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 5package text 6 7import ( 8 "bytes" 9 "strconv" 10 "strings" 11 "unicode" 12 "unicode/utf16" 13 "unicode/utf8" 14 15 "google.golang.org/protobuf/internal/strs" 16) 17 18// parseStringValue parses string field token. 19// This differs from parseString since the text format allows 20// multiple back-to-back string literals where they are semantically treated 21// as a single large string with all values concatenated. 22// 23// E.g., `"foo" "bar" "baz"` => "foobarbaz" 24func (d *Decoder) parseStringValue() (Token, error) { 25 // Note that the ending quote is sufficient to unambiguously mark the end 26 // of a string. Thus, the text grammar does not require intervening 27 // whitespace or control characters in-between strings. 28 // Thus, the following is valid: 29 // `"foo"'bar'"baz"` => "foobarbaz" 30 in0 := d.in 31 var ss []string 32 for len(d.in) > 0 && (d.in[0] == '"' || d.in[0] == '\'') { 33 s, err := d.parseString() 34 if err != nil { 35 return Token{}, err 36 } 37 ss = append(ss, s) 38 } 39 // d.in already points to the end of the value at this point. 40 return Token{ 41 kind: Scalar, 42 attrs: stringValue, 43 pos: len(d.orig) - len(in0), 44 raw: in0[:len(in0)-len(d.in)], 45 str: strings.Join(ss, ""), 46 }, nil 47} 48 49// parseString parses a string value enclosed in " or '. 50func (d *Decoder) parseString() (string, error) { 51 in := d.in 52 if len(in) == 0 { 53 return "", ErrUnexpectedEOF 54 } 55 quote := in[0] 56 in = in[1:] 57 i := indexNeedEscapeInBytes(in) 58 in, out := in[i:], in[:i:i] // set cap to prevent mutations 59 for len(in) > 0 { 60 switch r, n := utf8.DecodeRune(in); { 61 case r == utf8.RuneError && n == 1: 62 return "", d.newSyntaxError("invalid UTF-8 detected") 63 case r == 0 || r == '\n': 64 return "", d.newSyntaxError("invalid character %q in string", r) 65 case r == rune(quote): 66 in = in[1:] 67 d.consume(len(d.in) - len(in)) 68 return string(out), nil 69 case r == '\\': 70 if len(in) < 2 { 71 return "", ErrUnexpectedEOF 72 } 73 switch r := in[1]; r { 74 case '"', '\'', '\\', '?': 75 in, out = in[2:], append(out, r) 76 case 'a': 77 in, out = in[2:], append(out, '\a') 78 case 'b': 79 in, out = in[2:], append(out, '\b') 80 case 'n': 81 in, out = in[2:], append(out, '\n') 82 case 'r': 83 in, out = in[2:], append(out, '\r') 84 case 't': 85 in, out = in[2:], append(out, '\t') 86 case 'v': 87 in, out = in[2:], append(out, '\v') 88 case 'f': 89 in, out = in[2:], append(out, '\f') 90 case '0', '1', '2', '3', '4', '5', '6', '7': 91 // One, two, or three octal characters. 92 n := len(in[1:]) - len(bytes.TrimLeft(in[1:], "01234567")) 93 if n > 3 { 94 n = 3 95 } 96 v, err := strconv.ParseUint(string(in[1:1+n]), 8, 8) 97 if err != nil { 98 return "", d.newSyntaxError("invalid octal escape code %q in string", in[:1+n]) 99 } 100 in, out = in[1+n:], append(out, byte(v)) 101 case 'x': 102 // One or two hexadecimal characters. 103 n := len(in[2:]) - len(bytes.TrimLeft(in[2:], "0123456789abcdefABCDEF")) 104 if n > 2 { 105 n = 2 106 } 107 v, err := strconv.ParseUint(string(in[2:2+n]), 16, 8) 108 if err != nil { 109 return "", d.newSyntaxError("invalid hex escape code %q in string", in[:2+n]) 110 } 111 in, out = in[2+n:], append(out, byte(v)) 112 case 'u', 'U': 113 // Four or eight hexadecimal characters 114 n := 6 115 if r == 'U' { 116 n = 10 117 } 118 if len(in) < n { 119 return "", ErrUnexpectedEOF 120 } 121 v, err := strconv.ParseUint(string(in[2:n]), 16, 32) 122 if utf8.MaxRune < v || err != nil { 123 return "", d.newSyntaxError("invalid Unicode escape code %q in string", in[:n]) 124 } 125 in = in[n:] 126 127 r := rune(v) 128 if utf16.IsSurrogate(r) { 129 if len(in) < 6 { 130 return "", ErrUnexpectedEOF 131 } 132 v, err := strconv.ParseUint(string(in[2:6]), 16, 16) 133 r = utf16.DecodeRune(r, rune(v)) 134 if in[0] != '\\' || in[1] != 'u' || r == unicode.ReplacementChar || err != nil { 135 return "", d.newSyntaxError("invalid Unicode escape code %q in string", in[:6]) 136 } 137 in = in[6:] 138 } 139 out = append(out, string(r)...) 140 default: 141 return "", d.newSyntaxError("invalid escape code %q in string", in[:2]) 142 } 143 default: 144 i := indexNeedEscapeInBytes(in[n:]) 145 in, out = in[n+i:], append(out, in[:n+i]...) 146 } 147 } 148 return "", ErrUnexpectedEOF 149} 150 151// indexNeedEscapeInString returns the index of the character that needs 152// escaping. If no characters need escaping, this returns the input length. 153func indexNeedEscapeInBytes(b []byte) int { return indexNeedEscapeInString(strs.UnsafeString(b)) } 154 155// UnmarshalString returns an unescaped string given a textproto string value. 156// String value needs to contain single or double quotes. This is only used by 157// internal/encoding/defval package for unmarshaling bytes. 158func UnmarshalString(s string) (string, error) { 159 d := NewDecoder([]byte(s)) 160 return d.parseString() 161} 162