Fix an indexing out of bound error in CompleteInput for empty script input (#19501)

MartinGC94 · web-flow · commit bb3c8a281960 · 2023-05-10T13:56:33.000-07:00
diff --git a/src/System.Management.Automation/engine/CommandCompletion/CommandCompletion.cs b/src/System.Management.Automation/engine/CommandCompletion/CommandCompletion.cs
@@ -91,7 +91,7 @@ public static Tuple<Ast, Token[], IScriptPosition> MapStringInputToParsedInput(s
         /// <returns></returns>
         public static CommandCompletion CompleteInput(string input, int cursorIndex, Hashtable options)
         {
-            if (input == null)
+            if (input == null || input.Length == 0)
             {
                 return s_emptyCommandCompletion;
             }
@@ -124,6 +124,11 @@ public static CommandCompletion CompleteInput(Ast ast, Token[] tokens, IScriptPo
                 throw PSTraceSource.NewArgumentNullException(nameof(positionOfCursor));
             }
 
+            if (ast.Extent.Text.Length == 0)
+            {
+                return s_emptyCommandCompletion;
+            }
+
             return CompleteInputImpl(ast, tokens, positionOfCursor, options);
         }
 
@@ -138,7 +143,7 @@ public static CommandCompletion CompleteInput(Ast ast, Token[] tokens, IScriptPo
         [SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "powershell")]
         public static CommandCompletion CompleteInput(string input, int cursorIndex, Hashtable options, PowerShell powershell)
         {
-            if (input == null)
+            if (input == null || input.Length == 0)
             {
                 return s_emptyCommandCompletion;
             }
@@ -221,6 +226,11 @@ public static CommandCompletion CompleteInput(Ast ast, Token[] tokens, IScriptPo
                 throw PSTraceSource.NewArgumentNullException(nameof(powershell));
             }
 
+            if (ast.Extent.Text.Length == 0)
+            {
+                return s_emptyCommandCompletion;
+            }
+
             // If we are in a debugger stop, let the debugger do the command completion.
             var debugger = powershell.Runspace?.Debugger;
             if ((debugger != null) && debugger.InBreakpoint)
diff --git a/src/System.Management.Automation/engine/CommandCompletion/CompletionAnalysis.cs b/src/System.Management.Automation/engine/CommandCompletion/CompletionAnalysis.cs
@@ -155,6 +155,11 @@ internal static AstAnalysisContext ExtractAstContext(Ast inputAst, Token[] input
                 ast => IsCursorWithinOrJustAfterExtent(positionForAstSearch, ast.Extent),
                 searchNestedScriptBlocks: true).ToList();
 
+            if (relatedAsts.Count == 0)
+            {
+                relatedAsts.Add(inputAst);
+            }
+
             // If the last ast is an unnamed block that starts with "param" the cursor is inside a param block.
             // To avoid adding special handling to all the completers that look at the last ast, we remove it here because it's not useful for completion.
             if (relatedAsts[^1].Extent.Text.StartsWith("param", StringComparison.OrdinalIgnoreCase)
diff --git a/src/System.Management.Automation/engine/InitialSessionState.cs b/src/System.Management.Automation/engine/InitialSessionState.cs
@@ -4044,6 +4044,7 @@ internal void ImportCmdletsFromAssembly(Assembly assembly, PSModuleInfo module)
 [OutputType([System.Management.Automation.CommandCompletion])]
 Param(
     [Parameter(ParameterSetName = 'ScriptInputSet', Mandatory = $true, Position = 0)]
+    [AllowEmptyString()]
     [string] $inputScript,
 
     [Parameter(ParameterSetName = 'ScriptInputSet', Position = 1)]
@@ -4081,7 +4082,7 @@ internal void ImportCmdletsFromAssembly(Assembly assembly, PSModuleInfo module)
             <#options#>          $options)
     }
 }
-        ";
+";
 
         /// <summary>
         /// This is the default function to use for clear-host.
diff --git a/test/powershell/Host/TabCompletion/TabCompletion.Tests.ps1 b/test/powershell/Host/TabCompletion/TabCompletion.Tests.ps1
@@ -2050,6 +2050,14 @@ dir -Recurse `
             param($inputStr, $expected)
             $inputStr | Should -Throw -ErrorId $expected
         }
+
+        It "Should not throw errors in tab completion with empty input string" {
+            {[System.Management.Automation.CommandCompletion]::CompleteInput("", 0, $null)} | Should -Not -Throw
+        }
+
+        It "Should not throw errors in tab completion with empty input ast" {
+            {[System.Management.Automation.CommandCompletion]::CompleteInput({}.Ast, @(), {}.Ast.Extent.StartScriptPosition, $null)} | Should -Not -Throw
+        }
     }
 
