Re: PHP 8.4

On 18/12/2024 19:25, JEFFRY KILLEN wrote:

So, what I get from this is that what is troublesome is the possibility of an endless loop? When I wrote my recursive file system walking function every time it enters a directory it bypasses . (self) and .. (parent dir) listings via a switch statement... Note: the use of $_ in every variable name is my own practice. It helps me visually to spot variable references in code. $_list = scandir($_targetDir); for( $_i = 0; $_i < count($_list); $_i++)    {

     switch($_list[$_i])
         {
          case '.':
          case '..':
          // add other case labels representing file names that should be bypassed
          break;
          default:
          // process every other item in the list
          // recursion comes when a directory is encountered and the loop enters and begins the next level.
          // the looping ends when the end of a directory listing is reached and all of the included directories have been processed
          // it pops back to a higher level and continues there. Eventually the whole file tree has been processed.
          break;
         }

  } Note: It's unclear to me if you've actually encountered this problem with your code, or you're trying to work out when it might occur.

From a quick grep of the PHP source code[0], I believe the "Nesting level too deep" error does not refer to recursive function calls in the manner described above (which would likely result in either a SEGFAULT or an error referencing zend.max_allowed_stack_size such as in [1]). It specifically occurs when comparing arrays or objects in a manner that would result in an infinite loop due to self-references. See the .phpt results in the linked search for examples. If you're encountering the "Nesting level too deep" error, something else is going on in your code other than a straight-forward recursive function call. If objects aren't involved (where properties may directly or indirectly self-reference the object), explicit references  (eg. &$var) almost certainly are. Aside: When dealing with (Linux) filesystems, it may be possible to encounter infinite loops even when ignoring the . and .. special entries if symlinks are involved. If you're sure symlinks aren't involved (and specifically a symlink crafted to refer back to a parent directory), you'll likely never encounter this issue. The other solution is to limit the search depth - eg. never search more than 5 directory levels deep. (This situation would result in a stack overflow / stack size limit being reached as mentioned above, and not "Nesting level too deep") [0] https://github.com/search?q=repo%3Aphp%2Fphp-src+%22Nesting+level+too+deep%22&type=code [1] https://github.com/php/php-src/blob/master/Zend/tests/stack_limit/gh16041_002.phpt