readerc.go raw
1 package yaml
2
3 import (
4 "io"
5 )
6
7 // Set the reader error and return 0.
8 func yaml_parser_set_reader_error(parser *yaml_parser_t, problem string, offset int, value int) bool {
9 parser.error = yaml_READER_ERROR
10 parser.problem = problem
11 parser.problem_offset = offset
12 parser.problem_value = value
13 return false
14 }
15
16 // Byte order marks.
17 const (
18 bom_UTF8 = "\xef\xbb\xbf"
19 bom_UTF16LE = "\xff\xfe"
20 bom_UTF16BE = "\xfe\xff"
21 )
22
23 // Determine the input stream encoding by checking the BOM symbol. If no BOM is
24 // found, the UTF-8 encoding is assumed. Return 1 on success, 0 on failure.
25 func yaml_parser_determine_encoding(parser *yaml_parser_t) bool {
26 // Ensure that we had enough bytes in the raw buffer.
27 for !parser.eof && len(parser.raw_buffer)-parser.raw_buffer_pos < 3 {
28 if !yaml_parser_update_raw_buffer(parser) {
29 return false
30 }
31 }
32
33 // Determine the encoding.
34 buf := parser.raw_buffer
35 pos := parser.raw_buffer_pos
36 avail := len(buf) - pos
37 if avail >= 2 && buf[pos] == bom_UTF16LE[0] && buf[pos+1] == bom_UTF16LE[1] {
38 parser.encoding = yaml_UTF16LE_ENCODING
39 parser.raw_buffer_pos += 2
40 parser.offset += 2
41 } else if avail >= 2 && buf[pos] == bom_UTF16BE[0] && buf[pos+1] == bom_UTF16BE[1] {
42 parser.encoding = yaml_UTF16BE_ENCODING
43 parser.raw_buffer_pos += 2
44 parser.offset += 2
45 } else if avail >= 3 && buf[pos] == bom_UTF8[0] && buf[pos+1] == bom_UTF8[1] && buf[pos+2] == bom_UTF8[2] {
46 parser.encoding = yaml_UTF8_ENCODING
47 parser.raw_buffer_pos += 3
48 parser.offset += 3
49 } else {
50 parser.encoding = yaml_UTF8_ENCODING
51 }
52 return true
53 }
54
55 // Update the raw buffer.
56 func yaml_parser_update_raw_buffer(parser *yaml_parser_t) bool {
57 size_read := 0
58
59 // Return if the raw buffer is full.
60 if parser.raw_buffer_pos == 0 && len(parser.raw_buffer) == cap(parser.raw_buffer) {
61 return true
62 }
63
64 // Return on EOF.
65 if parser.eof {
66 return true
67 }
68
69 // Move the remaining bytes in the raw buffer to the beginning.
70 if parser.raw_buffer_pos > 0 && parser.raw_buffer_pos < len(parser.raw_buffer) {
71 copy(parser.raw_buffer, parser.raw_buffer[parser.raw_buffer_pos:])
72 }
73 parser.raw_buffer = parser.raw_buffer[:len(parser.raw_buffer)-parser.raw_buffer_pos]
74 parser.raw_buffer_pos = 0
75
76 // Call the read handler to fill the buffer.
77 size_read, err := parser.read_handler(parser, parser.raw_buffer[len(parser.raw_buffer):cap(parser.raw_buffer)])
78 parser.raw_buffer = parser.raw_buffer[:len(parser.raw_buffer)+size_read]
79 if err == io.EOF {
80 parser.eof = true
81 } else if err != nil {
82 return yaml_parser_set_reader_error(parser, "input error: "+err.Error(), parser.offset, -1)
83 }
84 return true
85 }
86
87 // Ensure that the buffer contains at least `length` characters.
88 // Return true on success, false on failure.
89 //
90 // The length is supposed to be significantly less that the buffer size.
91 func yaml_parser_update_buffer(parser *yaml_parser_t, length int) bool {
92 if parser.read_handler == nil {
93 panic("read handler must be set")
94 }
95
96 // [Go] This function was changed to guarantee the requested length size at EOF.
