proc/gdbserver: clean up rr directory on detach (#3570)

We used to autoremove the trace recorded by rr but as a result of
various refactorings done to implement follow exec mode this broke.
Restore the functionality.

Also remove the _fixtures/testfnpos.go file which is autogenerated
during testing.

_fixtures/testfnpos.go

@@ -1,16 +0,0 @@
-package main
-
-import "fmt"
-
-func f2() {
-	fmt.Printf("f2\n")
-}
-
-func f1() {
-	fmt.Printf("f1\n")
-}
-
-func main() {
-	f1()
-	f2()
-}

pkg/proc/core/core.go

@@ -452,6 +452,10 @@ func (p *process) Detach(int, bool) error {
 	return nil
 }
 
+func (p *process) Close() error {
+	return nil
+}
+
 // Valid returns whether the process is active. Always returns true
 // for core files as it cannot exit or be otherwise detached from.
 func (p *process) Valid() (bool, error) {

pkg/proc/gdbserial/gdbserver.go

@@ -1082,6 +1082,10 @@ func (p *gdbProcess) Detach(_pid int, kill bool) error {
 		p.process = nil
 	}
 	p.detached = true
+	return nil
+}
+
+func (p *gdbProcess) Close() error {
 	if p.onDetach != nil {
 		p.onDetach()
 	}

pkg/proc/interface.go

@@ -13,6 +13,7 @@ type ProcessGroup interface {
 	ContinueOnce(*ContinueOnceContext) (Thread, StopReason, error)
 	StepInstruction(int) error
 	Detach(int, bool) error
+	Close() error
 }
 
 // Process represents the target of the debugger. This

pkg/proc/native/proc.go

@@ -130,6 +130,10 @@ func (procgrp *processGroup) Detach(pid int, kill bool) (err error) {
 	return
 }
 
+func (procgrp *processGroup) Close() error {
+	return nil
+}
+
 // Valid returns whether the process is still attached to and
 // has not exited.
 func (dbp *nativeProcess) Valid() (bool, error) {

pkg/proc/target_exec.go

@@ -1098,12 +1098,13 @@ func skipAutogeneratedWrappersOut(tgt *Target, g *G, thread Thread, startTopfram
 	if err != nil {
 		return
 	}
+	bi := thread.BinInfo()
 	for i := 1; i < len(frames); i++ {
 		frame := frames[i]
 		if frame.Current.Fn == nil {
 			return
 		}
-		file, line := g.Thread.BinInfo().EntryLineForFunc(frame.Current.Fn)
+		file, line := bi.EntryLineForFunc(frame.Current.Fn)
 		if !isAutogeneratedOrDeferReturn(Location{File: file, Line: line, Fn: frame.Current.Fn}) {
 			return &frames[i-1], &frames[i]
 		}

pkg/proc/target_group.go

@@ -189,7 +189,7 @@ func (grp *TargetGroup) Detach(kill bool) error {
 	if len(errs) > 0 {
 		return fmt.Errorf("%s", strings.Join(errs, "\n"))
 	}
-	return nil
+	return grp.procgrp.Close()
 }
 
 // detachTarget will detach the target from the underlying process.

service/debugger/debugger.go

@@ -459,9 +459,6 @@ func (d *Debugger) Detach(kill bool) error {
 	d.log.Debug("detaching")
 	d.targetMutex.Lock()
 	defer d.targetMutex.Unlock()
-	if ok, _ := d.target.Valid(); !ok {
-		return nil
-	}
 	return d.detach(kill)
 }
 

service/test/integration2_test.go

@@ -2831,11 +2831,12 @@ func TestRestart_PreserveFunctionBreakpoint(t *testing.T) {
 	// even if the function changed position in the source file.
 
 	dir := protest.FindFixturesDir()
+	outpath := filepath.Join(dir, "testfnpos.go")
+	defer os.Remove(outpath)
 
 	copy := func(inpath string) {
 		buf, err := os.ReadFile(inpath)
 		assertNoError(err, t, fmt.Sprintf("Reading %q", inpath))
-		outpath := filepath.Join(dir, "testfnpos.go")
 		assertNoError(os.WriteFile(outpath, buf, 0o666), t, fmt.Sprintf("Creating %q", outpath))
 	}