forked from crosbymichael/runc
-
Notifications
You must be signed in to change notification settings - Fork 0
/
signals.go
139 lines (126 loc) · 3.52 KB
/
signals.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
// +build linux
package main
import (
"os"
"os/signal"
"syscall" // only for Signal
"github.com/opencontainers/runc/libcontainer"
"github.com/opencontainers/runc/libcontainer/system"
"github.com/opencontainers/runc/libcontainer/utils"
"github.com/sirupsen/logrus"
"golang.org/x/sys/unix"
)
const signalBufferSize = 2048
// newSignalHandler returns a signal handler for processing SIGCHLD and SIGWINCH signals
// while still forwarding all other signals to the process.
// If notifySocket is present, use it to read systemd notifications from the container and
// forward them to notifySocketHost.
func newSignalHandler(enableSubreaper bool, notifySocket *notifySocket) *signalHandler {
if enableSubreaper {
// set us as the subreaper before registering the signal handler for the container
if err := system.SetSubreaper(1); err != nil {
logrus.Warn(err)
}
}
// ensure that we have a large buffer size so that we do not miss any signals
// in case we are not processing them fast enough.
s := make(chan os.Signal, signalBufferSize)
// handle all signals for the process.
signal.Notify(s)
return &signalHandler{
signals: s,
notifySocket: notifySocket,
}
}
// exit models a process exit status with the pid and
// exit status.
type exit struct {
pid int
status int
}
type signalHandler struct {
signals chan os.Signal
notifySocket *notifySocket
}
// forward handles the main signal event loop forwarding, resizing, or reaping depending
// on the signal received.
func (h *signalHandler) forward(process *libcontainer.Process, tty *tty, detach bool) (int, error) {
// make sure we know the pid of our main process so that we can return
// after it dies.
if detach && h.notifySocket == nil {
return 0, nil
}
pid1, err := process.Pid()
if err != nil {
return -1, err
}
if h.notifySocket != nil {
if detach {
h.notifySocket.run(pid1)
return 0, nil
}
go h.notifySocket.run(0)
}
// Perform the initial tty resize. Always ignore errors resizing because
// stdout might have disappeared (due to races with when SIGHUP is sent).
_ = tty.resize()
// Handle and forward signals.
for s := range h.signals {
switch s {
case unix.SIGWINCH:
// Ignore errors resizing, as above.
_ = tty.resize()
case unix.SIGCHLD:
exits, err := h.reap()
if err != nil {
logrus.Error(err)
}
for _, e := range exits {
logrus.WithFields(logrus.Fields{
"pid": e.pid,
"status": e.status,
}).Debug("process exited")
if e.pid == pid1 {
// call Wait() on the process even though we already have the exit
// status because we must ensure that any of the go specific process
// fun such as flushing pipes are complete before we return.
process.Wait()
if h.notifySocket != nil {
h.notifySocket.Close()
}
return e.status, nil
}
}
default:
logrus.Debugf("sending signal to process %s", s)
if err := unix.Kill(pid1, s.(syscall.Signal)); err != nil {
logrus.Error(err)
}
}
}
return -1, nil
}
// reap runs wait4 in a loop until we have finished processing any existing exits
// then returns all exits to the main event loop for further processing.
func (h *signalHandler) reap() (exits []exit, err error) {
var (
ws unix.WaitStatus
rus unix.Rusage
)
for {
pid, err := unix.Wait4(-1, &ws, unix.WNOHANG, &rus)
if err != nil {
if err == unix.ECHILD {
return exits, nil
}
return nil, err
}
if pid <= 0 {
return exits, nil
}
exits = append(exits, exit{
pid: pid,
status: utils.ExitStatus(ws),
})
}
}