check for configured debugger before start to provide a nicer error message

Author: GitMensch

CHANGELOG.md

@@ -8,6 +8,13 @@ Versioning].
 [keep a changelog]: https://keepachangelog.com/en/1.0.0
 [semantic versioning]: https://semver.org/spec/v2.0.0.html
 
+## Unreleased
+
+### Added
+
+- check for configured debugger before start to provide a nicer error message
+  ([@GitMensch])
+
 ## [0.27.0] - 2024-02-07
 
 ### Added

src/gdb.ts

@@ -53,7 +53,12 @@ class GDBDebugSession extends MI2DebugSession {
 	}
 
 	protected launchRequest(response: DebugProtocol.LaunchResponse, args: LaunchRequestArguments): void {
-		this.miDebugger = new MI2(args.gdbpath || "gdb", ["-q", "--interpreter=mi2"], args.debugger_args, args.env);
+		const dbgCommand = args.gdbpath || "gdb";
+		if (this.checkCommand(dbgCommand)) {
+			this.sendErrorResponse(response, 104, `Configured debugger ${dbgCommand} not found.`);
+			return;
+		}
+		this.miDebugger = new MI2(dbgCommand, ["-q", "--interpreter=mi2"], args.debugger_args, args.env);
 		this.setPathSubstitutions(args.pathSubstitutions);
 		this.initDebugger();
 		this.quit = false;
@@ -94,7 +99,12 @@ class GDBDebugSession extends MI2DebugSession {
 	}
 
 	protected attachRequest(response: DebugProtocol.AttachResponse, args: AttachRequestArguments): void {
-		this.miDebugger = new MI2(args.gdbpath || "gdb", ["-q", "--interpreter=mi2"], args.debugger_args, args.env);
+		const dbgCommand = args.gdbpath || "gdb";
+		if (this.checkCommand(dbgCommand)) {
+			this.sendErrorResponse(response, 104, `Configured debugger ${dbgCommand} not found.`);
+			return;
+		}
+		this.miDebugger = new MI2(dbgCommand, ["-q", "--interpreter=mi2"], args.debugger_args, args.env);
 		this.setPathSubstitutions(args.pathSubstitutions);
 		this.initDebugger();
 		this.quit = false;

src/lldb.ts

@@ -48,7 +48,12 @@ class LLDBDebugSession extends MI2DebugSession {
 	}
 
 	protected launchRequest(response: DebugProtocol.LaunchResponse, args: LaunchRequestArguments): void {
-		this.miDebugger = new MI2_LLDB(args.lldbmipath || "lldb-mi", [], args.debugger_args, args.env);
+		const dbgCommand = args.lldbmipath || "lldb-mi";
+		if (this.checkCommand(dbgCommand)) {
+			this.sendErrorResponse(response, 104, `Configured debugger ${dbgCommand} not found.`);
+			return;
+		}
+		this.miDebugger = new MI2_LLDB(dbgCommand, [], args.debugger_args, args.env);
 		this.setPathSubstitutions(args.pathSubstitutions);
 		this.initDebugger();
 		this.quit = false;
@@ -89,7 +94,12 @@ class LLDBDebugSession extends MI2DebugSession {
 	}
 
 	protected attachRequest(response: DebugProtocol.AttachResponse, args: AttachRequestArguments): void {
-		this.miDebugger = new MI2_LLDB(args.lldbmipath || "lldb-mi", [], args.debugger_args, args.env);
+		const dbgCommand = args.lldbmipath || "lldb-mi";
+		if (this.checkCommand(dbgCommand)) {
+			this.sendErrorResponse(response, 104, `Configured debugger ${dbgCommand} not found.`);
+			return;
+		}
+		this.miDebugger = new MI2_LLDB(dbgCommand, [], args.debugger_args, args.env);
 		this.setPathSubstitutions(args.pathSubstitutions);
 		this.initDebugger();
 		this.quit = false;

