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
172
173
174
|
// 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"
exec "internal/execabs"
"io/ioutil"
"os"
"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 ioutil.TempFile.
// 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 := ioutil.TempFile(tmpdir, filepat)
if err != nil {
return nil, err
}
gofilename := f.Name()
f.Close()
defer os.Remove(gofilename)
if err := ioutil.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 {
// This has to build at boostrap time, so it has to build
// with Go 1.4, so we don't use strings.Builder.
bsl := make([]byte, 0, len(ppath))
changed := false
for _, c := range ppath {
if ('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z') || ('0' <= c && c <= '9') || c == '_' {
bsl = append(bsl, 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 = append(bsl, enc...)
changed = true
}
if !changed {
return ppath
}
return string(bsl)
}
// 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 {
// This has to build at boostrap time, so it has to build
// with Go 1.4, so we don't use strings.Builder.
bsl := make([]byte, 0, len(ppath))
changed := false
for _, c := range ppath {
if ('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z') || ('0' <= c && c <= '9') {
bsl = append(bsl, byte(c))
continue
}
if c < 0x80 {
if u, ok := v3UnderscoreCodes[byte(c)]; ok {
bsl = append(bsl, '_', 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 = append(bsl, enc...)
changed = true
}
if !changed {
return ppath
}
return string(bsl)
}
|
