我想用引号替换无效的UTF-8字符(PHP 5.3.5)。
到目前为止，我有这个解决方案，但无效字符被删除，而不是用'?'代替。
function replace_invalid_utf8($str)
{
return mb_convert_encoding($str, 'UTF-8', 'UTF-8');
}
echo mb_substitute_character()."'n";
echo replace_invalid_utf8('éééaaaàààeeé')."'n";
echo replace_invalid_utf8('eeeaaaaaaeeé')."'n";
应该输出:
63 // ASCII code for '?' character
???aaa???eé // or ??aa??eé
eeeaaaaaaeeé
但当前输出:
63
aaaee // removed invalid characters
eeeaaaaaaeeé
任何建议吗?
你会用另一种方式(例如使用preg_replace()吗?)
谢谢。
从PHP 5.4开始，可以使用mb_convert_encoding()或htmlspecialchars()'s ENT_SUBSTITUTE选项。当然，您也可以使用preg_match()。如果你使用intl，从PHP 5.5开始，你可以使用UConverter。
建议用U+FFFD代替无效字节序列。参见3.1.2替换病态子序列;在utr# 36: Unicode安全注意事项的细节。
当使用mb_convert_encoding()时，可以通过将Unicode code point传递给mb_substitute_character()或mbstring来指定替换字符。substitute_character 指令。替换的默认字符是?(问号- U+003F).
// REPLACEMENT CHARACTER (U+FFFD)
mb_substitute_character(0xFFFD);
function replace_invalid_byte_sequence($str)
{
return mb_convert_encoding($str, 'UTF-8', 'UTF-8');
}
function replace_invalid_byte_sequence2($str)
{
return htmlspecialchars_decode(htmlspecialchars($str, ENT_SUBSTITUTE, 'UTF-8'));
}
UConverter提供了过程和面向对象的API。
function replace_invalid_byte_sequence3($str)
{
return UConverter::transcode($str, 'UTF-8', 'UTF-8');
}
function replace_invalid_byte_sequence4($str)
{
return (new UConverter('UTF-8', 'UTF-8'))->convert($str);
}
在使用preg_match()时，需要注意字节范围，避免UTF-8非最短形式的漏洞。尾字节的范围取决于前导字节的范围。
lead byte: 0x00 - 0x7F, 0xC2 - 0xF4
trail byte: 0x80(or 0x90 or 0xA0) - 0xBF(or 0x8F)
您可以参考以下资源来检查字节范围。
- UTF-8字节序列的语法"在RFC 3629
- "表3 - 7。格式良好的UTF-8字节序列;Unicode Standard 6.1
- 多语言格式编码;在W3C国际化
字节范围表如下:
Code Points First Byte Second Byte Third Byte Fourth Byte
U+0000 - U+007F 00 - 7F
U+0080 - U+07FF C2 - DF 80 - BF
U+0800 - U+0FFF E0 A0 - BF 80 - BF
U+1000 - U+CFFF E1 - EC 80 - BF 80 - BF
U+D000 - U+D7FF ED 80 - 9F 80 - BF
U+E000 - U+FFFF EE - EF 80 - BF 80 - BF
U+10000 - U+3FFFF F0 90 - BF 80 - BF 80 - BF
U+40000 - U+FFFFF F1 - F3 80 - BF 80 - BF 80 - BF
U+100000 - U+10FFFF F4 80 - 8F 80 - BF 80 - BF
如何在不破坏有效字符的情况下替换无效的字节序列，请参见3.1.1不良子序列"在utr# 36: Unicode安全考虑和表3-8中。U+FFFD在UTF-8转换中的应用
Unicode标准给出了一个例子:
before: <61 F1 80 80 E1 80 C2 62 80 63 80 BF 64 >
after: <0061 FFFD FFFD FFFD 0062 FFFD 0063 FFFD FFFD 0064>
下面是preg_replace_callback()根据上述规则的实现。
function replace_invalid_byte_sequence5($str)
{
// REPLACEMENT CHARACTER (U+FFFD)
$substitute = "'xEF'xBF'xBD";
$regex = '/
(['x00-'x7F] # U+0000 - U+007F
|['xC2-'xDF]['x80-'xBF] # U+0080 - U+07FF