src/mago.ts

@@ -50,7 +50,12 @@ class MagoDebugSession extends MI2DebugSession {
 	}
 
 	protected launchRequest(response: DebugProtocol.LaunchResponse, args: LaunchRequestArguments): void {
-		this.miDebugger = new MI2_Mago(args.magomipath || "mago-mi", ["-q"], args.debugger_args, args.env);
+		const dbgCommand = args.magomipath || "mago-mi";
+		if (this.checkCommand(dbgCommand)) {
+			this.sendErrorResponse(response, 104, `Configured debugger ${dbgCommand} not found.`);
+			return;
+		}
+		this.miDebugger = new MI2_Mago(dbgCommand, ["-q"], args.debugger_args, args.env);
 		this.initDebugger();
 		this.quit = false;
 		this.attached = false;
@@ -69,7 +74,12 @@ class MagoDebugSession extends MI2DebugSession {
 	}
 
 	protected attachRequest(response: DebugProtocol.AttachResponse, args: AttachRequestArguments): void {
-		this.miDebugger = new MI2_Mago(args.magomipath || "mago-mi", [], args.debugger_args, args.env);
+		const dbgCommand = args.magomipath || "mago-mi";
+		if (this.checkCommand(dbgCommand)) {
+			this.sendErrorResponse(response, 104, `Configured debugger ${dbgCommand} not found.`);
+			return;
+		}
+		this.miDebugger = new MI2_Mago(dbgCommand, ["-q"], args.debugger_args, args.env);
 		this.initDebugger();
 		this.quit = false;
 		this.attached = true;

src/mibase.ts

@@ -5,6 +5,7 @@ import { Breakpoint, IBackend, Variable, VariableObject, ValuesFormattingMode, M
 import { MINode } from './backend/mi_parse';
 import { expandValue, isExpandable } from './backend/gdb_expansion';
 import { MI2 } from './backend/mi2/mi2';
+import { execSync } from 'child_process';
 import * as systemPath from "path";
 import * as net from "net";
 import * as os from "os";
@@ -17,10 +18,10 @@ class ExtendedVariable {
 }
 
 class VariableScope {
-	constructor (public readonly name: string, public readonly threadId: number, public readonly level: number) {
+	constructor(public readonly name: string, public readonly threadId: number, public readonly level: number) {
 	}
 
-	public static variableName (handle: number, name: string): string {
+	public static variableName(handle: number, name: string): string {
 		return `var_${handle}_${name}`;
 	}
 }
@@ -92,6 +93,17 @@ export class MI2DebugSession extends DebugSession {
 		}
 	}
 
+	// verifies that the specified command can be executed
+	protected checkCommand(debuggerName: string): boolean {
+		try {
+			const command = process.platform === 'win32' ? 'where' : 'command -v';
+			execSync(`${command} ${scriptName}`, { stdio: 'ignore' });
+			return true;
+		} catch (error) {
+			return false;
+		}
+	}
+
 	protected setValuesFormattingMode(mode: ValuesFormattingMode) {
 		switch (mode) {
 			case "disabled":
@@ -728,7 +740,7 @@ export class MI2DebugSession extends DebugSession {
 					id: 1,
 					label: args.source.name,
 					column: args.column,
-					line : args.line
+					line: args.line
 				}]
 			};
 			this.sendResponse(response);
@@ -743,7 +755,7 @@ export class MI2DebugSession extends DebugSession {
 
 	protected setSourceFileMap(configMap: { [index: string]: string }, fallbackGDB: string, fallbackIDE: string): void {
 		if (configMap === undefined) {
-			this.sourceFileMap = new SourceFileMap({[fallbackGDB]: fallbackIDE});
+			this.sourceFileMap = new SourceFileMap({ [fallbackGDB]: fallbackIDE });
 		} else {
 			this.sourceFileMap = new SourceFileMap(configMap, fallbackGDB);
 		}