David K. Bainbridge | e05cf0c | 2021-08-19 03:16:50 +0000 | [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 defval marshals and unmarshals textual forms of default values. |
| 6 | // |
| 7 | // This package handles both the form historically used in Go struct field tags |
| 8 | // and also the form used by google.protobuf.FieldDescriptorProto.default_value |
| 9 | // since they differ in superficial ways. |
| 10 | package defval |
| 11 | |
| 12 | import ( |
| 13 | "fmt" |
| 14 | "math" |
| 15 | "strconv" |
| 16 | |
| 17 | ptext "google.golang.org/protobuf/internal/encoding/text" |
| 18 | errors "google.golang.org/protobuf/internal/errors" |
| 19 | pref "google.golang.org/protobuf/reflect/protoreflect" |
| 20 | ) |
| 21 | |
| 22 | // Format is the serialization format used to represent the default value. |
| 23 | type Format int |
| 24 | |
| 25 | const ( |
| 26 | _ Format = iota |
| 27 | |
| 28 | // Descriptor uses the serialization format that protoc uses with the |
| 29 | // google.protobuf.FieldDescriptorProto.default_value field. |
| 30 | Descriptor |
| 31 | |
| 32 | // GoTag uses the historical serialization format in Go struct field tags. |
| 33 | GoTag |
| 34 | ) |
| 35 | |
| 36 | // Unmarshal deserializes the default string s according to the given kind k. |
| 37 | // When k is an enum, a list of enum value descriptors must be provided. |
| 38 | func Unmarshal(s string, k pref.Kind, evs pref.EnumValueDescriptors, f Format) (pref.Value, pref.EnumValueDescriptor, error) { |
| 39 | switch k { |
| 40 | case pref.BoolKind: |
| 41 | if f == GoTag { |
| 42 | switch s { |
| 43 | case "1": |
| 44 | return pref.ValueOfBool(true), nil, nil |
| 45 | case "0": |
| 46 | return pref.ValueOfBool(false), nil, nil |
| 47 | } |
| 48 | } else { |
| 49 | switch s { |
| 50 | case "true": |
| 51 | return pref.ValueOfBool(true), nil, nil |
| 52 | case "false": |
| 53 | return pref.ValueOfBool(false), nil, nil |
| 54 | } |
| 55 | } |
| 56 | case pref.EnumKind: |
| 57 | if f == GoTag { |
| 58 | // Go tags use the numeric form of the enum value. |
| 59 | if n, err := strconv.ParseInt(s, 10, 32); err == nil { |
| 60 | if ev := evs.ByNumber(pref.EnumNumber(n)); ev != nil { |
| 61 | return pref.ValueOfEnum(ev.Number()), ev, nil |
| 62 | } |
| 63 | } |
| 64 | } else { |
| 65 | // Descriptor default_value use the enum identifier. |
| 66 | ev := evs.ByName(pref.Name(s)) |
| 67 | if ev != nil { |
| 68 | return pref.ValueOfEnum(ev.Number()), ev, nil |
| 69 | } |
| 70 | } |
| 71 | case pref.Int32Kind, pref.Sint32Kind, pref.Sfixed32Kind: |
| 72 | if v, err := strconv.ParseInt(s, 10, 32); err == nil { |
| 73 | return pref.ValueOfInt32(int32(v)), nil, nil |
| 74 | } |
| 75 | case pref.Int64Kind, pref.Sint64Kind, pref.Sfixed64Kind: |
| 76 | if v, err := strconv.ParseInt(s, 10, 64); err == nil { |
| 77 | return pref.ValueOfInt64(int64(v)), nil, nil |
| 78 | } |
| 79 | case pref.Uint32Kind, pref.Fixed32Kind: |
| 80 | if v, err := strconv.ParseUint(s, 10, 32); err == nil { |
| 81 | return pref.ValueOfUint32(uint32(v)), nil, nil |
| 82 | } |
| 83 | case pref.Uint64Kind, pref.Fixed64Kind: |
| 84 | if v, err := strconv.ParseUint(s, 10, 64); err == nil { |
| 85 | return pref.ValueOfUint64(uint64(v)), nil, nil |
| 86 | } |
| 87 | case pref.FloatKind, pref.DoubleKind: |
| 88 | var v float64 |
| 89 | var err error |
| 90 | switch s { |
| 91 | case "-inf": |
| 92 | v = math.Inf(-1) |
| 93 | case "inf": |
| 94 | v = math.Inf(+1) |
| 95 | case "nan": |
| 96 | v = math.NaN() |
| 97 | default: |
| 98 | v, err = strconv.ParseFloat(s, 64) |
| 99 | } |
| 100 | if err == nil { |
| 101 | if k == pref.FloatKind { |
| 102 | return pref.ValueOfFloat32(float32(v)), nil, nil |
| 103 | } else { |
| 104 | return pref.ValueOfFloat64(float64(v)), nil, nil |
| 105 | } |
| 106 | } |
