fix(selftest): use channel for sync

attachgenericfd and perfbuffers selftests were using a goroutine without
any syncronization mechanism.

selftest/attachgenericfd/main.go

@@ -6,6 +6,7 @@ import (
  "fmt"
  "net"
  "os"
+ "time"
  "unsafe"
 
  bpf "github.com/aquasecurity/libbpfgo"
@@ -70,6 +71,8 @@ func main() {
  }
  }()
 
+ mapUpdateChan := make(chan struct{}, 1)
+
  go func() {
  acceptedFD, _, err := unix.Accept(serverFD)
  if err != nil {
@@ -82,6 +85,8 @@ func main() {
  fmt.Fprintln(os.Stderr, err)
  os.Exit(-1)
  }
+
+ mapUpdateChan <- struct{}{}
  }()
 
  c, err := net.Dial("tcp", "127.0.0.1:22345")
@@ -94,6 +99,16 @@ func main() {
  fmt.Fprintln(os.Stderr, err)
  os.Exit(-1)
  }
+
+ // Wait for the bpf map to be updated
+ select {
+ case <-mapUpdateChan:
+ // Continue with reading data from the socket
+ case <-time.After(15 * time.Second): // Same of the selftest
+ fmt.Fprintln(os.Stderr, "bpf map timeout")
+ os.Exit(-1)
+ }
+
  data := make([]byte, 10)
  if _, err = c.Read(data); err != nil {
  fmt.Fprintln(os.Stderr, err)

selftest/perfbuffers/main.go

@@ -67,26 +67,29 @@ func main() {
 
  pb.Poll(300)
 
- numberOfEventsReceived := 0
+ stop := make(chan struct{})
 
  go func() {
  for {
- syscall.Mmap(999, 999, 999, 1, 1)
+ select {
+ case <-stop:
+ return
+ default:
+ syscall.Mmap(999, 999, 999, 1, 1)
+ }
  }
  }()
-recvLoop:
- for {
+
+ for eReceived := 0; eReceived < 5; eReceived++ {
  b := <-eventsChannel
  if binary.LittleEndian.Uint32(b) != 2021 {
  fmt.Fprintf(os.Stderr, "invalid data retrieved\n")
  os.Exit(-1)
  }
- numberOfEventsReceived++
- if numberOfEventsReceived > 5 {
- break recvLoop
- }
  }
 
+ close(stop)
+
  // Test that it won't cause a panic or block if Stop or Close called multiple times
  pb.Stop()
  pb.Stop()