mirror of
https://github.com/strongdm/comply
synced 2024-11-05 15:35:25 +00:00
395 lines
12 KiB
Go
395 lines
12 KiB
Go
package yaml
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import (
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"io"
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)
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// Set the reader error and return 0.
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func yaml_parser_set_reader_error(parser *yaml_parser_t, problem string, offset int, value int) bool {
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parser.error = yaml_READER_ERROR
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parser.problem = problem
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parser.problem_offset = offset
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parser.problem_value = value
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return false
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}
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// Byte order marks.
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const (
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bom_UTF8 = "\xef\xbb\xbf"
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bom_UTF16LE = "\xff\xfe"
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bom_UTF16BE = "\xfe\xff"
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)
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// Determine the input stream encoding by checking the BOM symbol. If no BOM is
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// found, the UTF-8 encoding is assumed. Return 1 on success, 0 on failure.
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func yaml_parser_determine_encoding(parser *yaml_parser_t) bool {
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// Ensure that we had enough bytes in the raw buffer.
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for !parser.eof && len(parser.raw_buffer)-parser.raw_buffer_pos < 3 {
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if !yaml_parser_update_raw_buffer(parser) {
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return false
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}
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}
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// Determine the encoding.
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buf := parser.raw_buffer
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pos := parser.raw_buffer_pos
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avail := len(buf) - pos
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if avail >= 2 && buf[pos] == bom_UTF16LE[0] && buf[pos+1] == bom_UTF16LE[1] {
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parser.encoding = yaml_UTF16LE_ENCODING
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parser.raw_buffer_pos += 2
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parser.offset += 2
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} else if avail >= 2 && buf[pos] == bom_UTF16BE[0] && buf[pos+1] == bom_UTF16BE[1] {
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parser.encoding = yaml_UTF16BE_ENCODING
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parser.raw_buffer_pos += 2
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parser.offset += 2
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} else if avail >= 3 && buf[pos] == bom_UTF8[0] && buf[pos+1] == bom_UTF8[1] && buf[pos+2] == bom_UTF8[2] {
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parser.encoding = yaml_UTF8_ENCODING
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parser.raw_buffer_pos += 3
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parser.offset += 3
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} else {
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parser.encoding = yaml_UTF8_ENCODING
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}
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return true
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}
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// Update the raw buffer.
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func yaml_parser_update_raw_buffer(parser *yaml_parser_t) bool {
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size_read := 0
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// Return if the raw buffer is full.
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if parser.raw_buffer_pos == 0 && len(parser.raw_buffer) == cap(parser.raw_buffer) {
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return true
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}
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// Return on EOF.
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if parser.eof {
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return true
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}
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// Move the remaining bytes in the raw buffer to the beginning.
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if parser.raw_buffer_pos > 0 && parser.raw_buffer_pos < len(parser.raw_buffer) {
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copy(parser.raw_buffer, parser.raw_buffer[parser.raw_buffer_pos:])
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}
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parser.raw_buffer = parser.raw_buffer[:len(parser.raw_buffer)-parser.raw_buffer_pos]
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parser.raw_buffer_pos = 0
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// Call the read handler to fill the buffer.
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size_read, err := parser.read_handler(parser, parser.raw_buffer[len(parser.raw_buffer):cap(parser.raw_buffer)])
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parser.raw_buffer = parser.raw_buffer[:len(parser.raw_buffer)+size_read]
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if err == io.EOF {
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parser.eof = true
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} else if err != nil {
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return yaml_parser_set_reader_error(parser, "input error: "+err.Error(), parser.offset, -1)
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}
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return true
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}
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// Ensure that the buffer contains at least `length` characters.
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// Return true on success, false on failure.
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//
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// The length is supposed to be significantly less that the buffer size.
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func yaml_parser_update_buffer(parser *yaml_parser_t, length int) bool {
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if parser.read_handler == nil {
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panic("read handler must be set")
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}
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// If the EOF flag is set and the raw buffer is empty, do nothing.
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if parser.eof && parser.raw_buffer_pos == len(parser.raw_buffer) {
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return true
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}
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// Return if the buffer contains enough characters.
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if parser.unread >= length {
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return true
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}
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// Determine the input encoding if it is not known yet.
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if parser.encoding == yaml_ANY_ENCODING {
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if !yaml_parser_determine_encoding(parser) {
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return false
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}
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}
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// Move the unread characters to the beginning of the buffer.
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buffer_len := len(parser.buffer)
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if parser.buffer_pos > 0 && parser.buffer_pos < buffer_len {
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copy(parser.buffer, parser.buffer[parser.buffer_pos:])
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buffer_len -= parser.buffer_pos
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parser.buffer_pos = 0
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} else if parser.buffer_pos == buffer_len {
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buffer_len = 0
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parser.buffer_pos = 0
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}
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// Open the whole buffer for writing, and cut it before returning.
