kfuzztest: refactor ExtractData

Refactor ExtractData to simplify error handling.

Author: Ethan Graham

pkg/kfuzztest/kfuzztest.go

@@ -103,6 +103,53 @@ type KFuzzTestData struct {
 	Types       []prog.Type
 }
 
+func extractData(vmlinuxPath string) (KFuzzTestData, error) {
+	desc, err := ExtractDescription(vmlinuxPath)
+	if err != nil {
+		return KFuzzTestData{}, err
+	}
+
+	var astError error
+	eh := func(pos ast.Pos, msg string) {
+		astError = fmt.Errorf("ast error: %v: %v", pos, msg)
+	}
+	descAst := ast.Parse([]byte(desc), "kfuzztest-autogen", eh)
+	if astError != nil {
+		return KFuzzTestData{}, astError
+	}
+	if descAst == nil {
+		return KFuzzTestData{}, fmt.Errorf("failed to build AST for program")
+	}
+
+	// TODO: this assumes x86_64, but KFuzzTest supports (in theory) any
+	// architecture.
+	target := targets.Get(targets.Linux, targets.AMD64)
+	program := compiler.Compile(descAst, make(map[string]uint64), target, eh)
+	if astError != nil {
+		return KFuzzTestData{}, fmt.Errorf("failed to compile extracted KFuzzTest target: %w", astError)
+	}
+
+	kFuzzTestCalls := []*prog.Syscall{}
+	for _, call := range program.Syscalls {
+		// The generated descriptions contain some number of built-ins, which
+		// we want to filter out.
+		if call.Attrs.KFuzzTest {
+			kFuzzTestCalls = append(kFuzzTestCalls, call)
+		}
+	}
+
+	// We restore links on all generated system calls for completeness, but we
+	// only return the filtered slice.
+	prog.RestoreLinks(program.Syscalls, program.Resources, program.Types)
+
+	return KFuzzTestData{
+		Description: desc,
+		Calls:       kFuzzTestCalls,
+		Resources:   program.Resources,
+		Types:       program.Types,
+	}, nil
+}
+
 type extractKFuzzTestDataState struct {
 	once sync.Once
 	data KFuzzTestData
@@ -119,51 +166,7 @@ var extractState extractKFuzzTestDataState
 // based on their path.
 func ExtractData(vmlinuxPath string) (KFuzzTestData, error) {
 	extractState.once.Do(func() {
-		desc, err := ExtractDescription(vmlinuxPath)
-		if err != nil {
-			extractState.err = err
-			return
-		}
-
-		var astError error
-		eh := func(pos ast.Pos, msg string) {
-			astError = fmt.Errorf("ast error: %v: %v", pos, msg)
-		}
-		descAst := ast.Parse([]byte(desc), "kfuzztest-autogen", eh)
-		if astError != nil {
-			extractState.err = astError
-			return
-		}
-		if descAst == nil {
-			extractState.err = fmt.Errorf("failed to build AST for program")
-			return
-		}
-
-		target := targets.Get(targets.Linux, targets.AMD64)
-		program := compiler.Compile(descAst, make(map[string]uint64), target, eh)
-		if astError != nil {
-			extractState.err = fmt.Errorf("failed to compile extracted KFuzzTest target: %w", astError)
-		}
-
-		kFuzzTestCalls := []*prog.Syscall{}
-		for _, call := range program.Syscalls {
-			// The generated descriptions contain some number of built-ins, which
-			// we want to filter out.
-			if call.Attrs.KFuzzTest {
-				kFuzzTestCalls = append(kFuzzTestCalls, call)
-			}
-		}
-
-		// We restore links on all restored system calls for completeness, but we
-		// only return the filtered slice.
-		prog.RestoreLinks(program.Syscalls, program.Resources, program.Types)
-
-		extractState.data = KFuzzTestData{
-			Description: desc,
-			Calls:       kFuzzTestCalls,
-			Resources:   program.Resources,
-			Types:       program.Types,
-		}
+		extractState.data, extractState.err = extractData(vmlinuxPath)
 	})
 
 	return extractState.data, extractState.err