| 107 | case pref.StringKind: |
| 108 | // String values are already unescaped and can be used as is. |
| 109 | return pref.ValueOfString(s), nil, nil |
| 110 | case pref.BytesKind: |
| 111 | if b, ok := unmarshalBytes(s); ok { |
| 112 | return pref.ValueOfBytes(b), nil, nil |
| 113 | } |
| 114 | } |
| 115 | return pref.Value{}, nil, errors.New("could not parse value for %v: %q", k, s) |
| 116 | } |
| 117 | |
| 118 | // Marshal serializes v as the default string according to the given kind k. |
| 119 | // When specifying the Descriptor format for an enum kind, the associated |
| 120 | // enum value descriptor must be provided. |
| 121 | func Marshal(v pref.Value, ev pref.EnumValueDescriptor, k pref.Kind, f Format) (string, error) { |
| 122 | switch k { |
| 123 | case pref.BoolKind: |
| 124 | if f == GoTag { |
| 125 | if v.Bool() { |
| 126 | return "1", nil |
| 127 | } else { |
| 128 | return "0", nil |
| 129 | } |
| 130 | } else { |
| 131 | if v.Bool() { |
| 132 | return "true", nil |
| 133 | } else { |
| 134 | return "false", nil |
| 135 | } |
| 136 | } |
| 137 | case pref.EnumKind: |
| 138 | if f == GoTag { |
| 139 | return strconv.FormatInt(int64(v.Enum()), 10), nil |
| 140 | } else { |
| 141 | return string(ev.Name()), nil |
| 142 | } |
| 143 | case pref.Int32Kind, pref.Sint32Kind, pref.Sfixed32Kind, pref.Int64Kind, pref.Sint64Kind, pref.Sfixed64Kind: |
| 144 | return strconv.FormatInt(v.Int(), 10), nil |
| 145 | case pref.Uint32Kind, pref.Fixed32Kind, pref.Uint64Kind, pref.Fixed64Kind: |
| 146 | return strconv.FormatUint(v.Uint(), 10), nil |
| 147 | case pref.FloatKind, pref.DoubleKind: |
| 148 | f := v.Float() |
| 149 | switch { |
| 150 | case math.IsInf(f, -1): |
| 151 | return "-inf", nil |
| 152 | case math.IsInf(f, +1): |
| 153 | return "inf", nil |
| 154 | case math.IsNaN(f): |
| 155 | return "nan", nil |
| 156 | default: |
| 157 | if k == pref.FloatKind { |
| 158 | return strconv.FormatFloat(f, 'g', -1, 32), nil |
| 159 | } else { |
| 160 | return strconv.FormatFloat(f, 'g', -1, 64), nil |
| 161 | } |
| 162 | } |
| 163 | case pref.StringKind: |
| 164 | // String values are serialized as is without any escaping. |
| 165 | return v.String(), nil |
| 166 | case pref.BytesKind: |
| 167 | if s, ok := marshalBytes(v.Bytes()); ok { |
| 168 | return s, nil |
| 169 | } |
| 170 | } |
| 171 | return "", errors.New("could not format value for %v: %v", k, v) |
| 172 | } |
| 173 | |
| 174 | // unmarshalBytes deserializes bytes by applying C unescaping. |
| 175 | func unmarshalBytes(s string) ([]byte, bool) { |
| 176 | // Bytes values use the same escaping as the text format, |
| 177 | // however they lack the surrounding double quotes. |
| 178 | v, err := ptext.UnmarshalString(`"` + s + `"`) |
| 179 | if err != nil { |
| 180 | return nil, false |
| 181 | } |
| 182 | return []byte(v), true |
| 183 | } |
| 184 | |
| 185 | // marshalBytes serializes bytes by using C escaping. |
| 186 | // To match the exact output of protoc, this is identical to the |
| 187 | // CEscape function in strutil.cc of the protoc source code. |
| 188 | func marshalBytes(b []byte) (string, bool) { |
| 189 | var s []byte |
| 190 | for _, c := range b { |
| 191 | switch c { |
| 192 | case '\n': |
| 193 | s = append(s, `\n`...) |
| 194 | case '\r': |
| 195 | s = append(s, `\r`...) |
| 196 | case '\t': |
| 197 | s = append(s, `\t`...) |
| 198 | case '"': |
| 199 | s = append(s, `\"`...) |
| 200 | case '\'': |
| 201 | s = append(s, `\'`...) |
| 202 | case '\\': |
| 203 | s = append(s, `\\`...) |
| 204 | default: |
| 205 | if printableASCII := c >= 0x20 && c <= 0x7e; printableASCII { |
| 206 | s = append(s, c) |
| 207 | } else { |
| 208 | s = append(s, fmt.Sprintf(`\%03o`, c)...) |
| 209 | } |
| 210 | } |
| 211 | } |
| 212 | return string(s), true |
| 213 | } |