github.com/Aayushi-Bansal/sys@v0.0.0-20180118120756-90d962a959d8/unix/mkpost.go (about)

     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.
    12  package main
    13  
    14  import (
    15  	"bytes"
    16  	"fmt"
    17  	"go/format"
    18  	"io/ioutil"
    19  	"log"
    20  	"os"
    21  	"regexp"
    22  )
    23  
    24  func 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  	// If we have empty Ptrace structs, we should delete them. Only s390x emits
    46  	// nonempty Ptrace structs.
    47  	ptraceRexexp := regexp.MustCompile(`type Ptrace((Psw|Fpregs|Per) struct {\s*})`)
    48  	b = ptraceRexexp.ReplaceAll(b, nil)
    49  
    50  	// Replace the control_regs union with a blank identifier for now.
    51  	controlRegsRegex := regexp.MustCompile(`(Control_regs)\s+\[0\]uint64`)
    52  	b = controlRegsRegex.ReplaceAll(b, []byte("_ [0]uint64"))
    53  
    54  	// Remove fields that are added by glibc
    55  	// Note that this is unstable as the identifers are private.
    56  	removeFieldsRegex := regexp.MustCompile(`X__glibc\S*`)
    57  	b = removeFieldsRegex.ReplaceAll(b, []byte("_"))
    58  
    59  	// Convert [65]int8 to [65]byte in Utsname members to simplify
    60  	// conversion to string; see golang.org/issue/20753
    61  	convertUtsnameRegex := regexp.MustCompile(`((Sys|Node|Domain)name|Release|Version|Machine)(\s+)\[(\d+)\]u?int8`)
    62  	b = convertUtsnameRegex.ReplaceAll(b, []byte("$1$3[$4]byte"))
    63  
    64  	// Remove spare fields (e.g. in Statx_t)
    65  	spareFieldsRegex := regexp.MustCompile(`X__spare\S*`)
    66  	b = spareFieldsRegex.ReplaceAll(b, []byte("_"))
    67  
    68  	// We refuse to export private fields on s390x
    69  	if goarch == "s390x" && goos == "linux" {
    70  		// Remove cgo padding fields
    71  		removeFieldsRegex := regexp.MustCompile(`Pad_cgo_\d+`)
    72  		b = removeFieldsRegex.ReplaceAll(b, []byte("_"))
    73  
    74  		// Remove padding, hidden, or unused fields
    75  		removeFieldsRegex = regexp.MustCompile(`\bX_\S+`)
    76  		b = removeFieldsRegex.ReplaceAll(b, []byte("_"))
    77  	}
    78  
    79  	// Remove the first line of warning from cgo
    80  	b = b[bytes.IndexByte(b, '\n')+1:]
    81  	// Modify the command in the header to include:
    82  	//  mkpost, our own warning, and a build tag.
    83  	replacement := fmt.Sprintf(`$1 | go run mkpost.go
    84  // Code generated by the command above; see README.md. DO NOT EDIT.
    85  
    86  // +build %s,%s`, goarch, goos)
    87  	cgoCommandRegex := regexp.MustCompile(`(cgo -godefs .*)`)
    88  	b = cgoCommandRegex.ReplaceAll(b, []byte(replacement))
    89  
    90  	// gofmt
    91  	b, err = format.Source(b)
    92  	if err != nil {
    93  		log.Fatal(err)
    94  	}
    95  
    96  	os.Stdout.Write(b)
    97  }