#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)
{
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 (!yaml_parser_update_raw_buffer(parser)) return 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;
}
}
return 1;
}