PowerShell · rjmholt · Dec 9, 2020 · Sep 22, 2020 · Sep 22, 2020 · Sep 23, 2020
diff --git a/src/Microsoft.PowerShell.Commands.Utility/commands/utility/ImportPowerShellDataFile.cs b/src/Microsoft.PowerShell.Commands.Utility/commands/utility/ImportPowerShellDataFile.cs
@@ -39,6 +39,13 @@ public string[] LiteralPath
             set { _isLiteralPath = true; Path = value; }
         }
 
+        /// <summary>
+        /// Gets or sets switch that determines if built-in limits are applied to the data.
+        /// </summary>
+        [Experimental("Microsoft.PowerShell.Utility.PSImportPSDataFileSkipLimitCheck", ExperimentAction.Show)]
+        [Parameter]
+        public SwitchParameter SkipLimitCheck { get; set; }
+
         /// <summary>
         /// For each path, resolve it, parse it and write all hashtables to the output stream.
         /// </summary>
@@ -61,7 +68,7 @@ protected override void ProcessRecord()
                         var data = ast.Find(a => a is HashtableAst, false);
                         if (data != null)
                         {
-                            WriteObject(data.SafeGetValue());
+                            WriteObject(data.SafeGetValue(SkipLimitCheck));
                         }
                         else
                         {

diff --git a/src/Modules/Unix/Microsoft.PowerShell.Utility/Microsoft.PowerShell.Utility.psd1 b/src/Modules/Unix/Microsoft.PowerShell.Utility/Microsoft.PowerShell.Utility.psd1
@@ -38,6 +38,10 @@ PrivateData = @{
         Name        = 'Microsoft.PowerShell.Utility.PSManageBreakpointsInRunspace'
         Description = 'Enables -BreakAll parameter on Debug-Runspace and Debug-Job cmdlets to allow users to decide if they want PowerShell to break immediately in the current location when they attach a debugger. Enables -Runspace parameter on *-PSBreakpoint cmdlets to support management of breakpoints in another runspace.'
       }
+      @{
+        Name        = 'Microsoft.PowerShell.Utility.PSImportPSDataFileSkipLimitCheck'
+        Description = 'Enable -SkipLimitCheck switch for Import-PowerShellDataFile to not enforce built-in hashtable limits'
+      }
     )
   }
 }

diff --git a/src/Modules/Windows/Microsoft.PowerShell.Utility/Microsoft.PowerShell.Utility.psd1 b/src/Modules/Windows/Microsoft.PowerShell.Utility/Microsoft.PowerShell.Utility.psd1
@@ -37,6 +37,10 @@ PrivateData = @{
         Name        = 'Microsoft.PowerShell.Utility.PSManageBreakpointsInRunspace'
         Description = 'Enables -BreakAll parameter on Debug-Runspace and Debug-Job cmdlets to allow users to decide if they want PowerShell to break immediately in the current location when they attach a debugger. Enables -Runspace parameter on *-PSBreakpoint cmdlets to support management of breakpoints in another runspace.'
       }
+      @{
+        Name        = 'Microsoft.PowerShell.Utility.PSImportPSDataFileSkipLimitCheck'
+        Description = 'Enable -NoLimit switch for Import-PowerShellDataFile to not enforce built-in hashtable limits'
+      }
     )
   }
 }

@@ -362,7 +362,8 @@ internal enum SafeValueContext
         {
             Default,
             GetPowerShell,
-            ModuleAnalysis
+            ModuleAnalysis,
+            SkipHashtableSizeCheck,
         }
 
         // future proofing
@@ -371,7 +372,8 @@ private GetSafeValueVisitor() { }
         public static object GetSafeValue(Ast ast, ExecutionContext context, SafeValueContext safeValueContext)
         {
             t_context = context;
-            if (IsSafeValueVisitor.IsAstSafe(ast, safeValueContext))
+
+            if (safeValueContext == SafeValueContext.SkipHashtableSizeCheck || IsSafeValueVisitor.IsAstSafe(ast, safeValueContext))
             {
                 return ast.Accept(new GetSafeValueVisitor());
             }

@@ -195,6 +195,19 @@ public override string ToString()
         /// If <paramref name="extent"/> is deemed unsafe
         /// </exception>
         public object SafeGetValue()
+        {
+            return SafeGetValue(skipHashtableSizeCheck: false);
+        }
+
+        /// <summary>
+        /// Constructs the resultant object from the AST and returns it if it is safe.
+        /// </summary>
+        /// <param name="skipHashtableSizeCheck">Set to skip hashtable limit validation.</param>
+        /// <returns>The object represented by the AST as a safe object.</returns>
+        /// <exception cref="InvalidOperationException">
+        /// If <paramref name="extent"/> is deemed unsafe.
+        /// </exception>
+        public object SafeGetValue(bool skipHashtableSizeCheck)
         {
             try
             {
@@ -204,7 +217,7 @@ public object SafeGetValue()
                     context = System.Management.Automation.Runspaces.Runspace.DefaultRunspace.ExecutionContext;
                 }
 
-                return GetSafeValueVisitor.GetSafeValue(this, context, GetSafeValueVisitor.SafeValueContext.Default);
+                return GetSafeValueVisitor.GetSafeValue(this, context, skipHashtableSizeCheck ? GetSafeValueVisitor.SafeValueContext.SkipHashtableSizeCheck : GetSafeValueVisitor.SafeValueContext.Default);
             }
             catch
             {

diff --git a/test/powershell/Modules/Microsoft.PowerShell.Utility/PowerShellData.tests.ps1 b/test/powershell/Modules/Microsoft.PowerShell.Utility/PowerShellData.tests.ps1
@@ -1,6 +1,19 @@
 # Copyright (c) Microsoft Corporation.
 # Licensed under the MIT License.
 Describe "Tests for the Import-PowerShellDataFile cmdlet" -Tags "CI" {
+    BeforeAll {
+        $largePsd1Path = Join-Path -Path $TestDrive -ChildPath 'large.psd1'
+        $largePsd1Builder = [System.Text.StringBuilder]::new('@{')
+        1..501 | ForEach-Object {
+            $largePsd1Builder.Append("key$_ = $_;")
+        }
+        $largePsd1Builder.Append('}')
+        Set-Content -Path $largePsd1Path -Value $largePsd1Builder.ToString()
+
+        if ((Get-ExperimentalFeature Microsoft.PowerShell.Utility.PSImportPSDataFileSkipLimitCheck).Enabled -ne $true) {
+            $skipTest = $true
+        }
+    }
 
     It "Validates error on a missing path" {
         { Import-PowerShellDataFile -Path /SomeMissingDirectory -ErrorAction Stop } |
@@ -32,4 +45,12 @@ Describe "Tests for the Import-PowerShellDataFile cmdlet" -Tags "CI" {
         $result.Hello | Should -BeExactly "World"
     }
 
+    It 'Fails if psd1 file has more than 500 keys' {
+        { Import-PowerShellDataFile $largePsd1Path } | Should -Throw -ErrorId 'System.InvalidOperationException,Microsoft.PowerShell.Commands.ImportPowerShellDataFileCommand'
+    }
+
+    It 'Succeeds if -NoLimit is used and has more than 500 keys' -Skip:$skipTest {
+        $result = Import-PowerShellDataFile $largePsd1Path -SkipLimitCheck
+        $result.Keys.Count | Should -Be 501
+    }
 }