408 lines
12 KiB
Go
408 lines
12 KiB
Go
// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build ignore
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/*
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This program reads a file containing function prototypes
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(like syscall_darwin.go) and generates system call bodies.
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The prototypes are marked by lines beginning with "//sys"
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and read like func declarations if //sys is replaced by func, but:
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* The parameter lists must give a name for each argument.
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This includes return parameters.
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* The parameter lists must give a type for each argument:
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the (x, y, z int) shorthand is not allowed.
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* If the return parameter is an error number, it must be named errno.
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A line beginning with //sysnb is like //sys, except that the
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goroutine will not be suspended during the execution of the system
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call. This must only be used for system calls which can never
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block, as otherwise the system call could cause all goroutines to
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hang.
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*/
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package main
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import (
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"bufio"
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"flag"
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"fmt"
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"os"
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"regexp"
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"strings"
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)
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var (
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b32 = flag.Bool("b32", false, "32bit big-endian")
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l32 = flag.Bool("l32", false, "32bit little-endian")
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plan9 = flag.Bool("plan9", false, "plan9")
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openbsd = flag.Bool("openbsd", false, "openbsd")
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netbsd = flag.Bool("netbsd", false, "netbsd")
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dragonfly = flag.Bool("dragonfly", false, "dragonfly")
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arm = flag.Bool("arm", false, "arm") // 64-bit value should use (even, odd)-pair
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tags = flag.String("tags", "", "build tags")
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filename = flag.String("output", "", "output file name (standard output if omitted)")
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)
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// cmdLine returns this programs's commandline arguments
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func cmdLine() string {
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return "go run mksyscall.go " + strings.Join(os.Args[1:], " ")
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}
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// buildTags returns build tags
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func buildTags() string {
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return *tags
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}
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// Param is function parameter
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type Param struct {
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Name string
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Type string
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}
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// usage prints the program usage
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func usage() {
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fmt.Fprintf(os.Stderr, "usage: go run mksyscall.go [-b32 | -l32] [-tags x,y] [file ...]\n")
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os.Exit(1)
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}
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// parseParamList parses parameter list and returns a slice of parameters
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func parseParamList(list string) []string {
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list = strings.TrimSpace(list)
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if list == "" {
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return []string{}
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}
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return regexp.MustCompile(`\s*,\s*`).Split(list, -1)
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}
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// parseParam splits a parameter into name and type
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func parseParam(p string) Param {
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ps := regexp.MustCompile(`^(\S*) (\S*)$`).FindStringSubmatch(p)
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if ps == nil {
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fmt.Fprintf(os.Stderr, "malformed parameter: %s\n", p)
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os.Exit(1)
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}
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return Param{ps[1], ps[2]}
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}
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func main() {
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// Get the OS and architecture (using GOARCH_TARGET if it exists)
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goos := os.Getenv("GOOS")
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if goos == "" {
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fmt.Fprintln(os.Stderr, "GOOS not defined in environment")
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os.Exit(1)
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}
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goarch := os.Getenv("GOARCH_TARGET")
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if goarch == "" {
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goarch = os.Getenv("GOARCH")
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}
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// Check that we are using the Docker-based build system if we should
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if goos == "linux" {
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if os.Getenv("GOLANG_SYS_BUILD") != "docker" {
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fmt.Fprintf(os.Stderr, "In the Docker-based build system, mksyscall should not be called directly.\n")
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fmt.Fprintf(os.Stderr, "See README.md\n")
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os.Exit(1)
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}
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}
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flag.Usage = usage
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flag.Parse()
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if len(flag.Args()) <= 0 {
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fmt.Fprintf(os.Stderr, "no files to parse provided\n")
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usage()
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}
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endianness := ""
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if *b32 {
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endianness = "big-endian"
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} else if *l32 {
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endianness = "little-endian"
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}
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libc := false
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if goos == "darwin" && strings.Contains(buildTags(), ",go1.12") {
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libc = true
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}
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trampolines := map[string]bool{}
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text := ""
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for _, path := range flag.Args() {
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file, err := os.Open(path)
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if err != nil {
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fmt.Fprintf(os.Stderr, err.Error())
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os.Exit(1)
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}
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s := bufio.NewScanner(file)
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for s.Scan() {
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t := s.Text()
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t = strings.TrimSpace(t)
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t = regexp.MustCompile(`\s+`).ReplaceAllString(t, ` `)
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nonblock := regexp.MustCompile(`^\/\/sysnb `).FindStringSubmatch(t)
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if regexp.MustCompile(`^\/\/sys `).FindStringSubmatch(t) == nil && nonblock == nil {
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continue
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}
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// Line must be of the form
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// func Open(path string, mode int, perm int) (fd int, errno error)
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// Split into name, in params, out params.
