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1// Copyright 2016 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
5// +build ignore
6
7// mkpost processes the output of cgo -godefs to
8// modify the generated types. It is used to clean up
9// the sys API in an architecture specific manner.
10//
11// mkpost is run after cgo -godefs; see README.md.
12package main
13
14import (
15	"bytes"
16	"fmt"
17	"go/format"
18	"io/ioutil"
19	"log"
20	"os"
21	"regexp"
22)
23
24func main() {
25	// Get the OS and architecture (using GOARCH_TARGET if it exists)
26	goos := os.Getenv("GOOS")
27	goarch := os.Getenv("GOARCH_TARGET")
28	if goarch == "" {
29		goarch = os.Getenv("GOARCH")
30	}
31	// Check that we are using the new build system if we should be.
32	if goos == "linux" && goarch != "sparc64" {
33		if os.Getenv("GOLANG_SYS_BUILD") != "docker" {
34			os.Stderr.WriteString("In the new build system, mkpost should not be called directly.\n")
35			os.Stderr.WriteString("See README.md\n")
36			os.Exit(1)
37		}
38	}
39
40	b, err := ioutil.ReadAll(os.Stdin)
41	if err != nil {
42		log.Fatal(err)
43	}
44
45	// Intentionally export __val fields in Fsid and Sigset_t
46	valRegex := regexp.MustCompile(`type (Fsid|Sigset_t) struct {(\s+)X__val(\s+\S+\s+)}`)
47	b = valRegex.ReplaceAll(b, []byte("type $1 struct {${2}Val$3}"))
48
49	// If we have empty Ptrace structs, we should delete them. Only s390x emits
50	// nonempty Ptrace structs.
51	ptraceRexexp := regexp.MustCompile(`type Ptrace((Psw|Fpregs|Per) struct {\s*})`)
52	b = ptraceRexexp.ReplaceAll(b, nil)
53
54	// Replace the control_regs union with a blank identifier for now.
55	controlRegsRegex := regexp.MustCompile(`(Control_regs)\s+\[0\]uint64`)
56	b = controlRegsRegex.ReplaceAll(b, []byte("_ [0]uint64"))
57
58	// Remove fields that are added by glibc
59	// Note that this is unstable as the identifers are private.
60	removeFieldsRegex := regexp.MustCompile(`X__glibc\S*`)
61	b = removeFieldsRegex.ReplaceAll(b, []byte("_"))
62
63	// Convert [65]int8 to [65]byte in Utsname members to simplify
64	// conversion to string; see golang.org/issue/20753
65	convertUtsnameRegex := regexp.MustCompile(`((Sys|Node|Domain)name|Release|Version|Machine)(\s+)\[(\d+)\]u?int8`)
66	b = convertUtsnameRegex.ReplaceAll(b, []byte("$1$3[$4]byte"))
67
68	// Remove spare fields (e.g. in Statx_t)
69	spareFieldsRegex := regexp.MustCompile(`X__spare\S*`)
70	b = spareFieldsRegex.ReplaceAll(b, []byte("_"))
71
72	// Remove cgo padding fields
73	removePaddingFieldsRegex := regexp.MustCompile(`Pad_cgo_\d+`)
74	b = removePaddingFieldsRegex.ReplaceAll(b, []byte("_"))
75
76	// Remove padding, hidden, or unused fields
77	removeFieldsRegex = regexp.MustCompile(`\b(X_\S+|Padding)`)
78	b = removeFieldsRegex.ReplaceAll(b, []byte("_"))
79
80	// Remove the first line of warning from cgo
81	b = b[bytes.IndexByte(b, '\n')+1:]
82	// Modify the command in the header to include:
83	//  mkpost, our own warning, and a build tag.
84	replacement := fmt.Sprintf(`$1 | go run mkpost.go
85// Code generated by the command above; see README.md. DO NOT EDIT.
86
87// +build %s,%s`, goarch, goos)
88	cgoCommandRegex := regexp.MustCompile(`(cgo -godefs .*)`)
89	b = cgoCommandRegex.ReplaceAll(b, []byte(replacement))
90
91	// gofmt
92	b, err = format.Source(b)
93	if err != nil {
94		log.Fatal(err)
95	}
96
97	os.Stdout.Write(b)
98}
99