src/reader.c


#include "yaml_private.h"

/*
 * Declarations.
 */

static int
yaml_parser_set_reader_error(yaml_parser_t *parser, const char *problem,
        size_t offset, int value);

static int
yaml_parser_update_raw_buffer(yaml_parser_t *parser);

static int
yaml_parser_determine_encoding(yaml_parser_t *parser);

YAML_DECLARE(int)
yaml_parser_update_buffer(yaml_parser_t *parser, size_t length);

/*
 * Set the reader error and return 0.
 */

static int
yaml_parser_set_reader_error(yaml_parser_t *parser, const char *problem,
        size_t offset, int value)
{
    parser->error = YAML_READER_ERROR;
    parser->problem = problem;
    parser->problem_offset = offset;
    parser->problem_value = value;

    return 0;
}

/*
 * Byte order marks.
 */

#define BOM_UTF8    "\xef\xbb\xbf"
#define BOM_UTF16LE "\xff\xfe"
#define BOM_UTF16BE "\xfe\xff"

/*
 * Determine the input stream encoding by checking the BOM symbol. If no BOM is
 * found, the UTF-8 encoding is assumed. Return 1 on success, 0 on failure.
 */

static int
yaml_parser_determine_encoding(yaml_parser_t *parser)
{
    /* Ensure that we had enough bytes in the raw buffer. */

    while (!parser->eof
            && parser->raw_buffer.last - parser->raw_buffer.pointer < 3) {
        if (!yaml_parser_update_raw_buffer(parser)) {
            return 0;
        }
    }

    /* Determine the encoding. */

    if (parser->raw_buffer.last - parser->raw_buffer.pointer >= 2
            && !memcmp(parser->raw_buffer.pointer, BOM_UTF16LE, 2)) {
        parser->encoding = YAML_UTF16LE_ENCODING;
        parser->raw_buffer.pointer += 2;
        parser->offset += 2;
    }
    else if (parser->raw_buffer.last - parser->raw_buffer.pointer >= 2
            && !memcmp(parser->raw_buffer.pointer, BOM_UTF16BE, 2)) {
        parser->encoding = YAML_UTF16BE_ENCODING;
        parser->raw_buffer.pointer += 2;
        parser->offset += 2;
    }
    else if (parser->raw_buffer.last - parser->raw_buffer.pointer >= 3
            && !memcmp(parser->raw_buffer.pointer, BOM_UTF8, 3)) {
        parser->encoding = YAML_UTF8_ENCODING;
        parser->raw_buffer.pointer += 3;
        parser->offset += 3;
    }
    else {
        parser->encoding = YAML_UTF8_ENCODING;
    }

    return 1;
}

/*
 * Update the raw buffer.
 */

static int
yaml_parser_update_raw_buffer(yaml_parser_t *parser)
{
    size_t size_read = 0;

    /* Return if the raw buffer is full. */

    if (parser->raw_buffer.start == parser->raw_buffer.pointer
            && parser->raw_buffer.last == parser->raw_buffer.end)
        return 1;

    /* Return on EOF. */

    if (parser->eof) return 1;

    /* Move the remaining bytes in the raw buffer to the beginning. */

    if (parser->raw_buffer.start < parser->raw_buffer.pointer
            && parser->raw_buffer.pointer < parser->raw_buffer.last) {
        memmove(parser->raw_buffer.start, parser->raw_buffer.pointer,
                parser->raw_buffer.last - parser->raw_buffer.pointer);
    }
    parser->raw_buffer.last -=
        parser->raw_buffer.pointer - parser->raw_buffer.start;
    parser->raw_buffer.pointer = parser->raw_buffer.start;

    /* Call the read handler to fill the buffer. */

    if (!parser->read_handler(parser->read_handler_data, parser->raw_buffer.last,
                parser->raw_buffer.end - parser->raw_buffer.last, &size_read)) {
        return yaml_parser_set_reader_error(parser, "input error",
                parser->offset, -1);
    }
    parser->raw_buffer.last += size_read;
    if (!size_read) {
        parser->eof = 1;
    }

    return 1;
}

/*
 * Ensure that the buffer contains at least `length` characters.
 * Return 1 on success, 0 on failure.
 *
 * The length is supposed to be significantly less that the buffer size.
 */

YAML_DECLARE(int)
yaml_parser_update_buffer(yaml_parser_t *parser, size_t length)
{
    int first = 1;

    assert(parser->read_handler);   /* Read handler must be set. */

    /* If the EOF flag is set and the raw buffer is empty, do nothing. */

    if (parser->eof && parser->raw_buffer.pointer == parser->raw_buffer.last)
        return 1;

