Actual source code: reader.c
2: #include "yaml_private.h"
4: /*
5: * Declarations.
6: */
8: static int
9: yaml_parser_set_reader_error(yaml_parser_t *parser, const char *problem,
10: size_t offset, int value);
12: static int
13: yaml_parser_update_raw_buffer(yaml_parser_t *parser);
15: static int
16: yaml_parser_determine_encoding(yaml_parser_t *parser);
18: YAML_DECLARE(int)
19: yaml_parser_update_buffer(yaml_parser_t *parser, size_t length);
21: /*
22: * Set the reader error and return 0.
23: */
25: static int
26: yaml_parser_set_reader_error(yaml_parser_t *parser, const char *problem,
27: size_t offset, int value)
28: {
29: parser->error = YAML_READER_ERROR;
30: parser->problem = problem;
31: parser->problem_offset = offset;
32: parser->problem_value = value;
34: return 0;
35: }
37: /*
38: * Byte order marks.
39: */
41: #define BOM_UTF8 "\xef\xbb\xbf"
42: #define BOM_UTF16LE "\xff\xfe"
43: #define BOM_UTF16BE "\xfe\xff"
45: /*
46: * Determine the input stream encoding by checking the BOM symbol. If no BOM is
47: * found, the UTF-8 encoding is assumed. Return 1 on success, 0 on failure.
48: */
50: static int
51: yaml_parser_determine_encoding(yaml_parser_t *parser)
52: {
53: /* Ensure that we had enough bytes in the raw buffer. */
55: while (!parser->eof
56: && parser->raw_buffer.last - parser->raw_buffer.pointer < 3) {
57: if (!yaml_parser_update_raw_buffer(parser)) {
58: return 0;
59: }
60: }
62: /* Determine the encoding. */
64: if (parser->raw_buffer.last - parser->raw_buffer.pointer >= 2
65: && !memcmp(parser->raw_buffer.pointer, BOM_UTF16LE, 2)) {
66: parser->encoding = YAML_UTF16LE_ENCODING;
67: parser->raw_buffer.pointer += 2;
68: parser->offset += 2;
69: }
70: else if (parser->raw_buffer.last - parser->raw_buffer.pointer >= 2
71: && !memcmp(parser->raw_buffer.pointer, BOM_UTF16BE, 2)) {
72: parser->encoding = YAML_UTF16BE_ENCODING;
73: parser->raw_buffer.pointer += 2;
74: parser->offset += 2;
75: }
76: else if (parser->raw_buffer.last - parser->raw_buffer.pointer >= 3
77: && !memcmp(parser->raw_buffer.pointer, BOM_UTF8, 3)) {
78: parser->encoding = YAML_UTF8_ENCODING;
79: parser->raw_buffer.pointer += 3;
80: parser->offset += 3;
81: }
82: else {
83: parser->encoding = YAML_UTF8_ENCODING;
84: }
86: return 1;
87: }
89: /*
90: * Update the raw buffer.
91: */
93: static int
94: yaml_parser_update_raw_buffer(yaml_parser_t *parser)
95: {
96: size_t size_read = 0;
98: /* Return if the raw buffer is full. */
100: if (parser->raw_buffer.start == parser->raw_buffer.pointer
101: && parser->raw_buffer.last == parser->raw_buffer.end)
102: return 1;
104: /* Return on EOF. */
106: if (parser->eof) return 1;
108: /* Move the remaining bytes in the raw buffer to the beginning. */
110: if (parser->raw_buffer.start < parser->raw_buffer.pointer
111: && parser->raw_buffer.pointer < parser->raw_buffer.last) {
112: memmove(parser->raw_buffer.start, parser->raw_buffer.pointer,
113: parser->raw_buffer.last - parser->raw_buffer.pointer);
114: }
115: parser->raw_buffer.last -=
116: parser->raw_buffer.pointer - parser->raw_buffer.start;
117: parser->raw_buffer.pointer = parser->raw_buffer.start;
119: /* Call the read handler to fill the buffer. */
121: if (!parser->read_handler(parser->read_handler_data, parser->raw_buffer.last,
122: parser->raw_buffer.end - parser->raw_buffer.last, &size_read)) {
123: return yaml_parser_set_reader_error(parser, "input error",
124: parser->offset, -1);
125: }
126: parser->raw_buffer.last += size_read;
127: if (!size_read) {
128: parser->eof = 1;
129: }
131: return 1;
132: }
134: /*
135: * Ensure that the buffer contains at least `length` characters.
