vm: return Report from MonitorExecution

This allows callers to get access to Report.Corrupted.
Better than adding 6-th return value and will allow
to pipe other report properties if necessary.

1 files changed, 35 insertions, 12 deletions

diff --git a/vm/vm.go b/vm/vm.go
index b4933576f..24a5d55ae 100644
--- a/vm/vm.go
+++ b/vm/vm.go
@@ -96,8 +96,14 @@ func (inst *Instance) Close() {
 	os.RemoveAll(inst.workdir)
 }
 
-func MonitorExecution(outc <-chan []byte, errc <-chan error, reporter report.Reporter) (
-	title string, report, output []byte, crashed, timedout bool) {
+// MonitorExecution monitors execution of a program running inside of a VM.
+// It detects kernel oopses in output, lost connections, hangs, etc.
+// outc/errc is what vm.Instance.Run returns, reporter parses kernel output for oopses.
+// If canExit is false and the program exits, it is treated as an error.
+// Returns crash report and raw output around the crash, or nil if no error happens.
+func MonitorExecution(outc <-chan []byte, errc <-chan error, reporter report.Reporter, canExit bool) (
+	rep *report.Report, output []byte) {
+	//title string, report, output []byte, crashed, timedout bool) {
 	waitForOutput := func() {
 		timer := time.NewTimer(10 * time.Second).C
 		for {
@@ -118,14 +124,23 @@ func MonitorExecution(outc <-chan []byte, errc <-chan error, reporter report.Rep
 		beforeContext = 1024 << 10
 		afterContext  = 128 << 10
 	)
-	extractError := func(defaultError string) (string, []byte, []byte, bool, bool) {
+	extractError := func(defaultError string) (*report.Report, []byte) {
 		// Give it some time to finish writing the error message.
 		waitForOutput()
 		if bytes.Contains(output, []byte("SYZ-FUZZER: PREEMPTED")) {
-			return "preempted", nil, nil, false, true
+			return nil, nil
 		}
 		if !reporter.ContainsCrash(output[matchPos:]) {
-			return defaultError, nil, output, defaultError != "", false
+			if defaultError == "" {
+				if canExit {
+					return nil, nil
+				}
+				defaultError = "lost connection to test machine"
+			}
+			rep := &report.Report{
+				Title: defaultError,
+			}
+			return rep, output
 		}
 		rep := reporter.Parse(output[matchPos:])
 		if rep == nil {
@@ -139,7 +154,7 @@ func MonitorExecution(outc <-chan []byte, errc <-chan error, reporter report.Rep
 		if end > len(output) {
 			end = len(output)
 		}
-		return rep.Title, rep.Report, output[start:end], true, false
+		return rep, output[start:end]
 	}
 
 	lastExecuteTime := time.Now()
@@ -159,7 +174,7 @@ func MonitorExecution(outc <-chan []byte, errc <-chan error, reporter report.Rep
 				// but wait for kernel output in case there is some delayed oops.
 				return extractError("")
 			case TimeoutErr:
-				return err.Error(), nil, nil, false, true
+				return nil, nil
 			default:
 				// Note: connection lost can race with a kernel oops message.
 				// In such case we want to return the kernel oops.
@@ -167,10 +182,12 @@ func MonitorExecution(outc <-chan []byte, errc <-chan error, reporter report.Rep
 			}
 		case out := <-outc:
 			output = append(output, out...)
-			if bytes.Index(output[matchPos:], []byte("executing program")) != -1 { // syz-fuzzer output
+			// syz-fuzzer output
+			if bytes.Index(output[matchPos:], []byte("executing program")) != -1 {
 				lastExecuteTime = time.Now()
 			}
-			if bytes.Index(output[matchPos:], []byte("executed programs:")) != -1 { // syz-execprog output
+			// syz-execprog output
+			if bytes.Index(output[matchPos:], []byte("executed programs:")) != -1 {
 				lastExecuteTime = time.Now()
 			}
 			if reporter.ContainsCrash(output[matchPos:]) {
@@ -189,13 +206,19 @@ func MonitorExecution(outc <-chan []byte, errc <-chan error, reporter report.Rep
 			// We intentionally produce the same title as no output at all,
 			// because frequently it's the same condition.
 			if time.Since(lastExecuteTime) > 3*time.Minute {
-				return "no output from test machine", nil, output, true, false
+				rep := &report.Report{
+					Title: "no output from test machine",
+				}
+				return rep, output
 			}
 		case <-ticker.C:
 			tickerFired = true
-			return "no output from test machine", nil, output, true, false
+			rep := &report.Report{
+				Title: "no output from test machine",
+			}
+			return rep, output
 		case <-Shutdown:
-			return "", nil, nil, false, false
+			return nil, nil
 		}
 	}
 }