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74
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1 //
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2 // Copyright (c) 2011-2019 Canonical Ltd
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3 // Copyright (c) 2006-2010 Kirill Simonov
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4 //
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5 // Permission is hereby granted, free of charge, to any person obtaining a copy of
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6 // this software and associated documentation files (the "Software"), to deal in
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7 // the Software without restriction, including without limitation the rights to
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8 // use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
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9 // of the Software, and to permit persons to whom the Software is furnished to do
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10 // so, subject to the following conditions:
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11 //
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12 // The above copyright notice and this permission notice shall be included in all
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13 // copies or substantial portions of the Software.
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14 //
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15 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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16 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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17 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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18 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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19 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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20 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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21 // SOFTWARE.
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22
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23 package yaml
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24
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25 import (
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26 "io"
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27 )
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28
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29 // Set the reader error and return 0.
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30 func yaml_parser_set_reader_error(parser *yaml_parser_t, problem string, offset int, value int) bool {
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31 parser.error = yaml_READER_ERROR
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32 parser.problem = problem
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33 parser.problem_offset = offset
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34 parser.problem_value = value
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35 return false
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36 }
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37
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38 // Byte order marks.
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39 const (
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40 bom_UTF8 = "\xef\xbb\xbf"
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41 bom_UTF16LE = "\xff\xfe"
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42 bom_UTF16BE = "\xfe\xff"
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43 )
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44
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45 // Determine the input stream encoding by checking the BOM symbol. If no BOM is
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46 // found, the UTF-8 encoding is assumed. Return 1 on success, 0 on failure.
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47 func yaml_parser_determine_encoding(parser *yaml_parser_t) bool {
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48 // Ensure that we had enough bytes in the raw buffer.
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49 for !parser.eof && len(parser.raw_buffer)-parser.raw_buffer_pos < 3 {
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50 if !yaml_parser_update_raw_buffer(parser) {
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51 return false
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52 }
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53 }
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54
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55 // Determine the encoding.
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56 buf := parser.raw_buffer
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57 pos := parser.raw_buffer_pos
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58 avail := len(buf) - pos
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59 if avail >= 2 && buf[pos] == bom_UTF16LE[0] && buf[pos+1] == bom_UTF16LE[1] {
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60 parser.encoding = yaml_UTF16LE_ENCODING
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61 parser.raw_buffer_pos += 2
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62 parser.offset += 2
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63 } else if avail >= 2 && buf[pos] == bom_UTF16BE[0] && buf[pos+1] == bom_UTF16BE[1] {
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64 parser.encoding = yaml_UTF16BE_ENCODING
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65 parser.raw_buffer_pos += 2
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66 parser.offset += 2
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67 } 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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68 parser.encoding = yaml_UTF8_ENCODING
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69 parser.raw_buffer_pos += 3
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70 parser.offset += 3
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71 } else {
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72 parser.encoding = yaml_UTF8_ENCODING
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73 }
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74 return true
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75 }
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76
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77 // Update the raw buffer.
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78 func yaml_parser_update_raw_buffer(parser *yaml_parser_t) bool {
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79 size_read := 0
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80
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81 // Return if the raw buffer is full.
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82 if parser.raw_buffer_pos == 0 && len(parser.raw_buffer) == cap(parser.raw_buffer) {
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83 return true
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84 }
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85
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86 // Return on EOF.
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87 if parser.eof {
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88 return true
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89 }
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90
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91 // Move the remaining bytes in the raw buffer to the beginning.
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92 if parser.raw_buffer_pos > 0 && parser.raw_buffer_pos < len(parser.raw_buffer) {
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93 copy(parser.raw_buffer, parser.raw_buffer[parser.raw_buffer_pos:])
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94 }
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95 parser.raw_buffer = parser.raw_buffer[:len(parser.raw_buffer)-parser.raw_buffer_pos]
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96 parser.raw_buffer_pos = 0
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97
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98 // Call the read handler to fill the buffer.
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99 size_read, err := parser.read_handler(parser, parser.raw_buffer[len(parser.raw_buffer):cap(parser.raw_buffer)])
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100 parser.raw_buffer = parser.raw_buffer[:len(parser.raw_buffer)+size_read]
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101 if err == io.EOF {
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102 parser.eof = true
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103 } else if err != nil {
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104 return yaml_parser_set_reader_error(parser, "input error: "+err.Error(), parser.offset, -1)
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105 }
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106 return true
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107 }
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108
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109 // Ensure that the buffer contains at least `length` characters.