| 'xE0['xA0-'xBF]['x80-'xBF] # U+0800 - U+0FFF
|['xE1-'xEC'xEE'xEF]['x80-'xBF]{2} # U+1000 - U+CFFF
| 'xED['x80-'x9F]['x80-'xBF] # U+D000 - U+D7FF
| 'xF0['x90-'xBF]['x80-'xBF]{2} # U+10000 - U+3FFFF
|['xF1-'xF3]['x80-'xBF]{3} # U+40000 - U+FFFFF
| 'xF4['x80-'x8F]['x80-'xBF]{2}) # U+100000 - U+10FFFF
|('xE0['xA0-'xBF] # U+0800 - U+0FFF (invalid)
|['xE1-'xEC'xEE'xEF]['x80-'xBF] # U+1000 - U+CFFF (invalid)
| 'xED['x80-'x9F] # U+D000 - U+D7FF (invalid)
| 'xF0['x90-'xBF]['x80-'xBF]? # U+10000 - U+3FFFF (invalid)
|['xF1-'xF3]['x80-'xBF]{1,2} # U+40000 - U+FFFFF (invalid)
| 'xF4['x80-'x8F]['x80-'xBF]?) # U+100000 - U+10FFFF (invalid)
|(.) # invalid 1-byte
/xs';
// $matches[1]: valid character
// $matches[2]: invalid 3-byte or 4-byte character
// $matches[3]: invalid 1-byte
$ret = preg_replace_callback($regex, function($matches) use($substitute) {
if (isset($matches[2]) || isset($matches[3])) {
return $substitute;
}
return $matches[1];
}, $str);
return $ret;
}
可以直接比较字节，避免preg_match对字节大小的限制。
function replace_invalid_byte_sequence6($str) {
$size = strlen($str);
$substitute = "'xEF'xBF'xBD";
$ret = '';
$pos = 0;
$char;
$char_size;
$valid;
while (utf8_get_next_char($str, $size, $pos, $char, $char_size, $valid)) {
$ret .= $valid ? $char : $substitute;
}
return $ret;
}
function utf8_get_next_char($str, $str_size, &$pos, &$char, &$char_size, &$valid)
{
$valid = false;
if ($str_size <= $pos) {
return false;
}
if ($str[$pos] < "'x80") {
$valid = true;
$char_size = 1;
} else if ($str[$pos] < "'xC2") {
$char_size = 1;
} else if ($str[$pos] < "'xE0") {
if (!isset($str[$pos+1]) || $str[$pos+1] < "'x80" || "'xBF" < $str[$pos+1]) {
$char_size = 1;
} else {
$valid = true;
$char_size = 2;
}
} else if ($str[$pos] < "'xF0") {
$left = "'xE0" === $str[$pos] ? "'xA0" : "'x80";
$right = "'xED" === $str[$pos] ? "'x9F" : "'xBF";
if (!isset($str[$pos+1]) || $str[$pos+1] < $left || $right < $str[$pos+1]) {
$char_size = 1;
} else if (!isset($str[$pos+2]) || $str[$pos+2] < "'x80" || "'xBF" < $str[$pos+2]) {
$char_size = 2;
} else {
$valid = true;
$char_size = 3;
}
} else if ($str[$pos] < "'xF5") {
$left = "'xF0" === $str[$pos] ? "'x90" : "'x80";
$right = "'xF4" === $str[$pos] ? "'x8F" : "'xBF";
if (!isset($str[$pos+1]) || $str[$pos+1] < $left || $right < $str[$pos+1]) {
$char_size = 1;
} else if (!isset($str[$pos+2]) || $str[$pos+2] < "'x80" || "'xBF" < $str[$pos+2]) {
$char_size = 2;
} else if (!isset($str[$pos+3]) || $str[$pos+3] < "'x80" || "'xBF" < $str[$pos+3]) {
