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
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
|
// Copyright 2010 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 exec
import (
"errors"
"io/fs"
"os"
"path/filepath"
"strings"
"syscall"
)
// ErrNotFound is the error resulting if a path search failed to find an executable file.
var ErrNotFound = errors.New("executable file not found in %PATH%")
func chkStat(file string) error {
d, err := os.Stat(file)
if err != nil {
return err
}
if d.IsDir() {
return fs.ErrPermission
}
return nil
}
func hasExt(file string) bool {
i := strings.LastIndex(file, ".")
if i < 0 {
return false
}
return strings.LastIndexAny(file, `:\/`) < i
}
func findExecutable(file string, exts []string) (string, error) {
if len(exts) == 0 {
return file, chkStat(file)
}
if hasExt(file) {
if chkStat(file) == nil {
return file, nil
}
// Keep checking exts below, so that programs with weird names
// like "foo.bat.exe" will resolve instead of failing.
}
for _, e := range exts {
if f := file + e; chkStat(f) == nil {
return f, nil
}
}
if hasExt(file) {
return "", fs.ErrNotExist
}
return "", ErrNotFound
}
// LookPath searches for an executable named file in the
// directories named by the PATH environment variable.
// LookPath also uses PATHEXT environment variable to match
// a suitable candidate.
// If file contains a slash, it is tried directly and the PATH is not consulted.
// Otherwise, on success, the result is an absolute path.
//
// In older versions of Go, LookPath could return a path relative to the current directory.
// As of Go 1.19, LookPath will instead return that path along with an error satisfying
// errors.Is(err, ErrDot). See the package documentation for more details.
func LookPath(file string) (string, error) {
return lookPath(file, pathExt())
}
// lookExtensions finds windows executable by its dir and path.
// It uses LookPath to try appropriate extensions.
// lookExtensions does not search PATH, instead it converts `prog` into `.\prog`.
//
// If the path already has an extension found in PATHEXT,
// lookExtensions returns it directly without searching
// for additional extensions. For example,
// "C:\foo\example.com" would be returned as-is even if the
// program is actually "C:\foo\example.com.exe".
func lookExtensions(path, dir string) (string, error) {
if filepath.Base(path) == path {
path = "." + string(filepath.Separator) + path
}
exts := pathExt()
if ext := filepath.Ext(path); ext != "" {
for _, e := range exts {
if strings.EqualFold(ext, e) {
// Assume that path has already been resolved.
return path, nil
}
}
}
if dir == "" {
return lookPath(path, exts)
}
if filepath.VolumeName(path) != "" {
return lookPath(path, exts)
}
if len(path) > 1 && os.IsPathSeparator(path[0]) {
return lookPath(path, exts)
}
dirandpath := filepath.Join(dir, path)
// We assume that LookPath will only add file extension.
lp, err := lookPath(dirandpath, exts)
if err != nil {
return "", err
}
ext := strings.TrimPrefix(lp, dirandpath)
return path + ext, nil
}
func pathExt() []string {
var exts []string
x := os.Getenv(`PATHEXT`)
if x != "" {
for _, e := range strings.Split(strings.ToLower(x), `;`) {
if e == "" {
continue
}
if e[0] != '.' {
e = "." + e
}
exts = append(exts, e)
}
} else {
exts = []string{".com", ".exe", ".bat", ".cmd"}
}
return exts
}
// lookPath implements LookPath for the given PATHEXT list.
func lookPath(file string, exts []string) (string, error) {
if strings.ContainsAny(file, `:\/`) {
f, err := findExecutable(file, exts)
if err == nil {
return f, nil
}
return "", &Error{file, err}
}
// On Windows, creating the NoDefaultCurrentDirectoryInExePath
// environment variable (with any value or no value!) signals that
// path lookups should skip the current directory.
// In theory we are supposed to call NeedCurrentDirectoryForExePathW
// "as the registry location of this environment variable can change"
// but that seems exceedingly unlikely: it would break all users who
// have configured their environment this way!
// https://docs.microsoft.com/en-us/windows/win32/api/processenv/nf-processenv-needcurrentdirectoryforexepathw
// See also go.dev/issue/43947.
var (
dotf string
dotErr error
)
if _, found := syscall.Getenv("NoDefaultCurrentDirectoryInExePath"); !found {
if f, err := findExecutable(filepath.Join(".", file), exts); err == nil {
if execerrdot.Value() == "0" {
execerrdot.IncNonDefault()
return f, nil
}
dotf, dotErr = f, &Error{file, ErrDot}
}
}
path := os.Getenv("path")
for _, dir := range filepath.SplitList(path) {
if dir == "" {
// Skip empty entries, consistent with what PowerShell does.
// (See https://go.dev/issue/61493#issuecomment-1649724826.)
continue
}
if f, err := findExecutable(filepath.Join(dir, file), exts); err == nil {
if dotErr != nil {
// https://go.dev/issue/53536: if we resolved a relative path implicitly,
// and it is the same executable that would be resolved from the explicit %PATH%,
// prefer the explicit name for the executable (and, likely, no error) instead
// of the equivalent implicit name with ErrDot.
//
// Otherwise, return the ErrDot for the implicit path as soon as we find
// out that the explicit one doesn't match.
dotfi, dotfiErr := os.Lstat(dotf)
fi, fiErr := os.Lstat(f)
if dotfiErr != nil || fiErr != nil || !os.SameFile(dotfi, fi) {
return dotf, dotErr
}
}
if !filepath.IsAbs(f) {
if execerrdot.Value() != "0" {
// If this is the same relative path that we already found,
// dotErr is non-nil and we already checked it above.
// Otherwise, record this path as the one to which we must resolve,
// with or without a dotErr.
if dotErr == nil {
dotf, dotErr = f, &Error{file, ErrDot}
}
continue
}
execerrdot.IncNonDefault()
}
return f, nil
}
}
if dotErr != nil {
return dotf, dotErr
}
return "", &Error{file, ErrNotFound}
}
|
