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 package str 6 7 import ( 8 "os" 9 "path/filepath" 10 "runtime" 11 "strings" 12 ) 13 14 // HasPathPrefix reports whether the slash-separated path s 15 // begins with the elements in prefix. 16 func HasPathPrefix(s, prefix string) bool { 17 if len(s) == len(prefix) { 18 return s == prefix 19 } 20 if prefix == "" { 21 return true 22 } 23 if len(s) > len(prefix) { 24 if prefix[len(prefix)-1] == '/' || s[len(prefix)] == '/' { 25 return s[:len(prefix)] == prefix 26 } 27 } 28 return false 29 } 30 31 // HasFilePathPrefix reports whether the filesystem path s 32 // begins with the elements in prefix. 33 // 34 // HasFilePathPrefix is case-sensitive (except for volume names) even if the 35 // filesystem is not, does not apply Unicode normalization even if the 36 // filesystem does, and assumes that all path separators are canonicalized to 37 // filepath.Separator (as returned by filepath.Clean). 38 func HasFilePathPrefix(s, prefix string) bool { 39 sv := filepath.VolumeName(s) 40 pv := filepath.VolumeName(prefix) 41 42 // Strip the volume from both paths before canonicalizing sv and pv: 43 // it's unlikely that strings.ToUpper will change the length of the string, 44 // but doesn't seem impossible. 45 s = s[len(sv):] 46 prefix = prefix[len(pv):] 47 48 // Always treat Windows volume names as case-insensitive, even though 49 // we don't treat the rest of the path as such. 50 // 51 // TODO(bcmills): Why do we care about case only for the volume name? It's 52 // been this way since https://go.dev/cl/11316, but I don't understand why 53 // that problem doesn't apply to case differences in the entire path. 54 if sv != pv { 55 sv = strings.ToUpper(sv) 56 pv = strings.ToUpper(pv) 57 } 58 59 switch { 60 default: 61 return false 62 case sv != pv: 63 return false 64 case len(s) == len(prefix): 65 return s == prefix 66 case prefix == "": 67 return true 68 case len(s) > len(prefix): 69 if prefix[len(prefix)-1] == filepath.Separator { 70 return strings.HasPrefix(s, prefix) 71 } 72 return s[len(prefix)] == filepath.Separator && s[:len(prefix)] == prefix 73 } 74 } 75 76 // TrimFilePathPrefix returns s without the leading path elements in prefix, 77 // such that joining the string to prefix produces s. 78 // 79 // If s does not start with prefix (HasFilePathPrefix with the same arguments 80 // returns false), TrimFilePathPrefix returns s. If s equals prefix, 81 // TrimFilePathPrefix returns "". 82 func TrimFilePathPrefix(s, prefix string) string { 83 if prefix == "" { 84 // Trimming the empty string from a path should join to produce that path. 85 // (Trim("/tmp/foo", "") should give "/tmp/foo", not "tmp/foo".) 86 return s 87 } 88 if !HasFilePathPrefix(s, prefix) { 89 return s 90 } 91 92 trimmed := s[len(prefix):] 93 if len(trimmed) > 0 && os.IsPathSeparator(trimmed[0]) { 94 if runtime.GOOS == "windows" && prefix == filepath.VolumeName(prefix) && len(prefix) == 2 && prefix[1] == ':' { 95 // Joining a relative path to a bare Windows drive letter produces a path 96 // relative to the working directory on that drive, but the original path 97 // was absolute, not relative. Keep the leading path separator so that it 98 // remains absolute when joined to prefix. 99 } else { 100 // Prefix ends in a regular path element, so strip the path separator that 101 // follows it. 102 trimmed = trimmed[1:] 103 } 104 } 105 return trimmed 106 } 107 108 // WithFilePathSeparator returns s with a trailing path separator, or the empty 109 // string if s is empty. 110 func WithFilePathSeparator(s string) string { 111 if s == "" || os.IsPathSeparator(s[len(s)-1]) { 112 return s 113 } 114 return s + string(filepath.Separator) 115 } 116 117 // QuoteGlob returns s with all Glob metacharacters quoted. 118 // We don't try to handle backslash here, as that can appear in a 119 // file path on Windows. 120 func QuoteGlob(s string) string { 121 if !strings.ContainsAny(s, `*?[]`) { 122 return s 123 } 124 var sb strings.Builder 125 for _, c := range s { 126 switch c { 127 case '*', '?', '[', ']': 128 sb.WriteByte('\\') 129 } 130 sb.WriteRune(c) 131 } 132 return sb.String() 133 } 134