fix(pkg/btf): fix FindBTFStruct to return first found btf type.

In case of multiple matches, the code expects the first one found with correct type to be used.

Signed-off-by: Federico Di Pierro <[email protected]>

Author: FedeDP

pkg/btf/btf.go

@@ -6,6 +6,7 @@
 package btf
 
 import (
+	"errors"
 	"fmt"
 	"os"
 	"path"
@@ -109,6 +110,30 @@ func FindBTFStruct(name string) (*btf.Struct, error) {
 	}
 
 	err = spec.TypeByName(name, &ty)
+	if err != nil && errors.Is(err, btf.ErrMultipleMatches) {
+		logger.GetLogger().Warn("Multiple matches found in BTF spec; using first one", "struct", name)
+		// In case of multiple matches, fallback at using first available
+		// NOTE: we can skip all error checking here
+		// as it was already done for us by spec.TypeByName()
+		typeInterface := reflect.TypeOf((*btf.Type)(nil)).Elem()
+		typValue := reflect.ValueOf(&ty)
+		typPtr := typValue.Elem()
+		types, _ := spec.AnyTypesByName(name)
+		wanted := typPtr.Type()
+		if wanted == typeInterface {
+			// This is *Type. Unwrap the value's type.
+			wanted = typPtr.Elem().Type()
+		}
+		for _, typ := range types {
+			if reflect.TypeOf(typ) != wanted {
+				continue
+			}
+			typPtr.Set(reflect.ValueOf(typ))
+			// reset err
+			err = nil
+			break
+		}
+	}
 	return ty, err
 }
 

pkg/sensors/tracing/generic.go

@@ -6,7 +6,6 @@
 package tracing
 
 import (
-	"errors"
 	"fmt"
 	"strings"
 
@@ -74,7 +73,7 @@ func resolveBTFArg(hook string, arg *v1alpha1.KProbeArg, tp bool) (*ebtf.Type, [
 	// - real argument value
 	if hasCurrentTaskSource(arg) {
 		st, err := btf.FindBTFStruct("task_struct")
-		if err != nil && !errors.Is(err, ebtf.ErrMultipleMatches) {
+		if err != nil {
 			return nil, [api.MaxBTFArgDepth]api.ConfigBTFArg{}, err
 		}
 		ty = ebtf.Type(st)