all: cleanup executor/ipc status checking

This is mostly a cleanup change with little functional change.

In ipc.command.exec, remove the status fallback from the pipe to the
exit status. Once the executor is serving, it always writes the status
over the pipe; anything else is an error.

Remove the panic check in syz-stress, which is no longer needed.

3 files changed, 17 insertions, 20 deletions

diff --git a/executor/executor.cc b/executor/executor.cc
index cb31e0697..044410792 100644
--- a/executor/executor.cc
+++ b/executor/executor.cc
@@ -226,7 +226,8 @@ int main(int argc, char** argv)
 	// ptrace(PTRACE_SEIZE, 1, 0, 0x100040)
 	// This is unfortunate, but I don't have a better solution than ignoring it for now.
 	exitf("loop exited with status %d", status);
-	return 0;
+	// Unreachable.
+	return 1;
 }
 
 void loop()
diff --git a/ipc/ipc.go b/ipc/ipc.go
index ce951aab6..5d579b479 100644
--- a/ipc/ipc.go
+++ b/ipc/ipc.go
@@ -617,36 +617,28 @@ func (c *command) exec(opts *ExecOpts) (output []byte, failed, hanged, restart b
 		}
 		status = int(reply[0])
 		if status == 0 {
+			// Program was OK.
 			<-hang
 			return
 		}
 		// Executor writes magic values into the pipe before exiting,
 		// so proceed with killing and joining it.
-		status = int(reply[0])
 	}
-	err0 = fmt.Errorf("executor did not answer")
 	c.abort()
 	output = <-c.readDone
-	if err := c.wait(); <-hang && err != nil {
+	if err := c.wait(); <-hang {
 		hanged = true
+		// In all likelihood, this will be duplicated by the default
+		// case below, but that's fine.
 		output = append(output, []byte(err.Error())...)
 		output = append(output, '\n')
 	}
-	switch status {
-	case statusFail, statusError, statusRetry:
-	default:
-		if c.cmd.ProcessState != nil {
-			sys := c.cmd.ProcessState.Sys()
-			if ws, ok := sys.(syscall.WaitStatus); ok {
-				status = ws.ExitStatus()
-			}
-		}
-	}
 	// Handle magic values returned by executor.
 	switch status {
 	case statusFail:
 		err0 = ExecutorFailure(fmt.Sprintf("executor failed: %s", output))
 	case statusError:
+		err0 = fmt.Errorf("executor detected kernel bug")
 		failed = true
 	case statusRetry:
 		// This is a temporal error (ENOMEM) or an unfortunate
@@ -656,6 +648,14 @@ func (c *command) exec(opts *ExecOpts) (output []byte, failed, hanged, restart b
 		err0 = nil
 		hanged = false
 		restart = true
+	default:
+		// Failed to get a valid (or perhaps any) status from the
+		// executor.
+		//
+		// Once the executor is serving the status is always written to
+		// the pipe, so we don't bother to check the specific exit
+		// codes from wait.
+		err0 = fmt.Errorf("invalid (or no) executor status received: %d, executor exit: %s", status, c.cmd.ProcessState)
 	}
 	return
 }
diff --git a/tools/syz-stress/stress.go b/tools/syz-stress/stress.go
index 5885e233d..4cf8d931f 100644
--- a/tools/syz-stress/stress.go
+++ b/tools/syz-stress/stress.go
@@ -8,7 +8,6 @@ import (
 	"fmt"
 	"math/rand"
 	"os"
-	"regexp"
 	"runtime"
 	"sync"
 	"sync/atomic"
@@ -30,8 +29,6 @@ var (
 	flagLogProg  = flag.Bool("logprog", false, "print programs before execution")
 	flagGenerate = flag.Bool("generate", true, "generate new programs, otherwise only mutate corpus")
 
-	failedRe = regexp.MustCompile("runtime error: |panic: |Panic: ")
-
 	statExec uint64
 	gate     *ipc.Gate
 )
@@ -105,11 +102,10 @@ func execute(pid int, env *ipc.Env, p *prog.Prog) {
 	if err != nil {
 		fmt.Printf("failed to execute executor: %v\n", err)
 	}
-	paniced := failedRe.Match(output)
-	if failed || hanged || paniced || err != nil {
+	if failed || hanged || err != nil {
 		fmt.Printf("PROGRAM:\n%s\n", p.Serialize())
 	}
-	if failed || hanged || paniced || err != nil || *flagOutput {
+	if failed || hanged || err != nil || *flagOutput {
 		os.Stdout.Write(output)
 	}
 }