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// Copyright 2018 Google Inc. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package paths
import (
"context"
"encoding/gob"
"fmt"
"io/ioutil"
"net"
"os"
"path/filepath"
"runtime"
"sync"
"syscall"
"time"
)
type LogProcess struct {
Pid int
Command string
}
type LogEntry struct {
Basename string
Args []string
Parents []LogProcess
}
const timeoutDuration = time.Duration(100) * time.Millisecond
type socketAddrFunc func(string) (string, func(), error)
func procFallback(name string) (string, func(), error) {
d, err := os.Open(filepath.Dir(name))
if err != nil {
return "", func() {}, err
}
return fmt.Sprintf("/proc/self/fd/%d/%s", d.Fd(), filepath.Base(name)), func() {
d.Close()
}, nil
}
func tmpFallback(name string) (addr string, cleanup func(), err error) {
d, err := ioutil.TempDir("/tmp", "log_sock")
if err != nil {
cleanup = func() {}
return
}
cleanup = func() {
os.RemoveAll(d)
}
dir := filepath.Dir(name)
absDir, err := filepath.Abs(dir)
if err != nil {
return
}
err = os.Symlink(absDir, filepath.Join(d, "d"))
if err != nil {
return
}
addr = filepath.Join(d, "d", filepath.Base(name))
return
}
func getSocketAddr(name string) (string, func(), error) {
maxNameLen := len(syscall.RawSockaddrUnix{}.Path)
if len(name) < maxNameLen {
return name, func() {}, nil
}
if runtime.GOOS == "linux" {
addr, cleanup, err := procFallback(name)
if err == nil {
if len(addr) < maxNameLen {
return addr, cleanup, nil
}
}
cleanup()
}
addr, cleanup, err := tmpFallback(name)
if err == nil {
if len(addr) < maxNameLen {
return addr, cleanup, nil
}
}
cleanup()
return name, func() {}, fmt.Errorf("Path to socket is still over size limit, fallbacks failed.")
}
func dial(name string, lookup socketAddrFunc, timeout time.Duration) (net.Conn, error) {
socket, cleanup, err := lookup(name)
defer cleanup()
if err != nil {
return nil, err
}
dialer := &net.Dialer{
Timeout: timeout,
}
return dialer.Dial("unix", socket)
}
func listen(name string, lookup socketAddrFunc) (net.Listener, error) {
socket, cleanup, err := lookup(name)
defer cleanup()
if err != nil {
return nil, err
}
return net.Listen("unix", socket)
}
func SendLog(logSocket string, entry *LogEntry, done chan interface{}) {
sendLog(logSocket, getSocketAddr, timeoutDuration, entry, done)
}
func sendLog(logSocket string, lookup socketAddrFunc, timeout time.Duration, entry *LogEntry, done chan interface{}) {
defer close(done)
conn, err := dial(logSocket, lookup, timeout)
if err != nil {
return
}
defer conn.Close()
if timeout != 0 {
conn.SetDeadline(time.Now().Add(timeout))
}
enc := gob.NewEncoder(conn)
enc.Encode(entry)
}
func LogListener(ctx context.Context, logSocket string) (chan *LogEntry, error) {
return logListener(ctx, logSocket, getSocketAddr)
}
func logListener(ctx context.Context, logSocket string, lookup socketAddrFunc) (chan *LogEntry, error) {
ret := make(chan *LogEntry, 5)
if err := os.Remove(logSocket); err != nil && !os.IsNotExist(err) {
return nil, err
}
ln, err := listen(logSocket, lookup)
if err != nil {
return nil, err
}
go func() {
for {
select {
case <-ctx.Done():
ln.Close()
}
}
}()
go func() {
var wg sync.WaitGroup
defer func() {
wg.Wait()
close(ret)
}()
for {
conn, err := ln.Accept()
if err != nil {
ln.Close()
break
}
conn.SetDeadline(time.Now().Add(timeoutDuration))
wg.Add(1)
go func() {
defer wg.Done()
defer conn.Close()
dec := gob.NewDecoder(conn)
entry := &LogEntry{}
if err := dec.Decode(entry); err != nil {
return
}
ret <- entry
}()
}
}()
return ret, nil
}
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