Description:
------------
any function whose definition is started with `FileFunction(PHP_FN` in `ext/standard/filestat.c` will call the system call ,stat , in linux , which will finally return false  when recieving a path with more than 20 symbolic links 

the affected functions are as follows:
fileperms、fileinode、filesize、fileowner、filegroup、fileatime、filemtime、filectime、filetype、is_writable、is_readable、is_executable、is_file、is_dir、is_link、file_exists ........

you can read `ext/standard/filestat.c` to find more

Test script:
---------------
<?php 
$f = "/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/etc/passwd";
var_dump(file_exists($f));
readfile($f);

?>
file exists but `file_exists($f)` return false , is_writable、is_readable、is_executable、is_file、is_dir、is_link、file_exists ...... will return false as well

Expected result:
----------------
bool(true)
the content of /etc/passwd

Actual result:
--------------
bool(false)
the content of /etc/passwd