From 9bf512ff5d6b9803c1098b71bbbd1b07338692fa Mon Sep 17 00:00:00 2001
From: Steve Lee <slee@microsoft.com>
Date: Mon, 28 Sep 2020 09:22:40 -0700
Subject: [PATCH] Emit warning if `ConvertTo-Json` exceeds `-Depth` value
 (#13692)

---
 .../commands/utility/WebCmdlet/JsonObject.cs        | 13 +++++++++++++
 .../resources/WebCmdletStrings.resx                 |  3 +++
 .../SecureString.Tests.ps1                          |  9 ++++++---
 .../Microsoft.PowerShell.Utility/Json.Tests.ps1     |  7 +++++++
 4 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/src/Microsoft.PowerShell.Commands.Utility/commands/utility/WebCmdlet/JsonObject.cs b/src/Microsoft.PowerShell.Commands.Utility/commands/utility/WebCmdlet/JsonObject.cs
index 2b15f15098..2b9bce8fd8 100644
--- a/src/Microsoft.PowerShell.Commands.Utility/commands/utility/WebCmdlet/JsonObject.cs
+++ b/src/Microsoft.PowerShell.Commands.Utility/commands/utility/WebCmdlet/JsonObject.cs
@@ -457,6 +457,7 @@ namespace Microsoft.PowerShell.Commands
             {
                 // Pre-process the object so that it serializes the same, except that properties whose
                 // values cannot be evaluated are treated as having the value null.
+                _maxDepthWarningWritten = false;
                 object preprocessedObject = ProcessValue(objectToProcess, currentDepth: 0, in context);
                 var jsonSettings = new JsonSerializerSettings
                 {
@@ -484,6 +485,8 @@ namespace Microsoft.PowerShell.Commands
             }
         }
 
+        private static bool _maxDepthWarningWritten;
+
         /// <summary>
         /// Return an alternate representation of the specified object that serializes the same JSON, except
         /// that properties that cannot be evaluated are treated as having the value null.
@@ -561,6 +564,16 @@ namespace Microsoft.PowerShell.Commands
                 {
                     if (currentDepth > context.MaxDepth)
                     {
+                        if (!_maxDepthWarningWritten && context.Cmdlet != null)
+                        {
+                            _maxDepthWarningWritten = true;
+                            string maxDepthMessage = string.Format(
+                                CultureInfo.CurrentCulture,
+                                WebCmdletStrings.JsonMaxDepthReached,
+                                context.MaxDepth);
+                            context.Cmdlet.WriteWarning(maxDepthMessage);
+                        }
+
                         if (pso != null && pso.ImmediateBaseObjectIsEmpty)
                         {
                             // The obj is a pure PSObject, we convert the original PSObject to a string,
diff --git a/src/Microsoft.PowerShell.Commands.Utility/resources/WebCmdletStrings.resx b/src/Microsoft.PowerShell.Commands.Utility/resources/WebCmdletStrings.resx
index 397718a09b..bb9b3002d6 100644
--- a/src/Microsoft.PowerShell.Commands.Utility/resources/WebCmdletStrings.resx
+++ b/src/Microsoft.PowerShell.Commands.Utility/resources/WebCmdletStrings.resx
@@ -261,4 +261,7 @@
   <data name="RetryVerboseMsg" xml:space="preserve">
     <value>Retrying after interval of {0} seconds. Status code for previous attempt: {1}</value>
   </data>
+  <data name="JsonMaxDepthReached" xml:space="preserve">
+    <value>Resulting JSON is truncated as serialization has exceeded the set depth of {0}.</value>
+  </data>
 </root>
diff --git a/test/powershell/Modules/Microsoft.PowerShell.Security/SecureString.Tests.ps1 b/test/powershell/Modules/Microsoft.PowerShell.Security/SecureString.Tests.ps1
index 1a0f7e0095..6b8f45d509 100644
--- a/test/powershell/Modules/Microsoft.PowerShell.Security/SecureString.Tests.ps1
+++ b/test/powershell/Modules/Microsoft.PowerShell.Security/SecureString.Tests.ps1
@@ -1,5 +1,9 @@
 # Copyright (c) Microsoft Corporation.
 # Licensed under the MIT License.
+
+[Diagnostics.CodeAnalysis.SuppressMessageAttribute('PSAvoidUsingConvertToSecureStringWithPlainText', '')]
+param()
+
 Describe "SecureString conversion tests" -Tags "CI" {
     BeforeAll {
         $string = "ABCD"
@@ -24,9 +28,8 @@ Describe "SecureString conversion tests" -Tags "CI" {
     }
 
     It "can convert back from a secure string" {
-        $secret = "abcd"
-        $ss1 = ConvertTo-SecureString -AsPlainText -Force $secret
+        $ss1 = ConvertTo-SecureString -AsPlainText -Force $string
         $ss2 = ConvertFrom-SecureString $ss1 | ConvertTo-SecureString
-        $ss2 | ConvertFrom-SecureString -AsPlainText | Should -Be $secret
+        $ss2 | ConvertFrom-SecureString -AsPlainText | Should -Be $string
     }
 }
diff --git a/test/powershell/Modules/Microsoft.PowerShell.Utility/Json.Tests.ps1 b/test/powershell/Modules/Microsoft.PowerShell.Utility/Json.Tests.ps1
index acd3f095d8..35926eab9d 100644
--- a/test/powershell/Modules/Microsoft.PowerShell.Utility/Json.Tests.ps1
+++ b/test/powershell/Modules/Microsoft.PowerShell.Utility/Json.Tests.ps1
@@ -1463,4 +1463,11 @@ Describe "Json Bug fixes"  -Tags "Feature" {
         $result = "[1,","2,","3]" | ConvertFrom-Json
         $result.Count | Should -Be 3
     }
+
+    It 'ConvertTo-Json will output warning if depth is exceeded.' {
+        $a = @{ a = @{ b = @{ c = @{ d = 1 } } } }
+        $json = $a | ConvertTo-Json -Depth 2 -WarningVariable warningMessage -WarningAction SilentlyContinue
+        $json | Should -Not -BeNullOrEmpty
+        $warningMessage | Should -Not -BeNullOrEmpty
+    }
 }