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// Copyright 2016 The etcd Authors
//
// 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 expect implements a small expect-style interface
package expect
import (
"bufio"
"fmt"
"io"
"os"
"os/exec"
"strings"
"sync"
"syscall"
"github.com/kr/pty"
)
type ExpectProcess struct {
cmd *exec.Cmd
fpty *os.File
wg sync.WaitGroup
ptyMu sync.Mutex // protects accessing fpty
cond *sync.Cond // for broadcasting updates are available
mu sync.Mutex // protects lines and err
lines []string
count int // increment whenever new line gets added
err error
// StopSignal is the signal Stop sends to the process; defaults to SIGKILL.
StopSignal os.Signal
}
// NewExpect creates a new process for expect testing.
func NewExpect(name string, arg ...string) (ep *ExpectProcess, err error) {
// if env[] is nil, use current system env
return NewExpectWithEnv(name, arg, nil)
}
// NewExpectWithEnv creates a new process with user defined env variables for expect testing.
func NewExpectWithEnv(name string, args []string, env []string) (ep *ExpectProcess, err error) {
cmd := exec.Command(name, args...)
cmd.Env = env
ep = &ExpectProcess{
cmd: cmd,
StopSignal: syscall.SIGKILL,
}
ep.cond = sync.NewCond(&ep.mu)
ep.cmd.Stderr = ep.cmd.Stdout
ep.cmd.Stdin = nil
if ep.fpty, err = pty.Start(ep.cmd); err != nil {
return nil, err
}
ep.wg.Add(1)
go ep.read()
return ep, nil
}
func (ep *ExpectProcess) read() {
defer ep.wg.Done()
printDebugLines := os.Getenv("EXPECT_DEBUG") != ""
r := bufio.NewReader(ep.fpty)
for ep.err == nil {
ep.ptyMu.Lock()
l, rerr := r.ReadString('\n')
ep.ptyMu.Unlock()
ep.mu.Lock()
ep.err = rerr
if l != "" {
if printDebugLines {
fmt.Printf("%s-%d: %s", ep.cmd.Path, ep.cmd.Process.Pid, l)
}
ep.lines = append(ep.lines, l)
ep.count++
if len(ep.lines) == 1 {
ep.cond.Signal()
}
}
ep.mu.Unlock()
}
ep.cond.Signal()
}
// ExpectFunc returns the first line satisfying the function f.
func (ep *ExpectProcess) ExpectFunc(f func(string) bool) (string, error) {
ep.mu.Lock()
for {
for len(ep.lines) == 0 && ep.err == nil {
ep.cond.Wait()
}
if len(ep.lines) == 0 {
break
}
l := ep.lines[0]
ep.lines = ep.lines[1:]
if f(l) {
ep.mu.Unlock()
return l, nil
}
}
ep.mu.Unlock()
return "", ep.err
}
// Expect returns the first line containing the given string.
func (ep *ExpectProcess) Expect(s string) (string, error) {
return ep.ExpectFunc(func(txt string) bool { return strings.Contains(txt, s) })
}
// LineCount returns the number of recorded lines since
// the beginning of the process.
func (ep *ExpectProcess) LineCount() int {
ep.mu.Lock()
defer ep.mu.Unlock()
return ep.count
}
// Stop kills the expect process and waits for it to exit.
func (ep *ExpectProcess) Stop() error { return ep.close(true) }
// Signal sends a signal to the expect process
func (ep *ExpectProcess) Signal(sig os.Signal) error {
return ep.cmd.Process.Signal(sig)
}
// Close waits for the expect process to exit.
func (ep *ExpectProcess) Close() error { return ep.close(false) }
func (ep *ExpectProcess) close(kill bool) error {
if ep.cmd == nil {
return ep.err
}
if kill {
ep.Signal(ep.StopSignal)
}
err := ep.cmd.Wait()
ep.ptyMu.Lock()
ep.fpty.Close()
ep.ptyMu.Unlock()
ep.wg.Wait()
if err != nil {
ep.err = err
if !kill && strings.Contains(err.Error(), "exit status") {
// non-zero exit code
err = nil
} else if kill && strings.Contains(err.Error(), "signal:") {
err = nil
}
}
ep.cmd = nil
return err
}
func (ep *ExpectProcess) Send(command string) error {
_, err := io.WriteString(ep.fpty, command)
return err
}
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