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f := regexp.MustCompile(`^\/\/sys(nb)? (\w+)\(([^()]*)\)\s*(?:\(([^()]+)\))?\s*(?:=\s*((?i)SYS_[A-Z0-9_]+))?$`).FindStringSubmatch(t)
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if f == nil {
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fmt.Fprintf(os.Stderr, "%s:%s\nmalformed //sys declaration\n", path, t)
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os.Exit(1)
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}
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funct, inps, outps, sysname := f[2], f[3], f[4], f[5]
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// ClockGettime doesn't have a syscall number on Darwin, only generate libc wrappers.
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if goos == "darwin" && !libc && funct == "ClockGettime" {
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continue
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}
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// Split argument lists on comma.
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in := parseParamList(inps)
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out := parseParamList(outps)
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// Try in vain to keep people from editing this file.
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// The theory is that they jump into the middle of the file
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// without reading the header.
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text += "// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT\n\n"
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// Go function header.
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outDecl := ""
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if len(out) > 0 {
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outDecl = fmt.Sprintf(" (%s)", strings.Join(out, ", "))
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}
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text += fmt.Sprintf("func %s(%s)%s {\n", funct, strings.Join(in, ", "), outDecl)
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// Check if err return available
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errvar := ""
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for _, param := range out {
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p := parseParam(param)
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if p.Type == "error" {
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errvar = p.Name
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break
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}
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}
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// Prepare arguments to Syscall.
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var args []string
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n := 0
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for _, param := range in {
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p := parseParam(param)
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if regexp.MustCompile(`^\*`).FindStringSubmatch(p.Type) != nil {
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args = append(args, "uintptr(unsafe.Pointer("+p.Name+"))")
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} else if p.Type == "string" && errvar != "" {
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text += fmt.Sprintf("\tvar _p%d *byte\n", n)
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text += fmt.Sprintf("\t_p%d, %s = BytePtrFromString(%s)\n", n, errvar, p.Name)
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text += fmt.Sprintf("\tif %s != nil {\n\t\treturn\n\t}\n", errvar)
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args = append(args, fmt.Sprintf("uintptr(unsafe.Pointer(_p%d))", n))
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n++
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} else if p.Type == "string" {
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fmt.Fprintf(os.Stderr, path+":"+funct+" uses string arguments, but has no error return\n")
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text += fmt.Sprintf("\tvar _p%d *byte\n", n)
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text += fmt.Sprintf("\t_p%d, _ = BytePtrFromString(%s)\n", n, p.Name)
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args = append(args, fmt.Sprintf("uintptr(unsafe.Pointer(_p%d))", n))
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n++
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} else if regexp.MustCompile(`^\[\](.*)`).FindStringSubmatch(p.Type) != nil {
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// Convert slice into pointer, length.
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// Have to be careful not to take address of &a[0] if len == 0:
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// pass dummy pointer in that case.
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// Used to pass nil, but some OSes or simulators reject write(fd, nil, 0).
