Add support for using extended-remote with launch configurations

This extends gdb launch configurations to support extended-remote.
It can be used for remote debugging where code is compiled on host, and
transferred and debugged on target using a remote gdbserver (or something
else speaking GDB/MI).

Note, this is not touching the code added in commit
318ece4 ("Added special commands for extended-remote fix #91"),
as that is only related to gdb attach configuration, although the
example in package.json is confusingly put with launch, which is
opposite of the code change.
I did not fixup that change, as I am not sure exactly what to put
instead.

package.json

@@ -436,6 +436,20 @@
 							]
 						},
 						"valuesFormatting": "parseText"
+					},
+					{
+						"label": "GDB: Debug on remote device",
+						"description": "Transfer program to and debug it on a remote device",
+						"body": {
+							"type": "gdb",
+							"request": "launch",
+							"name": "${3:Debug remote device}",
+							"target": "${2:192.168.0.1:2345}",
+							"remote": true,
+							"executable": "${1:./bin/executable}",
+							"cwd": "^\"\\${workspaceRoot}\""
+						},
+						"valuesFormatting": "parseText"
 					}
 				]
 			},

src/backend/mi2/mi2.ts

@@ -50,18 +50,33 @@ export class MI2 extends EventEmitter implements IBackend {
 		}
 	}
 
-	load(cwd: string, target: string, procArgs: string, separateConsole: string): Thenable<any> {
-		if (!nativePath.isAbsolute(target))
+	load(cwd: string, target: string, procArgs: string, separateConsole: string, executable?: string, remote?: boolean): Thenable<any> {
+		if (!remote && !nativePath.isAbsolute(target))
 			target = nativePath.join(cwd, target);
+		if (remote && !nativePath.isAbsolute(executable))
+			executable = nativePath.join(cwd, executable);
 		return new Promise((resolve, reject) => {
 			this.isSSH = false;
 			const args = this.preargs.concat(this.extraargs || []);
+			if (executable !== undefined)
+				args.push(executable);
 			this.process = ChildProcess.spawn(this.application, args, { cwd: cwd, env: this.procEnv });
 			this.process.stdout.on("data", this.stdout.bind(this));
 			this.process.stderr.on("data", this.stderr.bind(this));
 			this.process.on("exit", (() => { this.emit("quit"); }).bind(this));
 			this.process.on("error", ((err) => { this.emit("launcherror", err); }).bind(this));
-			const promises = this.initCommands(target, cwd);
+			let promises;
+			if (remote) {
+				let remoteExecutable = nativePath.basename(executable);
+				promises = [
+					this.sendCommand(`set target-async on`, true),
+					this.sendCommand(`environment-directory "${escape(cwd)}"`, true),
+					this.sendCommand(`target-select extended-remote ${target}`),
+					this.sendCommand(`target-file-put "${escape(executable)}" ${remoteExecutable}`),
+					this.sendCommand(`gdb-set remote exec-file ./${remoteExecutable}`),
+				];
+			} else
+				promises = this.initCommands(target, cwd);
 			if (procArgs && procArgs.length)
 				promises.push(this.sendCommand("exec-arguments " + procArgs));
 			if (process.platform == "win32") {

src/gdb.ts

@@ -12,6 +12,8 @@ export interface LaunchRequestArguments extends DebugProtocol.LaunchRequestArgum
 	debugger_args: string[];
 	arguments: string;
 	terminal: string;
+	executable: string;
+	remote: boolean;
 	autorun: string[];
 	ssh: SSHArguments;
 	valuesFormatting: ValuesFormattingMode;
@@ -93,7 +95,7 @@ class GDBDebugSession extends MI2DebugSession {
 				this.sendErrorResponse(response, 102, `Failed to SSH: ${err.toString()}`);
 			});
 		} else {
-			this.miDebugger.load(args.cwd, args.target, args.arguments, args.terminal).then(() => {
+			this.miDebugger.load(args.cwd, args.target, args.arguments, args.terminal, args.executable, args.remote).then(() => {
 				if (args.autorun)
 					args.autorun.forEach(command => {
 						this.miDebugger.sendUserInput(command);