    /* Return if the buffer contains enough characters. */

    if (parser->unread >= length)
        return 1;

    /* Determine the input encoding if it is not known yet. */

    if (!parser->encoding) {
        if (!yaml_parser_determine_encoding(parser))
            return 0;
    }

    /* Move the unread characters to the beginning of the buffer. */

    if (parser->buffer.start < parser->buffer.pointer
            && parser->buffer.pointer < parser->buffer.last) {
        size_t size = parser->buffer.last - parser->buffer.pointer;
        memmove(parser->buffer.start, parser->buffer.pointer, size);
        parser->buffer.pointer = parser->buffer.start;
        parser->buffer.last = parser->buffer.start + size;
    }
    else if (parser->buffer.pointer == parser->buffer.last) {
        parser->buffer.pointer = parser->buffer.start;
        parser->buffer.last = parser->buffer.start;
    }

    /* Fill the buffer until it has enough characters. */

    while (parser->unread < length)
    {
        /* Fill the raw buffer if necessary. */

        if (!first || parser->raw_buffer.pointer == parser->raw_buffer.last) {
            if (!yaml_parser_update_raw_buffer(parser)) return 0;
        }
        first = 0;

        /* Decode the raw buffer. */

        while (parser->raw_buffer.pointer != parser->raw_buffer.last)
        {
            unsigned int value = 0, value2 = 0;
            int incomplete = 0;
            unsigned char octet;
            unsigned int width = 0;
            int low, high;
            size_t k;
            size_t raw_unread = parser->raw_buffer.last - parser->raw_buffer.pointer;

            /* Decode the next character. */

            switch (parser->encoding)
            {
                case YAML_UTF8_ENCODING:

                    /*
                     * Decode a UTF-8 character.  Check RFC 3629
                     * (http://www.ietf.org/rfc/rfc3629.txt) for more details.
                     *
                     * The following table (taken from the RFC) is used for
                     * decoding.
                     *
                     *    Char. number range |        UTF-8 octet sequence
                     *      (hexadecimal)    |              (binary)
                     *   --------------------+------------------------------------
                     *   0000 0000-0000 007F | 0xxxxxxx
                     *   0000 0080-0000 07FF | 110xxxxx 10xxxxxx
                     *   0000 0800-0000 FFFF | 1110xxxx 10xxxxxx 10xxxxxx
                     *   0001 0000-0010 FFFF | 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
                     *
                     * Additionally, the characters in the range 0xD800-0xDFFF
                     * are prohibited as they are reserved for use with UTF-16
                     * surrogate pairs.
                     */

                    /* Determine the length of the UTF-8 sequence. */

                    octet = parser->raw_buffer.pointer[0];
                    width = (octet & 0x80) == 0x00 ? 1 :
                            (octet & 0xE0) == 0xC0 ? 2 :
                            (octet & 0xF0) == 0xE0 ? 3 :
                            (octet & 0xF8) == 0xF0 ? 4 : 0;

                    /* Check if the leading octet is valid. */

                    if (!width)
                        return yaml_parser_set_reader_error(parser,
                                "invalid leading UTF-8 octet",
                                parser->offset, octet);

                    /* Check if the raw buffer contains an incomplete character. */

                    if (width > raw_unread) {
                        if (parser->eof) {
                            return yaml_parser_set_reader_error(parser,
                                    "incomplete UTF-8 octet sequence",
                                    parser->offset, -1);
                        }
                        incomplete = 1;
                        break;
                    }

                    /* Decode the leading octet. */

                    value = (octet & 0x80) == 0x00 ? octet & 0x7F :
                            (octet & 0xE0) == 0xC0 ? octet & 0x1F :
                            (octet & 0xF0) == 0xE0 ? octet & 0x0F :
                            (octet & 0xF8) == 0xF0 ? octet & 0x07 : 0;

                    /* Check and decode the trailing octets. */

                    for (k = 1; k < width; k ++)
                    {
                        octet = parser->raw_buffer.pointer[k];

                        /* Check if the octet is valid. */

                        if ((octet & 0xC0) != 0x80)
                            return yaml_parser_set_reader_error(parser,
                                    "invalid trailing UTF-8 octet",
                                    parser->offset+k, octet);

                        /* Decode the octet. */

                        value = (value << 6) + (octet & 0x3F);
                    }

                    /* Check the length of the sequence against the value. */

                    if (!((width == 1) ||
                            (width == 2 && value >= 0x80) ||
                            (width == 3 && value >= 0x800) ||
                            (width == 4 && value >= 0x10000)))
                        return yaml_parser_set_reader_error(parser,
                                "invalid length of a UTF-8 sequence",
                                parser->offset, -1);