136: * Return 1 on success, 0 on failure.
137: *
138: * The length is supposed to be significantly less that the buffer size.
139: */
141: YAML_DECLARE(int)
142: yaml_parser_update_buffer(yaml_parser_t *parser, size_t length)
143: {
144: int first = 1;
146: assert(parser->read_handler); /* Read handler must be set. */
148: /* If the EOF flag is set and the raw buffer is empty, do nothing. */
150: if (parser->eof && parser->raw_buffer.pointer == parser->raw_buffer.last)
151: return 1;
153: /* Return if the buffer contains enough characters. */
155: if (parser->unread >= length)
156: return 1;
158: /* Determine the input encoding if it is not known yet. */
160: if (!parser->encoding) {
161: if (!yaml_parser_determine_encoding(parser))
162: return 0;
163: }
165: /* Move the unread characters to the beginning of the buffer. */
167: if (parser->buffer.start < parser->buffer.pointer
168: && parser->buffer.pointer < parser->buffer.last) {
169: size_t size = parser->buffer.last - parser->buffer.pointer;
170: memmove(parser->buffer.start, parser->buffer.pointer, size);
171: parser->buffer.pointer = parser->buffer.start;
172: parser->buffer.last = parser->buffer.start + size;
173: }
174: else if (parser->buffer.pointer == parser->buffer.last) {
175: parser->buffer.pointer = parser->buffer.start;
176: parser->buffer.last = parser->buffer.start;
177: }
179: /* Fill the buffer until it has enough characters. */
181: while (parser->unread < length)
182: {
183: /* Fill the raw buffer if necessary. */
185: if (!first || parser->raw_buffer.pointer == parser->raw_buffer.last) {
186: if (!yaml_parser_update_raw_buffer(parser)) return 0;
187: }
188: first = 0;
190: /* Decode the raw buffer. */
192: while (parser->raw_buffer.pointer != parser->raw_buffer.last)
193: {
194: unsigned int value = 0, value2 = 0;
195: int incomplete = 0;
196: unsigned char octet;
197: unsigned int width = 0;
198: int low, high;
199: size_t k;
200: size_t raw_unread = parser->raw_buffer.last - parser->raw_buffer.pointer;
202: /* Decode the next character. */
204: switch (parser->encoding)
205: {
206: case YAML_UTF8_ENCODING:
208: /*
209: * Decode a UTF-8 character. Check RFC 3629
210: * (http://www.ietf.org/rfc/rfc3629.txt) for more details.
211: *
212: * The following table (taken from the RFC) is used for
213: * decoding.
214: *
215: * Char. number range | UTF-8 octet sequence
216: * (hexadecimal) | (binary)
217: * --------------------+------------------------------------
218: * 0000 0000-0000 007F | 0xxxxxxx
219: * 0000 0080-0000 07FF | 110xxxxx 10xxxxxx
220: * 0000 0800-0000 FFFF | 1110xxxx 10xxxxxx 10xxxxxx
221: * 0001 0000-0010 FFFF | 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
222: *
223: * Additionally, the characters in the range 0xD800-0xDFFF
224: * are prohibited as they are reserved for use with UTF-16
225: * surrogate pairs.