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parser.buffer = parser.buffer[:cap(parser.buffer)]
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// Fill the buffer until it has enough characters.
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first := true
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for parser.unread < length {
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// Fill the raw buffer if necessary.
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if !first || parser.raw_buffer_pos == len(parser.raw_buffer) {
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if !yaml_parser_update_raw_buffer(parser) {
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parser.buffer = parser.buffer[:buffer_len]
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return false
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}
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}
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first = false
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// Decode the raw buffer.
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inner:
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for parser.raw_buffer_pos != len(parser.raw_buffer) {
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var value rune
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var width int
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raw_unread := len(parser.raw_buffer) - parser.raw_buffer_pos
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// Decode the next character.
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switch parser.encoding {
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case yaml_UTF8_ENCODING:
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// Decode a UTF-8 character. Check RFC 3629
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// (http://www.ietf.org/rfc/rfc3629.txt) for more details.
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//
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// The following table (taken from the RFC) is used for
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// decoding.
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//
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// Char. number range | UTF-8 octet sequence
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// (hexadecimal) | (binary)
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// --------------------+------------------------------------
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// 0000 0000-0000 007F | 0xxxxxxx
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// 0000 0080-0000 07FF | 110xxxxx 10xxxxxx
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// 0000 0800-0000 FFFF | 1110xxxx 10xxxxxx 10xxxxxx
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// 0001 0000-0010 FFFF | 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
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//
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// Additionally, the characters in the range 0xD800-0xDFFF
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// are prohibited as they are reserved for use with UTF-16
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// surrogate pairs.
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// Determine the length of the UTF-8 sequence.
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octet := parser.raw_buffer[parser.raw_buffer_pos]
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switch {
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case octet&0x80 == 0x00:
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width = 1
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case octet&0xE0 == 0xC0:
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width = 2
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case octet&0xF0 == 0xE0:
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width = 3
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case octet&0xF8 == 0xF0:
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width = 4
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default:
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// The leading octet is invalid.
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return yaml_parser_set_reader_error(parser,
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"invalid leading UTF-8 octet",
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parser.offset, int(octet))
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}
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// Check if the raw buffer contains an incomplete character.
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if width > raw_unread {
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if parser.eof {
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return yaml_parser_set_reader_error(parser,
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"incomplete UTF-8 octet sequence",
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parser.offset, -1)
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}
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break inner
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}
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// Decode the leading octet.
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switch {
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case octet&0x80 == 0x00:
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value = rune(octet & 0x7F)
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case octet&0xE0 == 0xC0:
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value = rune(octet & 0x1F)
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case octet&0xF0 == 0xE0:
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value = rune(octet & 0x0F)
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case octet&0xF8 == 0xF0:
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value = rune(octet & 0x07)
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default:
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value = 0
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}
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// Check and decode the trailing octets.
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for k := 1; k < width; k++ {
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octet = parser.raw_buffer[parser.raw_buffer_pos+k]
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// Check if the octet is valid.
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if (octet & 0xC0) != 0x80 {
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return yaml_parser_set_reader_error(parser,
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"invalid trailing UTF-8 octet",
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parser.offset+k, int(octet))
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}
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// Decode the octet.
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value = (value << 6) + rune(octet&0x3F)
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}
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// Check the length of the sequence against the value.
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switch {
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case width == 1:
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case width == 2 && value >= 0x80:
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case width == 3 && value >= 0x800:
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case width == 4 && value >= 0x10000:
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default:
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return yaml_parser_set_reader_error(parser,
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"invalid length of a UTF-8 sequence",
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parser.offset, -1)
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}
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// Check the range of the value.
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if value >= 0xD800 && value <= 0xDFFF || value > 0x10FFFF {
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return yaml_parser_set_reader_error(parser,
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"invalid Unicode character",
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parser.offset, int(value))
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}
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case yaml_UTF16LE_ENCODING, yaml_UTF16BE_ENCODING:
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var low, high int
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if parser.encoding == yaml_UTF16LE_ENCODING {
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low, high = 0, 1
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} else {
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low, high = 1, 0
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}
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// The UTF-16 encoding is not as simple as one might
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// naively think. Check RFC 2781
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// (http://www.ietf.org/rfc/rfc2781.txt).
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//
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// Normally, two subsequent bytes describe a Unicode
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// character. However a special technique (called a
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// surrogate pair) is used for specifying character
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// values larger than 0xFFFF.
