github.com/Andyfoo/golang/x/sys@v0.0.0-20190901054642-57c1bf301704/unix/linux/mksysnum.go (about)

     1  // Copyright 2018 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  package main
     8  
     9  import (
    10  	"bufio"
    11  	"fmt"
    12  	"os"
    13  	"os/exec"
    14  	"regexp"
    15  	"strconv"
    16  	"strings"
    17  )
    18  
    19  var (
    20  	goos, goarch string
    21  )
    22  
    23  // cmdLine returns this programs's commandline arguments
    24  func cmdLine() string {
    25  	return "go run linux/mksysnum.go " + strings.Join(os.Args[1:], " ")
    26  }
    27  
    28  // buildTags returns build tags
    29  func buildTags() string {
    30  	return fmt.Sprintf("%s,%s", goarch, goos)
    31  }
    32  
    33  func format(name string, num int, offset int) string {
    34  	if num > 999 {
    35  		// ignore deprecated syscalls that are no longer implemented
    36  		// https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/include/uapi/asm-generic/unistd.h?id=refs/heads/master#n716
    37  		return ""
    38  	}
    39  	name = strings.ToUpper(name)
    40  	num = num + offset
    41  	return fmt.Sprintf("	SYS_%s = %d;\n", name, num)
    42  }
    43  
    44  func checkErr(err error) {
    45  	if err != nil {
    46  		fmt.Fprintf(os.Stderr, "%v\n", err)
    47  		os.Exit(1)
    48  	}
    49  }
    50  
    51  // source string and substring slice for regexp
    52  type re struct {
    53  	str string   // source string
    54  	sub []string // matched sub-string
    55  }
    56  
    57  // Match performs regular expression match
    58  func (r *re) Match(exp string) bool {
    59  	r.sub = regexp.MustCompile(exp).FindStringSubmatch(r.str)
    60  	if r.sub != nil {
    61  		return true
    62  	}
    63  	return false
    64  }
    65  
    66  func main() {
    67  	// Get the OS and architecture (using GOARCH_TARGET if it exists)
    68  	goos = os.Getenv("GOOS")
    69  	goarch = os.Getenv("GOARCH_TARGET")
    70  	if goarch == "" {
    71  		goarch = os.Getenv("GOARCH")
    72  	}
    73  	// Check if GOOS and GOARCH environment variables are defined
    74  	if goarch == "" || goos == "" {
    75  		fmt.Fprintf(os.Stderr, "GOARCH or GOOS not defined in environment\n")
    76  		os.Exit(1)
    77  	}
    78  	// Check that we are using the new build system if we should
    79  	if os.Getenv("GOLANG_SYS_BUILD") != "docker" {
    80  		fmt.Fprintf(os.Stderr, "In the new build system, mksysnum should not be called directly.\n")
    81  		fmt.Fprintf(os.Stderr, "See README.md\n")
    82  		os.Exit(1)
    83  	}
    84  
    85  	cc := os.Getenv("CC")
    86  	if cc == "" {
    87  		fmt.Fprintf(os.Stderr, "CC is not defined in environment\n")
    88  		os.Exit(1)
    89  	}
    90  	args := os.Args[1:]
    91  	args = append([]string{"-E", "-dD"}, args...)
    92  	cmd, err := exec.Command(cc, args...).Output() // execute command and capture output
    93  	if err != nil {
    94  		fmt.Fprintf(os.Stderr, "can't run %s", cc)
    95  		os.Exit(1)
    96  	}
    97  	text := ""
    98  	s := bufio.NewScanner(strings.NewReader(string(cmd)))
    99  	var offset, prev int
   100  	for s.Scan() {
   101  		t := re{str: s.Text()}
   102  		if t.Match(`^#define __NR_Linux\s+([0-9]+)`) {
   103  			// mips/mips64: extract offset
   104  			offset, _ = strconv.Atoi(t.sub[1]) // Make offset=0 if empty or non-numeric
   105  		} else if t.Match(`^#define __NR(\w*)_SYSCALL_BASE\s+([0-9]+)`) {
   106  			// arm: extract offset
   107  			offset, _ = strconv.Atoi(t.sub[1]) // Make offset=0 if empty or non-numeric
   108  		} else if t.Match(`^#define __NR_syscalls\s+`) {
   109  			// ignore redefinitions of __NR_syscalls
   110  		} else if t.Match(`^#define __NR_(\w*)Linux_syscalls\s+`) {
   111  			// mips/mips64: ignore definitions about the number of syscalls
   112  		} else if t.Match(`^#define __NR_(\w+)\s+([0-9]+)`) {
   113  			prev, err = strconv.Atoi(t.sub[2])
   114  			checkErr(err)
   115  			text += format(t.sub[1], prev, offset)
   116  		} else if t.Match(`^#define __NR3264_(\w+)\s+([0-9]+)`) {
   117  			prev, err = strconv.Atoi(t.sub[2])
   118  			checkErr(err)
   119  			text += format(t.sub[1], prev, offset)
   120  		} else if t.Match(`^#define __NR_(\w+)\s+\(\w+\+\s*([0-9]+)\)`) {
   121  			r2, err := strconv.Atoi(t.sub[2])
   122  			checkErr(err)
   123  			text += format(t.sub[1], prev+r2, offset)
   124  		} else if t.Match(`^#define __NR_(\w+)\s+\(__NR_(?:SYSCALL_BASE|Linux) \+ ([0-9]+)`) {
   125  			r2, err := strconv.Atoi(t.sub[2])
   126  			checkErr(err)
   127  			text += format(t.sub[1], r2, offset)
   128  		}
   129  	}
   130  	err = s.Err()
   131  	checkErr(err)
   132  	fmt.Printf(template, cmdLine(), buildTags(), text)
   133  }
   134  
   135  const template = `// %s
   136  // Code generated by the command above; see README.md. DO NOT EDIT.
   137  
   138  // +build %s
   139  
   140  package unix
   141  
   142  const(
   143  %s)`