aboutsummaryrefslogtreecommitdiff
path: root/src/cmd/go/internal/get/path.go
blob: ce2e0cdd709828efab7803c1df744152888e4105 (plain)
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
// Copyright 2018 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 get

import (
	"fmt"
	"strings"
	"unicode"
	"unicode/utf8"
)

// The following functions are copied verbatim from golang.org/x/mod/module/module.go,
// with a change to additionally reject Windows short-names,
// and one to accept arbitrary letters (golang.org/issue/29101).
//
// TODO(bcmills): After the call site for this function is backported,
// consolidate this back down to a single copy.
//
// NOTE: DO NOT MERGE THESE UNTIL WE DECIDE ABOUT ARBITRARY LETTERS IN MODULE MODE.

// CheckImportPath checks that an import path is valid.
func CheckImportPath(path string) error {
	if err := checkPath(path, false); err != nil {
		return fmt.Errorf("malformed import path %q: %v", path, err)
	}
	return nil
}

// checkPath checks that a general path is valid.
// It returns an error describing why but not mentioning path.
// Because these checks apply to both module paths and import paths,
// the caller is expected to add the "malformed ___ path %q: " prefix.
// fileName indicates whether the final element of the path is a file name
// (as opposed to a directory name).
func checkPath(path string, fileName bool) error {
	if !utf8.ValidString(path) {
		return fmt.Errorf("invalid UTF-8")
	}
	if path == "" {
		return fmt.Errorf("empty string")
	}
	if path[0] == '-' {
		return fmt.Errorf("leading dash")
	}
	if strings.Contains(path, "//") {
		return fmt.Errorf("double slash")
	}
	if path[len(path)-1] == '/' {
		return fmt.Errorf("trailing slash")
	}
	elemStart := 0
	for i, r := range path {
		if r == '/' {
			if err := checkElem(path[elemStart:i], fileName); err != nil {
				return err
			}
			elemStart = i + 1
		}
	}
	if err := checkElem(path[elemStart:], fileName); err != nil {
		return err
	}
	return nil
}

// checkElem checks whether an individual path element is valid.
// fileName indicates whether the element is a file name (not a directory name).
func checkElem(elem string, fileName bool) error {
	if elem == "" {
		return fmt.Errorf("empty path element")
	}
	if strings.Count(elem, ".") == len(elem) {
		return fmt.Errorf("invalid path element %q", elem)
	}
	if elem[0] == '.' && !fileName {
		return fmt.Errorf("leading dot in path element")
	}
	if elem[len(elem)-1] == '.' {
		return fmt.Errorf("trailing dot in path element")
	}

	charOK := pathOK
	if fileName {
		charOK = fileNameOK
	}
	for _, r := range elem {
		if !charOK(r) {
			return fmt.Errorf("invalid char %q", r)
		}
	}

	// Windows disallows a bunch of path elements, sadly.
	// See https://docs.microsoft.com/en-us/windows/desktop/fileio/naming-a-file
	short := elem
	if i := strings.Index(short, "."); i >= 0 {
		short = short[:i]
	}
	for _, bad := range badWindowsNames {
		if strings.EqualFold(bad, short) {
			return fmt.Errorf("disallowed path element %q", elem)
		}
	}

	// Reject path components that look like Windows short-names.
	// Those usually end in a tilde followed by one or more ASCII digits.
	if tilde := strings.LastIndexByte(short, '~'); tilde >= 0 && tilde < len(short)-1 {
		suffix := short[tilde+1:]
		suffixIsDigits := true
		for _, r := range suffix {
			if r < '0' || r > '9' {
				suffixIsDigits = false
				break
			}
		}
		if suffixIsDigits {
			return fmt.Errorf("trailing tilde and digits in path element")
		}
	}

	return nil
}

// pathOK reports whether r can appear in an import path element.
//
// NOTE: This function DIVERGES from module mode pathOK by accepting Unicode letters.
func pathOK(r rune) bool {
	if r < utf8.RuneSelf {
		return r == '+' || r == '-' || r == '.' || r == '_' || r == '~' ||
			'0' <= r && r <= '9' ||
			'A' <= r && r <= 'Z' ||
			'a' <= r && r <= 'z'
	}
	return unicode.IsLetter(r)
}

// fileNameOK reports whether r can appear in a file name.
// For now we allow all Unicode letters but otherwise limit to pathOK plus a few more punctuation characters.
// If we expand the set of allowed characters here, we have to
// work harder at detecting potential case-folding and normalization collisions.
// See note about "safe encoding" below.
func fileNameOK(r rune) bool {
	if r < utf8.RuneSelf {
		// Entire set of ASCII punctuation, from which we remove characters:
		//     ! " # $ % & ' ( ) * + , - . / : ; < = > ? @ [ \ ] ^ _ ` { | } ~
		// We disallow some shell special characters: " ' * < > ? ` |
		// (Note that some of those are disallowed by the Windows file system as well.)
		// We also disallow path separators / : and \ (fileNameOK is only called on path element characters).
		// We allow spaces (U+0020) in file names.
		const allowed = "!#$%&()+,-.=@[]^_{}~ "
		if '0' <= r && r <= '9' || 'A' <= r && r <= 'Z' || 'a' <= r && r <= 'z' {
			return true
		}
		for i := 0; i < len(allowed); i++ {
			if rune(allowed[i]) == r {
				return true
			}
		}
		return false
	}
	// It may be OK to add more ASCII punctuation here, but only carefully.
	// For example Windows disallows < > \, and macOS disallows :, so we must not allow those.
	return unicode.IsLetter(r)
}

// badWindowsNames are the reserved file path elements on Windows.
// See https://docs.microsoft.com/en-us/windows/desktop/fileio/naming-a-file
var badWindowsNames = []string{
	"CON",
	"PRN",
	"AUX",
	"NUL",
	"COM1",
	"COM2",
	"COM3",
	"COM4",
	"COM5",
	"COM6",
	"COM7",
	"COM8",
	"COM9",
	"LPT1",
	"LPT2",
	"LPT3",
	"LPT4",
	"LPT5",
	"LPT6",
	"LPT7",
	"LPT8",
	"LPT9",
}