readerc.go

Documentation: gopkg.in/yaml.v3

     1  // 
     2  // Copyright (c) 2011-2019 Canonical Ltd
     3  // Copyright (c) 2006-2010 Kirill Simonov
     4  // 
     5  // Permission is hereby granted, free of charge, to any person obtaining a copy of
     6  // this software and associated documentation files (the "Software"), to deal in
     7  // the Software without restriction, including without limitation the rights to
     8  // use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
     9  // of the Software, and to permit persons to whom the Software is furnished to do
    10  // so, subject to the following conditions:
    11  // 
    12  // The above copyright notice and this permission notice shall be included in all
    13  // copies or substantial portions of the Software.
    14  // 
    15  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    16  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    17  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    18  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    19  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    20  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
    21  // SOFTWARE.
    22  
    23  package yaml
    24  
    25  import (
    26  	"io"
    27  )
    28  
    29  // Set the reader error and return 0.
    30  func yaml_parser_set_reader_error(parser *yaml_parser_t, problem string, offset int, value int) bool {
    31  	parser.error = yaml_READER_ERROR
    32  	parser.problem = problem
    33  	parser.problem_offset = offset
    34  	parser.problem_value = value
    35  	return false
    36  }
    37  
    38  // Byte order marks.
    39  const (
    40  	bom_UTF8    = "\xef\xbb\xbf"
    41  	bom_UTF16LE = "\xff\xfe"
    42  	bom_UTF16BE = "\xfe\xff"
    43  )
    44  
    45  // Determine the input stream encoding by checking the BOM symbol. If no BOM is
    46  // found, the UTF-8 encoding is assumed. Return 1 on success, 0 on failure.
    47  func yaml_parser_determine_encoding(parser *yaml_parser_t) bool {
    48  	// Ensure that we had enough bytes in the raw buffer.
    49  	for !parser.eof && len(parser.raw_buffer)-parser.raw_buffer_pos < 3 {
    50  		if !yaml_parser_update_raw_buffer(parser) {
    51  			return false
    52  		}
    53  	}
    54  
    55  	// Determine the encoding.
    56  	buf := parser.raw_buffer
    57  	pos := parser.raw_buffer_pos
    58  	avail := len(buf) - pos
    59  	if avail >= 2 && buf[pos] == bom_UTF16LE[0] && buf[pos+1] == bom_UTF16LE[1] {
    60  		parser.encoding = yaml_UTF16LE_ENCODING
    61  		parser.raw_buffer_pos += 2
    62  		parser.offset += 2
    63  	} else if avail >= 2 && buf[pos] == bom_UTF16BE[0] && buf[pos+1] == bom_UTF16BE[1] {
    64  		parser.encoding = yaml_UTF16BE_ENCODING
    65  		parser.raw_buffer_pos += 2
    66  		parser.offset += 2
    67  	} else if avail >= 3 && buf[pos] == bom_UTF8[0] && buf[pos+1] == bom_UTF8[1] && buf[pos+2] == bom_UTF8[2] {
    68  		parser.encoding = yaml_UTF8_ENCODING
    69  		parser.raw_buffer_pos += 3
    70  		parser.offset += 3
    71  	} else {
    72  		parser.encoding = yaml_UTF8_ENCODING
    73  	}
    74  	return true
    75  }
    76  
    77  // Update the raw buffer.
    78  func yaml_parser_update_raw_buffer(parser *yaml_parser_t) bool {
    79  	size_read := 0
    80  
    81  	// Return if the raw buffer is full.
    82  	if parser.raw_buffer_pos == 0 && len(parser.raw_buffer) == cap(parser.raw_buffer) {
    83  		return true
    84  	}
    85  
    86  	// Return on EOF.
    87  	if parser.eof {
    88  		return true
    89  	}
    90  
    91  	// Move the remaining bytes in the raw buffer to the beginning.
    92  	if parser.raw_buffer_pos > 0 && parser.raw_buffer_pos < len(parser.raw_buffer) {
    93  		copy(parser.raw_buffer, parser.raw_buffer[parser.raw_buffer_pos:])
    94  	}
    95  	parser.raw_buffer = parser.raw_buffer[:len(parser.raw_buffer)-parser.raw_buffer_pos]
    96  	parser.raw_buffer_pos = 0
    97  
    98  	// Call the read handler to fill the buffer.
    99  	size_read, err := parser.read_handler(parser, parser.raw_buffer[len(parser.raw_buffer):cap(parser.raw_buffer)])
   100  	parser.raw_buffer = parser.raw_buffer[:len(parser.raw_buffer)+size_read]
   101  	if err == io.EOF {
   102  		parser.eof = true
   103  	} else if err != nil {
   104  		return yaml_parser_set_reader_error(parser, "input error: "+err.Error(), parser.offset, -1)
   105  	}
   106  	return true
   107  }
   108  
   109  // Ensure that the buffer contains at least `length` characters.
