[lldb-dap] Support vscode launch URLs

This commit adds support for starting debug sessions through special
`vscode://llvm-vs-code-extensions.lldb-dap/launch/config?config={launch-config}`
URIs. This allows tighter integration with custom scripts. One potential
use case is providing similar functionality to `xcdebug`, see #125777
for some discussion on that use case.

The functionality was inspired by @vadimcn's CodeLLDB extension, which
[provides similar functionality](https://github.com/vadimcn/codelldb/blob/master/MANUAL.md#debugging-externally-launched-code).

Author: vogelsgesang

lldb/tools/lldb-dap/README.md

@@ -174,6 +174,20 @@ The default hostname being used `localhost`.
 }
 ```
 
+### Launching via `vscode://` URIs
+
+Debugging sessions can also be starting using special URIs.
+
+The `vscode://llvm-vs-code-extensions.lldb-dap/launch/config?config={launch-config}`
+URI accepts a [URL-encoded](https://en.wikipedia.org/wiki/Percent-encoding)
+JSON launch config.
+
+This is useful, e.g., to integrate with custom scripts which start debugging
+sessions. The URIs might be printed to the terminal, potentially using
+[OSC-8 hyperlinks](https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda),
+or passed to `vscode --open-url` or `xdg-open`, although mileage may vary
+depending on your specific debugging setup.
+
 ### Configuration Settings Reference
 
 For both launch and attach configurations, lldb-dap accepts the following `lldb-dap`
@@ -328,4 +342,4 @@ The source code is part of the [LLVM repository](https://github.com/llvm/llvm-pr
 We use Github's [issue tracker](https://github.com/llvm/llvm-project/issues?q=label%3Alldb-dap) and patches can be submitted via [pull requests](https://github.com/llvm/llvm-project/pulls?q=label%3Alldb-dap).
 Furthermore, there is a [LLDB category](https://discourse.llvm.org/c/subprojects/lldb/8) on the LLVM discourse forum.
 
-For instructions on how to get started with development on lldb-dap, see the "[Contributing to lldb-dap](https://lldb.llvm.org/resources/lldbdap.html)"
+For instructions on how to get started with development on lldb-dap, see the "[Contributing to lldb-dap](https://lldb.llvm.org/resources/lldbdap.html)" guide.

lldb/tools/lldb-dap/package.json

@@ -35,7 +35,8 @@
     "typescript": "^5.7.3"
   },
   "activationEvents": [
-    "onDebug"
+    "onDebug",
+    "onUri"
   ],
   "main": "./out/extension",
   "scripts": {

lldb/tools/lldb-dap/src-ts/extension.ts

@@ -5,6 +5,7 @@ import {
   isExecutable,
 } from "./debug-adapter-factory";
 import { DisposableContext } from "./disposable-context";
+import { LaunchUriHandler } from "./uri-launch-handler";
 
 /**
  * This class represents the extension and manages its life cycle. Other extensions
@@ -37,6 +38,10 @@ export class LLDBDapExtension extends DisposableContext {
         }
       }),
     );
+
+    this.pushSubscription(
+      vscode.window.registerUriHandler(new LaunchUriHandler())
+    );
   }
 }
 

lldb/tools/lldb-dap/src-ts/uri-launch-handler.ts

@@ -0,0 +1,37 @@
+import * as vscode from "vscode";
+
+export class LaunchUriHandler implements vscode.UriHandler {
+    async handleUri(uri: vscode.Uri) {
+        try {
+            const params = new URLSearchParams(uri.query);
+            if (uri.path == '/launch/config') {
+                const configJson = params.get("config");
+                if (configJson === null) {
+                    throw new Error("Missing `config` URI parameter");
+                }
+                // Build the debug config
+                let debugConfig: vscode.DebugConfiguration = {
+                    type: 'lldb-dap',
+                    request: 'launch',
+                    name: '',
+                };
+                Object.assign(debugConfig, JSON.parse(configJson));
+                debugConfig.name = debugConfig.name || debugConfig.program || "Adhoc Launch";
+                // Force the type to `lldb-dap`. We don't want to allow launching any other
+                // Debug Adapters using this URI scheme.
+                if (debugConfig.type != "lldb-dap") {
+                    throw new Error(`Unsupported debugger type: ${debugConfig.type}`);
+                }
+                await vscode.debug.startDebugging(undefined, debugConfig);
+            } else {
+                throw new Error(`Unsupported Uri path: ${uri.path}`);
+            }
+        } catch (err) {
+            if (err instanceof Error) {
+                await vscode.window.showErrorMessage(`Failed to handle lldb-dap URI request: ${err.message}`);
+            } else {
+                await vscode.window.showErrorMessage(`Failed to handle lldb-dap URI request`);
+            }
+        }
+    }
+}