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110 // Return true on success, false on failure.
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111 //
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112 // The length is supposed to be significantly less that the buffer size.
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113 func yaml_parser_update_buffer(parser *yaml_parser_t, length int) bool {
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114 if parser.read_handler == nil {
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115 panic("read handler must be set")
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116 }
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117
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118 // [Go] This function was changed to guarantee the requested length size at EOF.
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119 // The fact we need to do this is pretty awful, but the description above implies
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120 // for that to be the case, and there are tests
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121
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122 // If the EOF flag is set and the raw buffer is empty, do nothing.
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123 if parser.eof && parser.raw_buffer_pos == len(parser.raw_buffer) {
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124 // [Go] ACTUALLY! Read the documentation of this function above.
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125 // This is just broken. To return true, we need to have the
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126 // given length in the buffer. Not doing that means every single
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127 // check that calls this function to make sure the buffer has a
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128 // given length is Go) panicking; or C) accessing invalid memory.
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129 //return true
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130 }
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131
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132 // Return if the buffer contains enough characters.
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133 if parser.unread >= length {
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134 return true
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135 }
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136
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137 // Determine the input encoding if it is not known yet.
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138 if parser.encoding == yaml_ANY_ENCODING {
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139 if !yaml_parser_determine_encoding(parser) {
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140 return false
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141 }
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142 }
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143
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144 // Move the unread characters to the beginning of the buffer.
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145 buffer_len := len(parser.buffer)
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146 if parser.buffer_pos > 0 && parser.buffer_pos < buffer_len {
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147 copy(parser.buffer, parser.buffer[parser.buffer_pos:])
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148 buffer_len -= parser.buffer_pos
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149 parser.buffer_pos = 0
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150 } else if parser.buffer_pos == buffer_len {
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151 buffer_len = 0
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152 parser.buffer_pos = 0
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153 }
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154
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155 // Open the whole buffer for writing, and cut it before returning.
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156 parser.buffer = parser.buffer[:cap(parser.buffer)]
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157
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158 // Fill the buffer until it has enough characters.
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159 first := true
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160 for parser.unread < length {
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161
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162 // Fill the raw buffer if necessary.
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163 if !first || parser.raw_buffer_pos == len(parser.raw_buffer) {
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164 if !yaml_parser_update_raw_buffer(parser) {
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165 parser.buffer = parser.buffer[:buffer_len]
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166 return false
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167 }
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168 }
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169 first = false
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170
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171 // Decode the raw buffer.
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172 inner:
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173 for parser.raw_buffer_pos != len(parser.raw_buffer) {
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174 var value rune
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175 var width int
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176
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177 raw_unread := len(parser.raw_buffer) - parser.raw_buffer_pos
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178
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179 // Decode the next character.
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180 switch parser.encoding {
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181 case yaml_UTF8_ENCODING:
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182 // Decode a UTF-8 character. Check RFC 3629
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183 // (http://www.ietf.org/rfc/rfc3629.txt) for more details.
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184 //
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185 // The following table (taken from the RFC) is used for
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186 // decoding.
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187 //
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188 // Char. number range | UTF-8 octet sequence
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189 // (hexadecimal) | (binary)
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190 // --------------------+------------------------------------
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191 // 0000 0000-0000 007F | 0xxxxxxx
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192 // 0000 0080-0000 07FF | 110xxxxx 10xxxxxx
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193 // 0000 0800-0000 FFFF | 1110xxxx 10xxxxxx 10xxxxxx
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194 // 0001 0000-0010 FFFF | 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
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195 //
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196 // Additionally, the characters in the range 0xD800-0xDFFF
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197 // are prohibited as they are reserved for use with UTF-16
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198 // surrogate pairs.
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199
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200 // Determine the length of the UTF-8 sequence.
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201 octet := parser.raw_buffer[parser.raw_buffer_pos]
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202 switch {
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203 case octet&0x80 == 0x00:
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204 width = 1
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205 case octet&0xE0 == 0xC0:
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206 width = 2
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207 case octet&0xF0 == 0xE0:
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208 width = 3
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209 case octet&0xF8 == 0xF0:
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210 width = 4
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211 default:
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212 // The leading octet is invalid.
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213 return yaml_parser_set_reader_error(parser,
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214 "invalid leading UTF-8 octet",
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215 parser.offset, int(octet))
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216 }
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217
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218 // Check if the raw buffer contains an incomplete character.