   110  // Return true on success, false on failure.
   111  //
   112  // The length is supposed to be significantly less that the buffer size.
   113  func yaml_parser_update_buffer(parser *yaml_parser_t, length int) bool {
   114  	if parser.read_handler == nil {
   115  		panic("read handler must be set")
   116  	}
   117  
   118  	// [Go] This function was changed to guarantee the requested length size at EOF.
   119  	// The fact we need to do this is pretty awful, but the description above implies
   120  	// for that to be the case, and there are tests
   121  
   122  	// If the EOF flag is set and the raw buffer is empty, do nothing.
   123  	if parser.eof && parser.raw_buffer_pos == len(parser.raw_buffer) {
   124  		// [Go] ACTUALLY! Read the documentation of this function above.
   125  		// This is just broken. To return true, we need to have the
   126  		// given length in the buffer. Not doing that means every single
   127  		// check that calls this function to make sure the buffer has a
   128  		// given length is Go) panicking; or C) accessing invalid memory.
   129  		//return true
   130  	}
   131  
   132  	// Return if the buffer contains enough characters.
   133  	if parser.unread >= length {
   134  		return true
   135  	}
   136  
   137  	// Determine the input encoding if it is not known yet.
   138  	if parser.encoding == yaml_ANY_ENCODING {
   139  		if !yaml_parser_determine_encoding(parser) {
   140  			return false
   141  		}
   142  	}
   143  
   144  	// Move the unread characters to the beginning of the buffer.
   145  	buffer_len := len(parser.buffer)
   146  	if parser.buffer_pos > 0 && parser.buffer_pos < buffer_len {
   147  		copy(parser.buffer, parser.buffer[parser.buffer_pos:])
   148  		buffer_len -= parser.buffer_pos
   149  		parser.buffer_pos = 0
   150  	} else if parser.buffer_pos == buffer_len {
   151  		buffer_len = 0
   152  		parser.buffer_pos = 0
   153  	}
   154  
   155  	// Open the whole buffer for writing, and cut it before returning.
   156  	parser.buffer = parser.buffer[:cap(parser.buffer)]
   157  
   158  	// Fill the buffer until it has enough characters.
   159  	first := true
   160  	for parser.unread < length {
   161  
   162  		// Fill the raw buffer if necessary.
   163  		if !first || parser.raw_buffer_pos == len(parser.raw_buffer) {
   164  			if !yaml_parser_update_raw_buffer(parser) {
   165  				parser.buffer = parser.buffer[:buffer_len]
   166  				return false
   167  			}
   168  		}
   169  		first = false
   170  
   171  		// Decode the raw buffer.
   172  	inner:
   173  		for parser.raw_buffer_pos != len(parser.raw_buffer) {
   174  			var value rune
   175  			var width int
   176  
   177  			raw_unread := len(parser.raw_buffer) - parser.raw_buffer_pos
   178  
   179  			// Decode the next character.
   180  			switch parser.encoding {
   181  			case yaml_UTF8_ENCODING:
   182  				// Decode a UTF-8 character.  Check RFC 3629
   183  				// (http://www.ietf.org/rfc/rfc3629.txt) for more details.
   184  				//
   185  				// The following table (taken from the RFC) is used for
   186  				// decoding.
   187  				//
   188  				//    Char. number range |        UTF-8 octet sequence
   189  				//      (hexadecimal)    |              (binary)
   190  				//   --------------------+------------------------------------
   191  				//   0000 0000-0000 007F | 0xxxxxxx
   192  				//   0000 0080-0000 07FF | 110xxxxx 10xxxxxx
   193  				//   0000 0800-0000 FFFF | 1110xxxx 10xxxxxx 10xxxxxx
   194  				//   0001 0000-0010 FFFF | 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
   195  				//
   196  				// Additionally, the characters in the range 0xD800-0xDFFF
   197  				// are prohibited as they are reserved for use with UTF-16
   198  				// surrogate pairs.
   199  
   200  				// Determine the length of the UTF-8 sequence.
   201  				octet := parser.raw_buffer[parser.raw_buffer_pos]
   202  				switch {
   203  				case octet&0x80 == 0x00:
   204  					width = 1
   205  				case octet&0xE0 == 0xC0:
   206  					width = 2
   207  				case octet&0xF0 == 0xE0:
   208  					width = 3
   209  				case octet&0xF8 == 0xF0:
   210  					width = 4
   211  				default:
   212  					// The leading octet is invalid.
