service/dap: add substitutePath configuration (#2379)

* service/dap: add substitutePath configuration

Similar to substitute-path configuration in the dlv cli, substitutePath
in dap allows users to specify path mappings that are applied to the
source files in stacktrace and breakpoint requests.

Updates #2203

* service/dap: refactor the startup of the fixture for attach

Add a helper function for starting up a process to attach to.

* service/dap: update substitute path tests for windows

* service/dap: remove lines that should have been removed in merge

* respond to comments on pr

* move logging to helper functions

* make test comments more clear

* Add comments about absolute paths

* fix log messages

* clarify test comments

* remove comment about absolute paths

service/dap/server.go

@@ -25,6 +25,7 @@ import (
 	"sync"
 
 	"github.com/go-delve/delve/pkg/gobuild"
+	"github.com/go-delve/delve/pkg/locspec"
 	"github.com/go-delve/delve/pkg/logflags"
 	"github.com/go-delve/delve/pkg/proc"
 	"github.com/go-delve/delve/service"
@@ -85,13 +86,21 @@ type launchAttachArgs struct {
 	stackTraceDepth int
 	// showGlobalVariables indicates if global package variables should be loaded.
 	showGlobalVariables bool
+	// substitutePathClientToServer indicates rules for converting file paths between client and debugger.
+	// These must be directory paths.
+	substitutePathClientToServer [][2]string
+	// substitutePathServerToClient indicates rules for converting file paths between debugger and client.
+	// These must be directory paths.
+	substitutePathServerToClient [][2]string
 }
 
 // defaultArgs borrows the defaults for the arguments from the original vscode-go adapter.
 var defaultArgs = launchAttachArgs{
-	stopOnEntry:         false,
+	stopOnEntry:                  false,
-	stackTraceDepth:     50,
+	stackTraceDepth:              50,
-	showGlobalVariables: false,
+	showGlobalVariables:          false,
+	substitutePathClientToServer: [][2]string{},
+	substitutePathServerToClient: [][2]string{},
 }
 
 // DefaultLoadConfig controls how variables are loaded from the target's memory, borrowing the
@@ -126,7 +135,7 @@ func NewServer(config *service.Config) *Server {
 
 // If user-specified options are provided via Launch/AttachRequest,
 // we override the defaults for optional args.
-func (s *Server) setLaunchAttachArgs(request dap.LaunchAttachRequest) {
+func (s *Server) setLaunchAttachArgs(request dap.LaunchAttachRequest) error {
 	stop, ok := request.GetArguments()["stopOnEntry"].(bool)
 	if ok {
 		s.args.stopOnEntry = stop
@@ -139,6 +148,35 @@ func (s *Server) setLaunchAttachArgs(request dap.LaunchAttachRequest) {
 	if ok {
 		s.args.showGlobalVariables = globals
 	}
+	paths, ok := request.GetArguments()["substitutePath"]
+	if ok {
+		typeMismatchError := fmt.Errorf("'substitutePath' attribute '%v' in debug configuration is not a []{'from': string, 'to': string}", paths)
+		pathsParsed, ok := paths.([]interface{})
+		if !ok {
+			return typeMismatchError
+		}
+		clientToServer := make([][2]string, 0, len(pathsParsed))
+		serverToClient := make([][2]string, 0, len(pathsParsed))
+		for _, arg := range pathsParsed {
+			pathMapping, ok := arg.(map[string]interface{})
+			if !ok {
+				return typeMismatchError
+			}
+			from, ok := pathMapping["from"].(string)
+			if !ok {
+				return typeMismatchError
+			}
+			to, ok := pathMapping["to"].(string)
+			if !ok {
+				return typeMismatchError
+			}
+			clientToServer = append(clientToServer, [2]string{from, to})
+			serverToClient = append(serverToClient, [2]string{to, from})
+		}
+		s.args.substitutePathClientToServer = clientToServer
+		s.args.substitutePathServerToClient = serverToClient
+	}
+	return nil
 }
 
 // Stop stops the DAP debugger service, closes the listener and the client
@@ -534,7 +572,13 @@ func (s *Server) onLaunchRequest(request *dap.LaunchRequest) {
 		s.mu.Unlock()
 	}
 
