internal: add context to BPF setup failures (task 416)

2 files changed, 39 insertions, 5 deletions

diff --git a/internal/ior.go b/internal/ior.go
index 9f58821..ad46feb 100644
--- a/internal/ior.go
+++ b/internal/ior.go
@@ -308,31 +308,38 @@ func newLogger(verbose bool) func(...any) {
 	return func(args ...any) { _, _ = fmt.Println(args...) }
 }
 
+func setupBPFModuleError(stage string, err error) error {
+	if err == nil {
+		return nil
+	}
+	return fmt.Errorf("setup BPF module: %s: %w", stage, err)
+}
+
 func setupBPFModule(parentCtx context.Context, cfg flags.Config) (*bpf.Module, *probemanager.Manager, func(), error) {
 	releaseBindings := func() {}
 
 	bpfModule, err := bpf.NewModuleFromFile("ior.bpf.o")
 	if err != nil {
-		return nil, nil, releaseBindings, err
+		return nil, nil, releaseBindings, setupBPFModuleError("load module from file", err)
 	}
 	if err := resizeBPFMaps(cfg, bpfModule); err != nil {
 		bpfModule.Close()
-		return nil, nil, releaseBindings, err
+		return nil, nil, releaseBindings, setupBPFModuleError("resize maps", err)
 	}
 	if err := setBPFGlobals(cfg, bpfModule); err != nil {
 		bpfModule.Close()
-		return nil, nil, releaseBindings, err
+		return nil, nil, releaseBindings, setupBPFModuleError("set globals", err)
 	}
 	if err := bpfModule.BPFLoadObject(); err != nil {
 		bpfModule.Close()
-		return nil, nil, releaseBindings, err
+		return nil, nil, releaseBindings, setupBPFModuleError("load object", err)
 	}
 
 	mgr := probemanager.NewManager(libbpfTracepointModule{module: bpfModule})
 	if err := mgr.AttachAll(cfg.ShouldIAttachTracepoint, tracepoints.List); err != nil {
 		mgr.Close()
 		bpfModule.Close()
-		return nil, nil, releaseBindings, err
+		return nil, nil, releaseBindings, setupBPFModuleError("attach probes", err)
 	}
 	if bindings, ok := tui.RuntimeBindingsFromContext(parentCtx); ok {
 		bindings.SetProbeManager(mgr)
diff --git a/internal/ior_setup_test.go b/internal/ior_setup_test.go
new file mode 100644
index 0000000..9c8b1b3
--- /dev/null
+++ b/internal/ior_setup_test.go
@@ -0,0 +1,27 @@
+package internal
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestSetupBPFModuleErrorWrapsStage(t *testing.T) {
+	cause := errors.New("boom")
+
+	err := setupBPFModuleError("load object", cause)
+	if err == nil {
+		t.Fatalf("expected wrapped error")
+	}
+	if got, want := err.Error(), "setup BPF module: load object: boom"; got != want {
+		t.Fatalf("wrapped error = %q, want %q", got, want)
+	}
+	if !errors.Is(err, cause) {
+		t.Fatalf("expected wrapped error to retain original cause")
+	}
+}
+
+func TestSetupBPFModuleErrorNil(t *testing.T) {
+	if err := setupBPFModuleError("attach probes", nil); err != nil {
+		t.Fatalf("expected nil error passthrough, got %v", err)
+	}
+}