resolve.go raw
1 //
2 // Copyright (c) 2011-2019 Canonical Ltd
3 //
4 // Licensed under the Apache License, Version 2.0 (the "License");
5 // you may not use this file except in compliance with the License.
6 // You may obtain a copy of the License at
7 //
8 // http://www.apache.org/licenses/LICENSE-2.0
9 //
10 // Unless required by applicable law or agreed to in writing, software
11 // distributed under the License is distributed on an "AS IS" BASIS,
12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 // See the License for the specific language governing permissions and
14 // limitations under the License.
15
16 package yaml
17
18 import (
19 "encoding/base64"
20 "math"
21 "regexp"
22 "strconv"
23 "strings"
24 "time"
25 )
26
27 type resolveMapItem struct {
28 value interface{}
29 tag string
30 }
31
32 var resolveTable = make([]byte, 256)
33 var resolveMap = make(map[string]resolveMapItem)
34
35 func init() {
36 t := resolveTable
37 t[int('+')] = 'S' // Sign
38 t[int('-')] = 'S'
39 for _, c := range "0123456789" {
40 t[int(c)] = 'D' // Digit
41 }
42 for _, c := range "yYnNtTfFoO~" {
43 t[int(c)] = 'M' // In map
44 }
45 t[int('.')] = '.' // Float (potentially in map)
46
47 var resolveMapList = []struct {
48 v interface{}
49 tag string
50 l []string
51 }{
52 {true, boolTag, []string{"true", "True", "TRUE"}},
53 {false, boolTag, []string{"false", "False", "FALSE"}},
54 {nil, nullTag, []string{"", "~", "null", "Null", "NULL"}},
55 {math.NaN(), floatTag, []string{".nan", ".NaN", ".NAN"}},
56 {math.Inf(+1), floatTag, []string{".inf", ".Inf", ".INF"}},
57 {math.Inf(+1), floatTag, []string{"+.inf", "+.Inf", "+.INF"}},
58 {math.Inf(-1), floatTag, []string{"-.inf", "-.Inf", "-.INF"}},
59 {"<<", mergeTag, []string{"<<"}},
60 }
61
62 m := resolveMap
63 for _, item := range resolveMapList {
64 for _, s := range item.l {
65 m[s] = resolveMapItem{item.v, item.tag}
66 }
67 }
68 }
69
70 const (
71 nullTag = "!!null"
72 boolTag = "!!bool"
73 strTag = "!!str"
74 intTag = "!!int"
75 floatTag = "!!float"
76 timestampTag = "!!timestamp"
77 seqTag = "!!seq"
78 mapTag = "!!map"
79 binaryTag = "!!binary"
80 mergeTag = "!!merge"
81 )
82
83 var longTags = make(map[string]string)
84 var shortTags = make(map[string]string)
85
86 func init() {
87 for _, stag := range []string{nullTag, boolTag, strTag, intTag, floatTag, timestampTag, seqTag, mapTag, binaryTag, mergeTag} {
88 ltag := longTag(stag)
89 longTags[stag] = ltag
90 shortTags[ltag] = stag
91 }
92 }
93
94 const longTagPrefix = "tag:yaml.org,2002:"
95
96 func shortTag(tag string) string {
97 if strings.HasPrefix(tag, longTagPrefix) {
98 if stag, ok := shortTags[tag]; ok {
99 return stag
100 }
101 return "!!" + tag[len(longTagPrefix):]
102 }
103 return tag
104 }
105
106 func longTag(tag string) string {
107 if strings.HasPrefix(tag, "!!") {
108 if ltag, ok := longTags[tag]; ok {
109 return ltag
110 }
111 return longTagPrefix + tag[2:]
112 }
113 return tag
114 }
115
116 func resolvableTag(tag string) bool {
117 switch tag {
118 case "", strTag, boolTag, intTag, floatTag, nullTag, timestampTag:
119 return true
120 }
121 return false
122 }
123
124 var yamlStyleFloat = regexp.MustCompile(`^[-+]?(\.[0-9]+|[0-9]+(\.[0-9]*)?)([eE][-+]?[0-9]+)?$`)
125
126 func resolve(tag string, in string) (rtag string, out interface{}) {
127 tag = shortTag(tag)
128 if !resolvableTag(tag) {
129 return tag, in
130 }
131
132 defer func() {
133 switch tag {
134 case "", rtag, strTag, binaryTag:
135 return
136 case floatTag:
137 if rtag == intTag {
138 switch v := out.(type) {
139 case int64:
140 rtag = floatTag
141 out = float64(v)
142 return
143 case int:
144 rtag = floatTag
145 out = float64(v)
146 return
147 }
148 }
149 }
150 failf("cannot decode %s `%s` as a %s", shortTag(rtag), in, shortTag(tag))
151 }()
152
153 // Any data is accepted as a !!str or !!binary.
154 // Otherwise, the prefix is enough of a hint about what it might be.
155 hint := byte('N')
156 if in != "" {
157 hint = resolveTable[in[0]]
158 }
159 if hint != 0 && tag != strTag && tag != binaryTag {
160 // Handle things we can lookup in a map.
161 if item, ok := resolveMap[in]; ok {
162 return item.tag, item.value
163 }
164
165 // Base 60 floats are a bad idea, were dropped in YAML 1.2, and
166 // are purposefully unsupported here. They're still quoted on
167 // the way out for compatibility with other parser, though.