-	s.setLaunchAttachArgs(request)
+	err := s.setLaunchAttachArgs(request)
+	if err != nil {
+		s.sendErrorResponse(request.Request,
+			FailedToLaunch, "Failed to launch",
+			err.Error())
+		return
+	}
 
 	var targetArgs []string
 	args, ok := request.Arguments["args"]
@@ -601,7 +645,6 @@ func (s *Server) onLaunchRequest(request *dap.LaunchRequest) {
 		return
 	}
 
-	var err error
 	if s.debugger, err = debugger.New(&s.config.Debugger, s.config.ProcessArgs); err != nil {
 		s.sendErrorResponse(request.Request, FailedToLaunch, "Failed to launch", err.Error())
 		return
@@ -724,6 +767,9 @@ func (s *Server) onSetBreakpointsRequest(request *dap.SetBreakpointsRequest) {
 		return
 	}
 
+	clientPath := request.Arguments.Source.Path
+	serverPath := s.toServerPath(clientPath)
+
 	// According to the spec we should "set multiple breakpoints for a single source
 	// and clear all previous breakpoints in that source." The simplest way is
 	// to clear all and then set all.
@@ -744,7 +790,7 @@ func (s *Server) onSetBreakpointsRequest(request *dap.SetBreakpointsRequest) {
 		}
 		// Skip other source files.
 		// TODO(polina): should this be normalized because of different OSes?
-		if bp.File != request.Arguments.Source.Path {
+		if bp.File != serverPath {
 			continue
 		}
 		_, err := s.debugger.ClearBreakpoint(bp)
@@ -759,7 +805,7 @@ func (s *Server) onSetBreakpointsRequest(request *dap.SetBreakpointsRequest) {
 	response.Body.Breakpoints = make([]dap.Breakpoint, len(request.Arguments.Breakpoints))
 	for i, want := range request.Arguments.Breakpoints {
 		got, err := s.debugger.CreateBreakpoint(
-			&api.Breakpoint{File: request.Arguments.Source.Path, Line: want.Line, Cond: want.Condition})
+			&api.Breakpoint{File: serverPath, Line: want.Line, Cond: want.Condition})
 		response.Body.Breakpoints[i].Verified = (err == nil)
 		if err != nil {
 			response.Body.Breakpoints[i].Line = want.Line
@@ -767,7 +813,7 @@ func (s *Server) onSetBreakpointsRequest(request *dap.SetBreakpointsRequest) {
 		} else {
 			response.Body.Breakpoints[i].Id = got.ID
 			response.Body.Breakpoints[i].Line = got.Line
-			response.Body.Breakpoints[i].Source = dap.Source{Name: request.Arguments.Source.Name, Path: request.Arguments.Source.Path}
+			response.Body.Breakpoints[i].Source = dap.Source{Name: request.Arguments.Source.Name, Path: clientPath}
 		}
 	}
 	s.send(response)
@@ -881,8 +927,13 @@ func (s *Server) onAttachRequest(request *dap.AttachRequest) {
 			return
 		}
 		s.config.Debugger.AttachPid = int(pid)
-		s.setLaunchAttachArgs(request)
+		err := s.setLaunchAttachArgs(request)
-		var err error
+		if err != nil {
+			s.sendErrorResponse(request.Request,
+				FailedToAttach, "Failed to attach",
+				err.Error())
+			return
+		}
 		if s.debugger, err = debugger.New(&s.config.Debugger, nil); err != nil {
 			s.sendErrorResponse(request.Request,
 				FailedToAttach, "Failed to attach", err.Error())
@@ -981,7 +1032,8 @@ func (s *Server) onStackTraceRequest(request *dap.StackTraceRequest) {
 		uniqueStackFrameID := s.stackFrameHandles.create(stackFrame{goroutineID, i})
 		stackFrames[i] = dap.StackFrame{Id: uniqueStackFrameID, Line: loc.Line, Name: fnName(loc)}
 		if loc.File != "<autogenerated>" {
-			stackFrames[i].Source = dap.Source{Name: filepath.Base(loc.File), Path: loc.File}
+			clientPath := s.toClientPath(loc.File)
+			stackFrames[i].Source = dap.Source{Name: filepath.Base(clientPath), Path: clientPath}
 		}
 		stackFrames[i].Column = 0
 	}
@@ -1636,3 +1688,25 @@ func (s *Server) doCommand(command string) {
 			}})
 	}
 }
+
+func (s *Server) toClientPath(path string) string {
+	if len(s.args.substitutePathServerToClient) == 0 {
+		return path
+	}
+	clientPath := locspec.SubstitutePath(path, s.args.substitutePathServerToClient)
+	if clientPath != path {
+		s.log.Debugf("server path=%s converted to client path=%s\n", path, clientPath)
+	}
+	return clientPath
+}
+
+func (s *Server) toServerPath(path string) string {
+	if len(s.args.substitutePathClientToServer) == 0 {
+		return path
+	}
+	serverPath := locspec.SubstitutePath(path, s.args.substitutePathClientToServer)
+	if serverPath != path {
+		s.log.Debugf("client path=%s converted to server path=%s\n", path, serverPath)
+	}
+	return serverPath
+}

