pkg/build: add build signatures

Add optional build signature for images, currently only implemented for linux.
This can be used in bisection process to detect changes that does not affect kernel.

Update #1271

1 files changed, 82 insertions, 0 deletions

diff --git a/pkg/build/linux_test.go b/pkg/build/linux_test.go
new file mode 100644
index 000000000..a3fae056a
--- /dev/null
+++ b/pkg/build/linux_test.go
@@ -0,0 +1,82 @@
+// Copyright 2019 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.
+
+// +build linux
+
+package build
+
+import (
+	"bytes"
+	"os"
+	"testing"
+	"text/template"
+
+	"github.com/google/syzkaller/pkg/osutil"
+)
+
+func TestElfBinarySignature(t *testing.T) {
+	enumerateFlags(t, nil, []string{"-g", "-O1", "-O2", "-no-pie", "-static"})
+}
+
+func enumerateFlags(t *testing.T, flags, allFlags []string) {
+	if len(allFlags) != 0 {
+		enumerateFlags(t, flags, allFlags[1:])
+		enumerateFlags(t, append(flags, allFlags[0]), allFlags[1:])
+		return
+	}
+	t.Logf("testing: %+v", flags)
+	sign1 := sign(t, flags, false, false)
+	sign2 := sign(t, flags, false, true)
+	sign3 := sign(t, flags, true, false)
+	if sign1 != sign2 {
+		t.Errorf("signature has changed after a comment-only change")
+	}
+	if sign1 == sign3 {
+		t.Errorf("signature has not changed after a change")
+	}
+
+	//func elfBinarySignature(bin string) (string, error) {
+}
+
+func sign(t *testing.T, flags []string, changed, comment bool) string {
+	buf := new(bytes.Buffer)
+	if err := srcTemplate.Execute(buf, SrcParams{Changed: changed, Comment: comment}); err != nil {
+		t.Fatal(err)
+	}
+	src := buf.Bytes()
+	bin, err := osutil.TempFile("syz-build-test")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(bin)
+	cmd := osutil.Command("gcc", append(flags, "-pthread", "-o", bin, "-x", "c", "-")...)
+	cmd.Stdin = buf
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("compiler failed: %v\n%s\n\n%s", err, src, out)
+	}
+	sign, err := elfBinarySignature(bin)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return sign
+}
+
+type SrcParams struct {
+	Changed bool
+	Comment bool
+}
+
+var srcTemplate = template.Must(template.New("").Parse(`
+#include <stdio.h>
+#include <pthread.h>
+
+int main() {
+	int x = {{if .Changed}}0{{else}}1{{end}};
+	{{if .Comment}}
+	// Some comment goes here.
+	// It affects line numbers in debug info.
+	{{end}}
+	printf("%d %p\n", x, pthread_create);
+}
+`))