97 // The fact we need to do this is pretty awful, but the description above implies
98 // for that to be the case, and there are tests
99
100 // If the EOF flag is set and the raw buffer is empty, do nothing.
101 if parser.eof && parser.raw_buffer_pos == len(parser.raw_buffer) {
102 // [Go] ACTUALLY! Read the documentation of this function above.
103 // This is just broken. To return true, we need to have the
104 // given length in the buffer. Not doing that means every single
105 // check that calls this function to make sure the buffer has a
106 // given length is Go) panicking; or C) accessing invalid memory.
107 //return true
108 }
109
110 // Return if the buffer contains enough characters.
111 if parser.unread >= length {
112 return true
113 }
114
115 // Determine the input encoding if it is not known yet.
116 if parser.encoding == yaml_ANY_ENCODING {
117 if !yaml_parser_determine_encoding(parser) {
118 return false
119 }
120 }
121
122 // Move the unread characters to the beginning of the buffer.
123 buffer_len := len(parser.buffer)
124 if parser.buffer_pos > 0 && parser.buffer_pos < buffer_len {
125 copy(parser.buffer, parser.buffer[parser.buffer_pos:])
126 buffer_len -= parser.buffer_pos
127 parser.buffer_pos = 0
128 } else if parser.buffer_pos == buffer_len {
129 buffer_len = 0
130 parser.buffer_pos = 0
131 }
132
133 // Open the whole buffer for writing, and cut it before returning.
134 parser.buffer = parser.buffer[:cap(parser.buffer)]
135
136 // Fill the buffer until it has enough characters.
137 first := true
138 for parser.unread < length {
139
140 // Fill the raw buffer if necessary.
141 if !first || parser.raw_buffer_pos == len(parser.raw_buffer) {
142 if !yaml_parser_update_raw_buffer(parser) {
143 parser.buffer = parser.buffer[:buffer_len]
144 return false
145 }
146 }
147 first = false
148
149 // Decode the raw buffer.
150 inner:
151 for parser.raw_buffer_pos != len(parser.raw_buffer) {
152 var value rune
153 var width int
154
155 raw_unread := len(parser.raw_buffer) - parser.raw_buffer_pos
156
157 // Decode the next character.
158 switch parser.encoding {
159 case yaml_UTF8_ENCODING:
160 // Decode a UTF-8 character. Check RFC 3629
161 // (http://www.ietf.org/rfc/rfc3629.txt) for more details.
162 //
163 // The following table (taken from the RFC) is used for
164 // decoding.
165 //
166 // Char. number range | UTF-8 octet sequence
167 // (hexadecimal) | (binary)
168 // --------------------+------------------------------------
169 // 0000 0000-0000 007F | 0xxxxxxx
170 // 0000 0080-0000 07FF | 110xxxxx 10xxxxxx
171 // 0000 0800-0000 FFFF | 1110xxxx 10xxxxxx 10xxxxxx
172 // 0001 0000-0010 FFFF | 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
173 //
174 // Additionally, the characters in the range 0xD800-0xDFFF
175 // are prohibited as they are reserved for use with UTF-16
176 // surrogate pairs.
177
178 // Determine the length of the UTF-8 sequence.
179 octet := parser.raw_buffer[parser.raw_buffer_pos]
180 switch {
181 case octet&0x80 == 0x00:
182 width = 1
183 case octet&0xE0 == 0xC0:
184 width = 2
185 case octet&0xF0 == 0xE0:
186 width = 3
187 case octet&0xF8 == 0xF0:
188 width = 4
189 default:
190 // The leading octet is invalid.
191 return yaml_parser_set_reader_error(parser,
192 "invalid leading UTF-8 octet",
193 parser.offset, int(octet))
194 }
195
196 // Check if the raw buffer contains an incomplete character.
197 if width > raw_unread {
198 if parser.eof {
199 return yaml_parser_set_reader_error(parser,
200 "incomplete UTF-8 octet sequence",
201 parser.offset, -1)
202 }
203 break inner
204 }
205
206 // Decode the leading octet.
