tests: save gocryptfs process id in test_helpers.MountPID

This will allow to tests to monitor fd usage and maybe other things.

tests/matrix/matrix_test.go

@@ -76,6 +76,8 @@ func TestMain(m *testing.M) {
 		test_helpers.MountOrExit(test_helpers.DefaultCipherDir, test_helpers.DefaultPlainDir, opts...)
 		before := test_helpers.ListFds()
 		r := m.Run()
+		// Catch fd leaks in the tests. NOTE: this does NOT catch leaks in
+		// the gocryptfs FUSE process, but only in the tests that access it!
 		after := test_helpers.ListFds()
 		if len(before) != len(after) {
 			fmt.Printf("fd leak? before, after:\n%v\n%v\n", before, after)

tests/test_helpers/helpers.go

@@ -12,6 +12,7 @@ import (
 	"net"
 	"os"
 	"os/exec"
+	"os/signal"
 	"path/filepath"
 	"syscall"
 	"testing"
@@ -44,6 +45,9 @@ var DefaultPlainDir string
 // DefaultCipherDir is TmpDir + "/default-cipher"
 var DefaultCipherDir string
 
+// PID of the running gocryptfs process. Set by Mount().
+var MountPID int
+
 // SwitchTMPDIR changes TMPDIR and hence the directory the test are performed in.
 // This is used when you want to perform tests on a special filesystem. The
 // xattr tests cannot run on tmpfs and use /var/tmp instead of /tmp.
@@ -155,13 +159,11 @@ func InitFS(t *testing.T, extraArgs ...string) string {
 // Mount CIPHERDIR "c" on PLAINDIR "p"
 // Creates "p" if it does not exist.
 func Mount(c string, p string, showOutput bool, extraArgs ...string) error {
-	var args []string
-	args = append(args, "-q", "-wpanic", "-nosyslog")
+	args := []string{"-q", "-wpanic", "-nosyslog", "-fg", fmt.Sprintf("-notifypid=%d", os.Getpid())}
 	args = append(args, extraArgs...)
 	//args = append(args, "-fusedebug")
 	//args = append(args, "-d")
-	args = append(args, c)
-	args = append(args, p)
+	args = append(args, c, p)
 
 	if _, err := os.Stat(p); err != nil {
 		err = os.Mkdir(p, 0777)
@@ -190,7 +192,34 @@ func Mount(c string, p string, showOutput bool, extraArgs ...string) error {
 		}()
 	}
 
-	return cmd.Run()
+	// Two things can happen:
+	// 1) The mount fails and the process exits
+	// 2) The mount succeeds and the process sends us USR1
+	chanExit := make(chan error, 1)
+	chanUsr1 := make(chan os.Signal, 1)
+	signal.Notify(chanUsr1, syscall.SIGUSR1)
+
+	// Start the process and save the PID
+	err := cmd.Start()
+	if err != nil {
+		return err
+	}
+	MountPID = cmd.Process.Pid
+
+	// Wait for exit or usr1
+	go func() {
+		chanExit <- cmd.Wait()
+	}()
+	select {
+	case err := <-chanExit:
+		return err
+	case <-chanUsr1:
+		return nil
+	case <-time.After(1 * time.Second):
+		log.Panicf("Timeout waiting for process %d", MountPID)
+	}
+
+	return nil
 }
 
 // MountOrExit calls Mount() and exits on failure.