service/dap/server_test.go

@@ -1703,6 +1703,95 @@ func TestSetBreakpoint(t *testing.T) {
 	})
 }
 
+// TestLaunchSubstitutePath sets a breakpoint using a path
+// that does not exist and expects the substitutePath attribute
+// in the launch configuration to take care of the mapping.
+func TestLaunchSubstitutePath(t *testing.T) {
+	runTest(t, "loopprog", func(client *daptest.Client, fixture protest.Fixture) {
+		substitutePathTestHelper(t, fixture, client, "launch", map[string]interface{}{"mode": "exec", "program": fixture.Path})
+	})
+}
+
+// TestAttachSubstitutePath sets a breakpoint using a path
+// that does not exist and expects the substitutePath attribute
+// in the launch configuration to take care of the mapping.
+func TestAttachSubstitutePath(t *testing.T) {
+	if runtime.GOOS == "freebsd" {
+		t.SkipNow()
+	}
+	if runtime.GOOS == "windows" {
+		t.Skip("test skipped on windows, see https://delve.beta.teamcity.com/project/Delve_windows for details")
+	}
+	runTest(t, "loopprog", func(client *daptest.Client, fixture protest.Fixture) {
+		cmd := execFixture(t, fixture)
+
+		substitutePathTestHelper(t, fixture, client, "attach", map[string]interface{}{"mode": "local", "processId": cmd.Process.Pid})
+	})
+}
+
+func substitutePathTestHelper(t *testing.T, fixture protest.Fixture, client *daptest.Client, request string, launchAttachConfig map[string]interface{}) {
+	t.Helper()
+	nonexistentDir := filepath.Join(string(filepath.Separator), "path", "that", "does", "not", "exist")
+	if runtime.GOOS == "windows" {
+		nonexistentDir = "C:" + nonexistentDir
+	}
+
+	launchAttachConfig["stopOnEntry"] = false
+	// The rules in 'substitutePath' will be applied as follows:
+	// - mapping paths from client to server:
+	//		The first rule["from"] to match a prefix of 'path' will be applied:
+	//			strings.Replace(path, rule["from"], rule["to"], 1)
+	// - mapping paths from server to client:
+	//		The first rule["to"] to match a prefix of 'path' will be applied:
+	//			strings.Replace(path, rule["to"], rule["from"], 1)
+	launchAttachConfig["substitutePath"] = []map[string]string{
+		{"from": nonexistentDir, "to": filepath.Dir(fixture.Source)},
+		// Since the path mappings are ordered, when converting from client path to
+		// server path, this mapping will not apply, because nonexistentDir appears in
+		// an earlier rule.
+		{"from": nonexistentDir, "to": "this_is_a_bad_path"},
+		// Since the path mappings are ordered, when converting from server path to
+		// client path, this mapping will not apply, because filepath.Dir(fixture.Source)
+		// appears in an earlier rule.
+		{"from": "this_is_a_bad_path", "to": filepath.Dir(fixture.Source)},
+	}
+
+	runDebugSessionWithBPs(t, client, request,
+		func() {
+			switch request {
+			case "attach":
+				client.AttachRequest(launchAttachConfig)
+			case "launch":
+				client.LaunchRequestWithArgs(launchAttachConfig)
+			default:
+				t.Fatalf("invalid request: %s", request)
+			}
+		},
+		// Set breakpoints
+		filepath.Join(nonexistentDir, "loopprog.go"), []int{8},
+		[]onBreakpoint{{
+
+			execute: func() {
+				handleStop(t, client, 1, "main.loop", 8)
+			},
+			disconnect: true,
+		}})
+}
+
+// execFixture runs the binary fixture.Path and hooks up stdout and stderr
+// to os.Stdout and os.Stderr.
+func execFixture(t *testing.T, fixture protest.Fixture) *exec.Cmd {
+	t.Helper()
+	// TODO(polina): do I need to sanity check testBackend and runtime.GOOS?
+	cmd := exec.Command(fixture.Path)
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	if err := cmd.Start(); err != nil {
+		t.Fatal(err)
+	}
+	return cmd
+}
+
 // TestWorkingDir executes to a breakpoint and tests that the specified
 // working directory is the one used to run the program.
 func TestWorkingDir(t *testing.T) {
@@ -2702,13 +2791,7 @@ func TestAttachRequest(t *testing.T) {
 	}
 	runTest(t, "loopprog", func(client *daptest.Client, fixture protest.Fixture) {
 		// Start the program to attach to
-		// TODO(polina): do I need to sanity check testBackend and runtime.GOOS?
+		cmd := execFixture(t, fixture)
-		cmd := exec.Command(fixture.Path)
-		cmd.Stdout = os.Stdout
-		cmd.Stderr = os.Stderr
-		if err := cmd.Start(); err != nil {
-			t.Fatal(err)
-		}
 
