pkg/vcs: fix config bisection tests more

config-bisect.pl uses bash-isms and can't run on non-linux.
It also silently ignores all errors which made failures
very obscure -- the script happily succeeds in presence
of any errors. So the test failed later reading .config.
Use "set -eu" to not fail silently.
Also trace all config-bisect.pl invocations and output.
good/bad decisions are important and we always log them
in the normal bisection.

3 files changed, 11 insertions, 2 deletions

diff --git a/pkg/vcs/linux.go b/pkg/vcs/linux.go
index 3509c361a..a9a823621 100644
--- a/pkg/vcs/linux.go
+++ b/pkg/vcs/linux.go
@@ -273,6 +273,7 @@ func (ctx *linux) Minimize(original, baseline []byte, trace io.Writer,
 	if err != nil {
 		return nil, fmt.Errorf("config bisect failed: %v", err)
 	}
+	fmt.Fprintf(trace, "# config-bisect.pl -r:\n%s", output)
 	for {
 		config, err := ioutil.ReadFile(filepath.Join(ctx.git.dir, ".config"))
 		if err != nil {
@@ -293,6 +294,7 @@ func (ctx *linux) Minimize(original, baseline []byte, trace io.Writer,
 
 		output1, err := osutil.RunCmd(time.Hour, "", configBisect,
 			"-l", ctx.git.dir, "-b", ctx.git.dir, kernelBaselineConfig, kernelConfig, verdict)
+		fmt.Fprintf(trace, "# config-bisect.pl %v:\n%s", verdict, output1)
 		output = append(output, output1...)
 		if err != nil {
 			if verr, ok := err.(*osutil.VerboseError); ok && verr.ExitCode == 2 {
diff --git a/pkg/vcs/linux_test.go b/pkg/vcs/linux_test.go
index a249dc6c9..bacf89edb 100644
--- a/pkg/vcs/linux_test.go
+++ b/pkg/vcs/linux_test.go
@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
+	"runtime"
 	"strings"
 	"testing"
 
@@ -24,6 +25,10 @@ type MinimizationTest struct {
 }
 
 func TestConfigMinimizer(t *testing.T) {
+	if runtime.GOOS != "linux" {
+		// The test config-bisect.pl uses bash-isms and can't run on OS that don't have bash.
+		t.Skipf("skipping on non-linux")
+	}
 	t.Parallel()
 	tests := []MinimizationTest{
 		{
@@ -67,6 +72,7 @@ func TestConfigMinimizer(t *testing.T) {
 			trace := new(bytes.Buffer)
 			outConfig, err := minimizer.Minimize([]byte(test.config),
 				[]byte(test.baselineConfig), trace, pred)
+			t.Log(trace.String())
 			if test.passing && err != nil {
 				t.Fatalf("failed to run Minimize: %v", err)
 			} else if test.passing && !strings.Contains(string(outConfig),
@@ -74,7 +80,6 @@ func TestConfigMinimizer(t *testing.T) {
 				t.Fatalf("output is not expected %v vs. %v", string(outConfig),
 					test.expectedConfig)
 			}
-			t.Log(trace.String())
 		})
 	}
 }
diff --git a/pkg/vcs/testdata/linux/config-bisect.pl b/pkg/vcs/testdata/linux/config-bisect.pl
index 3388e3da0..29a488e58 100755
--- a/pkg/vcs/testdata/linux/config-bisect.pl
+++ b/pkg/vcs/testdata/linux/config-bisect.pl
@@ -1,8 +1,10 @@
-#!/bin/sh
+#!/bin/bash
 # Copyright 2020 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.
 # config-bisect.pl -l ctx.git.dir -r -b ctx.git.dir kernelBaselineConfig kernelConfig
 
+set -eu
+
 if [ "$3" == "-r" ]
 then
     baseline=`cat $6`