mountinfo: refactored

Signed-off-by: Akihiro Suda <suda.akihiro@lab.ntt.co.jp>

mountinfo/mountinfo.go

@@ -23,23 +23,18 @@ type Info struct {
 	// Mountpoint indicates the mount point relative to the process's root.
 	Mountpoint string
 
-	// Opts represents mount-specific options.
+	// Options represents mount-specific options.
-	Opts string
+	Options string
 
 	// Optional represents optional fields.
 	Optional string
 
-	// Fstype indicates the type of filesystem, such as EXT3.
+	// FSType indicates the type of filesystem, such as EXT3.
-	Fstype string
+	FSType string
 
 	// Source indicates filesystem specific information or "none".
 	Source string
 
-	// VfsOpts represents per super block options.
+	// VFSOptions represents per super block options.
-	VfsOpts string
+	VFSOptions string
-}
-
-// GetMounts retrieves a list of mounts for the current running process.
-func GetMounts() ([]*Info, error) {
-	return parseMountTable()
 }

mountinfo/mountinfo_freebsd.go

@@ -13,9 +13,8 @@ import (
 	"unsafe"
 )
 
-// Parse /proc/self/mountinfo because comparing Dev and ino does not work from
+// Self retrieves a list of mounts for the current running process.
-// bind mounts.
+func Self() ([]Info, error) {
-func parseMountTable() ([]*Info, error) {
 	var rawEntries *C.struct_statfs
 
 	count := int(C.getmntinfo(&rawEntries, C.MNT_WAIT))
@@ -29,13 +28,18 @@ func parseMountTable() ([]*Info, error) {
 	header.Len = count
 	header.Data = uintptr(unsafe.Pointer(rawEntries))
 
-	var out []*Info
+	var out []Info
 	for _, entry := range entries {
 		var mountinfo Info
 		mountinfo.Mountpoint = C.GoString(&entry.f_mntonname[0])
 		mountinfo.Source = C.GoString(&entry.f_mntfromname[0])
-		mountinfo.Fstype = C.GoString(&entry.f_fstypename[0])
+		mountinfo.FSType = C.GoString(&entry.f_fstypename[0])
-		out = append(out, &mountinfo)
+		out = append(out, mountinfo)
 	}
 	return out, nil
 }
+
+// PID collects the mounts for a specific process ID.
+func PID(pid int) ([]Info, error) {
+	return nil, fmt.Errorf("mountinfo.PID is not implemented on freebsd")
+}

mountinfo/mountinfo_linux.go

@@ -28,9 +28,8 @@ const (
 	mountinfoFormat = "%d %d %d:%d %s %s %s %s"
 )
 
-// Parse /proc/self/mountinfo because comparing Dev and ino does not work from
+// Self retrieves a list of mounts for the current running process.
-// bind mounts
+func Self() ([]Info, error) {
-func parseMountTable() ([]*Info, error) {
 	f, err := os.Open("/proc/self/mountinfo")
 	if err != nil {
 		return nil, err
@@ -40,10 +39,10 @@ func parseMountTable() ([]*Info, error) {
 	return parseInfoFile(f)
 }
 
-func parseInfoFile(r io.Reader) ([]*Info, error) {
+func parseInfoFile(r io.Reader) ([]Info, error) {
 	var (
 		s   = bufio.NewScanner(r)
-		out = []*Info{}
+		out = []Info{}
 	)
 
 	for s.Scan() {
@@ -52,14 +51,14 @@ func parseInfoFile(r io.Reader) ([]*Info, error) {
 		}
 
 		var (
-			p              = &Info{}
+			p              = Info{}
 			text           = s.Text()
 			optionalFields string
 		)
 
 		if _, err := fmt.Sscanf(text, mountinfoFormat,
 			&p.ID, &p.Parent, &p.Major, &p.Minor,
-			&p.Root, &p.Mountpoint, &p.Opts, &optionalFields); err != nil {
+			&p.Root, &p.Mountpoint, &p.Options, &optionalFields); err != nil {
 			return nil, fmt.Errorf("Scanning '%s' failed: %s", text, err)
 		}
 		// Safe as mountinfo encodes mountpoints with spaces as \040.
@@ -73,18 +72,18 @@ func parseInfoFile(r io.Reader) ([]*Info, error) {
 			p.Optional = optionalFields
 		}
 
-		p.Fstype = postSeparatorFields[0]
+		p.FSType = postSeparatorFields[0]
 		p.Source = postSeparatorFields[1]
-		p.VfsOpts = strings.Join(postSeparatorFields[2:], " ")
+		p.VFSOptions = strings.Join(postSeparatorFields[2:], " ")
 		out = append(out, p)
 	}
 	return out, nil
 }
 