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219 if width > raw_unread {
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220 if parser.eof {
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221 return yaml_parser_set_reader_error(parser,
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222 "incomplete UTF-8 octet sequence",
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223 parser.offset, -1)
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224 }
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225 break inner
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226 }
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227
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228 // Decode the leading octet.
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229 switch {
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230 case octet&0x80 == 0x00:
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231 value = rune(octet & 0x7F)
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232 case octet&0xE0 == 0xC0:
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233 value = rune(octet & 0x1F)
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234 case octet&0xF0 == 0xE0:
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235 value = rune(octet & 0x0F)
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236 case octet&0xF8 == 0xF0:
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237 value = rune(octet & 0x07)
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238 default:
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239 value = 0
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240 }
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241
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242 // Check and decode the trailing octets.
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243 for k := 1; k < width; k++ {
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244 octet = parser.raw_buffer[parser.raw_buffer_pos+k]
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245
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246 // Check if the octet is valid.
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247 if (octet & 0xC0) != 0x80 {
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248 return yaml_parser_set_reader_error(parser,
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249 "invalid trailing UTF-8 octet",
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250 parser.offset+k, int(octet))
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251 }
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252
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253 // Decode the octet.
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254 value = (value << 6) + rune(octet&0x3F)
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255 }
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256
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257 // Check the length of the sequence against the value.
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258 switch {
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259 case width == 1:
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260 case width == 2 && value >= 0x80:
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261 case width == 3 && value >= 0x800:
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262 case width == 4 && value >= 0x10000:
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263 default:
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264 return yaml_parser_set_reader_error(parser,
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265 "invalid length of a UTF-8 sequence",
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266 parser.offset, -1)
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267 }
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268
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269 // Check the range of the value.
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270 if value >= 0xD800 && value <= 0xDFFF || value > 0x10FFFF {
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271 return yaml_parser_set_reader_error(parser,
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272 "invalid Unicode character",
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273 parser.offset, int(value))
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274 }
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275
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276 case yaml_UTF16LE_ENCODING, yaml_UTF16BE_ENCODING:
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277 var low, high int
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278 if parser.encoding == yaml_UTF16LE_ENCODING {
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279 low, high = 0, 1
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280 } else {
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281 low, high = 1, 0
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282 }
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283
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284 // The UTF-16 encoding is not as simple as one might
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285 // naively think. Check RFC 2781
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286 // (http://www.ietf.org/rfc/rfc2781.txt).
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287 //
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288 // Normally, two subsequent bytes describe a Unicode
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289 // character. However a special technique (called a
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290 // surrogate pair) is used for specifying character
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291 // values larger than 0xFFFF.
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292 //
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293 // A surrogate pair consists of two pseudo-characters:
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294 // high surrogate area (0xD800-0xDBFF)
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295 // low surrogate area (0xDC00-0xDFFF)
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296 //
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297 // The following formulas are used for decoding
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298 // and encoding characters using surrogate pairs:
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299 //
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300 // U = U' + 0x10000 (0x01 00 00 <= U <= 0x10 FF FF)
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301 // U' = yyyyyyyyyyxxxxxxxxxx (0 <= U' <= 0x0F FF FF)
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302 // W1 = 110110yyyyyyyyyy
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303 // W2 = 110111xxxxxxxxxx
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304 //
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305 // where U is the character value, W1 is the high surrogate
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306 // area, W2 is the low surrogate area.
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307
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308 // Check for incomplete UTF-16 character.
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309 if raw_unread < 2 {
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310 if parser.eof {
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311 return yaml_parser_set_reader_error(parser,
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312 "incomplete UTF-16 character",
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313 parser.offset, -1)
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314 }
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315 break inner
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316 }
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317
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318 // Get the character.
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319 value = rune(parser.raw_buffer[parser.raw_buffer_pos+low]) +
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320 (rune(parser.raw_buffer[parser.raw_buffer_pos+high]) << 8)
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321
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322 // Check for unexpected low surrogate area.
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323 if value&0xFC00 == 0xDC00 {
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324 return yaml_parser_set_reader_error(parser,
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325 "unexpected low surrogate area",
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326 parser.offset, int(value))
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327 }
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328
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329 // Check for a high surrogate area.
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330 if value&0xFC00 == 0xD800 {
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331 width = 4
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332
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333 // Check for incomplete surrogate pair.
