之前一直没问题的，系统从freebsd 6.0升级到6.2后，wForum下的头像就上传不了了，提示文件名有问题。经过一段穷举法的翻查，发现在
"dopostface.php"的第46行
$act_attachname=substr($act_attachname,-60);
//这句大概是指只取名字的后60个字符吧
执行过后
$act_attachname就会变成null了.
翻了下php手册，手册上说
string substr ( string $string, int $start [, int $length] )
substr() returns the portion of string specified by the start and length parameters.
If start is non-negative, the returned string will start at the start'th position in string, counting from zero. For instance, in the string 'abcdef', the character at position 0 is 'a', the character at position 2 is 'c', and so forth.
例 2290. Basic substr() usage
<?php
echo substr('abcdef', 1); // bcdef
echo substr('abcdef', 1, 3); // bcd
echo substr('abcdef', 0, 4); // abcd
echo substr('abcdef', 0, 8); // abcdef
echo substr('abcdef', -1, 1); // f
// Accessing single characters in a string
// can also be achived using "curly braces"
$string = 'abcdef';
echo $string{0}; // a
echo $string{3}; // d
echo $string{strlen($string)-1}; // f
?>
If start is negative, the returned string will start at the start'th character from the end of string.
例 2291. Using a negative start
<?php
$rest = substr("abcdef", -1); // returns "f"
$rest = substr("abcdef", -2); // returns "ef"
$rest = substr("abcdef", -3, 1); // returns "d"
?>
If length is given and is positive, the string returned will contain at most length characters beginning from start (depending on the length of string). If string is less than or equal to start characters long, FALSE will be returned.
If length is given and is negative, then that many characters will be omitted from the end of string (after the start position has been calculated when a start is negative). If start denotes a position beyond this truncation, an empty string will be returned.
例 2292. Using a negative length
<?php
$rest = substr("abcdef", 0, -1); // returns "abcde"
$rest = substr("abcdef", 2, -1); // returns "cde"
$rest = substr("abcdef", 4, -4); // returns ""
$rest = substr("abcdef", -3, -1); // returns "de"
?>
实在没看出问题所在,是不是字符串长度没有指定开始位置长的时候就会变成null呢？
然后我试了下把-60改成-5,再上传一个名字叫54.gif
经过substr后就变成4.gif
把-5改成-10后，丫又变成null了。
所以我加多个判断条件，长度大于60再给它substr
为什么要60，而不是59，或者61呢？
这个可能得问问acore了。。。
--
修改:PowerRC FROM 58.60.63.*
FROM 58.60.63.*