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refactor inotify implementation

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This commit is contained in:
Dominic Breuker
2018-02-26 09:29:06 +01:00
parent 6c79b80623
commit d38cb18712
9 changed files with 154 additions and 235 deletions
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65
internal/fswatcher/event.go
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@@ -1,75 +1,22 @@
package fswatcher
import (
"bytes"
"fmt"
"strconv"
"unsafe"
"github.com/dominicbreuker/pspy/internal/fswatcher/inotify"
"golang.org/x/sys/unix"
)
var InotifyEvents = map[uint32]string{
unix.IN_ACCESS: "ACCESS",
unix.IN_ATTRIB: "ATTRIB",
unix.IN_CLOSE_NOWRITE: "CLOSE_NOWRITE",
unix.IN_CLOSE_WRITE: "CLOSE_WRITE",
unix.IN_CREATE: "CREATE",
unix.IN_DELETE: "DELETE",
unix.IN_DELETE_SELF: "DELETE_SELF",
unix.IN_MODIFY: "MODIFY",
unix.IN_MOVED_FROM: "MOVED_FROM",
unix.IN_MOVED_TO: "MOVED_TO",
unix.IN_MOVE_SELF: "MOVE_SELF",
unix.IN_OPEN: "OPEN",
(unix.IN_ACCESS | unix.IN_ISDIR): "ACCESS DIR",
(unix.IN_ATTRIB | unix.IN_ISDIR): "ATTRIB DIR",
(unix.IN_CLOSE_NOWRITE | unix.IN_ISDIR): "CLOSE_NOWRITE DIR",
(unix.IN_CLOSE_WRITE | unix.IN_ISDIR): "CLOSE_WRITE DIR",
(unix.IN_CREATE | unix.IN_ISDIR): "CREATE DIR",
(unix.IN_DELETE | unix.IN_ISDIR): "DELETE DIR",
(unix.IN_DELETE_SELF | unix.IN_ISDIR): "DELETE_SELF DIR",
(unix.IN_MODIFY | unix.IN_ISDIR): "MODIFY DIR",
(unix.IN_MOVED_FROM | unix.IN_ISDIR): "MOVED_FROM DIR",
(unix.IN_MOVE_SELF | unix.IN_ISDIR): "MODE_SELF DIR",
(unix.IN_OPEN | unix.IN_ISDIR): "OPEN DIR",
}
func parseEvents(i *inotify.Inotify, dataCh chan []byte, eventCh chan string, errCh chan error) {
for buf := range dataCh {
n := len(buf)
if n < unix.SizeofInotifyEvent {
errCh <- fmt.Errorf("Inotify event parser: incomplete read: n=%d", n)
continue
}
var ptr uint32
var name string
for ptr <= uint32(n-unix.SizeofInotifyEvent) {
sys := (*unix.InotifyEvent)(unsafe.Pointer(&buf[ptr]))
ptr += unix.SizeofInotifyEvent
watcher, ok := i.Watchers[int(sys.Wd)]
if !ok {
errCh <- fmt.Errorf("Inotify event parser: unknown watcher ID: %d", sys.Wd)
for len(buf[ptr:]) > 0 {
event, size, err := i.ParseNextEvent(buf[ptr:])
if err != nil {
errCh <- fmt.Errorf("parsing events: %v", err)
continue
}
name = watcher.Dir + "/"
if sys.Len > 0 && len(buf) >= int(ptr+sys.Len) {
name += string(bytes.TrimRight(buf[ptr:ptr+sys.Len], "\x00"))
ptr += sys.Len
}
eventCh <- formatEvent(name, sys.Mask)
ptr += size
eventCh <- fmt.Sprintf("%20s | %s", event.Op, event.Name)
}
}
}
func formatEvent(name string, mask uint32) string {
op, ok := InotifyEvents[mask]
if !ok {
op = strconv.FormatInt(int64(mask), 2)
}
return fmt.Sprintf("%20s | %s", op, name)
}

