bash_unix.go RawHistoryFolder

1//go:build !windows
2
3package tools
4
5import (
6	"io"
7	"os/exec"
8	"sync"
9	"syscall"
10	"time"
11)
12
13const bashProcessWaitDelay = 5 * time.Second
14
15// configureBashProcess makes context cancellation terminate the shell's
16// process group and closes the output pipe exactly once. CommandContext calls
17// cmd.Cancel from its context watcher, so no second cancellation watcher is
18// needed here.
19func configureBashProcess(cmd *exec.Cmd, output io.Closer) func() {
20	setProcessGroup(cmd)
21	cmd.WaitDelay = bashProcessWaitDelay
22	var closeOutput sync.Once
23	closePipe := func() {
24		closeOutput.Do(func() {
25			if output != nil {
26				_ = output.Close()
27			}
28		})
29	}
30	cmd.Cancel = func() error {
31		closePipe()
32		return killBashProcessGroup(cmd)
33	}
34	return closePipe
35}
36
37// setProcessGroup puts the command in its own process group so
38// killProcessGroup can target the entire tree including background
39// children spawned with &.
40func setProcessGroup(cmd *exec.Cmd) {
41	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
42}
43
44// killBashProcessGroup forcefully terminates the entire process group so
45// backgrounded children (cmd &) cannot survive cancellation or retain an
46// output pipe.
47func killBashProcessGroup(cmd *exec.Cmd) error {
48	if cmd == nil || cmd.Process == nil {
49		return nil
50	}
51	pgid := cmd.Process.Pid
52	err := syscall.Kill(-pgid, syscall.SIGKILL)
53	if err == syscall.ESRCH {
54		return nil
55	}
56	return err
57}
58
59// killProcessGroup sends SIGTERM then SIGKILL to the entire process group.
60// It is also used by the worktree Git helper, which keeps graceful
61// cancellation behavior.
62func killProcessGroup(cmd *exec.Cmd) {
63	if cmd == nil || cmd.Process == nil {
64		return
65	}
66	pgid := cmd.Process.Pid
67	_ = syscall.Kill(-pgid, syscall.SIGTERM)
68	time.AfterFunc(3*time.Second, func() {
69		_ = syscall.Kill(-pgid, syscall.SIGKILL)
70	})
71}