New rule: AvoidOverwritingBuiltInCmdlets

RuleDocumentation/AvoidOverwritingBuiltInCmdlets.md

@@ -0,0 +1,33 @@
+# AvoidOverwritingBuiltInCmdlets
+
+**Severity Level: Warning**
+
+## Description
+
+This rule flags cmdlets that are available in a given edition/version of PowerShell on a given operating system which are overwritten by a function declaration. It works by comparing function declarations against a set of whitelists which ship with PSScriptAnalyzer. These whitelist files are used by other PSScriptAnalyzer rules. More information can be found in the documentation for the [UseCompatibleCmdlets](./UseCompatibleCmdlets.md) rule.
+
+## Configuration
+
+To enable the rule to check if your script is compatible on PowerShell Core on Windows, put the following your settings file.
+
+
+```PowerShell
+@{
+    'Rules' = @{
+        'PSAvoidOverwritingBuiltInCmdlets' = @{
+            'PowerShellVersion' = @("core-6.1.0-windows")
+        }
+    }
+}
+```
+
+### Parameters
+
+#### PowerShellVersion
+
+The parameter `PowerShellVersion` is a list of whitelists that ship with PSScriptAnalyzer.
+
+**Note**: The default value for `PowerShellVersion` is `"core-6.1.0-windows"` if PowerShell 6 or later is installed, and `"desktop-5.1.14393.206-windows"` if it is not.
+
+Usually, patched versions of PowerShell have the same cmdlet data, therefore only settings of major and minor versions of PowerShell are supplied. One can also create a custom settings file as well with the [New-CommandDataFile.ps1](https://github.com/PowerShell/PSScriptAnalyzer/blob/development/Utils/New-CommandDataFile.ps1) script and use it by placing the created `JSON` into the `Settings` folder of the `PSScriptAnalyzer` module installation folder, then the `PowerShellVersion` parameter is just its file name (that can also be changed if desired).
+Note that the `core-6.0.2-*` files were removed in PSScriptAnalyzer 1.18 since PowerShell 6.0 reached it's end of life.

RuleDocumentation/README.md

@@ -13,6 +13,7 @@
 |[AvoidGlobalVars](./AvoidGlobalVars.md) | Warning | |
 |[AvoidInvokingEmptyMembers](./AvoidInvokingEmptyMembers.md) | Warning | |
 |[AvoidLongLines](./AvoidLongLines.md) | Warning | |
+|[AvoidOverwritingBuiltInCmdlets](./AvoidOverwritingBuiltInCmdlets.md) | Warning | |
 |[AvoidNullOrEmptyHelpMessageAttribute](./AvoidNullOrEmptyHelpMessageAttribute.md) | Warning | |
 |[AvoidShouldContinueWithoutForce](./AvoidShouldContinueWithoutForce.md) | Warning | |
 |[AvoidUsingCmdletAliases](./AvoidUsingCmdletAliases.md) | Warning | Yes |

