(PHP 8 >= 8.3.0)
posix_fpathconf — Returns the value of a configurable limit
   Returns the value of a configurable limit from name
   for file_descriptor.
  
file_descriptorThe file descriptor, which is expected to be either a file resource or an int. An int will be assumed to be a file descriptor that can be passed directly to the underlying system call.
name
       The name of the configurable limit, one of the following.
       POSIX_PC_LINK_MAX, POSIX_PC_MAX_CANON,
       POSIX_PC_MAX_INPUT, POSIX_PC_NAME_MAX,
       POSIX_PC_PATH_MAX, POSIX_PC_PIPE_BUF,
       POSIX_PC_CHOWN_RESTRICTED, POSIX_PC_NO_TRUNC,
       POSIX_PC_ALLOC_SIZE_MIN, POSIX_PC_SYMLINK_MAX.
      
   Returns the configurable limit or false.
  
   Throws a ValueError
   when resource is invalid.
  
示例 #1 posix_fpathconf() example
This example will get the max path name's length in bytes for the current dir.
<?php
$fd = fopen(__DIR__, "r");
echo posix_fpathconf($fd, POSIX_PC_PATH_MAX);
?>以上示例会输出:
4096