     Context "DSC tab completion tests" {

Original file line number	Diff line number	Diff line change
`@@ -91,7 +91,7 @@ public static Tuple<Ast, Token[], IScriptPosition> MapStringInputToParsedInput(s`
`91`	`91`	`/// <returns></returns>`
`92`	`92`	`public static CommandCompletion CompleteInput(string input, int cursorIndex, Hashtable options)`
`93`	`93`	`{`
`94`		`- if (input == null)`
	`94`	`+ if (input == null \|\| input.Length == 0)`
`95`	`95`	`{`
`96`	`96`	`return s_emptyCommandCompletion;`
`97`	`97`	`}`
`@@ -124,6 +124,11 @@ public static CommandCompletion CompleteInput(Ast ast, Token[] tokens, IScriptPo`
`124`	`124`	`throw PSTraceSource.NewArgumentNullException(nameof(positionOfCursor));`
`125`	`125`	`}`
`126`	`126`
	`127`	`+ if (ast.Extent.Text.Length == 0)`
	`128`	`+ {`
	`129`	`+ return s_emptyCommandCompletion;`
	`130`	`+ }`
	`131`	`+`
`127`	`132`	`return CompleteInputImpl(ast, tokens, positionOfCursor, options);`
`128`	`133`	`}`
`129`	`134`
`@@ -138,7 +143,7 @@ public static CommandCompletion CompleteInput(Ast ast, Token[] tokens, IScriptPo`
`138`	`143`	`[SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "powershell")]`
`139`	`144`	`public static CommandCompletion CompleteInput(string input, int cursorIndex, Hashtable options, PowerShell powershell)`
`140`	`145`	`{`
`141`		`- if (input == null)`
	`146`	`+ if (input == null \|\| input.Length == 0)`
`142`	`147`	`{`
`143`	`148`	`return s_emptyCommandCompletion;`
`144`	`149`	`}`
`@@ -221,6 +226,11 @@ public static CommandCompletion CompleteInput(Ast ast, Token[] tokens, IScriptPo`
`221`	`226`	`throw PSTraceSource.NewArgumentNullException(nameof(powershell));`
`222`	`227`	`}`
`223`	`228`
	`229`	`+ if (ast.Extent.Text.Length == 0)`
	`230`	`+ {`
	`231`	`+ return s_emptyCommandCompletion;`
	`232`	`+ }`
	`233`	`+`
`224`	`234`	`// If we are in a debugger stop, let the debugger do the command completion.`
`225`	`235`	`var debugger = powershell.Runspace?.Debugger;`
`226`	`236`	`if ((debugger != null) && debugger.InBreakpoint)`
Original file line number	Diff line number	Diff line change
`@@ -4044,6 +4044,7 @@ internal void ImportCmdletsFromAssembly(Assembly assembly, PSModuleInfo module)`
`4044`	`4044`	`[OutputType([System.Management.Automation.CommandCompletion])]`
`4045`	`4045`	`Param(`
`4046`	`4046`	`[Parameter(ParameterSetName = 'ScriptInputSet', Mandatory = $true, Position = 0)]`
	`4047`	`+ [AllowEmptyString()]`
`4047`	`4048`	`[string] $inputScript,`
`4048`	`4049`
`4049`	`4050`	`[Parameter(ParameterSetName = 'ScriptInputSet', Position = 1)]`
`@@ -4081,7 +4082,7 @@ internal void ImportCmdletsFromAssembly(Assembly assembly, PSModuleInfo module)`
`4081`	`4082`	`<#options#> $options)`
`4082`	`4083`	`}`
`4083`	`4084`	`}`
`4084`		`- ";`
	`4085`	`+";`
`4085`	`4086`
`4086`	`4087`	`/// <summary>`
`4087`	`4088`	`/// This is the default function to use for clear-host.`
Original file line number	Diff line number	Diff line change
@@ -2050,6 +2050,14 @@ dir -Recurse `
`2050`	`2050`	`param($inputStr, $expected)`
`2051`	`2051`	`$inputStr \| Should -Throw -ErrorId $expected`
`2052`	`2052`	`}`
	`2053`	`+`
	`2054`	`+ It "Should not throw errors in tab completion with empty input string" {`
	`2055`	`+ {[System.Management.Automation.CommandCompletion]::CompleteInput("", 0, $null)} \| Should -Not -Throw`
	`2056`	`+ }`
	`2057`	`+`
	`2058`	`+ It "Should not throw errors in tab completion with empty input ast" {`
	`2059`	`+ {[System.Management.Automation.CommandCompletion]::CompleteInput({}.Ast, @(), {}.Ast.Extent.StartScriptPosition, $null)} \| Should -Not -Throw`
	`2060`	`+ }`
`2053`	`2061`	`}`
`2054`	`2062`
`2055`	`2063`	`Context "DSC tab completion tests" {`