                    /* Check the range of the value. */

                    if ((value >= 0xD800 && value <= 0xDFFF) || value > 0x10FFFF)
                        return yaml_parser_set_reader_error(parser,
                                "invalid Unicode character",
                                parser->offset, value);

                    break;

                case YAML_UTF16LE_ENCODING:
                case YAML_UTF16BE_ENCODING:

                    low = (parser->encoding == YAML_UTF16LE_ENCODING ? 0 : 1);
                    high = (parser->encoding == YAML_UTF16LE_ENCODING ? 1 : 0);

                    /*
                     * The UTF-16 encoding is not as simple as one might
                     * naively think.  Check RFC 2781
                     * (http://www.ietf.org/rfc/rfc2781.txt).
                     *
                     * Normally, two subsequent bytes describe a Unicode
                     * character.  However a special technique (called a
                     * surrogate pair) is used for specifying character
                     * values larger than 0xFFFF.
                     *
                     * A surrogate pair consists of two pseudo-characters:
                     *      high surrogate area (0xD800-0xDBFF)
                     *      low surrogate area (0xDC00-0xDFFF)
                     *
                     * The following formulas are used for decoding
                     * and encoding characters using surrogate pairs:
                     *
                     *  U  = U' + 0x10000   (0x01 00 00 <= U <= 0x10 FF FF)
                     *  U' = yyyyyyyyyyxxxxxxxxxx   (0 <= U' <= 0x0F FF FF)
                     *  W1 = 110110yyyyyyyyyy
                     *  W2 = 110111xxxxxxxxxx
                     *
                     * where U is the character value, W1 is the high surrogate
                     * area, W2 is the low surrogate area.
                     */

                    /* Check for incomplete UTF-16 character. */

                    if (raw_unread < 2) {
                        if (parser->eof) {
                            return yaml_parser_set_reader_error(parser,
                                    "incomplete UTF-16 character",
                                    parser->offset, -1);
                        }
                        incomplete = 1;
                        break;
                    }

                    /* Get the character. */

                    value = parser->raw_buffer.pointer[low]
                        + (parser->raw_buffer.pointer[high] << 8);

                    /* Check for unexpected low surrogate area. */

                    if ((value & 0xFC00) == 0xDC00)
                        return yaml_parser_set_reader_error(parser,
                                "unexpected low surrogate area",
                                parser->offset, value);

                    /* Check for a high surrogate area. */

                    if ((value & 0xFC00) == 0xD800) {

                        width = 4;

                        /* Check for incomplete surrogate pair. */

                        if (raw_unread < 4) {
                            if (parser->eof) {
                                return yaml_parser_set_reader_error(parser,
                                        "incomplete UTF-16 surrogate pair",
                                        parser->offset, -1);
                            }
                            incomplete = 1;
                            break;
                        }

                        /* Get the next character. */

                        value2 = parser->raw_buffer.pointer[low+2]
                            + (parser->raw_buffer.pointer[high+2] << 8);

                        /* Check for a low surrogate area. */

                        if ((value2 & 0xFC00) != 0xDC00)
                            return yaml_parser_set_reader_error(parser,
                                    "expected low surrogate area",
                                    parser->offset+2, value2);

                        /* Generate the value of the surrogate pair. */

                        value = 0x10000 + ((value & 0x3FF) << 10) + (value2 & 0x3FF);
                    }

                    else {
                        width = 2;
                    }

                    break;

                default:
                    assert(1);      /* Impossible. */
            }

            /* Check if the raw buffer contains enough bytes to form a character. */

            if (incomplete) break;

            /*
             * Check if the character is in the allowed range:
             *      #x9 | #xA | #xD | [#x20-#x7E]               (8 bit)
             *      | #x85 | [#xA0-#xD7FF] | [#xE000-#xFFFD]    (16 bit)
             *      | [#x10000-#x10FFFF]                        (32 bit)
             */

            if (! (value == 0x09 || value == 0x0A || value == 0x0D
                        || (value >= 0x20 && value <= 0x7E)
                        || (value == 0x85) || (value >= 0xA0 && value <= 0xD7FF)
                        || (value >= 0xE000 && value <= 0xFFFD)
                        || (value >= 0x10000 && value <= 0x10FFFF)))
                return yaml_parser_set_reader_error(parser,
                        "control characters are not allowed",
                        parser->offset, value);

            /* Move the raw pointers. */

            parser->raw_buffer.pointer += width;
            parser->offset += width;

