program: reuse kconfig package for LINUX_HAS_SYSCALL_WRAPPER

Export a function from the kconfig package which allows writing an
integer into a slice based on a btf.Int.

Signed-off-by: Lorenz Bauer <lmb@isovalent.com>

collection.go

@@ -630,24 +630,15 @@ func resolveKconfig(m *MapSpec) error {
 			if !ok {
 				return fmt.Errorf("variable %s must be an integer, got %s", n, v.Type)
 			}
-			var value uint8 = 1
+			var value uint64 = 1
 			if err := haveSyscallWrapper(); errors.Is(err, ErrNotSupported) {
 				value = 0
 			} else if err != nil {
 				return fmt.Errorf("unable to derive a value for LINUX_HAS_SYSCALL_WRAPPER: %w", err)
 			}
 
-			switch integer.Size {
-			case 1:
-				data[vsi.Offset] = value
-			case 2:
-				internal.NativeEndian.PutUint16(data[vsi.Offset:], uint16(value))
-			case 4:
-				internal.NativeEndian.PutUint32(data[vsi.Offset:], uint32(value))
-			case 8:
-				internal.NativeEndian.PutUint64(data[vsi.Offset:], uint64(value))
-			default:
-				return fmt.Errorf("variable %s must be a 8, 16, 32, or 64 bits integer, got %s", n, v.Type)
+			if err := kconfig.PutInteger(data[vsi.Offset:], integer, value); err != nil {
+				return fmt.Errorf("set LINUX_HAS_SYSCALL_WRAPPER: %w", err)
 			}
 
 		default: // Catch CONFIG_*.

internal/kconfig/kconfig.go

@@ -250,7 +250,20 @@ func putValueNumber(data []byte, typ btf.Type, value string) error {
 		return fmt.Errorf("cannot parse value: %w", err)
 	}
 
-	switch size {
+	return PutInteger(data, integer, n)
+}
+
+// PutInteger writes n into data.
+//
+// integer determines how much is written into data and what the valid values
+// are.
+func PutInteger(data []byte, integer *btf.Int, n uint64) error {
+	// This function should match set_kcfg_value_num in libbpf.
+	if integer.Encoding == btf.Bool && n > 1 {
+		return fmt.Errorf("invalid boolean value: %d", n)
+	}
+
+	switch integer.Size {
 	case 1:
 		data[0] = byte(n)
 	case 2:
@@ -260,7 +273,7 @@ func putValueNumber(data []byte, typ btf.Type, value string) error {
 	case 8:
 		internal.NativeEndian.PutUint64(data, uint64(n))
 	default:
-		return fmt.Errorf("size (%d) is not valid, expected: 1, 2, 4 or 8", size)
+		return fmt.Errorf("size (%d) is not valid, expected: 1, 2, 4 or 8", integer.Size)
 	}
 
 	return nil