29
internal/fswatcher/inotify/event.go Normal file
View File

@@ -0,0 +1,29 @@
package inotify
import "golang.org/x/sys/unix"
var InotifyEvents = map[uint32]string{
unix.IN_ACCESS: "ACCESS",
unix.IN_ATTRIB: "ATTRIB",
unix.IN_CLOSE_NOWRITE: "CLOSE_NOWRITE",
unix.IN_CLOSE_WRITE: "CLOSE_WRITE",
unix.IN_CREATE: "CREATE",
unix.IN_DELETE: "DELETE",
unix.IN_DELETE_SELF: "DELETE_SELF",
unix.IN_MODIFY: "MODIFY",
unix.IN_MOVED_FROM: "MOVED_FROM",
unix.IN_MOVED_TO: "MOVED_TO",
unix.IN_MOVE_SELF: "MOVE_SELF",
unix.IN_OPEN: "OPEN",
(unix.IN_ACCESS | unix.IN_ISDIR): "ACCESS DIR",
(unix.IN_ATTRIB | unix.IN_ISDIR): "ATTRIB DIR",
(unix.IN_CLOSE_NOWRITE | unix.IN_ISDIR): "CLOSE_NOWRITE DIR",
(unix.IN_CLOSE_WRITE | unix.IN_ISDIR): "CLOSE_WRITE DIR",
(unix.IN_CREATE | unix.IN_ISDIR): "CREATE DIR",
(unix.IN_DELETE | unix.IN_ISDIR): "DELETE DIR",
(unix.IN_DELETE_SELF | unix.IN_ISDIR): "DELETE_SELF DIR",
(unix.IN_MODIFY | unix.IN_ISDIR): "MODIFY DIR",
(unix.IN_MOVED_FROM | unix.IN_ISDIR): "MOVED_FROM DIR",
(unix.IN_MOVE_SELF | unix.IN_ISDIR): "MODE_SELF DIR",
(unix.IN_OPEN | unix.IN_ISDIR): "OPEN DIR",
}

95
internal/fswatcher/inotify/inotify.go
View File

@@ -1,40 +1,50 @@
package inotify
import (
"bytes"
"fmt"
"io/ioutil"
"strconv"
"strings"
"unsafe"
"golang.org/x/sys/unix"
)
type InotifySyscalls interface {
Init() (int, error)
AddWatch(int, string) (int, error)
Close(int) error
}
const maximumWatchersFile = "/proc/sys/fs/inotify/max_user_watches"
type Inotify struct {
FD int
Watchers map[int]*Watcher
sys InotifySyscalls
}
func NewInotify(isys InotifySyscalls) (*Inotify, error) {
fd, err := isys.Init()
if err != nil {
return nil, fmt.Errorf("initializing inotify: %v", err)
type Watcher struct {
WD int
Dir string
}
type Event struct {
Name string
Op string
}
func NewInotify() (*Inotify, error) {
fd, errno := unix.InotifyInit1(unix.IN_CLOEXEC)
if fd < 0 {
return nil, fmt.Errorf("initializing inotify: errno: %d", errno)
}
i := &Inotify{
FD: fd,
Watchers: make(map[int]*Watcher),
sys: isys,
}
return i, nil
}
func (i *Inotify) Watch(dir string) error {
wd, err := i.sys.AddWatch(i.FD, dir)
if err != nil {
return fmt.Errorf("adding watcher on %s: %v", dir, err)
wd, errno := unix.InotifyAddWatch(i.FD, dir, unix.IN_ALL_EVENTS)
if wd < 0 {
return fmt.Errorf("adding watch: errno: %d", errno)
}
i.Watchers[wd] = &Watcher{
WD: wd,
@@ -43,9 +53,45 @@ func (i *Inotify) Watch(dir string) error {
return nil
}
func (i *Inotify) Read(buf []byte) (int, error) {
n, errno := unix.Read(i.FD, buf)
if n < 0 {
return n, fmt.Errorf("reading from inotify fd %d: errno: %d", i.FD, errno)
}
return n, nil
}
func (i *Inotify) ParseNextEvent(buf []byte) (*Event, uint32, error) {
n := len(buf)
if n < unix.SizeofInotifyEvent {
return nil, uint32(n), fmt.Errorf("incomplete read: n=%d", n)
}
sys := (*unix.InotifyEvent)(unsafe.Pointer(&buf[0]))
offset := unix.SizeofInotifyEvent + sys.Len
watcher, ok := i.Watchers[int(sys.Wd)]
if !ok {
return nil, offset, fmt.Errorf("unknown watcher ID: %d", sys.Wd)
}
name := watcher.Dir + "/"
if sys.Len > 0 && len(buf) >= int(offset) {
name += string(bytes.TrimRight(buf[unix.SizeofInotifyEvent:offset], "\x00"))
}
op, ok := InotifyEvents[sys.Mask]
if !ok {
op = strconv.FormatInt(int64(sys.Mask), 2)
}
return &Event{
Name: name,
Op: op,
}, offset, nil
}
func (i *Inotify) Close() error {
if err := i.sys.Close(i.FD); err != nil {
return fmt.Errorf("closing inotify file descriptor: %v", err)
if err := unix.Close(i.FD); err != nil {
return fmt.Errorf("closing inotify fd: %v", err)
}
return nil
}
@@ -65,3 +111,18 @@ func (i *Inotify) String() string {
return fmt.Sprintf("Watching %d directories", len(i.Watchers))
}
}
func GetMaxWatchers() (int, error) {
b, err := ioutil.ReadFile(maximumWatchersFile)
if err != nil {
return 0, fmt.Errorf("reading from %s: %v", maximumWatchersFile, err)
}
s := strings.TrimSpace(string(b))
m, err := strconv.Atoi(s)
if err != nil {
return 0, fmt.Errorf("converting to integer: %v", err)
}
return m, nil
}