-// PidMountInfo collects the mounts for a specific process ID. If the process
+// PID collects the mounts for a specific process ID. If the process
-// ID is unknown, it is better to use `GetMounts` which will inspect
+// ID is unknown, it is better to use `Self` which will inspect
 // "/proc/self/mountinfo" instead.
-func PidMountInfo(pid int) ([]*Info, error) {
+func PID(pid int) ([]Info, error) {
 	f, err := os.Open(fmt.Sprintf("/proc/%d/mountinfo", pid))
 	if err != nil {
 		return nil, err

mountinfo/mountinfo_linux_test.go

@@ -463,14 +463,14 @@ func TestParseFedoraMountinfoFields(t *testing.T) {
 		Minor:      3,
 		Root:       "/",
 		Mountpoint: "/proc",
-		Opts:       "rw,nosuid,nodev,noexec,relatime",
+		Options:    "rw,nosuid,nodev,noexec,relatime",
 		Optional:   "shared:5",
-		Fstype:     "proc",
+		FSType:     "proc",
 		Source:     "proc",
-		VfsOpts:    "rw",
+		VFSOptions: "rw",
 	}
 
-	if *infos[0] != mi {
+	if infos[0] != mi {
 		t.Fatalf("expected %#v, got %#v", mi, infos[0])
 	}
 }

mountinfo/mountinfo_solaris.go

@@ -12,13 +12,14 @@ import (
 	"fmt"
 )
 
-func parseMountTable() ([]*Info, error) {
+// Self retrieves a list of mounts for the current running process.
+func Self() ([]Info, error) {
 	mnttab := C.fopen(C.CString(C.MNTTAB), C.CString("r"))
 	if mnttab == nil {
 		return nil, fmt.Errorf("Failed to open %s", C.MNTTAB)
 	}
 
-	var out []*Info
+	var out []Info
 	var mp C.struct_mnttab
 
 	ret := C.getmntent(mnttab, &mp)
@@ -26,12 +27,17 @@ func parseMountTable() ([]*Info, error) {
 		var mountinfo Info
 		mountinfo.Mountpoint = C.GoString(mp.mnt_mountp)
 		mountinfo.Source = C.GoString(mp.mnt_special)
-		mountinfo.Fstype = C.GoString(mp.mnt_fstype)
+		mountinfo.FSType = C.GoString(mp.mnt_fstype)
-		mountinfo.Opts = C.GoString(mp.mnt_mntopts)
+		mountinfo.Options = C.GoString(mp.mnt_mntopts)
-		out = append(out, &mountinfo)
+		out = append(out, mountinfo)
 		ret = C.getmntent(mnttab, &mp)
 	}
 
 	C.fclose(mnttab)
 	return out, nil
 }
+
+// PID collects the mounts for a specific process ID.
+func PID(pid int) ([]Info, error) {
+	return nil, fmt.Errorf("mountinfo.PID is not implemented on solaris")
+}

mountinfo/mountinfo_unsupported.go

@@ -1,4 +1,4 @@
-// +build !windows,!linux,!freebsd,!solaris freebsd,!cgo solaris,!cgo
+// +build !linux,!freebsd,!solaris freebsd,!cgo solaris,!cgo
 
 package mountinfo
 
@@ -7,6 +7,12 @@ import (
 	"runtime"
 )
 
-func parseMountTable() ([]*Info, error) {
+// Self retrieves a list of mounts for the current running process.
-	return nil, fmt.Errorf("mount.parseMountTable is not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
+func Self() ([]Info, error) {
+	return nil, fmt.Errorf("mountinfo.Self is not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
+}
+
+// PID collects the mounts for a specific process ID.
+func PID(pid int) ([]Info, error) {
+	return nil, fmt.Errorf("mountinfo.PID is not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
 }

mountinfo/mountinfo_windows.go

@@ -1,6 +0,0 @@
-package mountinfo
-
-func parseMountTable() ([]*Info, error) {
-	// Do NOT return an error!
-	return nil, nil
-}

snapshot/btrfs/btrfs.go

@@ -36,17 +36,17 @@ type snapshotter struct {
 	ms     *storage.MetaStore
 }
 
-func getBtrfsDevice(root string, mounts []*mountinfo.Info) (string, error) {
+func getBtrfsDevice(root string, mounts []mountinfo.Info) (string, error) {
 	device := ""
 	deviceMountpoint := ""
 	for _, info := range mounts {
 		if (info.Root == "/" || info.Root == "") && strings.HasPrefix(root, info.Mountpoint) {
-			if info.Fstype == "btrfs" && len(info.Mountpoint) > len(deviceMountpoint) {
+			if info.FSType == "btrfs" && len(info.Mountpoint) > len(deviceMountpoint) {
 				device = info.Source
 				deviceMountpoint = info.Mountpoint
 			}
-			if root == info.Mountpoint && info.Fstype != "btrfs" {
+			if root == info.Mountpoint && info.FSType != "btrfs" {
-				return "", fmt.Errorf("%s needs to be btrfs, but seems %s", root, info.Fstype)
+				return "", fmt.Errorf("%s needs to be btrfs, but seems %s", root, info.FSType)
 			}
 		}
 	}
@@ -62,7 +62,7 @@ func getBtrfsDevice(root string, mounts []*mountinfo.Info) (string, error) {
 // a file in the provided root.
 // root needs to be a mount point of btrfs.
 func NewSnapshotter(root string) (snapshot.Snapshotter, error) {
-	mounts, err := mountinfo.GetMounts()
+	mounts, err := mountinfo.Self()
 	if err != nil {
 		return nil, err
 	}

