path: root/contrib/libs/yaml/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 >= MAX_FILE_SIZE) {
        return yaml_parser_set_reader_error(parser, "input is too long", 
            parser->offset, -1);
    }
 
    return 1; 
}