purego: Fix string conversion when calling Go callbacks from C

Signed-off-by: Felicitas Pojtinger <felicitas@pojtinger.com>

commit: a44f95eedfa12c7a98d733ff4c4ab4490d2d61ad
author: Felicitas Pojtinger · 8mo ago · 2026-01-28 03:13 UTC
committer: brice · 25d ago · 2026-09-27 05:38 UTC
parent: dea872e
signature: GPG VerifiedCD88F9E564E0102646FB6077A1A07C7C7C3E349D · arch-gpg Verified for the committer email

1 file · +37 -0

M callback_test.go +37 -0


@@ -51,6 +51,43 @@ func TestCallGoFromSharedLib(t *testing.T) {
51	51		}
52	52		}
53	53
	54	+	// TestCallbackStringConversion tests that C char* arguments are correctly
	55	+	// converted to Go strings when the callback signature uses string type.
	56	+	func TestCallbackStringConversion(t *testing.T) {
	57	+	libFileName := filepath.Join(t.TempDir(), "libcbtest.so")
	58	+	t.Logf("Build %v", libFileName)
	59	+
	60	+	if err := buildSharedLib("CC", libFileName, filepath.Join("testdata", "libcbtest", "callback_test.c")); err != nil {
	61	+	t.Fatal(err)
	62	+	}
	63	+	defer os.Remove(libFileName)
	64	+
	65	+	lib, err := purego.Dlopen(libFileName, purego.RTLD_NOW\|purego.RTLD_GLOBAL)
	66	+	if err != nil {
	67	+	t.Fatalf("Dlopen(%q) failed: %v", libFileName, err)
	68	+	}
	69	+
	70	+	var callCallback func(p uintptr, s string) int
	71	+	purego.RegisterLibFunc(&callCallback, lib, "callCallback")
	72	+
	73	+	const expected = "a test string"
	74	+	var got string
	75	+	goFunc := func(s string, n int) int {
	76	+	got = s
	77	+	if len(s) != n {
	78	+	t.Errorf("string length mismatch: got %d, want %d", len(s), n)
	79	+	}
	80	+	return 1
	81	+	}
	82	+
	83	+	cb := purego.NewCallback(goFunc)
	84	+	callCallback(cb, expected)
	85	+
	86	+	if got != expected {
	87	+	t.Errorf("string callback got %q, want %q", got, expected)
	88	+	}
	89	+	}
	90	+
54	91		func TestNewCallbackFloat64(t *testing.T) {
55	92		// This tests the maximum number of arguments a function to NewCallback can take
56	93		const (


@@ -51,6 +51,43 @@ func TestCallGoFromSharedLib(t *testing.T) {
51	}	51		}
52	}	52		}
53		53
		54	+	// TestCallbackStringConversion tests that C char* arguments are correctly
		55	+	// converted to Go strings when the callback signature uses string type.
		56	+	func TestCallbackStringConversion(t *testing.T) {
		57	+	libFileName := filepath.Join(t.TempDir(), "libcbtest.so")
		58	+	t.Logf("Build %v", libFileName)
		59	+
		60	+	if err := buildSharedLib("CC", libFileName, filepath.Join("testdata", "libcbtest", "callback_test.c")); err != nil {
		61	+	t.Fatal(err)
		62	+	}
		63	+	defer os.Remove(libFileName)
		64	+
		65	+	lib, err := purego.Dlopen(libFileName, purego.RTLD_NOW\|purego.RTLD_GLOBAL)
		66	+	if err != nil {
		67	+	t.Fatalf("Dlopen(%q) failed: %v", libFileName, err)
		68	+	}
		69	+
		70	+	var callCallback func(p uintptr, s string) int
		71	+	purego.RegisterLibFunc(&callCallback, lib, "callCallback")
		72	+
		73	+	const expected = "a test string"
		74	+	var got string
		75	+	goFunc := func(s string, n int) int {
		76	+	got = s
		77	+	if len(s) != n {
		78	+	t.Errorf("string length mismatch: got %d, want %d", len(s), n)
		79	+	}
		80	+	return 1
		81	+	}
		82	+
		83	+	cb := purego.NewCallback(goFunc)
		84	+	callCallback(cb, expected)
		85	+
		86	+	if got != expected {
		87	+	t.Errorf("string callback got %q, want %q", got, expected)
		88	+	}
		89	+	}
		90	+
54	func TestNewCallbackFloat64(t *testing.T) {	91		func TestNewCallbackFloat64(t *testing.T) {
55	// This tests the maximum number of arguments a function to NewCallback can take	92		// This tests the maximum number of arguments a function to NewCallback can take
56	const (	93		const (