226: */
228: /* Determine the length of the UTF-8 sequence. */
230: octet = parser->raw_buffer.pointer[0];
231: width = (octet & 0x80) == 0x00 ? 1 :
232: (octet & 0xE0) == 0xC0 ? 2 :
233: (octet & 0xF0) == 0xE0 ? 3 :
234: (octet & 0xF8) == 0xF0 ? 4 : 0;
236: /* Check if the leading octet is valid. */
238: if (!width)
239: return yaml_parser_set_reader_error(parser,
240: "invalid leading UTF-8 octet",
241: parser->offset, octet);
243: /* Check if the raw buffer contains an incomplete character. */
245: if (width > raw_unread) {
246: if (parser->eof) {
247: return yaml_parser_set_reader_error(parser,
248: "incomplete UTF-8 octet sequence",
249: parser->offset, -1);
250: }
251: incomplete = 1;
252: break;
253: }
255: /* Decode the leading octet. */
257: value = (octet & 0x80) == 0x00 ? octet & 0x7F :
258: (octet & 0xE0) == 0xC0 ? octet & 0x1F :
259: (octet & 0xF0) == 0xE0 ? octet & 0x0F :
260: (octet & 0xF8) == 0xF0 ? octet & 0x07 : 0;
262: /* Check and decode the trailing octets. */
264: for (k = 1; k < width; k ++)
265: {
266: octet = parser->raw_buffer.pointer[k];
268: /* Check if the octet is valid. */
270: if ((octet & 0xC0) != 0x80)
271: return yaml_parser_set_reader_error(parser,
272: "invalid trailing UTF-8 octet",
273: parser->offset+k, octet);
275: /* Decode the octet. */
277: value = (value << 6) + (octet & 0x3F);
278: }
280: /* Check the length of the sequence against the value. */
282: if (!((width == 1) ||
283: (width == 2 && value >= 0x80) ||
284: (width == 3 && value >= 0x800) ||
285: (width == 4 && value >= 0x10000)))
286: return yaml_parser_set_reader_error(parser,
287: "invalid length of a UTF-8 sequence",
288: parser->offset, -1);
290: /* Check the range of the value. */
292: if ((value >= 0xD800 && value <= 0xDFFF) || value > 0x10FFFF)
293: return yaml_parser_set_reader_error(parser,
294: "invalid Unicode character",
295: parser->offset, value);
297: break;
299: case YAML_UTF16LE_ENCODING:
300: case YAML_UTF16BE_ENCODING:
302: low = (parser->encoding == YAML_UTF16LE_ENCODING ? 0 : 1);
303: high = (parser->encoding == YAML_UTF16LE_ENCODING ? 1 : 0);
305: /*
306: * The UTF-16 encoding is not as simple as one might
307: * naively think. Check RFC 2781
308: * (http://www.ietf.org/rfc/rfc2781.txt).
309: *
310: * Normally, two subsequent bytes describe a Unicode
311: * character. However a special technique (called a
312: * surrogate pair) is used for specifying character
313: * values larger than 0xFFFF.
314: *
315: * A surrogate pair consists of two pseudo-characters:
316: * high surrogate area (0xD800-0xDBFF)
317: * low surrogate area (0xDC00-0xDFFF)
318: *
319: * The following formulas are used for decoding
320: * and encoding characters using surrogate pairs:
321: *
322: * U = U' + 0x10000 (0x01 00 00 <= U <= 0x10 FF FF)
323: * U' = yyyyyyyyyyxxxxxxxxxx (0 <= U' <= 0x0F FF FF)
324: * W1 = 110110yyyyyyyyyy
325: * W2 = 110111xxxxxxxxxx
326: *
327: * where U is the character value, W1 is the high surrogate
328: * area, W2 is the low surrogate area.
