147 lines
4.4 KiB
Go
147 lines
4.4 KiB
Go
// Copyright 2021 Google Inc. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// run_with_timeout is a utility that can kill a wrapped command after a configurable timeout,
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// optionally running a command to collect debugging information first.
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package main
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import (
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"flag"
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"fmt"
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"io"
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"os"
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"os/exec"
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"sync"
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"syscall"
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"time"
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)
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var (
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timeout = flag.Duration("timeout", 0, "time after which to kill command (example: 60s)")
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onTimeoutCmd = flag.String("on_timeout", "", "command to run with `PID=<pid> sh -c` after timeout.")
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)
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func usage() {
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fmt.Fprintf(os.Stderr, "usage: %s [--timeout N] [--on_timeout CMD] -- command [args...]\n", os.Args[0])
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flag.PrintDefaults()
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fmt.Fprintln(os.Stderr, "run_with_timeout is a utility that can kill a wrapped command after a configurable timeout,")
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fmt.Fprintln(os.Stderr, "optionally running a command to collect debugging information first.")
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os.Exit(2)
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}
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func main() {
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flag.Usage = usage
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flag.Parse()
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if flag.NArg() < 1 {
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fmt.Fprintf(os.Stderr, "%s: error: command is required\n", os.Args[0])
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usage()
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}
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err := runWithTimeout(flag.Arg(0), flag.Args()[1:], *timeout, *onTimeoutCmd,
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os.Stdin, os.Stdout, os.Stderr)
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if err != nil {
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if exitErr, ok := err.(*exec.ExitError); ok {
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fmt.Fprintf(os.Stderr, "%s: process exited with error: %s\n", os.Args[0], exitErr.Error())
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} else {
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fmt.Fprintf(os.Stderr, "%s: error: %s\n", os.Args[0], err.Error())
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}
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os.Exit(1)
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}
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}
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// concurrentWriter wraps a writer to make it thread-safe to call Write.
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type concurrentWriter struct {
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w io.Writer
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sync.Mutex
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}
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// Write writes the data to the wrapped writer with a lock to allow for concurrent calls.
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func (c *concurrentWriter) Write(data []byte) (n int, err error) {
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c.Lock()
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defer c.Unlock()
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if c.w == nil {
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return 0, nil
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}
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return c.w.Write(data)
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}
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// Close ends the concurrentWriter, causing future calls to Write to be no-ops. It does not close
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// the underlying writer.
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func (c *concurrentWriter) Close() {
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c.Lock()
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defer c.Unlock()
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c.w = nil
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}
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func runWithTimeout(command string, args []string, timeout time.Duration, onTimeoutCmdStr string,
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stdin io.Reader, stdout, stderr io.Writer) error {
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cmd := exec.Command(command, args...)
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// Wrap the writers in a locking writer so that cmd and onTimeoutCmd don't try to write to
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// stdout or stderr concurrently.
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concurrentStdout := &concurrentWriter{w: stdout}
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concurrentStderr := &concurrentWriter{w: stderr}
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defer concurrentStdout.Close()
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defer concurrentStderr.Close()
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cmd.Stdin, cmd.Stdout, cmd.Stderr = stdin, concurrentStdout, concurrentStderr
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err := cmd.Start()
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if err != nil {
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return err
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}
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// waitCh will signal the subprocess exited.
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waitCh := make(chan error)
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go func() {
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waitCh <- cmd.Wait()
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}()
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// timeoutCh will signal the subprocess timed out if timeout was set.
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var timeoutCh <-chan time.Time = make(chan time.Time)
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if timeout > 0 {
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timeoutCh = time.After(timeout)
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}
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startTime := time.Now()
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select {
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case err := <-waitCh:
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if exitErr, ok := err.(*exec.ExitError); ok {
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return fmt.Errorf("process exited with error: %w", exitErr)
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}
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return err
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case <-timeoutCh:
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// Continue below.
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}
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fmt.Fprintf(concurrentStderr, "%s: process timed out after %s\n", os.Args[0], time.Since(startTime))
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// Process timed out before exiting.
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defer cmd.Process.Signal(syscall.SIGKILL)
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if onTimeoutCmdStr != "" {
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fmt.Fprintf(concurrentStderr, "%s: running on_timeout command `%s`\n", os.Args[0], onTimeoutCmdStr)
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onTimeoutCmd := exec.Command("sh", "-c", onTimeoutCmdStr)
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onTimeoutCmd.Stdin, onTimeoutCmd.Stdout, onTimeoutCmd.Stderr = stdin, concurrentStdout, concurrentStderr
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onTimeoutCmd.Env = append(os.Environ(), fmt.Sprintf("PID=%d", cmd.Process.Pid))
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err := onTimeoutCmd.Run()
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if err != nil {
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return fmt.Errorf("on_timeout command %q exited with error: %w", onTimeoutCmdStr, err)
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}
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}
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return fmt.Errorf("timed out after %s", timeout.String())
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}
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