whatcanGOwrong

go/pkg/mod/github.com/cilium/ebpf@v0.11.0/btf/strings_test.go

@@ -0,0 +1,110 @@
+package btf
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+
+	qt "github.com/frankban/quicktest"
+)
+
+func TestStringTable(t *testing.T) {
+	const in = "\x00one\x00two\x00"
+	const splitIn = "three\x00four\x00"
+
+	st, err := readStringTable(strings.NewReader(in), nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var buf bytes.Buffer
+	if err := st.Marshal(&buf); err != nil {
+		t.Fatal("Can't marshal string table:", err)
+	}
+
+	if !bytes.Equal([]byte(in), buf.Bytes()) {
+		t.Error("String table doesn't match input")
+	}
+
+	// Parse string table of split BTF
+	split, err := readStringTable(strings.NewReader(splitIn), st)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	testcases := []struct {
+		offset uint32
+		want   string
+	}{
+		{0, ""},
+		{1, "one"},
+		{5, "two"},
+		{9, "three"},
+		{15, "four"},
+	}
+
+	for _, tc := range testcases {
+		have, err := split.Lookup(tc.offset)
+		if err != nil {
+			t.Errorf("Offset %d: %s", tc.offset, err)
+			continue
+		}
+
+		if have != tc.want {
+			t.Errorf("Offset %d: want %s but have %s", tc.offset, tc.want, have)
+		}
+	}
+
+	if _, err := st.Lookup(2); err == nil {
+		t.Error("No error when using offset pointing into middle of string")
+	}
+
+	// Make sure we reject bogus tables
+	_, err = readStringTable(strings.NewReader("\x00one"), nil)
+	if err == nil {
+		t.Fatal("Accepted non-terminated string")
+	}
+
+	_, err = readStringTable(strings.NewReader("one\x00"), nil)
+	if err == nil {
+		t.Fatal("Accepted non-empty first item")
+	}
+}
+
+func TestStringTableBuilder(t *testing.T) {
+	stb := newStringTableBuilder(0)
+
+	_, err := readStringTable(bytes.NewReader(stb.AppendEncoded(nil)), nil)
+	qt.Assert(t, err, qt.IsNil, qt.Commentf("Can't parse string table"))
+
+	_, err = stb.Add("foo\x00bar")
+	qt.Assert(t, err, qt.IsNotNil)
+
+	empty, err := stb.Add("")
+	qt.Assert(t, err, qt.IsNil)
+	qt.Assert(t, empty, qt.Equals, uint32(0), qt.Commentf("The empty string is not at index 0"))
+
+	foo1, _ := stb.Add("foo")
+	foo2, _ := stb.Add("foo")
+	qt.Assert(t, foo1, qt.Equals, foo2, qt.Commentf("Adding the same string returns different offsets"))
+
+	table := stb.AppendEncoded(nil)
+	if n := bytes.Count(table, []byte("foo")); n != 1 {
+		t.Fatalf("Marshalled string table contains foo %d times instead of once", n)
+	}
+
+	_, err = readStringTable(bytes.NewReader(table), nil)
+	qt.Assert(t, err, qt.IsNil, qt.Commentf("Can't parse string table"))
+}
+
+func newStringTable(strings ...string) *stringTable {
+	offsets := make([]uint32, len(strings))
+
+	var offset uint32
+	for i, str := range strings {
+		offsets[i] = offset
+		offset += uint32(len(str)) + 1 // account for NUL
+	}
+
+	return &stringTable{nil, offsets, strings}
+}