75
internal/fswatcher/inotify/inotify_test.go
View File

@@ -1,49 +1,46 @@
package inotify
import (
"errors"
"io/ioutil"
"os"
"testing"
"golang.org/x/sys/unix"
)
func TestNewInotify(t *testing.T) {
mis := &MockInotifySyscalls{fd: 1}
func TestInotify(t *testing.T) {
i, err := NewInotify()
expectNoError(t, err)
i, err := NewInotify(mis)
err = i.Watch("testdata/folder")
expectNoError(t, err)
err = ioutil.WriteFile("testdata/folder/f1", []byte("file content"), 0644)
expectNoError(t, err)
defer os.Remove("testdata/folder/f1")
buf := make([]byte, 5*unix.SizeofInotifyEvent)
_, err = i.Read(buf)
expectNoError(t, err)
e, offset, err := i.ParseNextEvent(buf[0:])
expectNoError(t, err)
if e.Name != "testdata/folder/f1" {
t.Fatalf("Wrong event name: %s", e.Name)
}
if e.Op != "CREATE" {
t.Fatalf("Wrong op: %s", e.Op)
}
if offset != 32 {
t.Fatalf("Wrong offset: %d", offset)
}
err = i.Close()
expectNoError(t, err)
}
func expectNoError(t *testing.T, err error) {
if err != nil {
t.Fatalf("Unexpected error")
}
if i.FD != mis.fd {
t.Fatalf("Did not set FD of inotify object")
t.Fatalf("Unexpected error: %v", err)
}
}
func TestNewInotifyError(t *testing.T) {
mis := &MockInotifySyscalls{fd: -1}
_, err := NewInotify(mis)
if err == nil || err.Error() != "initializing inotify: syscall error" {
t.Fatalf("Expected syscall error but did not get: %v", err)
}
}
// mock
type MockInotifySyscalls struct {
fd int
}
func (mis *MockInotifySyscalls) Init() (int, error) {
if mis.fd >= 0 {
return mis.fd, nil
} else {
return -1, errors.New("syscall error")
}
}
func (mis *MockInotifySyscalls) AddWatch(fd int, dir string) (int, error) {
return 2, nil
}
func (mis *MockInotifySyscalls) Close(fd int) error {
return nil
}

36
internal/fswatcher/inotify/sys/syscalls.go
View File

@@ -1,36 +0,0 @@
// +build linux
package sys
import (
"fmt"
"golang.org/x/sys/unix"
)
const events = unix.IN_ALL_EVENTS
type InotifySyscallsUNIX struct{}
func (isu *InotifySyscallsUNIX) Init() (int, error) {
fd, errno := unix.InotifyInit1(unix.IN_CLOEXEC)
if fd < 0 {
return fd, fmt.Errorf("errno: %d", errno)
}
return fd, nil
}
func (isu *InotifySyscallsUNIX) AddWatch(fd int, dir string) (int, error) {
wd, errno := unix.InotifyAddWatch(fd, dir, events)
if wd < 0 {
return wd, fmt.Errorf("errno: %d", errno)
}
return wd, nil
}
func (isu *InotifySyscallsUNIX) Close(fd int) error {
if err := unix.Close(fd); err != nil {
return err
}
return nil
}

