File size: 4,297 Bytes
e36aeda | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 | // Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package pkgpath determines the package path used by gccgo/GoLLVM symbols.
// This package is not used for the gc compiler.
package pkgpath
import (
"bytes"
"errors"
"fmt"
"os"
"os/exec"
"strings"
)
// ToSymbolFunc returns a function that may be used to convert a
// package path into a string suitable for use as a symbol.
// cmd is the gccgo/GoLLVM compiler in use, and tmpdir is a temporary
// directory to pass to os.CreateTemp().
// For example, this returns a function that converts "net/http"
// into a string like "net..z2fhttp". The actual string varies for
// different gccgo/GoLLVM versions, which is why this returns a function
// that does the conversion appropriate for the compiler in use.
func ToSymbolFunc(cmd, tmpdir string) (func(string) string, error) {
// To determine the scheme used by cmd, we compile a small
// file and examine the assembly code. Older versions of gccgo
// use a simple mangling scheme where there can be collisions
// between packages whose paths are different but mangle to
// the same string. More recent versions use a new mangler
// that avoids these collisions.
const filepat = "*_gccgo_manglechck.go"
f, err := os.CreateTemp(tmpdir, filepat)
if err != nil {
return nil, err
}
gofilename := f.Name()
f.Close()
defer os.Remove(gofilename)
if err := os.WriteFile(gofilename, []byte(mangleCheckCode), 0644); err != nil {
return nil, err
}
command := exec.Command(cmd, "-S", "-o", "-", gofilename)
buf, err := command.Output()
if err != nil {
return nil, err
}
// Original mangling: go.l__ufer.Run
// Mangling v2: go.l..u00e4ufer.Run
// Mangling v3: go_0l_u00e4ufer.Run
if bytes.Contains(buf, []byte("go_0l_u00e4ufer.Run")) {
return toSymbolV3, nil
} else if bytes.Contains(buf, []byte("go.l..u00e4ufer.Run")) {
return toSymbolV2, nil
} else if bytes.Contains(buf, []byte("go.l__ufer.Run")) {
return toSymbolV1, nil
} else {
return nil, errors.New(cmd + ": unrecognized mangling scheme")
}
}
// mangleCheckCode is the package we compile to determine the mangling scheme.
const mangleCheckCode = `
package läufer
func Run(x int) int {
return 1
}
`
// toSymbolV1 converts a package path using the original mangling scheme.
func toSymbolV1(ppath string) string {
clean := func(r rune) rune {
switch {
case 'A' <= r && r <= 'Z', 'a' <= r && r <= 'z',
'0' <= r && r <= '9':
return r
}
return '_'
}
return strings.Map(clean, ppath)
}
// toSymbolV2 converts a package path using the second mangling scheme.
func toSymbolV2(ppath string) string {
var bsl strings.Builder
changed := false
for _, c := range ppath {
if ('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z') || ('0' <= c && c <= '9') || c == '_' {
bsl.WriteByte(byte(c))
continue
}
var enc string
switch {
case c == '.':
enc = ".x2e"
case c < 0x80:
enc = fmt.Sprintf("..z%02x", c)
case c < 0x10000:
enc = fmt.Sprintf("..u%04x", c)
default:
enc = fmt.Sprintf("..U%08x", c)
}
bsl.WriteString(enc)
changed = true
}
if !changed {
return ppath
}
return bsl.String()
}
// v3UnderscoreCodes maps from a character that supports an underscore
// encoding to the underscore encoding character.
var v3UnderscoreCodes = map[byte]byte{
'_': '_',
'.': '0',
'/': '1',
'*': '2',
',': '3',
'{': '4',
'}': '5',
'[': '6',
']': '7',
'(': '8',
')': '9',
'"': 'a',
' ': 'b',
';': 'c',
}
// toSymbolV3 converts a package path using the third mangling scheme.
func toSymbolV3(ppath string) string {
var bsl strings.Builder
changed := false
for _, c := range ppath {
if ('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z') || ('0' <= c && c <= '9') {
bsl.WriteByte(byte(c))
continue
}
if c < 0x80 {
if u, ok := v3UnderscoreCodes[byte(c)]; ok {
bsl.WriteByte('_')
bsl.WriteByte(u)
changed = true
continue
}
}
var enc string
switch {
case c < 0x80:
enc = fmt.Sprintf("_x%02x", c)
case c < 0x10000:
enc = fmt.Sprintf("_u%04x", c)
default:
enc = fmt.Sprintf("_U%08x", c)
}
bsl.WriteString(enc)
changed = true
}
if !changed {
return ppath
}
return bsl.String()
}
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