            /* Finally put the character into the buffer. */

            /* 0000 0000-0000 007F -> 0xxxxxxx */
            if (value <= 0x7F) {
                *(parser->buffer.last++) = value;
            }
            /* 0000 0080-0000 07FF -> 110xxxxx 10xxxxxx */
            else if (value <= 0x7FF) {
                *(parser->buffer.last++) = 0xC0 + (value >> 6);
                *(parser->buffer.last++) = 0x80 + (value & 0x3F);
            }
            /* 0000 0800-0000 FFFF -> 1110xxxx 10xxxxxx 10xxxxxx */
            else if (value <= 0xFFFF) {
                *(parser->buffer.last++) = 0xE0 + (value >> 12);
                *(parser->buffer.last++) = 0x80 + ((value >> 6) & 0x3F);
                *(parser->buffer.last++) = 0x80 + (value & 0x3F);
            }
            /* 0001 0000-0010 FFFF -> 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx */
            else {
                *(parser->buffer.last++) = 0xF0 + (value >> 18);
                *(parser->buffer.last++) = 0x80 + ((value >> 12) & 0x3F);
                *(parser->buffer.last++) = 0x80 + ((value >> 6) & 0x3F);
                *(parser->buffer.last++) = 0x80 + (value & 0x3F);
            }

            parser->unread ++;
        }

        /* On EOF, put NUL into the buffer and return. */

        if (parser->eof) {
            *(parser->buffer.last++) = '\0';
            parser->unread ++;
            return 1;
        }

    }

    if (parser->offset >= PTRDIFF_MAX)
        return yaml_parser_set_reader_error(parser, "input is too long",
                PTRDIFF_MAX, -1);

