--- /dev/null
+package yaml
+
+import (
+ "io"
+)
+
+// Set the reader error and return 0.
+func yaml_parser_set_reader_error(parser *yaml_parser_t, problem string, offset int, value int) bool {
+ parser.error = yaml_READER_ERROR
+ parser.problem = problem
+ parser.problem_offset = offset
+ parser.problem_value = value
+ return false
+}
+
+// Byte order marks.
+const (
+ bom_UTF8 = "\xef\xbb\xbf"
+ bom_UTF16LE = "\xff\xfe"
+ 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.
+func yaml_parser_determine_encoding(parser *yaml_parser_t) bool {
+ // Ensure that we had enough bytes in the raw buffer.
+ for !parser.eof && len(parser.raw_buffer)-parser.raw_buffer_pos < 3 {
+ if !yaml_parser_update_raw_buffer(parser) {
+ return false
+ }
+ }
+
+ // Determine the encoding.
+ buf := parser.raw_buffer
+ pos := parser.raw_buffer_pos
+ avail := len(buf) - pos
+ if avail >= 2 && buf[pos] == bom_UTF16LE[0] && buf[pos+1] == bom_UTF16LE[1] {
+ parser.encoding = yaml_UTF16LE_ENCODING
+ parser.raw_buffer_pos += 2
+ parser.offset += 2
+ } else if avail >= 2 && buf[pos] == bom_UTF16BE[0] && buf[pos+1] == bom_UTF16BE[1] {
+ parser.encoding = yaml_UTF16BE_ENCODING
+ parser.raw_buffer_pos += 2
+ parser.offset += 2
+ } else if avail >= 3 && buf[pos] == bom_UTF8[0] && buf[pos+1] == bom_UTF8[1] && buf[pos+2] == bom_UTF8[2] {
+ parser.encoding = yaml_UTF8_ENCODING
+ parser.raw_buffer_pos += 3
+ parser.offset += 3
+ } else {
+ parser.encoding = yaml_UTF8_ENCODING
+ }
+ return true
+}
+
+// Update the raw buffer.
+func yaml_parser_update_raw_buffer(parser *yaml_parser_t) bool {
+ size_read := 0
+
+ // Return if the raw buffer is full.
+ if parser.raw_buffer_pos == 0 && len(parser.raw_buffer) == cap(parser.raw_buffer) {
+ return true
+ }
+
+ // Return on EOF.
+ if parser.eof {
+ return true
+ }
+
+ // Move the remaining bytes in the raw buffer to the beginning.
+ if parser.raw_buffer_pos > 0 && parser.raw_buffer_pos < len(parser.raw_buffer) {
+ copy(parser.raw_buffer, parser.raw_buffer[parser.raw_buffer_pos:])
+ }
+ parser.raw_buffer = parser.raw_buffer[:len(parser.raw_buffer)-parser.raw_buffer_pos]
+ parser.raw_buffer_pos = 0
+
+ // Call the read handler to fill the buffer.
+ size_read, err := parser.read_handler(parser, parser.raw_buffer[len(parser.raw_buffer):cap(parser.raw_buffer)])
+ parser.raw_buffer = parser.raw_buffer[:len(parser.raw_buffer)+size_read]
+ if err == io.EOF {
+ parser.eof = true
+ } else if err != nil {
+ return yaml_parser_set_reader_error(parser, "input error: "+err.Error(), parser.offset, -1)
+ }
+ return true
+}
+
+// Ensure that the buffer contains at least `length` characters.
+// Return true on success, false on failure.
+//
+// The length is supposed to be significantly less that the buffer size.
+func yaml_parser_update_buffer(parser *yaml_parser_t, length int) bool {
+ if parser.read_handler == nil {
+ panic("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_pos == len(parser.raw_buffer) {
+ return true
+ }
+
+ // Return if the buffer contains enough characters.
+ if parser.unread >= length {
+ return true
+ }
+
+ // Determine the input encoding if it is not known yet.
+ if parser.encoding == yaml_ANY_ENCODING {
+ if !yaml_parser_determine_encoding(parser) {
+ return false
+ }
+ }
+
+ // Move the unread characters to the beginning of the buffer.
+ buffer_len := len(parser.buffer)
+ if parser.buffer_pos > 0 && parser.buffer_pos < buffer_len {
+ copy(parser.buffer, parser.buffer[parser.buffer_pos:])
+ buffer_len -= parser.buffer_pos
+ parser.buffer_pos = 0
+ } else if parser.buffer_pos == buffer_len {
+ buffer_len = 0
+ parser.buffer_pos = 0
+ }
+
+ // Open the whole buffer for writing, and cut it before returning.
+ parser.buffer = parser.buffer[:cap(parser.buffer)]
+
+ // Fill the buffer until it has enough characters.
+ first := true
+ for parser.unread < length {
+
+ // Fill the raw buffer if necessary.
+ if !first || parser.raw_buffer_pos == len(parser.raw_buffer) {
+ if !yaml_parser_update_raw_buffer(parser) {
+ parser.buffer = parser.buffer[:buffer_len]
+ return false
+ }
+ }
+ first = false
+
+ // Decode the raw buffer.
