github.com/nibnait/go-learn@v0.0.0-20220227013611-dfa47ea6d2da/src/pkg/mod/golang.org/x/sys@v0.0.0-20210630005230-0f9fa26af87c/unix/mkasm_darwin.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  //go:build ignore
     6  // +build ignore
     7  
     8  // mkasm_darwin.go generates assembly trampolines to call libSystem routines from Go.
     9  //This program must be run after mksyscall.go.
    10  package main
    11  
    12  import (
    13  	"bytes"
    14  	"fmt"
    15  	"io/ioutil"
    16  	"log"
    17  	"os"
    18  	"strings"
    19  )
    20  
    21  const ptrsize = 8 // Pointer size. All supported platforms are 64-bit.
    22  
    23  func writeASMFile(in string, fileName string, buildTags string) {
    24  	trampolines := map[string]bool{}
    25  
    26  	var out bytes.Buffer
    27  
    28  	fmt.Fprintf(&out, "// go run mkasm_darwin.go %s\n", strings.Join(os.Args[1:], " "))
    29  	fmt.Fprintf(&out, "// Code generated by the command above; DO NOT EDIT.\n")
    30  	fmt.Fprintf(&out, "\n")
    31  	fmt.Fprintf(&out, "//go:build %s\n", buildTags)
    32  	fmt.Fprintf(&out, "// +build %s\n", buildTags)
    33  	fmt.Fprintf(&out, "\n")
    34  	fmt.Fprintf(&out, "#include \"textflag.h\"\n")
    35  	for _, line := range strings.Split(in, "\n") {
    36  		const prefix = "var "
    37  		const suffix = "_trampoline_addr uintptr"
    38  		if !strings.HasPrefix(line, prefix) || !strings.HasSuffix(line, suffix) {
    39  			continue
    40  		}
    41  		fn := strings.TrimSuffix(strings.TrimPrefix(line, prefix), suffix)
    42  		if !trampolines[fn] {
    43  			trampolines[fn] = true
    44  			fmt.Fprintf(&out, "\nTEXT %s_trampoline<>(SB),NOSPLIT,$0-0\n", fn)
    45  			fmt.Fprintf(&out, "\tJMP\t%s(SB)\n\n", fn)
    46  			fmt.Fprintf(&out, "GLOBL\t·%s_trampoline_addr(SB), RODATA, $%d\n", fn, ptrsize)
    47  			fmt.Fprintf(&out, "DATA\t·%s_trampoline_addr(SB)/%d, $%s_trampoline<>(SB)\n", fn, ptrsize, fn)
    48  		}
    49  	}
    50  	err := ioutil.WriteFile(fileName, out.Bytes(), 0644)
    51  	if err != nil {
    52  		log.Fatalf("can't write %s: %s", fileName, err)
    53  	}
    54  }
    55  
    56  func main() {
    57  	in1, err := ioutil.ReadFile("syscall_darwin.go")
    58  	if err != nil {
    59  		log.Fatalf("can't open syscall_darwin.go: %s", err)
    60  	}
    61  	arch := os.Args[1]
    62  	in2, err := ioutil.ReadFile(fmt.Sprintf("syscall_darwin_%s.go", arch))
    63  	if err != nil {
    64  		log.Fatalf("can't open syscall_darwin_%s.go: %s", arch, err)
    65  	}
    66  	in3, err := ioutil.ReadFile(fmt.Sprintf("zsyscall_darwin_%s.go", arch))
    67  	if err != nil {
    68  		log.Fatalf("can't open zsyscall_darwin_%s.go: %s", arch, err)
    69  	}
    70  	in := string(in1) + string(in2) + string(in3)
    71  
    72  	writeASMFile(in, fmt.Sprintf("zsyscall_darwin_%s.s", arch), "go1.12")
    73  
    74  	in1, err = ioutil.ReadFile("syscall_darwin.1_13.go")
    75  	if err != nil {
    76  		log.Fatalf("can't open syscall_darwin.1_13.go: %s", err)
    77  	}
    78  	in2, err = ioutil.ReadFile(fmt.Sprintf("zsyscall_darwin_%s.1_13.go", arch))
    79  	if err != nil {
    80  		log.Fatalf("can't open zsyscall_darwin_%s.1_13.go: %s", arch, err)
    81  	}
    82  
    83  	in = string(in1) + string(in2)
    84  
    85  	writeASMFile(in, fmt.Sprintf("zsyscall_darwin_%s.1_13.s", arch), "go1.13")
    86  }