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// Package eows is used to Execute commands Over WebSocket
package eows
import (
"fmt"
"os"
"strings"
"time"
"github.com/Sirupsen/logrus"
"github.com/googollee/go-socket.io"
)
// OnInputCB is the function callback used to receive data
type OnInputCB func(e *ExecOverWS, stdin string) (string, error)
// EmitOutputCB is the function callback used to emit data
type EmitOutputCB func(e *ExecOverWS, stdout, stderr string)
// EmitExitCB is the function callback used to emit exit proc code
type EmitExitCB func(e *ExecOverWS, code int, err error)
// SplitType Type of spliting method to tokenize stdout/stderr
type SplitType uint8
const (
// SplitLine Split line by line
SplitLine SplitType = iota
// SplitChar Split character by character
SplitChar
)
// Inspired by :
// https://github.com/gorilla/websocket/blob/master/examples/command/main.go
// ExecOverWS .
type ExecOverWS struct {
Cmd string // command name to execute
Args []string // command arguments
SocketIO *socketio.Socket // websocket
Sid string // websocket ID
CmdID string // command ID
// Optional fields
Env []string // command environment variables
CmdExecTimeout int // command execution time timeout
Log *logrus.Logger // logger (nil if disabled)
InputEvent string // websocket input event name
InputCB OnInputCB // stdin callback
OutputCB EmitOutputCB // stdout/stderr callback
ExitCB EmitExitCB // exit proc callback
UserData *map[string]interface{} // user data passed to callbacks
OutSplit SplitType // split method to tokenize stdout/stderr
// Private fields
proc *os.Process
}
var cmdIDMap = make(map[string]*ExecOverWS)
// New creates a new instace of eows
func New(cmd string, args []string, so *socketio.Socket, soID, cmdID string) *ExecOverWS {
e := &ExecOverWS{
Cmd: cmd,
Args: args,
SocketIO: so,
Sid: soID,
CmdID: cmdID,
CmdExecTimeout: -1, // default no timeout
OutSplit: SplitChar, // default split by character
}
cmdIDMap[cmdID] = e
return e
}
// GetEows gets ExecOverWS object from command ID
func GetEows(cmdID string) *ExecOverWS {
if _, ok := cmdIDMap[cmdID]; !ok {
return nil
}
return cmdIDMap[cmdID]
}
// Start executes the command and redirect stdout/stderr into a WebSocket
func (e *ExecOverWS) Start() error {
var err error
var outr, outw, errr, errw, inr, inw *os.File
bashArgs := []string{"/bin/bash", "-c", e.Cmd + " " + strings.Join(e.Args, " ")}
// no timeout == 1 year
if e.CmdExecTimeout == -1 {
e.CmdExecTimeout = 365 * 24 * 60 * 60
}
// Create pipes
outr, outw, err = os.Pipe()
if err != nil {
err = fmt.Errorf("Pipe stdout error: " + err.Error())
goto exitErr
}
errr, errw, err = os.Pipe()
if err != nil {
err = fmt.Errorf("Pipe stderr error: " + err.Error())
goto exitErr
}
inr, inw, err = os.Pipe()
if err != nil {
err = fmt.Errorf("Pipe stdin error: " + err.Error())
goto exitErr
}
e.proc, err = os.StartProcess("/bin/bash", bashArgs, &os.ProcAttr{
Files: []*os.File{inr, outw, errw},
Env: append(os.Environ(), e.Env...),
})
if err != nil {
err = fmt.Errorf("Process start error: " + err.Error())
goto exitErr
}
go func() {
defer outr.Close()
defer outw.Close()
defer errr.Close()
defer errw.Close()
defer inr.Close()
defer inw.Close()
stdoutDone := make(chan struct{})
go e.cmdPumpStdout(outr, stdoutDone)
go e.cmdPumpStderr(errr)
// Blocking function that poll input or wait for end of process
e.cmdPumpStdin(inw)
// Some commands will exit when stdin is closed.
inw.Close()
defer outr.Close()
if status, err := e.proc.Wait(); err == nil {
// Other commands need a bonk on the head.
if !status.Exited() {
if err := e.proc.Signal(os.Interrupt); err != nil {
e.logError("Proc interrupt:", err)
}
select {
case <-stdoutDone:
case <-time.After(time.Second):
// A bigger bonk on the head.
if err := e.proc.Signal(os.Kill); err != nil {
e.logError("Proc term:", err)
}
<-stdoutDone
}
}
}
delete(cmdIDMap, e.CmdID)
}()
return nil
exitErr:
for _, pf := range []*os.File{outr, outw, errr, errw, inr, inw} {
pf.Close()
}
return err
}
func (e *ExecOverWS) logDebug(format string, a ...interface{}) {
if e.Log != nil {
e.Log.Debugf(format, a)
}
}
func (e *ExecOverWS) logError(format string, a ...interface{}) {
if e.Log != nil {
e.Log.Errorf(format, a)
}
}
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