// Copyright 2016 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.

// +build ignore

// mkpost processes the output of cgo -godefs to

// modify the generated types. It is used to clean up

// the sys API in an architecture specific manner.

//

// mkpost is run after cgo -godefs; see README.md.

package main

import (

	"bytes"

	"fmt"

	"go/format"

	"io/ioutil"

	"log"

	"os"

	"regexp"

)

func main() {

	// Get the OS and architecture (using GOARCH_TARGET if it exists)

	goos := os.Getenv("GOOS")

	goarch := os.Getenv("GOARCH_TARGET")

	if goarch == "" {

		goarch = os.Getenv("GOARCH")

	}

	// Check that we are using the new build system if we should be.

	if goos == "linux" && goarch != "sparc64" {

		if os.Getenv("GOLANG_SYS_BUILD") != "docker" {

			os.Stderr.WriteString("In the new build system, mkpost should not be called directly.\n")

			os.Stderr.WriteString("See README.md\n")

			os.Exit(1)

		}

	}

	b, err := ioutil.ReadAll(os.Stdin)

	if err != nil {

		log.Fatal(err)

	}

	// Intentionally export __val fields in Fsid and Sigset_t

	valRegex := regexp.MustCompile(`type (Fsid|Sigset_t) struct {(\s+)X__val(\s+\S+\s+)}`)

	b = valRegex.ReplaceAll(b, []byte("type $1 struct {${2}Val$3}"))

	// If we have empty Ptrace structs, we should delete them. Only s390x emits

	// nonempty Ptrace structs.

	ptraceRexexp := regexp.MustCompile(`type Ptrace((Psw|Fpregs|Per) struct {\s*})`)

	b = ptraceRexexp.ReplaceAll(b, nil)

	// Replace the control_regs union with a blank identifier for now.

	controlRegsRegex := regexp.MustCompile(`(Control_regs)\s+\[0\]uint64`)

	b = controlRegsRegex.ReplaceAll(b, []byte("_ [0]uint64"))

	// Remove fields that are added by glibc

	// Note that this is unstable as the identifers are private.

	removeFieldsRegex := regexp.MustCompile(`X__glibc\S*`)

	b = removeFieldsRegex.ReplaceAll(b, []byte("_"))

	// Convert [65]int8 to [65]byte in Utsname members to simplify

	// conversion to string; see golang.org/issue/20753

	convertUtsnameRegex := regexp.MustCompile(`((Sys|Node|Domain)name|Release|Version|Machine)(\s+)\[(\d+)\]u?int8`)

	b = convertUtsnameRegex.ReplaceAll(b, []byte("$1$3[$4]byte"))

	// Remove spare fields (e.g. in Statx_t)

	spareFieldsRegex := regexp.MustCompile(`X__spare\S*`)

	b = spareFieldsRegex.ReplaceAll(b, []byte("_"))

	// Remove cgo padding fields

	removePaddingFieldsRegex := regexp.MustCompile(`Pad_cgo_\d+`)

	b = removePaddingFieldsRegex.ReplaceAll(b, []byte("_"))

	// Remove padding, hidden, or unused fields

	removeFieldsRegex = regexp.MustCompile(`\b(X_\S+|Padding)`)

	b = removeFieldsRegex.ReplaceAll(b, []byte("_"))

	// Remove the first line of warning from cgo

	b = b[bytes.IndexByte(b, '\n')+1:]

	// Modify the command in the header to include:

	//  mkpost, our own warning, and a build tag.

	replacement := fmt.Sprintf(`$1 | go run mkpost.go

// Code generated by the command above; see README.md. DO NOT EDIT.

// +build %s,%s`, goarch, goos)

	cgoCommandRegex := regexp.MustCompile(`(cgo -godefs .*)`)

	b = cgoCommandRegex.ReplaceAll(b, []byte(replacement))

	// gofmt

	b, err = format.Source(b)

	if err != nil {

		log.Fatal(err)

	}

	os.Stdout.Write(b)

}