snapshot/btrfs/btrfs_test.go

@@ -222,45 +222,45 @@ func TestGetBtrfsDevice(t *testing.T) {
 		expectedDevice string
 		expectedError  string
 		root           string
-		mounts         []*mountinfo.Info
+		mounts         []mountinfo.Info
 	}{
 		{
 			expectedDevice: "/dev/loop0",
 			root:           "/var/lib/containerd/snapshot/btrfs",
-			mounts: []*mountinfo.Info{
+			mounts: []mountinfo.Info{
-				{Root: "/", Mountpoint: "/", Fstype: "ext4", Source: "/dev/sda1"},
+				{Root: "/", Mountpoint: "/", FSType: "ext4", Source: "/dev/sda1"},
-				{Root: "/", Mountpoint: "/var/lib/containerd/snapshot/btrfs", Fstype: "btrfs", Source: "/dev/loop0"},
+				{Root: "/", Mountpoint: "/var/lib/containerd/snapshot/btrfs", FSType: "btrfs", Source: "/dev/loop0"},
 			},
 		},
 		{
 			expectedError: "/var/lib/containerd/snapshot/btrfs is not mounted as btrfs",
 			root:          "/var/lib/containerd/snapshot/btrfs",
-			mounts: []*mountinfo.Info{
+			mounts: []mountinfo.Info{
-				{Root: "/", Mountpoint: "/", Fstype: "ext4", Source: "/dev/sda1"},
+				{Root: "/", Mountpoint: "/", FSType: "ext4", Source: "/dev/sda1"},
 			},
 		},
 		{
 			expectedDevice: "/dev/sda1",
 			root:           "/var/lib/containerd/snapshot/btrfs",
-			mounts: []*mountinfo.Info{
+			mounts: []mountinfo.Info{
-				{Root: "/", Mountpoint: "/", Fstype: "btrfs", Source: "/dev/sda1"},
+				{Root: "/", Mountpoint: "/", FSType: "btrfs", Source: "/dev/sda1"},
 			},
 		},
 		{
 			expectedDevice: "/dev/sda2",
 			root:           "/var/lib/containerd/snapshot/btrfs",
-			mounts: []*mountinfo.Info{
+			mounts: []mountinfo.Info{
-				{Root: "/", Mountpoint: "/", Fstype: "btrfs", Source: "/dev/sda1"},
+				{Root: "/", Mountpoint: "/", FSType: "btrfs", Source: "/dev/sda1"},
-				{Root: "/", Mountpoint: "/var/lib/containerd/snapshot/btrfs", Fstype: "btrfs", Source: "/dev/sda2"},
+				{Root: "/", Mountpoint: "/var/lib/containerd/snapshot/btrfs", FSType: "btrfs", Source: "/dev/sda2"},
 			},
 		},
 		{
 			expectedDevice: "/dev/sda2",
 			root:           "/var/lib/containerd/snapshot/btrfs",
-			mounts: []*mountinfo.Info{
+			mounts: []mountinfo.Info{
-				{Root: "/", Mountpoint: "/var/lib/containerd/snapshot/btrfs", Fstype: "btrfs", Source: "/dev/sda2"},
+				{Root: "/", Mountpoint: "/var/lib/containerd/snapshot/btrfs", FSType: "btrfs", Source: "/dev/sda2"},
-				{Root: "/", Mountpoint: "/var/lib/foooooooooooooooooooo/baaaaaaaaaaaaaaaaaaaar", Fstype: "btrfs", Source: "/dev/sda3"}, // mountpoint length longer than /var/lib/containerd/snapshot/btrfs
+				{Root: "/", Mountpoint: "/var/lib/foooooooooooooooooooo/baaaaaaaaaaaaaaaaaaaar", FSType: "btrfs", Source: "/dev/sda3"}, // mountpoint length longer than /var/lib/containerd/snapshot/btrfs
-				{Root: "/", Mountpoint: "/", Fstype: "btrfs", Source: "/dev/sda1"},
+				{Root: "/", Mountpoint: "/", FSType: "btrfs", Source: "/dev/sda1"},
 			},
 		},
 	}