+ inner:
+ for parser.raw_buffer_pos != len(parser.raw_buffer) {
+ var value rune
+ var width int
+
+ raw_unread := len(parser.raw_buffer) - parser.raw_buffer_pos
+
+ // 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[parser.raw_buffer_pos]
+ switch {
+ case octet&0x80 == 0x00:
+ width = 1
+ case octet&0xE0 == 0xC0:
+ width = 2
+ case octet&0xF0 == 0xE0:
+ width = 3
+ case octet&0xF8 == 0xF0:
+ width = 4
+ default:
+ // The leading octet is invalid.
+ return yaml_parser_set_reader_error(parser,
+ "invalid leading UTF-8 octet",
+ parser.offset, int(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)
+ }
+ break inner
+ }
+
+ // Decode the leading octet.
+ switch {
+ case octet&0x80 == 0x00:
+ value = rune(octet & 0x7F)
+ case octet&0xE0 == 0xC0:
+ value = rune(octet & 0x1F)
+ case octet&0xF0 == 0xE0:
+ value = rune(octet & 0x0F)
+ case octet&0xF8 == 0xF0:
+ value = rune(octet & 0x07)
+ default:
+ value = 0
+ }
+
+ // Check and decode the trailing octets.
+ for k := 1; k < width; k++ {
+ octet = parser.raw_buffer[parser.raw_buffer_pos+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, int(octet))
+ }
+
+ // Decode the octet.
+ value = (value << 6) + rune(octet&0x3F)
+ }
+
+ // Check the length of the sequence against the value.
+ switch {
+ case width == 1:
+ case width == 2 && value >= 0x80:
+ case width == 3 && value >= 0x800:
+ case width == 4 && value >= 0x10000:
+ default:
+ 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, int(value))
+ }
+
+ case yaml_UTF16LE_ENCODING, yaml_UTF16BE_ENCODING:
+ var low, high int
+ if parser.encoding == yaml_UTF16LE_ENCODING {
+ low, high = 0, 1
+ } else {
+ low, high = 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)
+ }
+ break inner
+ }
+
+ // Get the character.
+ value = rune(parser.raw_buffer[parser.raw_buffer_pos+low]) +
+ (rune(parser.raw_buffer[parser.raw_buffer_pos+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, int(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)
+ }
+ break inner
+ }
+
+ // Get the next character.
+ value2 := rune(parser.raw_buffer[parser.raw_buffer_pos+low+2]) +
+ (rune(parser.raw_buffer[parser.raw_buffer_pos+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, int(value2))
+ }
+
+ // Generate the value of the surrogate pair.
+ value = 0x10000 + ((value & 0x3FF) << 10) + (value2 & 0x3FF)
+ } else {
+ width = 2
+ }
+
+ default:
+ panic("impossible")
+ }
+
+ // 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)
+ switch {
+ case value == 0x09:
+ case value == 0x0A:
+ case value == 0x0D:
+ case value >= 0x20 && value <= 0x7E:
+ case value == 0x85:
+ case value >= 0xA0 && value <= 0xD7FF:
+ case value >= 0xE000 && value <= 0xFFFD:
+ case value >= 0x10000 && value <= 0x10FFFF:
+ default:
+ return yaml_parser_set_reader_error(parser,
+ "control characters are not allowed",
+ parser.offset, int(value))
+ }
+
+ // Move the raw pointers.
+ parser.raw_buffer_pos += width
+ parser.offset += width
+
+ // Finally put the character into the buffer.
+ if value <= 0x7F {
+ // 0000 0000-0000 007F . 0xxxxxxx
+ parser.buffer[buffer_len+0] = byte(value)
+ buffer_len += 1
+ } else if value <= 0x7FF {
+ // 0000 0080-0000 07FF . 110xxxxx 10xxxxxx
+ parser.buffer[buffer_len+0] = byte(0xC0 + (value >> 6))
+ parser.buffer[buffer_len+1] = byte(0x80 + (value & 0x3F))
+ buffer_len += 2
+ } else if value <= 0xFFFF {
+ // 0000 0800-0000 FFFF . 1110xxxx 10xxxxxx 10xxxxxx
+ parser.buffer[buffer_len+0] = byte(0xE0 + (value >> 12))
+ parser.buffer[buffer_len+1] = byte(0x80 + ((value >> 6) & 0x3F))
+ parser.buffer[buffer_len+2] = byte(0x80 + (value & 0x3F))
+ buffer_len += 3
+ } else {
+ // 0001 0000-0010 FFFF . 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
+ parser.buffer[buffer_len+0] = byte(0xF0 + (value >> 18))
+ parser.buffer[buffer_len+1] = byte(0x80 + ((value >> 12) & 0x3F))
+ parser.buffer[buffer_len+2] = byte(0x80 + ((value >> 6) & 0x3F))
+ parser.buffer[buffer_len+3] = byte(0x80 + (value & 0x3F))
+ buffer_len += 4
+ }
+
+ parser.unread++
+ }
+
+ // On EOF, put NUL into the buffer and return.
+ if parser.eof {
+ parser.buffer[buffer_len] = 0
+ buffer_len++
+ parser.unread++
+ break
+ }
+ }
+ parser.buffer = parser.buffer[:buffer_len]
+ return true
+}
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