fix(selftest): use channel for sync (#364)

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

selftest/attachgenericfd/main.go

@@ -3,9 +3,11 @@ package main
 import "C"
 
 import (
+ "bytes"
  "fmt"
  "net"
  "os"
+ "time"
  "unsafe"
 
  bpf "github.com/aquasecurity/libbpfgo"
@@ -32,6 +34,7 @@ func main() {
  os.Exit(-1)
  }
  defer unix.Close(serverFD)
+
  serverAddr := &unix.SockaddrInet4{
  Port: 22345,
  Addr: [4]byte{127, 0, 0, 1},
@@ -40,6 +43,7 @@ func main() {
  fmt.Fprintln(os.Stderr, err)
  os.Exit(-1)
  }
+
  if err := unix.Listen(serverFD, 100); err != nil {
  fmt.Fprintln(os.Stderr, err)
  os.Exit(-1)
@@ -60,6 +64,7 @@ func main() {
  os.Exit(-1)
  }
  }()
+
  prog2, err := bpfModule.GetProgram("bpf_prog_verdict")
  prog2.AttachGenericFD(sockMapRx.FileDescriptor(),
  bpf.BPFAttachTypeSKSKBStreamVerdict, bpf.BPFFNone)
@@ -70,6 +75,8 @@ func main() {
  }
  }()
 
+ mapUpdateChan := make(chan struct{}, 1)
+
  go func() {
  acceptedFD, _, err := unix.Accept(serverFD)
  if err != nil {
@@ -82,6 +89,8 @@ func main() {
  fmt.Fprintln(os.Stderr, err)
  os.Exit(-1)
  }
+
+ mapUpdateChan <- struct{}{}
  }()
 
  c, err := net.Dial("tcp", "127.0.0.1:22345")
@@ -90,13 +99,30 @@ func main() {
  os.Exit(-1)
  }
  defer c.Close()
- if _, err = c.Write([]byte("foobar")); err != nil {
+
+ // wait for the bpf map to be updated
+ select {
+ case <-mapUpdateChan:
+ // continue with write/read
+ case <-time.After(15 * time.Second): // Same of the selftest
+ fmt.Fprintln(os.Stderr, "bpf map timeout")
+ os.Exit(-1)
+ }
+
+ input := []byte("foobar")
+ if _, err = c.Write(input); err != nil {
  fmt.Fprintln(os.Stderr, err)
  os.Exit(-1)
  }
- data := make([]byte, 10)
- if _, err = c.Read(data); err != nil {
+
+ output := make([]byte, 6)
+ if _, err = c.Read(output); err != nil {
  fmt.Fprintln(os.Stderr, err)
  os.Exit(-1)
  }
+
+ if !bytes.Equal(output, input) {
+ fmt.Fprintln(os.Stderr, "data mismatch")
+ os.Exit(-1)
+ }
 }

selftest/perfbuffers/main.go

@@ -5,6 +5,7 @@ import "C"
 import (
  "os"
  "runtime"
+ "time"
 
  "encoding/binary"
  "fmt"
@@ -67,26 +68,32 @@ 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
+ case b := <-eventsChannel:
+ if binary.LittleEndian.Uint32(b) != 2021 {
+ fmt.Fprintf(os.Stderr, "invalid data retrieved\n")
+ os.Exit(-1)
+ }
+ }
  }
  }()
-recvLoop:
- for {
- 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
- }
+
+ // give some time for the upper goroutine to start
+ time.Sleep(100 * time.Millisecond)
+
+ for sent := 0; sent < 5; sent++ {
+ syscall.Mmap(999, 999, 999, 1, 1)
+ time.Sleep(100 * time.Millisecond)
  }
 
+ close(stop)
+
  // Test that it won't cause a panic or block if Stop or Close called multiple times
  pb.Stop()
  pb.Stop()