168
169 switch hint {
170 case 'M':
171 // We've already checked the map above.
172
173 case '.':
174 // Not in the map, so maybe a normal float.
175 floatv, err := strconv.ParseFloat(in, 64)
176 if err == nil {
177 return floatTag, floatv
178 }
179
180 case 'D', 'S':
181 // Int, float, or timestamp.
182 // Only try values as a timestamp if the value is unquoted or there's an explicit
183 // !!timestamp tag.
184 if tag == "" || tag == timestampTag {
185 t, ok := parseTimestamp(in)
186 if ok {
187 return timestampTag, t
188 }
189 }
190
191 plain := strings.Replace(in, "_", "", -1)
192 intv, err := strconv.ParseInt(plain, 0, 64)
193 if err == nil {
194 if intv == int64(int(intv)) {
195 return intTag, int(intv)
196 } else {
197 return intTag, intv
198 }
199 }
200 uintv, err := strconv.ParseUint(plain, 0, 64)
201 if err == nil {
202 return intTag, uintv
203 }
204 if yamlStyleFloat.MatchString(plain) {
205 floatv, err := strconv.ParseFloat(plain, 64)
206 if err == nil {
207 return floatTag, floatv
208 }
209 }
210 if strings.HasPrefix(plain, "0b") {
211 intv, err := strconv.ParseInt(plain[2:], 2, 64)
212 if err == nil {
213 if intv == int64(int(intv)) {
214 return intTag, int(intv)
215 } else {
216 return intTag, intv
217 }
218 }
219 uintv, err := strconv.ParseUint(plain[2:], 2, 64)
220 if err == nil {
221 return intTag, uintv
222 }
223 } else if strings.HasPrefix(plain, "-0b") {
224 intv, err := strconv.ParseInt("-"+plain[3:], 2, 64)
225 if err == nil {
226 if true || intv == int64(int(intv)) {
227 return intTag, int(intv)
228 } else {
229 return intTag, intv
230 }
231 }
232 }
233 // Octals as introduced in version 1.2 of the spec.
234 // Octals from the 1.1 spec, spelled as 0777, are still
235 // decoded by default in v3 as well for compatibility.
236 // May be dropped in v4 depending on how usage evolves.
237 if strings.HasPrefix(plain, "0o") {
238 intv, err := strconv.ParseInt(plain[2:], 8, 64)
239 if err == nil {
240 if intv == int64(int(intv)) {
241 return intTag, int(intv)
242 } else {
243 return intTag, intv
244 }
245 }
246 uintv, err := strconv.ParseUint(plain[2:], 8, 64)
247 if err == nil {
248 return intTag, uintv
249 }
250 } else if strings.HasPrefix(plain, "-0o") {
251 intv, err := strconv.ParseInt("-"+plain[3:], 8, 64)
252 if err == nil {
253 if true || intv == int64(int(intv)) {
254 return intTag, int(intv)
255 } else {
256 return intTag, intv
257 }
258 }
259 }
260 default:
261 panic("internal error: missing handler for resolver table: " + string(rune(hint)) + " (with " + in + ")")
262 }
263 }
264 return strTag, in
265 }
266
267 // encodeBase64 encodes s as base64 that is broken up into multiple lines
268 // as appropriate for the resulting length.
269 func encodeBase64(s string) string {
270 const lineLen = 70
271 encLen := base64.StdEncoding.EncodedLen(len(s))
272 lines := encLen/lineLen + 1
273 buf := make([]byte, encLen*2+lines)
274 in := buf[0:encLen]
275 out := buf[encLen:]
276 base64.StdEncoding.Encode(in, []byte(s))
277 k := 0
278 for i := 0; i < len(in); i += lineLen {
279 j := i + lineLen
280 if j > len(in) {
281 j = len(in)
282 }
283 k += copy(out[k:], in[i:j])
284 if lines > 1 {
285 out[k] = '\n'
286 k++
287 }
288 }
289 return string(out[:k])
290 }
291
292 // This is a subset of the formats allowed by the regular expression
293 // defined at http://yaml.org/type/timestamp.html.
294 var allowedTimestampFormats = []string{
295 "2006-1-2T15:4:5.999999999Z07:00", // RCF3339Nano with short date fields.
296 "2006-1-2t15:4:5.999999999Z07:00", // RFC3339Nano with short date fields and lower-case "t".
297 "2006-1-2 15:4:5.999999999", // space separated with no time zone
298 "2006-1-2", // date only
299 // Notable exception: time.Parse cannot handle: "2001-12-14 21:59:43.10 -5"
300 // from the set of examples.
301 }
302
303 // parseTimestamp parses s as a timestamp string and
304 // returns the timestamp and reports whether it succeeded.
305 // Timestamp formats are defined at http://yaml.org/type/timestamp.html
306 func parseTimestamp(s string) (time.Time, bool) {
307 // TODO write code to check all the formats supported by
308 // http://yaml.org/type/timestamp.html instead of using time.Parse.
309
310 // Quick check: all date formats start with YYYY-.
311 i := 0
312 for ; i < len(s); i++ {
313 if c := s[i]; c < '0' || c > '9' {
314 break
315 }
316 }
317 if i != 4 || i == len(s) || s[i] != '-' {
318 return time.Time{}, false
319 }
320 for _, format := range allowedTimestampFormats {
321 if t, err := time.Parse(format, s); err == nil {
322 return t, true
323 }
324 }
325 return time.Time{}, false
326 }
327