Improve interface by moving to subpkg

Enable builds on OSX

mount/MAINTAINERS

@@ -0,0 +1 @@
+Michael Crosby <michael@crosbymichael.com> (@crosbymichael)

mount/flags_darwin.go

@@ -0,0 +1,5 @@
+package mount
+
+func parseOptions(options string) (int, string) {
+	panic("Not implemented")
+}

mount/flags_linux.go

@@ -0,0 +1,61 @@
+package mount
+
+import (
+	"strings"
+	"syscall"
+)
+
+// Parse fstab type mount options into mount() flags
+// and device specific data
+func parseOptions(options string) (int, string) {
+	var (
+		flag int
+		data []string
+	)
+
+	flags := map[string]struct {
+		clear bool
+		flag  int
+	}{
+		"defaults":      {false, 0},
+		"ro":            {false, syscall.MS_RDONLY},
+		"rw":            {true, syscall.MS_RDONLY},
+		"suid":          {true, syscall.MS_NOSUID},
+		"nosuid":        {false, syscall.MS_NOSUID},
+		"dev":           {true, syscall.MS_NODEV},
+		"nodev":         {false, syscall.MS_NODEV},
+		"exec":          {true, syscall.MS_NOEXEC},
+		"noexec":        {false, syscall.MS_NOEXEC},
+		"sync":          {false, syscall.MS_SYNCHRONOUS},
+		"async":         {true, syscall.MS_SYNCHRONOUS},
+		"dirsync":       {false, syscall.MS_DIRSYNC},
+		"remount":       {false, syscall.MS_REMOUNT},
+		"mand":          {false, syscall.MS_MANDLOCK},
+		"nomand":        {true, syscall.MS_MANDLOCK},
+		"atime":         {true, syscall.MS_NOATIME},
+		"noatime":       {false, syscall.MS_NOATIME},
+		"diratime":      {true, syscall.MS_NODIRATIME},
+		"nodiratime":    {false, syscall.MS_NODIRATIME},
+		"bind":          {false, syscall.MS_BIND},
+		"rbind":         {false, syscall.MS_BIND | syscall.MS_REC},
+		"relatime":      {false, syscall.MS_RELATIME},
+		"norelatime":    {true, syscall.MS_RELATIME},
+		"strictatime":   {false, syscall.MS_STRICTATIME},
+		"nostrictatime": {true, syscall.MS_STRICTATIME},
+	}
+
+	for _, o := range strings.Split(options, ",") {
+		// If the option does not exist in the flags table then it is a
+		// data value for a specific fs type
+		if f, exists := flags[o]; exists {
+			if f.clear {
+				flag &= ^f.flag
+			} else {
+				flag |= f.flag
+			}
+		} else {
+			data = append(data, o)
+		}
+	}
+	return flag, strings.Join(data, ",")
+}

mount/mount.go

@@ -0,0 +1,53 @@
+package mount
+
+import (
+	"time"
+)
+
+// Looks at /proc/self/mountinfo to determine of the specified
+// mountpoint has been mounted
+func Mounted(mountpoint string) (bool, error) {
+	entries, err := parseMountTable()
+	if err != nil {
+		return false, err
+	}
+
+	// Search the table for the mountpoint
+	for _, e := range entries {
+		if e.mountpoint == mountpoint {
+			return true, nil
+		}
+	}
+	return false, nil
+}
+
+// Mount the specified options at the target path
+// Options must be specified as fstab style
+func Mount(device, target, mType, options string) error {
+	if mounted, err := Mounted(target); err != nil || mounted {
+		return err
+	}
+
+	flag, data := parseOptions(options)
+	if err := mount(device, target, mType, uintptr(flag), data); err != nil {
+		return err
+	}
+	return nil
+
+}
+
+// Unmount the target only if it is mounted
+func Unmount(target string) (err error) {
+	if mounted, err := Mounted(target); err != nil || !mounted {
+		return err
+	}
+
+	// Simple retry logic for unmount
+	for i := 0; i < 10; i++ {
+		if err = unmount(target, 0); err == nil {
+			return nil
+		}
+		time.Sleep(100 * time.Millisecond)
+	}
+	return
+}

mount/mount_test.go

@@ -0,0 +1,67 @@
+package mount
+
+import (
+	"os"
+	"path"
+	"syscall"
+	"testing"
+)
+
+func TestMountOptionsParsing(t *testing.T) {
+	options := "bind,ro,size=10k"
+
+	flag, data := parseOptions(options)
+
+	if data != "size=10k" {
+		t.Fatalf("Expected size=10 got %s", data)
+	}
+
+	expectedFlag := syscall.MS_BIND | syscall.MS_RDONLY
+
+	if flag != expectedFlag {
+		t.Fatalf("Expected %d got %d", expectedFlag, flag)
+	}
+}
+
+func TestMounted(t *testing.T) {
+	tmp := path.Join(os.TempDir(), "mount-tests")
+	if err := os.MkdirAll(tmp, 0777); err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(tmp)
+
+	var (
+		sourcePath = path.Join(tmp, "sourcefile.txt")
+		targetPath = path.Join(tmp, "targetfile.txt")
+	)
+
+	f, err := os.Create(sourcePath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.WriteString("hello")
+	f.Close()
+
+	f, err = os.Create(targetPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+
+	if err := Mount(sourcePath, targetPath, "none", "bind,ro"); err != nil {
+		t.Fatal(err)
+	}
+	defer func() {
+		if err := Unmount(targetPath); err != nil {
+			t.Fatal(err)
+		}
+	}()
+
+	mounted, err := Mounted(targetPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !mounted {
+		t.Fatalf("Expected %s to be mounted", targetPath)
+	}
+}

mount/mounter_darwin.go

@@ -0,0 +1,9 @@
+package mount
+
+func mount(device, target, mType string, flag uintptr, data string) error {
+	panic("Not implemented")
+}
+
+func unmount(target string, flag int) error {
+	panic("Not implemented")
+}

mount/mounter_linux.go

@@ -0,0 +1,13 @@
+package mount
+
+import (
+	"syscall"
+)
+
+func mount(device, target, mType string, flag uintptr, data string) error {
+	return syscall.Mount(device, target, mType, flag, data)
+}
+
+func unmount(target string, flag int) error {
+	return syscall.Unmount(target, flag)
+}

mount/mountinfo.go

@@ -0,0 +1,45 @@
+package mount
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+)
+
+const (
+	mountinfoFormat = "%d %d %d:%d %s %s %s - %s %s %s"
+)
+
+// Represents one line from /proc/self/mountinfo
+type procEntry struct {
+	id, parent, major, minor           int
+	source, mountpoint, fstype, device string
+	vfsopts, opts                      string
+}
+
+// Parse /proc/self/mountinfo because comparing Dev and ino does not work from bind mounts
+func parseMountTable() ([]*procEntry, error) {
+	f, err := os.Open("/proc/self/mountinfo")
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	s := bufio.NewScanner(f)
+	out := []*procEntry{}
+	for s.Scan() {
+		if err := s.Err(); err != nil {
+			return nil, err
+		}
+
+		p := &procEntry{}
+		if _, err := fmt.Sscanf(s.Text(), mountinfoFormat,
+			&p.id, &p.parent, &p.major, &p.minor,
+			&p.source, &p.mountpoint, &p.vfsopts, &p.fstype,
+			&p.device, &p.opts); err != nil {
+			return nil, err
+		}
+		out = append(out, p)
+	}
+	return out, nil
+}