$char_size = 3;
} else {
$valid = true;
$char_size = 4;
}
} else {
$char_size = 1;
}
$char = substr($str, $pos, $char_size);
$pos += $char_size;
return true;
}
测试用例在这里。
function run(array $callables, array $arguments)
{
return array_map(function($callable) use($arguments) {
return array_map($callable, $arguments);
}, $callables);
}
$data = [
// Table 3-8. Use of U+FFFD in UTF-8 Conversion
// http://www.unicode.org/versions/Unicode6.1.0/ch03.pdf)
"'x61"."'xF1'x80'x80"."'xE1'x80"."'xC2"."'x62"."'x80"."'x63"
."'x80"."'xBF"."'x64",
// 'FULL MOON SYMBOL' (U+1F315) and invalid byte sequence
"'xF0'x9F'x8C'x95"."'xF0'x9F'x8C"."'xF0'x9F'x8C"
];
var_dump(run([
'replace_invalid_byte_sequence',
'replace_invalid_byte_sequence2',
'replace_invalid_byte_sequence3',
'replace_invalid_byte_sequence4',
'replace_invalid_byte_sequence5',
'replace_invalid_byte_sequence6'
], $data));
$data = [
// U+20AC
"'xE2'x82'xAC"."'xE2'x82'xAC"."'xE2'x82'xAC",
"'xE2'x82" ."'xE2'x82'xAC"."'xE2'x82'xAC",
// U+24B62
"'xF0'xA4'xAD'xA2"."'xF0'xA4'xAD'xA2"."'xF0'xA4'xAD'xA2",
"'xF0'xA4'xAD" ."'xF0'xA4'xAD'xA2"."'xF0'xA4'xAD'xA2",
"'xA4'xAD'xA2"."'xF0'xA4'xAD'xA2"."'xF0'xA4'xAD'xA2",
// 'FULL MOON SYMBOL' (U+1F315)
"'xF0'x9F'x8C'x95" . "'xF0'x9F'x8C",
"'xF0'x9F'x8C'x95" . "'xF0'x9F'x8C" . "'xF0'x9F'x8C"
];
虽然preg_match()可以代替preg_replace_callback，但是这个函数对字节大小有限制。请参阅bug报告#36463了解详细信息。您可以通过以下测试用例进行确认。
str_repeat('a', 10000)
最后，我的基准测试结果如下:
mb_convert_encoding()
0.19628190994263
htmlspecialchars()
0.082863092422485
UConverter::transcode()
0.15999984741211
UConverter::convert()
0.29843020439148
preg_replace_callback()
0.63967490196228
direct comparision
0.71933102607727
基准代码在这里。
function timer(array $callables, array $arguments, $repeat = 10000)
{
$ret = [];
$save = $repeat;
foreach ($callables as $key => $callable) {
$start = microtime(true);
do {
array_map($callable, $arguments);
} while($repeat -= 1);
$stop = microtime(true);
$ret[$key] = $stop - $start;
$repeat = $save;
}
return $ret;
}
$functions = [
'mb_convert_encoding()' => 'replace_invalid_byte_sequence',
'htmlspecialchars()' => 'replace_invalid_byte_sequence2',
'UConverter::transcode()' => 'replace_invalid_byte_sequence3',
'UConverter::convert()' => 'replace_invalid_byte_sequence4',
'preg_replace_callback()' => 'replace_invalid_byte_sequence5',
'direct comparision' => 'replace_invalid_byte_sequence6'
];
foreach (timer($functions, $data) as $description => $time) {
echo $description, PHP_EOL,
$time, PHP_EOL;
}