service/dap: clarify handling of relative program path (#2653)

* service/dap: add test verifying handling of relative program path

* Add exec test, log build dir and document in --help

Co-authored-by: Polina Sokolova <polinasok@users.noreply.github.com>

Documentation/usage/dlv_dap.md

@@ -7,13 +7,15 @@
 [EXPERIMENTAL] Starts a headless TCP server communicating via Debug Adaptor Protocol (DAP).
 
 The server is always headless and requires a DAP client like vscode to connect and request a binary
-to be launched or process to be attached to. The following modes are supported:
+to be launched or process to be attached to. The following modes can be specified via client's launch config:
 - launch + exec (executes precompiled binary, like 'dlv exec')
 - launch + debug (builds and launches, like 'dlv debug')
 - launch + test (builds and tests, like 'dlv test')
 - launch + replay (replays an rr trace, like 'dlv replay')
 - launch + core (replays a core dump file, like 'dlv core')
 - attach + local (attaches to a running process, like 'dlv attach')
+Program and output binary paths will be interpreted relative to dlv's working directory.
+
 The server does not yet accept multiple client connections (--accept-multiclient).
 While --continue is not supported, stopOnEntry launch/attach attribute can be used to control if
 execution is resumed at the start of the debug session.

cmd/dlv/cmds/commands.go

@@ -180,13 +180,15 @@ option to let the process continue or kill it.
 		Long: `[EXPERIMENTAL] Starts a headless TCP server communicating via Debug Adaptor Protocol (DAP).
 
 The server is always headless and requires a DAP client like vscode to connect and request a binary
-to be launched or process to be attached to. The following modes are supported:
+to be launched or process to be attached to. The following modes can be specified via client's launch config:
 - launch + exec (executes precompiled binary, like 'dlv exec')
 - launch + debug (builds and launches, like 'dlv debug')
 - launch + test (builds and tests, like 'dlv test')
 - launch + replay (replays an rr trace, like 'dlv replay')
 - launch + core (replays a core dump file, like 'dlv core')
 - attach + local (attaches to a running process, like 'dlv attach')
+Program and output binary paths will be interpreted relative to dlv's working directory.
+
 The server does not yet accept multiple client connections (--accept-multiclient).
 While --continue is not supported, stopOnEntry launch/attach attribute can be used to control if
 execution is resumed at the start of the debug session.`,

service/dap/server.go

@@ -864,8 +864,8 @@ func (s *Server) onLaunchRequest(request *dap.LaunchRequest) {
 
 		var cmd string
 		var out []byte
-		// Log debug binary build
+		wd, _ := os.Getwd()
-		s.log.Debugf("building binary '%s' from '%s' with flags '%v'", debugbinary, program, buildFlags)
+		s.log.Debugf("building program '%s' in '%s' with flags '%v'", program, wd, buildFlags)
 		switch mode {
 		case "debug":
 			cmd, out, err = gobuild.GoBuildCombinedOutput(debugbinary, []string{program}, buildFlags)
@@ -936,7 +936,7 @@ func (s *Server) onLaunchRequest(request *dap.LaunchRequest) {
 		s.config.Debugger.WorkingDir = wdParsed
 	}
 
-	s.log.Debugf("running program in %s\n", s.config.Debugger.WorkingDir)
+	s.log.Debugf("running binary '%s' in '%s'", program, s.config.Debugger.WorkingDir)
 	if noDebug, ok := request.Arguments["noDebug"].(bool); ok && noDebug {
 		s.mu.Lock()
 		cmd, err := s.newNoDebugProcess(program, targetArgs, s.config.Debugger.WorkingDir)

service/dap/server_test.go

@@ -3978,8 +3978,9 @@ type onBreakpoint struct {
 //                     so the test author has full control of its arguments.
 //                     Note that he rest of the test sequence assumes that
 //                     stopOnEntry is false.
+//     source        - source file path, needed to set breakpoints, "" if none to be set.
 //     breakpoints   - list of lines, where breakpoints are to be set
-//     onBreakpoints - list of test sequences to execute at each of the set breakpoints.
+//     onBPs         - list of test sequences to execute at each of the set breakpoints.
 func runDebugSessionWithBPs(t *testing.T, client *daptest.Client, cmd string, cmdRequest func(), source string, breakpoints []int, onBPs []onBreakpoint) {
 	client.InitializeRequest()
 	client.ExpectInitializeResponseAndCapabilities(t)
@@ -3994,8 +3995,10 @@ func runDebugSessionWithBPs(t *testing.T, client *daptest.Client, cmd string, cm
 		panic("expected launch or attach command")
 	}
 
+	if source != "" {
 		client.SetBreakpointsRequest(source, breakpoints)
 		client.ExpectSetBreakpointsResponse(t)
+	}
 
