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1// Note: since nyc uses this module to output coverage, any lines
2// that are in the direct sync flow of nyc's outputCoverage are
3// ignored, since we can never get coverage for them.
4var assert = require('assert')
5var signals = require('./signals.js')
6
7var EE = require('events')
8/* istanbul ignore if */
9if (typeof EE !== 'function') {
10  EE = EE.EventEmitter
11}
12
13var emitter
14if (process.__signal_exit_emitter__) {
15  emitter = process.__signal_exit_emitter__
16} else {
17  emitter = process.__signal_exit_emitter__ = new EE()
18  emitter.count = 0
19  emitter.emitted = {}
20}
21
22// Because this emitter is a global, we have to check to see if a
23// previous version of this library failed to enable infinite listeners.
24// I know what you're about to say.  But literally everything about
25// signal-exit is a compromise with evil.  Get used to it.
26if (!emitter.infinite) {
27  emitter.setMaxListeners(Infinity)
28  emitter.infinite = true
29}
30
31module.exports = function (cb, opts) {
32  assert.equal(typeof cb, 'function', 'a callback must be provided for exit handler')
33
34  if (loaded === false) {
35    load()
36  }
37
38  var ev = 'exit'
39  if (opts && opts.alwaysLast) {
40    ev = 'afterexit'
41  }
42
43  var remove = function () {
44    emitter.removeListener(ev, cb)
45    if (emitter.listeners('exit').length === 0 &&
46        emitter.listeners('afterexit').length === 0) {
47      unload()
48    }
49  }
50  emitter.on(ev, cb)
51
52  return remove
53}
54
55module.exports.unload = unload
56function unload () {
57  if (!loaded) {
58    return
59  }
60  loaded = false
61
62  signals.forEach(function (sig) {
63    try {
64      process.removeListener(sig, sigListeners[sig])
65    } catch (er) {}
66  })
67  process.emit = originalProcessEmit
68  process.reallyExit = originalProcessReallyExit
69  emitter.count -= 1
70}
71
72function emit (event, code, signal) {
73  if (emitter.emitted[event]) {
74    return
75  }
76  emitter.emitted[event] = true
77  emitter.emit(event, code, signal)
78}
79
80// { <signal>: <listener fn>, ... }
81var sigListeners = {}
82signals.forEach(function (sig) {
83  sigListeners[sig] = function listener () {
84    // If there are no other listeners, an exit is coming!
85    // Simplest way: remove us and then re-send the signal.
86    // We know that this will kill the process, so we can
87    // safely emit now.
88    var listeners = process.listeners(sig)
89    if (listeners.length === emitter.count) {
90      unload()
91      emit('exit', null, sig)
92      /* istanbul ignore next */
93      emit('afterexit', null, sig)
94      /* istanbul ignore next */
95      process.kill(process.pid, sig)
96    }
97  }
98})
99
100module.exports.signals = function () {
101  return signals
102}
103
104module.exports.load = load
105
106var loaded = false
107
108function load () {
109  if (loaded) {
110    return
111  }
112  loaded = true
113
114  // This is the number of onSignalExit's that are in play.
115  // It's important so that we can count the correct number of
116  // listeners on signals, and don't wait for the other one to
117  // handle it instead of us.
118  emitter.count += 1
119
120  signals = signals.filter(function (sig) {
121    try {
122      process.on(sig, sigListeners[sig])
123      return true
124    } catch (er) {
125      return false
126    }
127  })
128
129  process.emit = processEmit
130  process.reallyExit = processReallyExit
131}
132
133var originalProcessReallyExit = process.reallyExit
134function processReallyExit (code) {
135  process.exitCode = code || 0
136  emit('exit', process.exitCode, null)
137  /* istanbul ignore next */
138  emit('afterexit', process.exitCode, null)
139  /* istanbul ignore next */
140  originalProcessReallyExit.call(process, process.exitCode)
141}
142
143var originalProcessEmit = process.emit
144function processEmit (ev, arg) {
145  if (ev === 'exit') {
146    if (arg !== undefined) {
147      process.exitCode = arg
148    }
149    var ret = originalProcessEmit.apply(this, arguments)
150    emit('exit', process.exitCode, null)
151    /* istanbul ignore next */
152    emit('afterexit', process.exitCode, null)
153    return ret
154  } else {
155    return originalProcessEmit.apply(this, arguments)
156  }
157}
158