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Commit 71d6ab68 authored by Colin Cross's avatar Colin Cross
Browse files

Fix concurrency issues in Test_runWithTimeout 

Use a concurrency-safe writer in runWithTimeout to avoid data races
on the bytes.Buffer passed in during tests.

Bug: 181095653
Fixes: 187149270
Test: Test_runWithTimeout
Test: go test -race ./cmd/run_with_timeout
Change-Id: I57a889765cb9ee7b42983f0906313e0c2d1e414e
parent 29c294b2

cmd/run_with_timeout/run_with_timeout.go

+35 −2
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ import ( 
	"io"

	"os"

	"os/exec"

	"sync"

	"syscall"

	"time"

)
@@ -62,10 +63,42 @@ func main() { 
	}

}



// concurrentWriter wraps a writer to make it thread-safe to call Write.

type concurrentWriter struct {

	w io.Writer

	sync.Mutex

}



// Write writes the data to the wrapped writer with a lock to allow for concurrent calls.

func (c *concurrentWriter) Write(data []byte) (n int, err error) {

	c.Lock()

	defer c.Unlock()

	if c.w == nil {

		return 0, nil

	}

	return c.w.Write(data)

}



// Close ends the concurrentWriter, causing future calls to Write to be no-ops.  It does not close

// the underlying writer.

func (c *concurrentWriter) Close() {

	c.Lock()

	defer c.Unlock()

	c.w = nil

}



func runWithTimeout(command string, args []string, timeout time.Duration, onTimeoutCmdStr string,

	stdin io.Reader, stdout, stderr io.Writer) error {

	cmd := exec.Command(command, args...)

	cmd.Stdin, cmd.Stdout, cmd.Stderr = stdin, stdout, stderr



	// Wrap the writers in a locking writer so that cmd and onTimeoutCmd don't try to write to

	// stdout or stderr concurrently.

	concurrentStdout := &concurrentWriter{w: stdout}

	concurrentStderr := &concurrentWriter{w: stderr}

	defer concurrentStdout.Close()

	defer concurrentStderr.Close()



	cmd.Stdin, cmd.Stdout, cmd.Stderr = stdin, concurrentStdout, concurrentStderr

	err := cmd.Start()

	if err != nil {

		return err
@@ -98,7 +131,7 @@ func runWithTimeout(command string, args []string, timeout time.Duration, onTime 


	if onTimeoutCmdStr != "" {

		onTimeoutCmd := exec.Command("sh", "-c", onTimeoutCmdStr)

		onTimeoutCmd.Stdin, onTimeoutCmd.Stdout, onTimeoutCmd.Stderr = stdin, stdout, stderr

		onTimeoutCmd.Stdin, onTimeoutCmd.Stdout, onTimeoutCmd.Stderr = stdin, concurrentStdout, concurrentStderr

		onTimeoutCmd.Env = append(os.Environ(), fmt.Sprintf("PID=%d", cmd.Process.Pid))

		err := onTimeoutCmd.Run()

		if err != nil {