   213  					return yaml_parser_set_reader_error(parser,
   214  						"invalid leading UTF-8 octet",
   215  						parser.offset, int(octet))
   216  				}
   217  
   218  				// Check if the raw buffer contains an incomplete character.
   219  				if width > raw_unread {
   220  					if parser.eof {
   221  						return yaml_parser_set_reader_error(parser,
   222  							"incomplete UTF-8 octet sequence",
   223  							parser.offset, -1)
   224  					}
   225  					break inner
   226  				}
   227  
   228  				// Decode the leading octet.
   229  				switch {
   230  				case octet&0x80 == 0x00:
   231  					value = rune(octet & 0x7F)
   232  				case octet&0xE0 == 0xC0:
   233  					value = rune(octet & 0x1F)
   234  				case octet&0xF0 == 0xE0:
   235  					value = rune(octet & 0x0F)
   236  				case octet&0xF8 == 0xF0:
   237  					value = rune(octet & 0x07)
   238  				default:
   239  					value = 0
   240  				}
   241  
   242  				// Check and decode the trailing octets.
   243  				for k := 1; k < width; k++ {
   244  					octet = parser.raw_buffer[parser.raw_buffer_pos+k]
   245  
   246  					// Check if the octet is valid.
   247  					if (octet & 0xC0) != 0x80 {
   248  						return yaml_parser_set_reader_error(parser,
   249  							"invalid trailing UTF-8 octet",
   250  							parser.offset+k, int(octet))
   251  					}
   252  
   253  					// Decode the octet.
   254  					value = (value << 6) + rune(octet&0x3F)
   255  				}
   256  
   257  				// Check the length of the sequence against the value.
   258  				switch {
   259  				case width == 1:
   260  				case width == 2 && value >= 0x80:
   261  				case width == 3 && value >= 0x800:
   262  				case width == 4 && value >= 0x10000:
   263  				default:
   264  					return yaml_parser_set_reader_error(parser,
   265  						"invalid length of a UTF-8 sequence",
   266  						parser.offset, -1)
   267  				}
   268  
   269  				// Check the range of the value.
   270  				if value >= 0xD800 && value <= 0xDFFF || value > 0x10FFFF {
   271  					return yaml_parser_set_reader_error(parser,
   272  						"invalid Unicode character",
   273  						parser.offset, int(value))
   274  				}
   275  
   276  			case yaml_UTF16LE_ENCODING, yaml_UTF16BE_ENCODING:
   277  				var low, high int
   278  				if parser.encoding == yaml_UTF16LE_ENCODING {
   279  					low, high = 0, 1
   280  				} else {
   281  					low, high = 1, 0
   282  				}
   283  
   284  				// The UTF-16 encoding is not as simple as one might
   285  				// naively think.  Check RFC 2781
   286  				// (http://www.ietf.org/rfc/rfc2781.txt).
   287  				//
   288  				// Normally, two subsequent bytes describe a Unicode
   289  				// character.  However a special technique (called a
   290  				// surrogate pair) is used for specifying character
   291  				// values larger than 0xFFFF.
   292  				//
   293  				// A surrogate pair consists of two pseudo-characters:
   294  				//      high surrogate area (0xD800-0xDBFF)
   295  				//      low surrogate area (0xDC00-0xDFFF)
   296  				//
   297  				// The following formulas are used for decoding
   298  				// and encoding characters using surrogate pairs:
   299  				//
   300  				//  U  = U' + 0x10000   (0x01 00 00 <= U <= 0x10 FF FF)
   301  				//  U' = yyyyyyyyyyxxxxxxxxxx   (0 <= U' <= 0x0F FF FF)
   302  				//  W1 = 110110yyyyyyyyyy
   303  				//  W2 = 110111xxxxxxxxxx
   304  				//
   305  				// where U is the character value, W1 is the high surrogate
   306  				// area, W2 is the low surrogate area.
   307  
   308  				// Check for incomplete UTF-16 character.
   309  				if raw_unread < 2 {
   310  					if parser.eof {
   311  						return yaml_parser_set_reader_error(parser,
   312  							"incomplete UTF-16 character",
   313  							parser.offset, -1)
   314  					}
   315  					break inner
   316  				}
   317  
   318  				// Get the character.
   319  				value = rune(parser.raw_buffer[parser.raw_buffer_pos+low]) +
   320  					(rune(parser.raw_buffer[parser.raw_buffer_pos+high]) << 8)
   321  
   322  				// Check for unexpected low surrogate area.
   323  				if value&0xFC00 == 0xDC00 {
   324  					return yaml_parser_set_reader_error(parser,
   325  						"unexpected low surrogate area",
   326  						parser.offset, int(value))
   327  				}
   328  
   329  				// Check for a high surrogate area.