    return 1;
}
Commit	Line	Data
	1
	2	#include "yaml_private.h"
	3
	4	/*
	5	* Declarations.
	6	*/
	7
	8	static int
	9	yaml_parser_set_reader_error(yaml_parser_t parser, const char problem,
	10	size_t offset, int value);
	11
	12	static int
	13	yaml_parser_update_raw_buffer(yaml_parser_t *parser);
	14
	15	static int
	16	yaml_parser_determine_encoding(yaml_parser_t *parser);
	17
	18	YAML_DECLARE(int)
	19	yaml_parser_update_buffer(yaml_parser_t *parser, size_t length);
	20
	21	/*
	22	* Set the reader error and return 0.
	23	*/
	24
	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;
	33
	34	return 0;
	35	}
	36
	37	/*
	38	* Byte order marks.
	39	*/
	40
	41	#define BOM_UTF8 "\xef\xbb\xbf"
	42	#define BOM_UTF16LE "\xff\xfe"
	43	#define BOM_UTF16BE "\xfe\xff"
	44
	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	*/
	49
	50	static int
	51	yaml_parser_determine_encoding(yaml_parser_t *parser)
	52	{
	53	/* Ensure that we had enough bytes in the raw buffer. */
	54
	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	}
	61
	62	/* Determine the encoding. */
	63
	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	}
	85
	86	return 1;
	87	}
	88
	89	/*
	90	* Update the raw buffer.
	91	*/
	92
	93	static int
	94	yaml_parser_update_raw_buffer(yaml_parser_t *parser)
	95	{
	96	size_t size_read = 0;
	97
	98	/* Return if the raw buffer is full. */
	99
	100	if (parser->raw_buffer.start == parser->raw_buffer.pointer
	101	&& parser->raw_buffer.last == parser->raw_buffer.end)
	102	return 1;
	103
	104	/* Return on EOF. */
	105
	106	if (parser->eof) return 1;
	107
	108	/* Move the remaining bytes in the raw buffer to the beginning. */
	109
	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;
	118
	119	/* Call the read handler to fill the buffer. */
	120
	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	}
	130
	131	return 1;
	132	}
	133
	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	*/
	140
	141	YAML_DECLARE(int)
	142	yaml_parser_update_buffer(yaml_parser_t *parser, size_t length)
	143	{
	144	int first = 1;
	145
	146	assert(parser->read_handler); /* Read handler must be set. */
	147
	148	/* If the EOF flag is set and the raw buffer is empty, do nothing. */
	149
	150	if (parser->eof && parser->raw_buffer.pointer == parser->raw_buffer.last)
	151	return 1;
	152
	153	/* Return if the buffer contains enough characters. */
	154
	155	if (parser->unread >= length)
	156	return 1;
	157
	158	/* Determine the input encoding if it is not known yet. */
	159
	160	if (!parser->encoding) {
	161	if (!yaml_parser_determine_encoding(parser))
	162	return 0;
	163	}
	164
	165	/* Move the unread characters to the beginning of the buffer. */
	166
	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	}
	178
	179	/* Fill the buffer until it has enough characters. */
	180
	181	while (parser->unread < length)
	182	{
	183	/* Fill the raw buffer if necessary. */
	184
	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;
	189
	190	/* Decode the raw buffer. */
	191
	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;
	201
	202	/* Decode the next character. */
	203
	204	switch (parser->encoding)
	205	{
	206	case YAML_UTF8_ENCODING:
	207
	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	*/
	227
	228	/* Determine the length of the UTF-8 sequence. */
	229
	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;
	235
	236	/* Check if the leading octet is valid. */
	237
	238	if (!width)
	239	return yaml_parser_set_reader_error(parser,
	240	"invalid leading UTF-8 octet",
	241	parser->offset, octet);
	242
	243	/* Check if the raw buffer contains an incomplete character. */
	244
	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	}
	254
	255	/* Decode the leading octet. */
	256
	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;
	261
	262	/* Check and decode the trailing octets. */
	263
	264	for (k = 1; k < width; k ++)
	265	{
	266	octet = parser->raw_buffer.pointer[k];
	267
	268	/* Check if the octet is valid. */
	269
	270	if ((octet & 0xC0) != 0x80)
	271	return yaml_parser_set_reader_error(parser,
	272	"invalid trailing UTF-8 octet",
	273	parser->offset+k, octet);
	274
	275	/* Decode the octet. */
	276
	277	value = (value << 6) + (octet & 0x3F);
	278	}
	279
	280	/* Check the length of the sequence against the value. */
	281
	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);
	289
	290	/* Check the range of the value. */
	291
	292	if ((value >= 0xD800 && value <= 0xDFFF) \|\| value > 0x10FFFF)
	293	return yaml_parser_set_reader_error(parser,
	294	"invalid Unicode character",
	295	parser->offset, value);
	296
	297	break;
	298
	299	case YAML_UTF16LE_ENCODING:
	300	case YAML_UTF16BE_ENCODING:
	301
	302	low = (parser->encoding == YAML_UTF16LE_ENCODING ? 0 : 1);
	303	high = (parser->encoding == YAML_UTF16LE_ENCODING ? 1 : 0);
	304
	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	*/
	330
	331	/* Check for incomplete UTF-16 character. */
	332
	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	}
	342
	343	/* Get the character. */
	344
	345	value = parser->raw_buffer.pointer[low]
	346	+ (parser->raw_buffer.pointer[high] << 8);
	347
	348	/* Check for unexpected low surrogate area. */
	349
	350	if ((value & 0xFC00) == 0xDC00)
	351	return yaml_parser_set_reader_error(parser,
	352	"unexpected low surrogate area",
	353	parser->offset, value);
	354
	355	/* Check for a high surrogate area. */
	356
	357	if ((value & 0xFC00) == 0xD800) {
	358
	359	width = 4;
	360
	361	/* Check for incomplete surrogate pair. */
	362
	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	}
	372
	373	/* Get the next character. */
	374
	375	value2 = parser->raw_buffer.pointer[low+2]
	376	+ (parser->raw_buffer.pointer[high+2] << 8);
	377
	378	/* Check for a low surrogate area. */
	379
	380	if ((value2 & 0xFC00) != 0xDC00)
	381	return yaml_parser_set_reader_error(parser,
	382	"expected low surrogate area",
	383	parser->offset+2, value2);
	384
	385	/* Generate the value of the surrogate pair. */
	386
	387	value = 0x10000 + ((value & 0x3FF) << 10) + (value2 & 0x3FF);
	388	}
	389
	390	else {
	391	width = 2;
	392	}
	393
	394	break;
	395
	396	default:
	397	assert(1); /* Impossible. */
	398	}
	399
	400	/* Check if the raw buffer contains enough bytes to form a character. */
	401
	402	if (incomplete) break;
	403
	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	*/
	410
	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);
	419
	420	/* Move the raw pointers. */
	421
	422	parser->raw_buffer.pointer += width;
	423	parser->offset += width;
	424
	425	/* Finally put the character into the buffer. */
	426
	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	}
	449
	450	parser->unread ++;
	451	}
	452
	453	/* On EOF, put NUL into the buffer and return. */
	454
	455	if (parser->eof) {
	456	*(parser->buffer.last++) = '\0';
	457	parser->unread ++;
	458	return 1;
	459	}
	460
	461	}
	462
	463	if (parser->offset >= PTRDIFF_MAX)
	464	return yaml_parser_set_reader_error(parser, "input is too long",
	465	PTRDIFF_MAX, -1);
	466
	467	return 1;
	468	}
	469