file.go

// Copyright 2011 The Go Authors.  All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package buildutil

import (
	"go/build"
	"strings"
)

// goodOSArchFile returns false if the name contains a $GOOS or $GOARCH
// suffix which does not match the current system.
// The recognized name formats are:
//
//	name_$(GOOS).*
//	name_$(GOARCH).*
//	name_$(GOOS)_$(GOARCH).*
//	name_$(GOOS)_test.*
//	name_$(GOARCH)_test.*
//	name_$(GOOS)_$(GOARCH)_test.*
//
// An exception: if GOOS=android, then files with GOOS=linux are also matched.
func goodOSArchFile(ctxt *build.Context, name string, allTags map[string]bool) bool {
	name, _, _ = strings.Cut(name, ".")

	// Before Go 1.4, a file called "linux.go" would be equivalent to having a
	// build tag "linux" in that file. For Go 1.4 and beyond, we require this
	// auto-tagging to apply only to files with a non-empty prefix, so
	// "foo_linux.go" is tagged but "linux.go" is not. This allows new operating
	// systems, such as android, to arrive without breaking existing code with
	// innocuous source code in "android.go". The easiest fix: cut everything
	// in the name before the initial _.
	i := strings.Index(name, "_")
	if i < 0 {
		return true
	}
	name = name[i:] // ignore everything before first _

	l := strings.Split(name, "_")
	if n := len(l); n > 0 && l[n-1] == "test" {
		l = l[:n-1]
	}
	n := len(l)
	if n >= 2 && knownOS[l[n-2]] && knownArch[l[n-1]] {
		okArch := matchTag(ctxt, l[n-1], allTags)
		okOS := matchTag(ctxt, l[n-2], allTags)
		return okArch && okOS
	}
	if n >= 1 && (knownOS[l[n-1]] || knownArch[l[n-1]]) {
		return matchTag(ctxt, l[n-1], allTags)
	}
	return true
}