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text += fmt.Sprintf("\tvar _p%d unsafe.Pointer\n", n)
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text += fmt.Sprintf("\tif len(%s) > 0 {\n\t\t_p%d = unsafe.Pointer(&%s[0])\n\t}", p.Name, n, p.Name)
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text += fmt.Sprintf(" else {\n\t\t_p%d = unsafe.Pointer(&_zero)\n\t}\n", n)
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args = append(args, fmt.Sprintf("uintptr(_p%d)", n), fmt.Sprintf("uintptr(len(%s))", p.Name))
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n++
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} else if p.Type == "int64" && (*openbsd || *netbsd) {
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args = append(args, "0")
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if endianness == "big-endian" {
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args = append(args, fmt.Sprintf("uintptr(%s>>32)", p.Name), fmt.Sprintf("uintptr(%s)", p.Name))
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} else if endianness == "little-endian" {
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args = append(args, fmt.Sprintf("uintptr(%s)", p.Name), fmt.Sprintf("uintptr(%s>>32)", p.Name))
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} else {
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args = append(args, fmt.Sprintf("uintptr(%s)", p.Name))
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}
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} else if p.Type == "int64" && *dragonfly {
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if regexp.MustCompile(`^(?i)extp(read|write)`).FindStringSubmatch(funct) == nil {
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args = append(args, "0")
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}
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if endianness == "big-endian" {
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args = append(args, fmt.Sprintf("uintptr(%s>>32)", p.Name), fmt.Sprintf("uintptr(%s)", p.Name))
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} else if endianness == "little-endian" {
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args = append(args, fmt.Sprintf("uintptr(%s)", p.Name), fmt.Sprintf("uintptr(%s>>32)", p.Name))
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} else {
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args = append(args, fmt.Sprintf("uintptr(%s)", p.Name))
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}
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} else if (p.Type == "int64" || p.Type == "uint64") && endianness != "" {
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if len(args)%2 == 1 && *arm {
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// arm abi specifies 64-bit argument uses
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// (even, odd) pair
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args = append(args, "0")
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}
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if endianness == "big-endian" {
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args = append(args, fmt.Sprintf("uintptr(%s>>32)", p.Name), fmt.Sprintf("uintptr(%s)", p.Name))
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} else {
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args = append(args, fmt.Sprintf("uintptr(%s)", p.Name), fmt.Sprintf("uintptr(%s>>32)", p.Name))
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}
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} else {
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args = append(args, fmt.Sprintf("uintptr(%s)", p.Name))
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}
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}
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// Determine which form to use; pad args with zeros.
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asm := "Syscall"
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if nonblock != nil {
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if errvar == "" && goos == "linux" {
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asm = "RawSyscallNoError"
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} else {
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asm = "RawSyscall"
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}
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} else {
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if errvar == "" && goos == "linux" {
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asm = "SyscallNoError"
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}
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}
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if len(args) <= 3 {
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for len(args) < 3 {
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args = append(args, "0")
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}
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} else if len(args) <= 6 {
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asm += "6"
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for len(args) < 6 {
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args = append(args, "0")
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}
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} else if len(args) <= 9 {
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asm += "9"
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for len(args) < 9 {
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args = append(args, "0")
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}
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} else {
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fmt.Fprintf(os.Stderr, "%s:%s too many arguments to system call\n", path, funct)
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}
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// System call number.
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if sysname == "" {
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sysname = "SYS_" + funct
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sysname = regexp.MustCompile(`([a-z])([A-Z])`).ReplaceAllString(sysname, `${1}_$2`)
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sysname = strings.ToUpper(sysname)
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}
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var libcFn string
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if libc {
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asm = "syscall_" + strings.ToLower(asm[:1]) + asm[1:] // internal syscall call
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sysname = strings.TrimPrefix(sysname, "SYS_") // remove SYS_
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sysname = strings.ToLower(sysname) // lowercase
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if sysname == "getdirentries64" {
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// Special case - libSystem name and
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// raw syscall name don't match.