207 switch {
208 case octet&0x80 == 0x00:
209 value = rune(octet & 0x7F)
210 case octet&0xE0 == 0xC0:
211 value = rune(octet & 0x1F)
212 case octet&0xF0 == 0xE0:
213 value = rune(octet & 0x0F)
214 case octet&0xF8 == 0xF0:
215 value = rune(octet & 0x07)
216 default:
217 value = 0
218 }
219
220 // Check and decode the trailing octets.
221 for k := 1; k < width; k++ {
222 octet = parser.raw_buffer[parser.raw_buffer_pos+k]
223
224 // Check if the octet is valid.
225 if (octet & 0xC0) != 0x80 {
226 return yaml_parser_set_reader_error(parser,
227 "invalid trailing UTF-8 octet",
228 parser.offset+k, int(octet))
229 }
230
231 // Decode the octet.
232 value = (value << 6) + rune(octet&0x3F)
233 }
234
235 // Check the length of the sequence against the value.
236 switch {
237 case width == 1:
238 case width == 2 && value >= 0x80:
239 case width == 3 && value >= 0x800:
240 case width == 4 && value >= 0x10000:
241 default:
242 return yaml_parser_set_reader_error(parser,
243 "invalid length of a UTF-8 sequence",
244 parser.offset, -1)
245 }
246
247 // Check the range of the value.
248 if value >= 0xD800 && value <= 0xDFFF || value > 0x10FFFF {
249 return yaml_parser_set_reader_error(parser,
250 "invalid Unicode character",
251 parser.offset, int(value))
252 }
253
254 case yaml_UTF16LE_ENCODING, yaml_UTF16BE_ENCODING:
255 var low, high int
256 if parser.encoding == yaml_UTF16LE_ENCODING {
257 low, high = 0, 1
258 } else {
259 low, high = 1, 0
260 }
261
262 // The UTF-16 encoding is not as simple as one might
263 // naively think. Check RFC 2781
264 // (http://www.ietf.org/rfc/rfc2781.txt).
265 //
266 // Normally, two subsequent bytes describe a Unicode
267 // character. However a special technique (called a
268 // surrogate pair) is used for specifying character
269 // values larger than 0xFFFF.
270 //
271 // A surrogate pair consists of two pseudo-characters:
272 // high surrogate area (0xD800-0xDBFF)
273 // low surrogate area (0xDC00-0xDFFF)
274 //
275 // The following formulas are used for decoding
276 // and encoding characters using surrogate pairs:
277 //
278 // U = U' + 0x10000 (0x01 00 00 <= U <= 0x10 FF FF)
279 // U' = yyyyyyyyyyxxxxxxxxxx (0 <= U' <= 0x0F FF FF)
280 // W1 = 110110yyyyyyyyyy
281 // W2 = 110111xxxxxxxxxx
282 //
283 // where U is the character value, W1 is the high surrogate
284 // area, W2 is the low surrogate area.
285
286 // Check for incomplete UTF-16 character.
287 if raw_unread < 2 {
288 if parser.eof {
289 return yaml_parser_set_reader_error(parser,
290 "incomplete UTF-16 character",
291 parser.offset, -1)
292 }
293 break inner
294 }
295
296 // Get the character.
297 value = rune(parser.raw_buffer[parser.raw_buffer_pos+low]) +
298 (rune(parser.raw_buffer[parser.raw_buffer_pos+high]) << 8)
299
300 // Check for unexpected low surrogate area.
301 if value&0xFC00 == 0xDC00 {
302 return yaml_parser_set_reader_error(parser,
303 "unexpected low surrogate area",
304 parser.offset, int(value))
305 }
306
307 // Check for a high surrogate area.
308 if value&0xFC00 == 0xD800 {
309 width = 4
310
311 // Check for incomplete surrogate pair.