329: */
331: /* Check for incomplete UTF-16 character. */
333: if (raw_unread < 2) {
334: if (parser->eof) {
335: return yaml_parser_set_reader_error(parser,
336: "incomplete UTF-16 character",
337: parser->offset, -1);
338: }
339: incomplete = 1;
340: break;
341: }
343: /* Get the character. */
345: value = parser->raw_buffer.pointer[low]
346: + (parser->raw_buffer.pointer[high] << 8);
348: /* Check for unexpected low surrogate area. */
350: if ((value & 0xFC00) == 0xDC00)
351: return yaml_parser_set_reader_error(parser,
352: "unexpected low surrogate area",
353: parser->offset, value);
355: /* Check for a high surrogate area. */
357: if ((value & 0xFC00) == 0xD800) {
359: width = 4;
361: /* Check for incomplete surrogate pair. */
363: if (raw_unread < 4) {
364: if (parser->eof) {
365: return yaml_parser_set_reader_error(parser,
366: "incomplete UTF-16 surrogate pair",
367: parser->offset, -1);
368: }
369: incomplete = 1;
370: break;
371: }
373: /* Get the next character. */
375: value2 = parser->raw_buffer.pointer[low+2]
376: + (parser->raw_buffer.pointer[high+2] << 8);
378: /* Check for a low surrogate area. */
380: if ((value2 & 0xFC00) != 0xDC00)
381: return yaml_parser_set_reader_error(parser,
382: "expected low surrogate area",
383: parser->offset+2, value2);
385: /* Generate the value of the surrogate pair. */
387: value = 0x10000 + ((value & 0x3FF) << 10) + (value2 & 0x3FF);
388: }
390: else {
391: width = 2;
392: }
394: break;
396: default:
397: assert(1); /* Impossible. */
398: }
400: /* Check if the raw buffer contains enough bytes to form a character. */
402: if (incomplete) break;
404: /*
405: * Check if the character is in the allowed range:
406: * #x9 | #xA | #xD | [#x20-#x7E] (8 bit)
407: * | #x85 | [#xA0-#xD7FF] | [#xE000-#xFFFD] (16 bit)
408: * | [#x10000-#x10FFFF] (32 bit)
409: */
411: if (! (value == 0x09 || value == 0x0A || value == 0x0D
412: || (value >= 0x20 && value <= 0x7E)
413: || (value == 0x85) || (value >= 0xA0 && value <= 0xD7FF)
414: || (value >= 0xE000 && value <= 0xFFFD)
415: || (value >= 0x10000 && value <= 0x10FFFF)))
416: return yaml_parser_set_reader_error(parser,
417: "control characters are not allowed",
418: parser->offset, value);
420: /* Move the raw pointers. */
422: parser->raw_buffer.pointer += width;
423: parser->offset += width;
425: /* Finally put the character into the buffer. */
427: /* 0000 0000-0000 007F -> 0xxxxxxx */
428: if (value <= 0x7F) {
429: *(parser->buffer.last++) = value;
430: }
431: /* 0000 0080-0000 07FF -> 110xxxxx 10xxxxxx */
432: else if (value <= 0x7FF) {
433: *(parser->buffer.last++) = 0xC0 + (value >> 6);
434: *(parser->buffer.last++) = 0x80 + (value & 0x3F);
435: }
436: /* 0000 0800-0000 FFFF -> 1110xxxx 10xxxxxx 10xxxxxx */
437: else if (value <= 0xFFFF) {
438: *(parser->buffer.last++) = 0xE0 + (value >> 12);
439: *(parser->buffer.last++) = 0x80 + ((value >> 6) & 0x3F);
440: *(parser->buffer.last++) = 0x80 + (value & 0x3F);
441: }
442: /* 0001 0000-0010 FFFF -> 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx */
443: else {
444: *(parser->buffer.last++) = 0xF0 + (value >> 18);
445: *(parser->buffer.last++) = 0x80 + ((value >> 12) & 0x3F);
446: *(parser->buffer.last++) = 0x80 + ((value >> 6) & 0x3F);
447: *(parser->buffer.last++) = 0x80 + (value & 0x3F);
448: }
450: parser->unread ++;
451: }
453: /* On EOF, put NUL into the buffer and return. */
455: if (parser->eof) {
456: *(parser->buffer.last++) = '\0';
457: parser->unread ++;
458: return 1;
459: }
461: }
463: if (parser->offset >= MAX_FILE_SIZE) {
464: return yaml_parser_set_reader_error(parser, "input is too long",
465: parser->offset, -1);
466: }
468: return 1;
469: }