45
internal/fswatcher/inotify/sys/syscalls_test.go
View File

@@ -1,45 +0,0 @@
// +build linux
package sys
import (
"testing"
)
func TestSyscalls(t *testing.T) {
is := &InotifySyscallsUNIX{}
fd, err := is.Init()
if err != nil {
t.Fatalf("Unexpected error for inotify init: %v", err)
}
_, err = is.AddWatch(fd, "testdata")
if err != nil {
t.Fatalf("Unexpected error adding watch to dir 'testdata': %v", err)
}
err = is.Close(fd)
if err != nil {
t.Fatalf("Unexpected error closing inotify: %v", err)
}
}
func TestSyscallsError(t *testing.T) {
is := &InotifySyscallsUNIX{}
fd, err := is.Init()
if err != nil {
t.Fatalf("Unexpected error for inotify init: %v", err)
}
_, err = is.AddWatch(fd, "non-existing-dir")
if err == nil || err.Error() != "errno: 2" {
t.Fatalf("Expected errno 2 for non-existing-dir but got: %v", err)
}
err = is.Close(fd)
if err != nil {
t.Fatalf("Unexpected error closing inotify: %v", err)
}
}

30
internal/fswatcher/inotify/watcher.go
View File

@@ -1,30 +0,0 @@
package inotify
import (
"fmt"
"io/ioutil"
"strconv"
"strings"
)
const maximumWatchersFile = "/proc/sys/fs/inotify/max_user_watches"
type Watcher struct {
WD int
Dir string
}
func GetLimit() (int, error) {
b, err := ioutil.ReadFile(maximumWatchersFile)
if err != nil {
return 0, fmt.Errorf("reading from %s: %v", maximumWatchersFile, err)
}
s := strings.TrimSpace(string(b))
m, err := strconv.Atoi(s)
if err != nil {
return 0, fmt.Errorf("converting to integer: %v", err)
}
return m, nil
}

9
internal/fswatcher/observer.go
View File

@@ -1,8 +1,6 @@
package fswatcher
import (
"fmt"
"github.com/dominicbreuker/pspy/internal/fswatcher/inotify"
"golang.org/x/sys/unix"
)
@@ -11,10 +9,9 @@ func Observe(i *inotify.Inotify, triggerCh chan struct{}, dataCh chan []byte, er
buf := make([]byte, 5*unix.SizeofInotifyEvent)
for {
n, errno := unix.Read(i.FD, buf)
if n == -1 {
errCh <- fmt.Errorf("reading from inotify fd: errno: %d", errno)
return
n, err := i.Read(buf)
if err != nil {
errCh <- err
}
triggerCh <- struct{}{}
bufCopy := make([]byte, n)

5
internal/fswatcher/setup.go
View File

@@ -4,7 +4,6 @@ import (
"fmt"
"github.com/dominicbreuker/pspy/internal/fswatcher/inotify"
isys "github.com/dominicbreuker/pspy/internal/fswatcher/inotify/sys"
"github.com/dominicbreuker/pspy/internal/fswatcher/walker"
)
@@ -17,7 +16,7 @@ func (iw *InotifyWatcher) Close() {
}
func NewInotifyWatcher() (*InotifyWatcher, error) {
i, err := inotify.NewInotify(&isys.InotifySyscallsUNIX{})
i, err := inotify.NewInotify()
if err != nil {
return nil, fmt.Errorf("setting up inotify: %v", err)
}
@@ -27,7 +26,7 @@ func NewInotifyWatcher() (*InotifyWatcher, error) {
}
func (iw *InotifyWatcher) Setup(rdirs, dirs []string, errCh chan error) (chan struct{}, chan string, error) {
maxWatchers, err := getLimit()
maxWatchers, err := inotify.GetMaxWatchers()
if err != nil {
errCh <- fmt.Errorf("Can't get inotify watcher limit...: %v\n", err)
maxWatchers = -1