fix: surface rb.Poll errors instead of silently dropping them

The libbpfgo RingBuffer.Poll() previously launched a background goroutine
that could fail with a fatal C-level errno (e.g. EBADF, EPERM) and silently
exit, causing BPF events to stop flowing with no diagnostic.

Changes:
- Patch ../libbpfgo (replace directive) so RingBuffer.Poll() returns a
  buffered <-chan error that the background goroutine sends to on failure.
- In setupEventChannel, capture the error channel and spawn a monitoring
  goroutine that logs any poll error to stderr.
- Update go.mod with the replace directive and drop the now-unused remote
  checksum entries from go.sum.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

3 files changed, 13 insertions, 3 deletions

diff --git a/go.mod b/go.mod
index 7e68ecd..886c481 100644
--- a/go.mod
+++ b/go.mod
@@ -39,3 +39,5 @@ require (
 	golang.org/x/sys v0.41.0 // indirect
 	google.golang.org/protobuf v1.34.2 // indirect
 )
+
+replace github.com/aquasecurity/libbpfgo => ../libbpfgo
diff --git a/go.sum b/go.sum
index 55dbc42..ecb8bf8 100644
--- a/go.sum
+++ b/go.sum
@@ -14,8 +14,6 @@ github.com/alecthomas/repr v0.4.0 h1:GhI2A8MACjfegCPVq9f1FLvIBS+DrQ2KQBFZP1iFzXc
 github.com/alecthomas/repr v0.4.0/go.mod h1:Fr0507jx4eOXV7AlPV6AVZLYrLIuIeSOWtW57eE/O/4=
 github.com/andybalholm/brotli v1.1.1 h1:PR2pgnyFznKEugtsUo0xLdDop5SKXd5Qf5ysW+7XdTA=
 github.com/andybalholm/brotli v1.1.1/go.mod h1:05ib4cKhjx3OQYUY22hTVd34Bc8upXjOLL2rKwwZBoA=
-github.com/aquasecurity/libbpfgo v0.9.2-libbpf-1.5.1 h1:TDN+16Nim3gimjuTxd+sFhb4v06mEeYH0JfRWAFowA0=
-github.com/aquasecurity/libbpfgo v0.9.2-libbpf-1.5.1/go.mod h1:JQNC5NuGwyYC7IZum6JqPNVHarFAuab+h4lO6t0jIhc=
 github.com/atotto/clipboard v0.1.4 h1:EH0zSVneZPSuFR11BlR9YppQTVDbh5+16AmcJi4g1z4=
 github.com/atotto/clipboard v0.1.4/go.mod h1:ZY9tmq7sm5xIbd9bOK4onWV4S6X0u6GY7Vn0Yu86PYI=
 github.com/aymanbagabas/go-udiff v0.4.0 h1:TKnLPh7IbnizJIBKFWa9mKayRUBQ9Kh1BPCk6w2PnYM=
diff --git a/internal/ior_bpfsetup.go b/internal/ior_bpfsetup.go
index 885d321..7575700 100644
--- a/internal/ior_bpfsetup.go
+++ b/internal/ior_bpfsetup.go
@@ -88,13 +88,23 @@ func setupBPFModule(parentCtx context.Context, cfg flags.Config) (*bpf.Module, *
 }
 
 // setupEventChannel initialises the BPF ring-buffer and returns the event channel.
+// It starts polling the ring buffer and logs any fatal poll error to stderr so
+// that a background ring-buffer failure does not go completely unnoticed.
 func setupEventChannel(bpfModule *bpf.Module) (chan []byte, error) {
 	ch := make(chan []byte, appconfig.DefaultChannelBufferSize)
 	rb, err := bpfModule.InitRingBuf("event_map", ch)
 	if err != nil {
 		return nil, err
 	}
-	rb.Poll(300)
+	// Poll returns a channel that receives any fatal error from the background
+	// polling goroutine. Monitor it in a goroutine so the error is logged and
+	// does not silently drop events.
+	pollErrCh := rb.Poll(300)
+	go func() {
+		if err := <-pollErrCh; err != nil {
+			fmt.Fprintf(os.Stderr, "ior: ring buffer poll failed: %v\n", err)
+		}
+	}()
 	return ch, nil
 }