   330  				if value&0xFC00 == 0xD800 {
   331  					width = 4
   332  
   333  					// Check for incomplete surrogate pair.
   334  					if raw_unread < 4 {
   335  						if parser.eof {
   336  							return yaml_parser_set_reader_error(parser,
   337  								"incomplete UTF-16 surrogate pair",
   338  								parser.offset, -1)
   339  						}
   340  						break inner
   341  					}
   342  
   343  					// Get the next character.
   344  					value2 := rune(parser.raw_buffer[parser.raw_buffer_pos+low+2]) +
   345  						(rune(parser.raw_buffer[parser.raw_buffer_pos+high+2]) << 8)
   346  
   347  					// Check for a low surrogate area.
   348  					if value2&0xFC00 != 0xDC00 {
   349  						return yaml_parser_set_reader_error(parser,
   350  							"expected low surrogate area",
   351  							parser.offset+2, int(value2))
   352  					}
   353  
   354  					// Generate the value of the surrogate pair.
   355  					value = 0x10000 + ((value & 0x3FF) << 10) + (value2 & 0x3FF)
   356  				} else {
   357  					width = 2
   358  				}
   359  
   360  			default:
   361  				panic("impossible")
   362  			}
   363  
   364  			// Check if the character is in the allowed range:
   365  			//      #x9 | #xA | #xD | [#x20-#x7E]               (8 bit)
   366  			//      | #x85 | [#xA0-#xD7FF] | [#xE000-#xFFFD]    (16 bit)
   367  			//      | [#x10000-#x10FFFF]                        (32 bit)
   368  			switch {
   369  			case value == 0x09:
   370  			case value == 0x0A:
   371  			case value == 0x0D:
   372  			case value >= 0x20 && value <= 0x7E:
   373  			case value == 0x85:
   374  			case value >= 0xA0 && value <= 0xD7FF:
   375  			case value >= 0xE000 && value <= 0xFFFD:
   376  			case value >= 0x10000 && value <= 0x10FFFF:
   377  			default:
   378  				return yaml_parser_set_reader_error(parser,
   379  					"control characters are not allowed",
   380  					parser.offset, int(value))
   381  			}
   382  
   383  			// Move the raw pointers.
   384  			parser.raw_buffer_pos += width
   385  			parser.offset += width
   386  
   387  			// Finally put the character into the buffer.
   388  			if value <= 0x7F {
   389  				// 0000 0000-0000 007F . 0xxxxxxx
   390  				parser.buffer[buffer_len+0] = byte(value)
   391  				buffer_len += 1
   392  			} else if value <= 0x7FF {
   393  				// 0000 0080-0000 07FF . 110xxxxx 10xxxxxx
   394  				parser.buffer[buffer_len+0] = byte(0xC0 + (value >> 6))
   395  				parser.buffer[buffer_len+1] = byte(0x80 + (value & 0x3F))
   396  				buffer_len += 2
   397  			} else if value <= 0xFFFF {
   398  				// 0000 0800-0000 FFFF . 1110xxxx 10xxxxxx 10xxxxxx
   399  				parser.buffer[buffer_len+0] = byte(0xE0 + (value >> 12))
   400  				parser.buffer[buffer_len+1] = byte(0x80 + ((value >> 6) & 0x3F))
   401  				parser.buffer[buffer_len+2] = byte(0x80 + (value & 0x3F))
   402  				buffer_len += 3
   403  			} else {
   404  				// 0001 0000-0010 FFFF . 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
   405  				parser.buffer[buffer_len+0] = byte(0xF0 + (value >> 18))
   406  				parser.buffer[buffer_len+1] = byte(0x80 + ((value >> 12) & 0x3F))
   407  				parser.buffer[buffer_len+2] = byte(0x80 + ((value >> 6) & 0x3F))
   408  				parser.buffer[buffer_len+3] = byte(0x80 + (value & 0x3F))
   409  				buffer_len += 4
   410  			}
   411  
   412  			parser.unread++
   413  		}
   414  
   415  		// On EOF, put NUL into the buffer and return.
   416  		if parser.eof {
   417  			parser.buffer[buffer_len] = 0
   418  			buffer_len++
   419  			parser.unread++
   420  			break
   421  		}
   422  	}
   423  	// [Go] Read the documentation of this function above. To return true,
   424  	// we need to have the given length in the buffer. Not doing that means
   425  	// every single check that calls this function to make sure the buffer
   426  	// has a given length is Go) panicking; or C) accessing invalid memory.
   427  	// This happens here due to the EOF above breaking early.
   428  	for buffer_len < length {
   429  		parser.buffer[buffer_len] = 0
   430  		buffer_len++
   431  	}
   432  	parser.buffer = parser.buffer[:buffer_len]
   433  	return true
   434  }
   435
View as plain text