 	// Skip no-op setExceptionBreakpoints
 
@@ -4045,8 +4048,8 @@ func runDebugSessionWithBPs(t *testing.T, client *daptest.Client, cmd string, cm
 // runDebugSession is a helper for executing the standard init and shutdown
 // sequences for a program that does not stop on entry
 // while specifying unique launch criteria via parameters.
-func runDebugSession(t *testing.T, client *daptest.Client, cmd string, cmdRequest func(), source string) {
+func runDebugSession(t *testing.T, client *daptest.Client, cmd string, cmdRequest func()) {
-	runDebugSessionWithBPs(t, client, cmd, cmdRequest, source, nil, nil)
+	runDebugSessionWithBPs(t, client, cmd, cmdRequest, "", nil, nil)
 }
 
 func TestLaunchDebugRequest(t *testing.T) {
@@ -4061,7 +4064,7 @@ func TestLaunchDebugRequest(t *testing.T) {
 		runDebugSession(t, client, "launch", func() {
 			client.LaunchRequestWithArgs(map[string]interface{}{
 				"mode": "debug", "program": fixture.Source, "output": tmpBin})
-		}, fixture.Source)
+		})
 	})
 	// Wait for the test to finish to capture all stderr
 	time.Sleep(100 * time.Millisecond)
@@ -4098,13 +4101,13 @@ func TestLaunchRequestDefaults(t *testing.T) {
 		runDebugSession(t, client, "launch", func() {
 			client.LaunchRequestWithArgs(map[string]interface{}{
 				"mode": "" /*"debug" by default*/, "program": fixture.Source, "output": "__mybin"})
-		}, fixture.Source)
+		})
 	})
 	runTest(t, "increment", func(client *daptest.Client, fixture protest.Fixture) {
 		runDebugSession(t, client, "launch", func() {
 			client.LaunchRequestWithArgs(map[string]interface{}{
 				/*"mode":"debug" by default*/ "program": fixture.Source, "output": "__mybin"})
-		}, fixture.Source)
+		})
 	})
 	runTest(t, "increment", func(client *daptest.Client, fixture protest.Fixture) {
 		runDebugSession(t, client, "launch", func() {
@@ -4112,7 +4115,7 @@ func TestLaunchRequestDefaults(t *testing.T) {
 			client.LaunchRequestWithArgs(map[string]interface{}{
 				"mode": "debug", "program": fixture.Source})
 			// writes to default output dir __debug_bin
-		}, fixture.Source)
+		})
 	})
 
 	// if noDebug is not a bool, behave as if it is the default value (false).
@@ -4120,7 +4123,7 @@ func TestLaunchRequestDefaults(t *testing.T) {
 		runDebugSession(t, client, "launch", func() {
 			client.LaunchRequestWithArgs(map[string]interface{}{
 				"mode": "debug", "program": fixture.Source, "noDebug": "true"})
-		}, fixture.Source)
+		})
 	})
 }
 
@@ -4219,16 +4222,48 @@ func TestNoDebug_AcceptNoRequestsButDisconnect(t *testing.T) {
 	})
 }
 
-func TestLaunchTestRequest(t *testing.T) {
+func TestLaunchRequestWithRelativeBuildPath(t *testing.T) {
-	runTest(t, "increment", func(client *daptest.Client, fixture protest.Fixture) {
+	client := startDapServer(t)
+	defer client.Close() // will trigger Stop()
+
+	fixdir := protest.FindFixturesDir()
+	if filepath.IsAbs(fixdir) {
+		t.Fatal("this test requires relative program path")
+	}
+	program := filepath.Join(protest.FindFixturesDir(), "buildtest")
+
+	// Use different working dir for target than dlv.
+	// Program path will be interpreted relative to dlv's.
+	dlvwd, _ := os.Getwd()
+	runDebugSession(t, client, "launch", func() {
+		client.LaunchRequestWithArgs(map[string]interface{}{
+			"mode": "debug", "program": program, "cwd": filepath.Dir(dlvwd)})
+	})
+}
+
+func TestLaunchRequestWithRelativeExecPath(t *testing.T) {
+	runTest(t, "increment", func(client *daptest.Client, fixture protest.Fixture) {
+		symlink := "./__thisexe"
+		err := os.Symlink(fixture.Path, symlink)
+		defer os.Remove(symlink)
+		if err != nil {
+			t.Fatal("unable to create relative symlink:", err)
+		}
+		runDebugSession(t, client, "launch", func() {
+			client.LaunchRequestWithArgs(map[string]interface{}{
+				"mode": "exec", "program": symlink})
+		})
+	})
+}
+
+func TestLaunchTestRequest(t *testing.T) {
+	client := startDapServer(t)
+	defer client.Close() // will trigger Stop()
 	runDebugSession(t, client, "launch", func() {
-			// We reuse the harness that builds, but ignore the built binary,
-			// only relying on the source to be built in response to LaunchRequest.
 		fixtures := protest.FindFixturesDir()
 		testdir, _ := filepath.Abs(filepath.Join(fixtures, "buildtest"))
 		client.LaunchRequestWithArgs(map[string]interface{}{
 			"mode": "test", "program": testdir, "output": "__mytestdir"})
-		}, fixture.Source)
 	})
 }
 
@@ -4242,7 +4277,7 @@ func TestLaunchRequestWithArgs(t *testing.T) {
 			client.LaunchRequestWithArgs(map[string]interface{}{
 				"mode": "exec", "program": fixture.Path,
 				"args": []string{"test", "pass flag"}})
-		}, fixture.Source)
+		})
 	})
 }
 
@@ -4258,7 +4293,7 @@ func TestLaunchRequestWithBuildFlags(t *testing.T) {
 			client.LaunchRequestWithArgs(map[string]interface{}{
 				"mode": "debug", "program": fixture.Source, "output": "__mybin",
 				"buildFlags": "-ldflags '-X main.Hello=World'"})
-		}, fixture.Source)
+		})
 	})
 }