occurs.

Fixes #214
Change-Id: I8f50d9d252b37621627a12e80429b446e34183b0

Author: Stewart Miles

source/PlayServicesResolver/src/CommandLine.cs

@@ -19,6 +19,7 @@ namespace GooglePlayServices
     using System.Collections.Generic;
     using System.Diagnostics;
     using System.IO;
+    using System.Text;
     using System.Text.RegularExpressions;
     using System.Threading;
     using System;
@@ -220,7 +221,7 @@ private void Read()
                                     byte[] copy = new byte[bytesRead];
                                     Array.Copy(buffer, copy, copy.Length);
                                     DataReceived(new StreamData(
-                                        handle, System.Text.Encoding.UTF8.GetString(copy), copy,
+                                        handle, Encoding.UTF8.GetString(copy), copy,
                                         complete));
                                 }
                             }
@@ -511,6 +512,11 @@ public static Result Run(string toolPath, string arguments, string workingDirect
                                envVars: envVars, ioHandler: ioHandler, useShellExecution: false);
         }
 
+        /// <summary>
+        /// Whether the console configuration warning has been displayed.
+        /// </summary>
+        private static bool displayedConsoleConfigurationWarning = false;
+
         /// <summary>
         /// Execute a command line tool.
         /// </summary>
@@ -537,19 +543,31 @@ public static Result RunViaShell(
                 Dictionary<string, string> envVars = null,
                 IOHandler ioHandler = null, bool useShellExecution = false,
                 bool stdoutRedirectionInShellMode = true) {
-            System.Text.Encoding inputEncoding = Console.InputEncoding;
-            System.Text.Encoding outputEncoding = Console.OutputEncoding;
+            bool consoleConfigurationWarning = false;
+            Encoding inputEncoding = Console.InputEncoding;
+            Encoding outputEncoding = Console.OutputEncoding;
             // Android SDK manager requires the input encoding to be set to
             // UFT8 to pipe data to the tool.
             // Cocoapods requires the output encoding to be set to UTF8 to
             // retrieve output.
             try {
-                Console.InputEncoding = System.Text.Encoding.UTF8;
-                Console.OutputEncoding = System.Text.Encoding.UTF8;
+                var utf8Type = Encoding.UTF8.GetType();
+                // Only compare the type of the encoding class since the configuration shouldn't
+                // matter.
+                if (inputEncoding.GetType() != utf8Type) {
+                    Console.InputEncoding = Encoding.UTF8;
+                }
+                if (outputEncoding.GetType() != utf8Type) {
+                    Console.OutputEncoding = Encoding.UTF8;
+                }
             } catch (Exception e) {
-                UnityEngine.Debug.LogWarning(String.Format(
-                    "Unable to set console input / output  encoding to UTF8 (e.g en_US.UTF8-8). " +
-                    "Some commands may fail. {0}", e));
+                if (!displayedConsoleConfigurationWarning) {
+                    UnityEngine.Debug.LogWarning(String.Format(
+                        "Unable to set console input / output encoding from {0} & {1} to {2} " +
+                        "(e.g en_US.UTF8-8). Some commands may fail. {3}",
+                        inputEncoding, outputEncoding, Encoding.UTF8, e));
+                    consoleConfigurationWarning = true;
+                }
             }
 
             // Mono 3.x on Windows can't execute tools with single quotes (apostrophes) in the path.
@@ -655,13 +673,21 @@ public static Result RunViaShell(
             result.message = FormatResultMessage(toolPath, arguments, result.stdout,
                                                  result.stderr, result.exitCode);
             try {
-                Console.InputEncoding = inputEncoding;
-                Console.OutputEncoding = outputEncoding;
+                if (Console.InputEncoding != inputEncoding) {
+                    Console.InputEncoding = inputEncoding;
+                }
+                if (Console.OutputEncoding != outputEncoding) {
+                    Console.OutputEncoding = outputEncoding;
+                }
             } catch (Exception e) {
-                UnityEngine.Debug.LogWarning(String.Format(
-                    "Unable to restore console input / output  encoding to {0} & {1}. {2}",
-                    inputEncoding, outputEncoding, e));
+                if (!displayedConsoleConfigurationWarning) {
+                  UnityEngine.Debug.LogWarning(String.Format(
+                      "Unable to restore console input / output  encoding to {0} & {1}. {2}",
+                      inputEncoding, outputEncoding, e));
+                  consoleConfigurationWarning = true;
+                }
             }
+            if (consoleConfigurationWarning) displayedConsoleConfigurationWarning = true;
             return result;
         }