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sysname = "__getdirentries64"
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}
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libcFn = sysname
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sysname = "funcPC(libc_" + sysname + "_trampoline)"
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}
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// Actual call.
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arglist := strings.Join(args, ", ")
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call := fmt.Sprintf("%s(%s, %s)", asm, sysname, arglist)
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// Assign return values.
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body := ""
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ret := []string{"_", "_", "_"}
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doErrno := false
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for i := 0; i < len(out); i++ {
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p := parseParam(out[i])
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reg := ""
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if p.Name == "err" && !*plan9 {
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reg = "e1"
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ret[2] = reg
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doErrno = true
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} else if p.Name == "err" && *plan9 {
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ret[0] = "r0"
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ret[2] = "e1"
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break
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} else {
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reg = fmt.Sprintf("r%d", i)
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ret[i] = reg
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}
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if p.Type == "bool" {
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reg = fmt.Sprintf("%s != 0", reg)
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}
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if p.Type == "int64" && endianness != "" {
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// 64-bit number in r1:r0 or r0:r1.
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if i+2 > len(out) {
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fmt.Fprintf(os.Stderr, "%s:%s not enough registers for int64 return\n", path, funct)
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}
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if endianness == "big-endian" {
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reg = fmt.Sprintf("int64(r%d)<<32 | int64(r%d)", i, i+1)
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} else {
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reg = fmt.Sprintf("int64(r%d)<<32 | int64(r%d)", i+1, i)
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}
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ret[i] = fmt.Sprintf("r%d", i)
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ret[i+1] = fmt.Sprintf("r%d", i+1)
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}
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if reg != "e1" || *plan9 {
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body += fmt.Sprintf("\t%s = %s(%s)\n", p.Name, p.Type, reg)
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}
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}
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if ret[0] == "_" && ret[1] == "_" && ret[2] == "_" {
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text += fmt.Sprintf("\t%s\n", call)
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} else {
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if errvar == "" && goos == "linux" {
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// raw syscall without error on Linux, see golang.org/issue/22924
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text += fmt.Sprintf("\t%s, %s := %s\n", ret[0], ret[1], call)
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} else {
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text += fmt.Sprintf("\t%s, %s, %s := %s\n", ret[0], ret[1], ret[2], call)
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}
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}
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text += body
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if *plan9 && ret[2] == "e1" {
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text += "\tif int32(r0) == -1 {\n"
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text += "\t\terr = e1\n"
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text += "\t}\n"
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} else if doErrno {
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text += "\tif e1 != 0 {\n"
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text += "\t\terr = errnoErr(e1)\n"
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text += "\t}\n"
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}
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text += "\treturn\n"
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text += "}\n\n"
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if libc && !trampolines[libcFn] {
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// some system calls share a trampoline, like read and readlen.
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trampolines[libcFn] = true
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// Declare assembly trampoline.
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text += fmt.Sprintf("func libc_%s_trampoline()\n", libcFn)
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// Assembly trampoline calls the libc_* function, which this magic
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// redirects to use the function from libSystem.
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text += fmt.Sprintf("//go:linkname libc_%s libc_%s\n", libcFn, libcFn)
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text += fmt.Sprintf("//go:cgo_import_dynamic libc_%s %s \"/usr/lib/libSystem.B.dylib\"\n", libcFn, libcFn)
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text += "\n"
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}
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}
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if err := s.Err(); err != nil {
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fmt.Fprintf(os.Stderr, err.Error())
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os.Exit(1)
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}
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file.Close()
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}
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fmt.Printf(srcTemplate, cmdLine(), buildTags(), text)
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}
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const srcTemplate = `// %s
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// Code generated by the command above; see README.md. DO NOT EDIT.
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// +build %s
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package unix
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import (
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"syscall"
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"unsafe"
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)
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var _ syscall.Errno
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%s
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`
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