swarm/api: support mounting manifests via FUSE (#3690)

1 files changed, 111 insertions, 0 deletions

diff --git a/vendor/bazil.org/fuse/mount_freebsd.go b/vendor/bazil.org/fuse/mount_freebsd.go
new file mode 100644
index 000000000..70bb41024
--- /dev/null
+++ b/vendor/bazil.org/fuse/mount_freebsd.go
@@ -0,0 +1,111 @@
+package fuse
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"os/exec"
+	"strings"
+	"sync"
+	"syscall"
+)
+
+func handleMountFusefsStderr(errCh chan<- error) func(line string) (ignore bool) {
+	return func(line string) (ignore bool) {
+		const (
+			noMountpointPrefix = `mount_fusefs: `
+			noMountpointSuffix = `: No such file or directory`
+		)
+		if strings.HasPrefix(line, noMountpointPrefix) && strings.HasSuffix(line, noMountpointSuffix) {
+			// re-extract it from the error message in case some layer
+			// changed the path
+			mountpoint := line[len(noMountpointPrefix) : len(line)-len(noMountpointSuffix)]
+			err := &MountpointDoesNotExistError{
+				Path: mountpoint,
+			}
+			select {
+			case errCh <- err:
+				return true
+			default:
+				// not the first error; fall back to logging it
+				return false
+			}
+		}
+
+		return false
+	}
+}
+
+// isBoringMountFusefsError returns whether the Wait error is
+// uninteresting; exit status 1 is.
+func isBoringMountFusefsError(err error) bool {
+	if err, ok := err.(*exec.ExitError); ok && err.Exited() {
+		if status, ok := err.Sys().(syscall.WaitStatus); ok && status.ExitStatus() == 1 {
+			return true
+		}
+	}
+	return false
+}
+
+func mount(dir string, conf *mountConfig, ready chan<- struct{}, errp *error) (*os.File, error) {
+	for k, v := range conf.options {
+		if strings.Contains(k, ",") || strings.Contains(v, ",") {
+			// Silly limitation but the mount helper does not
+			// understand any escaping. See TestMountOptionCommaError.
+			return nil, fmt.Errorf("mount options cannot contain commas on FreeBSD: %q=%q", k, v)
+		}
+	}
+
+	f, err := os.OpenFile("/dev/fuse", os.O_RDWR, 0000)
+	if err != nil {
+		*errp = err
+		return nil, err
+	}
+
+	cmd := exec.Command(
+		"/sbin/mount_fusefs",
+		"--safe",
+		"-o", conf.getOptions(),
+		"3",
+		dir,
+	)
+	cmd.ExtraFiles = []*os.File{f}
+
+	stdout, err := cmd.StdoutPipe()
+	if err != nil {
+		return nil, fmt.Errorf("setting up mount_fusefs stderr: %v", err)
+	}
+	stderr, err := cmd.StderrPipe()
+	if err != nil {
+		return nil, fmt.Errorf("setting up mount_fusefs stderr: %v", err)
+	}
+
+	if err := cmd.Start(); err != nil {
+		return nil, fmt.Errorf("mount_fusefs: %v", err)
+	}
+	helperErrCh := make(chan error, 1)
+	var wg sync.WaitGroup
+	wg.Add(2)
+	go lineLogger(&wg, "mount helper output", neverIgnoreLine, stdout)
+	go lineLogger(&wg, "mount helper error", handleMountFusefsStderr(helperErrCh), stderr)
+	wg.Wait()
+	if err := cmd.Wait(); err != nil {
+		// see if we have a better error to report
+		select {
+		case helperErr := <-helperErrCh:
+			// log the Wait error if it's not what we expected
+			if !isBoringMountFusefsError(err) {
+				log.Printf("mount helper failed: %v", err)
+			}
+			// and now return what we grabbed from stderr as the real
+			// error
+			return nil, helperErr
+		default:
+			// nope, fall back to generic message
+		}
+		return nil, fmt.Errorf("mount_fusefs: %v", err)
+	}
+
+	close(ready)
+	return f, nil
+}