pkg/kfuzztest: add pkg/kfuzztest

Add a new package, pkg/kfuzztest, that implements dynamic discovery of
KFuzzTest targets by parsing a vmlinux kernel binary.

Signed-off-by: Ethan Graham <ethangraham@google.com>

1 files changed, 103 insertions, 0 deletions

diff --git a/pkg/kfuzztest/description_generation_test.go b/pkg/kfuzztest/description_generation_test.go
new file mode 100644
index 000000000..d68a96b18
--- /dev/null
+++ b/pkg/kfuzztest/description_generation_test.go
@@ -0,0 +1,103 @@
+// Copyright 2025 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+package kfuzztest
+
+import (
+	"fmt"
+	"os"
+	"path"
+	"testing"
+	"time"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/google/syzkaller/pkg/osutil"
+	"github.com/google/syzkaller/sys/targets"
+	"github.com/stretchr/testify/require"
+)
+
+type testData struct {
+	dir  string
+	desc string
+}
+
+func TestBuildDescriptions(t *testing.T) {
+	testCases, err := readTestCases("./testdata")
+	require.NoError(t, err)
+
+	target := targets.Get(targets.Linux, targets.AMD64)
+	for _, tc := range testCases {
+		t.Run(tc.dir, func(t *testing.T) {
+			runTest(t, target, tc)
+		})
+	}
+}
+
+// Tests that the description inferred from a compiled binary matches an
+// expected description.
+func runTest(t *testing.T, target *targets.Target, tc testData) {
+	// Compile the C binary containing the metadata.
+	cmd := flags(tc.dir)
+	out, err := osutil.RunCmd(time.Hour, "", target.CCompiler, cmd...)
+	require.NoErrorf(t, err, "Failed to compile: %s", string(out))
+	// Cleanup the compiled binary.
+	defer func() {
+		out, err := osutil.RunCmd(time.Hour, "", "rm", path.Join(tc.dir, "bin"))
+		if err != nil {
+			require.NoErrorf(t, err, "Failed to cleanup: %s", string(out))
+		}
+	}()
+
+	binaryPath := path.Join(tc.dir, "bin")
+	desc, err := ExtractDescription(binaryPath)
+	require.NoError(t, err)
+
+	if diffDesc := cmp.Diff(tc.desc, desc); diffDesc != "" {
+		fmt.Print(diffDesc)
+		t.Fail()
+		return
+	}
+}
+
+func flags(testDir string) []string {
+	return []string{
+		"-g",
+		"-T",
+		path.Join(testDir, "..", "linker.ld"),
+		"-o",
+		path.Join(testDir, "bin"),
+		path.Join(testDir, "prog.c"),
+	}
+}
+
+func readTestCases(dir string) ([]testData, error) {
+	var testCases []testData
+	testDirs, err := os.ReadDir(dir)
+	if err != nil {
+		return nil, err
+	}
+
+	for _, subDir := range testDirs {
+		if !subDir.IsDir() {
+			continue
+		}
+		testData, err := readTestdata(path.Join(dir, subDir.Name()))
+		if err != nil {
+			return nil, err
+		}
+		testCases = append(testCases, testData)
+	}
+
+	return testCases, nil
+}
+
+func readTestdata(testDir string) (testData, error) {
+	content, err := os.ReadFile(path.Join(testDir, "desc.txt"))
+	if err != nil {
+		return testData{}, err
+	}
+
+	return testData{
+		dir:  testDir,
+		desc: string(content),
+	}, nil
+}