Rules/AvoidOverwritingBuiltInCmdlets.cs

@@ -0,0 +1,262 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+#if !CORECLR
+using System.ComponentModel.Composition;
+#endif
+using System.Globalization;
+using System.IO;
+using System.Linq;
+using System.Management.Automation.Language;
+using System.Text.RegularExpressions;
+using Microsoft.Windows.PowerShell.ScriptAnalyzer.Generic;
+
+using Newtonsoft.Json.Linq;
+
+namespace Microsoft.Windows.PowerShell.ScriptAnalyzer.BuiltinRules
+{
+    /// <summary>
+    /// AvoidOverwritingBuiltInCmdlets: Checks if a script overwrites a cmdlet that comes with PowerShell
+    /// </summary>
+#if !CORECLR
+    [Export(typeof(IScriptRule))]
+#endif
+    /// <summary>
+    /// A class to check if a script overwrites a cmdlet that comes with PowerShell
+    /// </summary>
+    public class AvoidOverwritingBuiltInCmdlets : ConfigurableRule
+    {
+        /// <summary>
+        /// Specify the version of PowerShell to compare against since different versions of PowerShell
+        /// ship with different sets of built in cmdlets. The default value for PowerShellVersion is
+        /// "core-6.1.0-windows" if PowerShell 6 or later is installed, and "desktop-5.1.14393.206-windows"
+        /// if it is not. The version specified aligns with a JSON file in `/path/to/PSScriptAnalyzerModule/Settings`.
+        /// These files are of the form, `PSEDITION-PSVERSION-OS.json` where `PSEDITION` can be either `Core` or
+        /// `Desktop`, `OS` can be either `Windows`, `Linux` or `MacOS`, and `Version` is the PowerShell version.
+        /// </summary>
+        [ConfigurableRuleProperty(defaultValue: "")]
+        public string[] PowerShellVersion { get; set; }
+        private readonly Dictionary<string, HashSet<string>> _cmdletMap;
+
+
+        /// <summary>
+        /// Construct an object of AvoidOverwritingBuiltInCmdlets type.
+        /// </summary>
+        public AvoidOverwritingBuiltInCmdlets()
+        {
+            _cmdletMap = new Dictionary<string, HashSet<string>>();
+            Enable = true;  // Enable rule by default
+        }
+
+
+        /// <summary>
+        /// Analyzes the given ast to find the [violation]
+        /// </summary>
+        /// <param name="ast">AST to be analyzed. This should be non-null</param>
+        /// <param name="fileName">Name of file that corresponds to the input AST.</param>
+        /// <returns>A an enumerable type containing the violations</returns>
+        public override IEnumerable<DiagnosticRecord> AnalyzeScript(Ast ast, string fileName)
+        {
+            if (ast == null)
+            {
+                throw new ArgumentNullException(nameof(ast));
+            }
+
+            var diagnosticRecords = new List<DiagnosticRecord>();
+
+            IEnumerable<FunctionDefinitionAst> functionDefinitions = ast.FindAll(testAst => testAst is FunctionDefinitionAst, true).OfType<FunctionDefinitionAst>();
+            if (!functionDefinitions.Any())
+            {
+                // There are no function definitions in this AST and so it's not worth checking the rest of this rule
+                return diagnosticRecords;
+            }
+
+
+            if (PowerShellVersion.Length == 0 || string.IsNullOrEmpty(PowerShellVersion[0]))
+            {
+                // PowerShellVersion is not already set to one of the acceptable defaults
+                // Try launching `pwsh -v` to see if PowerShell 6+ is installed, and use those cmdlets
+                // as a default. If 6+ is not installed this will throw an error, which when caught will
+                // allow us to use the PowerShell 5 cmdlets as a default.
+
+                PowerShellVersion = new[] { "desktop-5.1.14393.206-windows" };
+#if CORECLR
+                PowerShellVersion = new[] { "core-6.1.0-windows" };
+#endif
+
+            }
+
+            var psVerList = PowerShellVersion;
+            string settingsPath = Settings.GetShippedSettingsDirectory();
+
+            foreach (string reference in psVerList)
+            {
+                if (settingsPath == null || !ContainsReferenceFile(settingsPath, reference))
+                {
+                    throw new ArgumentException(nameof(PowerShellVersion));
+                }
+            }
+
+            ProcessDirectory(settingsPath, psVerList);
+
+            if (_cmdletMap.Keys.Count != psVerList.Count())
+            {
+                throw new ArgumentException(nameof(PowerShellVersion));
+            }
+
+            foreach (FunctionDefinitionAst functionDef in functionDefinitions)
+            {
+                string functionName = functionDef.Name;
+                foreach (KeyValuePair<string, HashSet<string>> cmdletSet in _cmdletMap)
+                {
+                    if (cmdletSet.Value.Contains(functionName))
+                    {
+                        diagnosticRecords.Add(CreateDiagnosticRecord(functionName, cmdletSet.Key, functionDef.Extent));
+                    }
+                }
+            }
+
+            return diagnosticRecords;
+        }
+
+
+        private DiagnosticRecord CreateDiagnosticRecord(string FunctionName, string PSVer, IScriptExtent ViolationExtent)
+        {
+            var record = new DiagnosticRecord(
+                string.Format(CultureInfo.CurrentCulture,
+                    string.Format(Strings.AvoidOverwritingBuiltInCmdletsError, FunctionName, PSVer)),
+                ViolationExtent,
+                GetName(),
+                GetDiagnosticSeverity(),
+                ViolationExtent.File,
+                null
+            );
+            return record;
+        }
+
+
+        private bool ContainsReferenceFile(string directory, string reference)
+        {
+            return File.Exists(Path.Combine(directory, reference + ".json"));
+        }
+
+
+        private void ProcessDirectory(string path, IEnumerable<string> acceptablePlatformSpecs)
+        {
+            foreach (var filePath in Directory.EnumerateFiles(path))
+            {
+                var extension = Path.GetExtension(filePath);
+                if (String.IsNullOrWhiteSpace(extension)
+                    || !extension.Equals(".json", StringComparison.OrdinalIgnoreCase))
+                {
+                    continue;
+                }
+
+                var fileNameWithoutExt = Path.GetFileNameWithoutExtension(filePath);
+                if (acceptablePlatformSpecs != null
+                    && !acceptablePlatformSpecs.Contains(fileNameWithoutExt, StringComparer.OrdinalIgnoreCase))
+                {
+                    continue;
+                }
+
+                if (_cmdletMap.Keys.Contains(fileNameWithoutExt))
+                {
+                    continue;
+                }
+
+                _cmdletMap.Add(fileNameWithoutExt, GetCmdletsFromData(JObject.Parse(File.ReadAllText(filePath))));
+            }
+        }
+
+
+        private HashSet<string> GetCmdletsFromData(dynamic deserializedObject)
+        {
+            var cmdlets = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+            dynamic modules = deserializedObject.Modules;
+            foreach (dynamic module in modules)
+            {
+                if (module.ExportedCommands == null)
+                {
+                    continue;
+                }
+
+                foreach (dynamic cmdlet in module.ExportedCommands)
+                {
+                    var name = cmdlet.Name as string;
+                    if (name == null)
+                    {
+                        name = cmdlet.Name.ToString();
+                    }
+                    cmdlets.Add(name);
+                }
+            }
+
+            return cmdlets;
+        }
+
+
+        /// <summary>
+        /// Retrieves the common name of this rule.
+        /// </summary>
+        public override string GetCommonName()
+        {
+            return string.Format(CultureInfo.CurrentCulture, Strings.AvoidOverwritingBuiltInCmdletsCommonName);
+        }
+
+        /// <summary>
+        /// Retrieves the description of this rule.
+        /// </summary>
+        public override string GetDescription()
+        {
+            return string.Format(CultureInfo.CurrentCulture, Strings.AvoidOverwritingBuiltInCmdletsDescription);
+        }
+
+        /// <summary>
+        /// Retrieves the name of this rule.
+        /// </summary>
+        public override string GetName()
+        {
+            return string.Format(
+                CultureInfo.CurrentCulture,
+                Strings.NameSpaceFormat,
+                GetSourceName(),
+                Strings.AvoidOverwritingBuiltInCmdletsName);
+        }
+
+        /// <summary>
+        /// Retrieves the severity of the rule: error, warning or information.
+        /// </summary>
+        public override RuleSeverity GetSeverity()
+        {
+            return RuleSeverity.Warning;
+        }
+
+        /// <summary>
+        /// Gets the severity of the returned diagnostic record: error, warning, or information.
+        /// </summary>
+        /// <returns></returns>
+        public DiagnosticSeverity GetDiagnosticSeverity()
+        {
+            return DiagnosticSeverity.Warning;
+        }
+
+        /// <summary>
+        /// Retrieves the name of the module/assembly the rule is from.
+        /// </summary>
+        public override string GetSourceName()
+        {
+            return string.Format(CultureInfo.CurrentCulture, Strings.SourceName);
+        }
+
+        /// <summary>
+        /// Retrieves the type of the rule, Builtin, Managed or Module.
+        /// </summary>
+        public override SourceType GetSourceType()
+        {
+            return SourceType.Builtin;
+        }
+    }
+}

