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.
4
5package cfile
6
7import "internal/runtime/exithook"
8
9// InitHook is invoked from the main package "init" routine in
10// programs built with "-cover". This function is intended to be
11// called only by the compiler (via runtime/coverage.initHook).
12//
13// If 'istest' is false, it indicates we're building a regular program
14// ("go build -cover ..."), in which case we immediately try to write
15// out the meta-data file, and register emitCounterData as an exit
16// hook.
17//
18// If 'istest' is true (indicating that the program in question is a
19// Go test binary), then we tentatively queue up both emitMetaData and
20// emitCounterData as exit hooks. In the normal case (e.g. regular "go
21// test -cover" run) the testmain.go boilerplate will run at the end
22// of the test, write out the coverage percentage, and then invoke
23// MarkProfileEmitted to indicate that no more work needs to be
24// done. If however that call is never made, this is a sign that the
25// test binary is being used as a replacement binary for the tool
26// being tested, hence we do want to run exit hooks when the program
27// terminates.
28func InitHook(istest bool) {
29	// Note: hooks are run in reverse registration order, so
30	// register the counter data hook before the meta-data hook
31	// (in the case where two hooks are needed).
32	exithook.Add(exithook.Hook{F: emitCounterData, RunOnFailure: true})
33	if istest {
34		exithook.Add(exithook.Hook{F: emitMetaData, RunOnFailure: true})
35	} else {
36		emitMetaData()
37	}
38}
39