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//
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// A surrogate pair consists of two pseudo-characters:
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// high surrogate area (0xD800-0xDBFF)
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// low surrogate area (0xDC00-0xDFFF)
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//
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// The following formulas are used for decoding
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// and encoding characters using surrogate pairs:
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//
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// U = U' + 0x10000 (0x01 00 00 <= U <= 0x10 FF FF)
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// U' = yyyyyyyyyyxxxxxxxxxx (0 <= U' <= 0x0F FF FF)
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// W1 = 110110yyyyyyyyyy
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// W2 = 110111xxxxxxxxxx
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//
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// where U is the character value, W1 is the high surrogate
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// area, W2 is the low surrogate area.
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// Check for incomplete UTF-16 character.
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if raw_unread < 2 {
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if parser.eof {
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return yaml_parser_set_reader_error(parser,
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"incomplete UTF-16 character",
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parser.offset, -1)
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}
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break inner
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}
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// Get the character.
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value = rune(parser.raw_buffer[parser.raw_buffer_pos+low]) +
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(rune(parser.raw_buffer[parser.raw_buffer_pos+high]) << 8)
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// Check for unexpected low surrogate area.
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if value&0xFC00 == 0xDC00 {
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return yaml_parser_set_reader_error(parser,
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"unexpected low surrogate area",
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parser.offset, int(value))
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}
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// Check for a high surrogate area.
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if value&0xFC00 == 0xD800 {
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width = 4
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// Check for incomplete surrogate pair.
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if raw_unread < 4 {
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if parser.eof {
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return yaml_parser_set_reader_error(parser,
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"incomplete UTF-16 surrogate pair",
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parser.offset, -1)
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}
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break inner
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}
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// Get the next character.
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value2 := rune(parser.raw_buffer[parser.raw_buffer_pos+low+2]) +
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(rune(parser.raw_buffer[parser.raw_buffer_pos+high+2]) << 8)
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// Check for a low surrogate area.
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if value2&0xFC00 != 0xDC00 {
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return yaml_parser_set_reader_error(parser,
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"expected low surrogate area",
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parser.offset+2, int(value2))
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}
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// Generate the value of the surrogate pair.
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value = 0x10000 + ((value & 0x3FF) << 10) + (value2 & 0x3FF)
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} else {
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width = 2
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}
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default:
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panic("impossible")
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}
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// Check if the character is in the allowed range:
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// #x9 | #xA | #xD | [#x20-#x7E] (8 bit)
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// | #x85 | [#xA0-#xD7FF] | [#xE000-#xFFFD] (16 bit)
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// | [#x10000-#x10FFFF] (32 bit)
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switch {
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case value == 0x09:
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case value == 0x0A:
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case value == 0x0D:
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case value >= 0x20 && value <= 0x7E:
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case value == 0x85:
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case value >= 0xA0 && value <= 0xD7FF:
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case value >= 0xE000 && value <= 0xFFFD:
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case value >= 0x10000 && value <= 0x10FFFF:
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default:
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return yaml_parser_set_reader_error(parser,
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"control characters are not allowed",
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parser.offset, int(value))
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}
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// Move the raw pointers.
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parser.raw_buffer_pos += width
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parser.offset += width
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// Finally put the character into the buffer.
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if value <= 0x7F {
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// 0000 0000-0000 007F . 0xxxxxxx
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parser.buffer[buffer_len+0] = byte(value)
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buffer_len += 1
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} else if value <= 0x7FF {
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// 0000 0080-0000 07FF . 110xxxxx 10xxxxxx
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parser.buffer[buffer_len+0] = byte(0xC0 + (value >> 6))
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parser.buffer[buffer_len+1] = byte(0x80 + (value & 0x3F))
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buffer_len += 2
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} else if value <= 0xFFFF {
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// 0000 0800-0000 FFFF . 1110xxxx 10xxxxxx 10xxxxxx
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parser.buffer[buffer_len+0] = byte(0xE0 + (value >> 12))
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parser.buffer[buffer_len+1] = byte(0x80 + ((value >> 6) & 0x3F))
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parser.buffer[buffer_len+2] = byte(0x80 + (value & 0x3F))
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buffer_len += 3
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} else {
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// 0001 0000-0010 FFFF . 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
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parser.buffer[buffer_len+0] = byte(0xF0 + (value >> 18))
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parser.buffer[buffer_len+1] = byte(0x80 + ((value >> 12) & 0x3F))
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parser.buffer[buffer_len+2] = byte(0x80 + ((value >> 6) & 0x3F))
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parser.buffer[buffer_len+3] = byte(0x80 + (value & 0x3F))
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buffer_len += 4
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}
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parser.unread++
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}
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// On EOF, put NUL into the buffer and return.
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if parser.eof {
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parser.buffer[buffer_len] = 0
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buffer_len++
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parser.unread++
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break
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}
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}
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parser.buffer = parser.buffer[:buffer_len]
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return true
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}
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