 		runDebugSessionWithBPs(t, client, "attach",
 			// Attach
@@ -2934,6 +3017,21 @@ func TestBadLaunchRequests(t *testing.T) {
 		expectFailedToLaunchWithMessage(client.ExpectErrorResponse(t),
 			"Failed to launch: 'buildFlags' attribute '123' in debug configuration is not a string.")
 
+		client.LaunchRequestWithArgs(map[string]interface{}{"mode": "debug", "program": fixture.Source, "substitutePath": 123})
+		expectFailedToLaunchWithMessage(client.ExpectErrorResponse(t),
+			"Failed to launch: 'substitutePath' attribute '123' in debug configuration is not a []{'from': string, 'to': string}")
+
+		client.LaunchRequestWithArgs(map[string]interface{}{"mode": "debug", "program": fixture.Source, "substitutePath": []interface{}{123}})
+		expectFailedToLaunchWithMessage(client.ExpectErrorResponse(t),
+			"Failed to launch: 'substitutePath' attribute '[123]' in debug configuration is not a []{'from': string, 'to': string}")
+
+		client.LaunchRequestWithArgs(map[string]interface{}{"mode": "debug", "program": fixture.Source, "substitutePath": []interface{}{map[string]interface{}{"to": "path2"}}})
+		expectFailedToLaunchWithMessage(client.ExpectErrorResponse(t),
+			"Failed to launch: 'substitutePath' attribute '[map[to:path2]]' in debug configuration is not a []{'from': string, 'to': string}")
+
+		client.LaunchRequestWithArgs(map[string]interface{}{"mode": "debug", "program": fixture.Source, "substitutePath": []interface{}{map[string]interface{}{"from": "path1", "to": 123}}})
+		expectFailedToLaunchWithMessage(client.ExpectErrorResponse(t),
+			"Failed to launch: 'substitutePath' attribute '[map[from:path1 to:123]]' in debug configuration is not a []{'from': string, 'to': string}")
 		client.LaunchRequestWithArgs(map[string]interface{}{"mode": "debug", "program": fixture.Source, "wd": 123})
 		expectFailedToLaunchWithMessage(client.ExpectErrorResponse(t),
 			"Failed to launch: 'wd' attribute '123' in debug configuration is not a string.")