Rules/Strings.resx

@@ -810,6 +810,18 @@
   <data name="UseCompatibleCmdletsError" xml:space="preserve">
     <value>'{0}' is not compatible with PowerShell edition '{1}', version '{2}' and OS '{3}'</value>
   </data>
+  <data name="AvoidOverwritingBuiltInCmdletsName" xml:space="preserve">
+    <value>AvoidOverwritingBuiltInCmdlets</value>
+  </data>
+  <data name="AvoidOverwritingBuiltInCmdletsCommonName" xml:space="preserve">
+    <value>Avoid overwriting built in cmdlets</value>
+  </data>
+  <data name="AvoidOverwritingBuiltInCmdletsDescription" xml:space="preserve">
+    <value>Do not overwrite the definition of a cmdlet that is included with PowerShell</value>
+  </data>
+  <data name="AvoidOverwritingBuiltInCmdletsError" xml:space="preserve">
+    <value>'{0}' is a cmdlet that is included with PowerShell (version {1}) whose definition should not be overridden</value>
+  </data>
   <data name="UseCompatibleCommandsName" xml:space="preserve">
     <value>UseCompatibleCommands</value>
   </data>

Tests/Engine/GetScriptAnalyzerRule.tests.ps1

@@ -58,8 +58,8 @@ Describe "Test Name parameters" {
         }
 
         It "get Rules with no parameters supplied" {
-			$defaultRules = Get-ScriptAnalyzerRule
-            $expectedNumRules = 61
+            $defaultRules = Get-ScriptAnalyzerRule
+            $expectedNumRules = 62
             if ((Test-PSEditionCoreClr) -or (Test-PSVersionV3) -or (Test-PSVersionV4))
             {
                 # for PSv3 PSAvoidGlobalAliases is not shipped because