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