khenaidoo | 106c61a | 2021-08-11 18:05:46 -0400 | [diff] [blame^] | 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 text |
| 6 | |
| 7 | import ( |
| 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" |
| 24 | func (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 '. |
| 50 | func (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. |
| 153 | func 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. |
| 158 | func UnmarshalString(s string) (string, error) { |
| 159 | d := NewDecoder([]byte(s)) |
| 160 | return d.parseString() |
| 161 | } |