1 // Copyright 2022 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
7 // addExitHook registers the specified function 'f' to be run at
8 // program termination (e.g. when someone invokes os.Exit(), or when
9 // main.main returns). Hooks are run in reverse order of registration:
10 // first hook added is the last one run.
12 // CAREFUL: the expectation is that addExitHook should only be called
13 // from a safe context (e.g. not an error/panic path or signal
14 // handler, preemption enabled, allocation allowed, write barriers
15 // allowed, etc), and that the exit function 'f' will be invoked under
16 // similar circumstances. That is the say, we are expecting that 'f'
17 // uses normal / high-level Go code as opposed to one of the more
18 // restricted dialects used for the trickier parts of the runtime.
19 func addExitHook(f func(), runOnNonZeroExit bool) {
20 exitHooks.hooks = append(exitHooks.hooks, exitHook{f: f, runOnNonZeroExit: runOnNonZeroExit})
23 // exitHook stores a function to be run on program exit, registered
24 // by the utility runtime.addExitHook.
25 type exitHook struct {
26 f func() // func to run
27 runOnNonZeroExit bool // whether to run on non-zero exit code
30 // exitHooks stores state related to hook functions registered to
31 // run when program execution terminates.
32 var exitHooks struct {
37 // runExitHooks runs any registered exit hook functions (funcs
38 // previously registered using runtime.addExitHook). Here 'exitCode'
39 // is the status code being passed to os.Exit, or zero if the program
40 // is terminating normally without calling os.Exit.
41 func runExitHooks(exitCode int) {
42 if exitHooks.runningExitHooks {
43 throw("internal error: exit hook invoked exit")
45 exitHooks.runningExitHooks = true
47 runExitHook := func(f func()) (caughtPanic bool) {
49 if x := recover(); x != nil {
58 for i := range exitHooks.hooks {
59 h := exitHooks.hooks[len(exitHooks.hooks)-i-1]
60 if exitCode != 0 && !h.runOnNonZeroExit {
63 if caughtPanic := runExitHook(h.f); caughtPanic {
64 throw("internal error: exit hook invoked panic")
68 exitHooks.runningExitHooks = false