Add hidden --ready-file

The --ready-file is created when all kprobes are attached. This is going
to be used to indicate readiness in the upcoming CI tests.

Signed-off-by: Martynas Pumputis <m@lambda.lt>

internal/pwru/types.go

@@ -39,6 +39,8 @@ type Flags struct {
 	PerCPUBuffer int
 	KMods        []string
 	AllKMods     bool
+
+	ReadyFile string
 }
 
 func (f *Flags) SetFlags() {
@@ -63,6 +65,9 @@ func (f *Flags) SetFlags() {
 	flag.IntVar(&f.PerCPUBuffer, "per-cpu-buffer", os.Getpagesize(), "per CPU buffer in bytes")
 
 	flag.StringVar(&f.OutputFile, "output-file", "", "write traces to file")
+
+	flag.StringVar(&f.ReadyFile, "ready-file", "", "create file after all BPF progs are attached")
+	flag.Lookup("ready-file").Hidden = true
 }
 
 type Tuple struct {

main.go

@@ -207,6 +207,14 @@ func main() {
 
 	log.Println("Listening for events..")
 
+	if flags.ReadyFile != "" {
+		file, err := os.Create(flags.ReadyFile)
+		if err != nil {
+			log.Fatalf("Failed to create ready file: %s", err)
+		}
+		file.Close()
+	}
+
 	output, err := pwru.NewOutput(&flags, printSkbMap, printStackMap, addr2name)
 	if err != nil {
 		log.Fatalf("Failed to create outputer: %s", err)