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Volker Schukai authored
readerc.go 13.76 KiB
//
// Copyright (c) 2011-2019 Canonical Ltd
// Copyright (c) 2006-2010 Kirill Simonov
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of
// this software and associated documentation files (the "Software"), to deal in
// the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
// of the Software, and to permit persons to whom the Software is furnished to do
// so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
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")
}
// [Go] This function was changed to guarantee the requested length size at EOF.
// The fact we need to do this is pretty awful, but the description above implies
// for that to be the case, and there are tests
// 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) {
// [Go] ACTUALLY! Read the documentation of this function above.
// This is just broken. To return true, we need to have the
// given length in the buffer. Not doing that means every single
// check that calls this function to make sure the buffer has a
// given length is Go) panicking; or C) accessing invalid memory.
//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 }
}
// [Go] Read the documentation of this function above. To return true,
// we need to have the given length in the buffer. Not doing that means
// every single check that calls this function to make sure the buffer
// has a given length is Go) panicking; or C) accessing invalid memory.
// This happens here due to the EOF above breaking early.
for buffer_len < length {
parser.buffer[buffer_len] = 0
buffer_len++
}
parser.buffer = parser.buffer[:buffer_len]
return true
}