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334 if raw_unread < 4 {
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335 if parser.eof {
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336 return yaml_parser_set_reader_error(parser,
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337 "incomplete UTF-16 surrogate pair",
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338 parser.offset, -1)
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339 }
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340 break inner
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341 }
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342
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343 // Get the next character.
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344 value2 := rune(parser.raw_buffer[parser.raw_buffer_pos+low+2]) +
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345 (rune(parser.raw_buffer[parser.raw_buffer_pos+high+2]) << 8)
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346
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347 // Check for a low surrogate area.
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348 if value2&0xFC00 != 0xDC00 {
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349 return yaml_parser_set_reader_error(parser,
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350 "expected low surrogate area",
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351 parser.offset+2, int(value2))
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352 }
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353
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354 // Generate the value of the surrogate pair.
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355 value = 0x10000 + ((value & 0x3FF) << 10) + (value2 & 0x3FF)
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356 } else {
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357 width = 2
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358 }
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359
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360 default:
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361 panic("impossible")
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362 }
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363
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364 // Check if the character is in the allowed range:
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365 // #x9 | #xA | #xD | [#x20-#x7E] (8 bit)
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366 // | #x85 | [#xA0-#xD7FF] | [#xE000-#xFFFD] (16 bit)
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367 // | [#x10000-#x10FFFF] (32 bit)
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368 switch {
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369 case value == 0x09:
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370 case value == 0x0A:
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371 case value == 0x0D:
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372 case value >= 0x20 && value <= 0x7E:
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373 case value == 0x85:
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374 case value >= 0xA0 && value <= 0xD7FF:
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375 case value >= 0xE000 && value <= 0xFFFD:
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376 case value >= 0x10000 && value <= 0x10FFFF:
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377 default:
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378 return yaml_parser_set_reader_error(parser,
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379 "control characters are not allowed",
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380 parser.offset, int(value))
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381 }
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382
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383 // Move the raw pointers.
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384 parser.raw_buffer_pos += width
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385 parser.offset += width
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386
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387 // Finally put the character into the buffer.
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388 if value <= 0x7F {
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389 // 0000 0000-0000 007F . 0xxxxxxx
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390 parser.buffer[buffer_len+0] = byte(value)
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391 buffer_len += 1
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392 } else if value <= 0x7FF {
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393 // 0000 0080-0000 07FF . 110xxxxx 10xxxxxx
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394 parser.buffer[buffer_len+0] = byte(0xC0 + (value >> 6))
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395 parser.buffer[buffer_len+1] = byte(0x80 + (value & 0x3F))
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396 buffer_len += 2
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397 } else if value <= 0xFFFF {
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398 // 0000 0800-0000 FFFF . 1110xxxx 10xxxxxx 10xxxxxx
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399 parser.buffer[buffer_len+0] = byte(0xE0 + (value >> 12))
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400 parser.buffer[buffer_len+1] = byte(0x80 + ((value >> 6) & 0x3F))
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401 parser.buffer[buffer_len+2] = byte(0x80 + (value & 0x3F))
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402 buffer_len += 3
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403 } else {
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404 // 0001 0000-0010 FFFF . 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
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405 parser.buffer[buffer_len+0] = byte(0xF0 + (value >> 18))
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406 parser.buffer[buffer_len+1] = byte(0x80 + ((value >> 12) & 0x3F))
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407 parser.buffer[buffer_len+2] = byte(0x80 + ((value >> 6) & 0x3F))
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408 parser.buffer[buffer_len+3] = byte(0x80 + (value & 0x3F))
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409 buffer_len += 4
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410 }
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411
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412 parser.unread++
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413 }
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414
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415 // On EOF, put NUL into the buffer and return.
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416 if parser.eof {
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417 parser.buffer[buffer_len] = 0
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418 buffer_len++
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419 parser.unread++
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420 break
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421 }
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422 }
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423 // [Go] Read the documentation of this function above. To return true,
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424 // we need to have the given length in the buffer. Not doing that means
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425 // every single check that calls this function to make sure the buffer
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426 // has a given length is Go) panicking; or C) accessing invalid memory.
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427 // This happens here due to the EOF above breaking early.
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428 for buffer_len < length {
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429 parser.buffer[buffer_len] = 0
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430 buffer_len++
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431 }
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432 parser.buffer = parser.buffer[:buffer_len]
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433 return true
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434 }
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