khenaidoo | 2672188 | 2021-08-11 17:42:52 -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 json |
| 6 | |
| 7 | import ( |
| 8 | "strconv" |
| 9 | "unicode" |
| 10 | "unicode/utf16" |
| 11 | "unicode/utf8" |
| 12 | |
| 13 | "google.golang.org/protobuf/internal/strs" |
| 14 | ) |
| 15 | |
| 16 | func (d *Decoder) parseString(in []byte) (string, int, error) { |
| 17 | in0 := in |
| 18 | if len(in) == 0 { |
| 19 | return "", 0, ErrUnexpectedEOF |
| 20 | } |
| 21 | if in[0] != '"' { |
| 22 | return "", 0, d.newSyntaxError(d.currPos(), "invalid character %q at start of string", in[0]) |
| 23 | } |
| 24 | in = in[1:] |
| 25 | i := indexNeedEscapeInBytes(in) |
| 26 | in, out := in[i:], in[:i:i] // set cap to prevent mutations |
| 27 | for len(in) > 0 { |
| 28 | switch r, n := utf8.DecodeRune(in); { |
| 29 | case r == utf8.RuneError && n == 1: |
| 30 | return "", 0, d.newSyntaxError(d.currPos(), "invalid UTF-8 in string") |
| 31 | case r < ' ': |
| 32 | return "", 0, d.newSyntaxError(d.currPos(), "invalid character %q in string", r) |
| 33 | case r == '"': |
| 34 | in = in[1:] |
| 35 | n := len(in0) - len(in) |
| 36 | return string(out), n, nil |
| 37 | case r == '\\': |
| 38 | if len(in) < 2 { |
| 39 | return "", 0, ErrUnexpectedEOF |
| 40 | } |
| 41 | switch r := in[1]; r { |
| 42 | case '"', '\\', '/': |
| 43 | in, out = in[2:], append(out, r) |
| 44 | case 'b': |
| 45 | in, out = in[2:], append(out, '\b') |
| 46 | case 'f': |
| 47 | in, out = in[2:], append(out, '\f') |
| 48 | case 'n': |
| 49 | in, out = in[2:], append(out, '\n') |
| 50 | case 'r': |
| 51 | in, out = in[2:], append(out, '\r') |
| 52 | case 't': |
| 53 | in, out = in[2:], append(out, '\t') |
| 54 | case 'u': |
| 55 | if len(in) < 6 { |
| 56 | return "", 0, ErrUnexpectedEOF |
| 57 | } |
| 58 | v, err := strconv.ParseUint(string(in[2:6]), 16, 16) |
| 59 | if err != nil { |
| 60 | return "", 0, d.newSyntaxError(d.currPos(), "invalid escape code %q in string", in[:6]) |
| 61 | } |
| 62 | in = in[6:] |
| 63 | |
| 64 | r := rune(v) |
| 65 | if utf16.IsSurrogate(r) { |
| 66 | if len(in) < 6 { |
| 67 | return "", 0, ErrUnexpectedEOF |
| 68 | } |
| 69 | v, err := strconv.ParseUint(string(in[2:6]), 16, 16) |
| 70 | r = utf16.DecodeRune(r, rune(v)) |
| 71 | if in[0] != '\\' || in[1] != 'u' || |
| 72 | r == unicode.ReplacementChar || err != nil { |
| 73 | return "", 0, d.newSyntaxError(d.currPos(), "invalid escape code %q in string", in[:6]) |
| 74 | } |
| 75 | in = in[6:] |
| 76 | } |
| 77 | out = append(out, string(r)...) |
| 78 | default: |
| 79 | return "", 0, d.newSyntaxError(d.currPos(), "invalid escape code %q in string", in[:2]) |
| 80 | } |
| 81 | default: |
| 82 | i := indexNeedEscapeInBytes(in[n:]) |
| 83 | in, out = in[n+i:], append(out, in[:n+i]...) |
| 84 | } |
| 85 | } |
| 86 | return "", 0, ErrUnexpectedEOF |
| 87 | } |
| 88 | |
| 89 | // indexNeedEscapeInBytes returns the index of the character that needs |
| 90 | // escaping. If no characters need escaping, this returns the input length. |
| 91 | func indexNeedEscapeInBytes(b []byte) int { return indexNeedEscapeInString(strs.UnsafeString(b)) } |