312 if raw_unread < 4 {
313 if parser.eof {
314 return yaml_parser_set_reader_error(parser,
315 "incomplete UTF-16 surrogate pair",
316 parser.offset, -1)
317 }
318 break inner
319 }
320
321 // Get the next character.
322 value2 := rune(parser.raw_buffer[parser.raw_buffer_pos+low+2]) +
323 (rune(parser.raw_buffer[parser.raw_buffer_pos+high+2]) << 8)
324
325 // Check for a low surrogate area.
326 if value2&0xFC00 != 0xDC00 {
327 return yaml_parser_set_reader_error(parser,
328 "expected low surrogate area",
329 parser.offset+2, int(value2))
330 }
331
332 // Generate the value of the surrogate pair.
333 value = 0x10000 + ((value & 0x3FF) << 10) + (value2 & 0x3FF)
334 } else {
335 width = 2
336 }
337
338 default:
339 panic("impossible")
340 }
341
342 // Check if the character is in the allowed range:
343 // #x9 | #xA | #xD | [#x20-#x7E] (8 bit)
344 // | #x85 | [#xA0-#xD7FF] | [#xE000-#xFFFD] (16 bit)
345 // | [#x10000-#x10FFFF] (32 bit)
346 switch {
347 case value == 0x09:
348 case value == 0x0A:
349 case value == 0x0D:
350 case value >= 0x20 && value <= 0x7E:
351 case value == 0x85:
352 case value >= 0xA0 && value <= 0xD7FF:
353 case value >= 0xE000 && value <= 0xFFFD:
354 case value >= 0x10000 && value <= 0x10FFFF:
355 default:
356 return yaml_parser_set_reader_error(parser,
357 "control characters are not allowed",
358 parser.offset, int(value))
359 }
360
361 // Move the raw pointers.
362 parser.raw_buffer_pos += width
363 parser.offset += width
364
365 // Finally put the character into the buffer.
366 if value <= 0x7F {
367 // 0000 0000-0000 007F . 0xxxxxxx
368 parser.buffer[buffer_len+0] = byte(value)
369 buffer_len += 1
370 } else if value <= 0x7FF {
371 // 0000 0080-0000 07FF . 110xxxxx 10xxxxxx
372 parser.buffer[buffer_len+0] = byte(0xC0 + (value >> 6))
373 parser.buffer[buffer_len+1] = byte(0x80 + (value & 0x3F))
374 buffer_len += 2
375 } else if value <= 0xFFFF {
376 // 0000 0800-0000 FFFF . 1110xxxx 10xxxxxx 10xxxxxx
377 parser.buffer[buffer_len+0] = byte(0xE0 + (value >> 12))
378 parser.buffer[buffer_len+1] = byte(0x80 + ((value >> 6) & 0x3F))
379 parser.buffer[buffer_len+2] = byte(0x80 + (value & 0x3F))
380 buffer_len += 3
381 } else {
382 // 0001 0000-0010 FFFF . 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
383 parser.buffer[buffer_len+0] = byte(0xF0 + (value >> 18))
384 parser.buffer[buffer_len+1] = byte(0x80 + ((value >> 12) & 0x3F))
385 parser.buffer[buffer_len+2] = byte(0x80 + ((value >> 6) & 0x3F))
386 parser.buffer[buffer_len+3] = byte(0x80 + (value & 0x3F))
387 buffer_len += 4
388 }
389
390 parser.unread++
391 }
392
393 // On EOF, put NUL into the buffer and return.
394 if parser.eof {
395 parser.buffer[buffer_len] = 0
396 buffer_len++
397 parser.unread++
398 break
399 }
400 }
401 // [Go] Read the documentation of this function above. To return true,
402 // we need to have the given length in the buffer. Not doing that means
403 // every single check that calls this function to make sure the buffer
404 // has a given length is Go) panicking; or C) accessing invalid memory.
405 // This happens here due to the EOF above breaking early.
406 for buffer_len < length {
407 parser.buffer[buffer_len] = 0
408 buffer_len++
409 }
410 parser.buffer = parser.buffer[:buffer_len]
411 return true
412 }
413