I am running apache in a chroot() and figured out yesterday that it breaks the uid checks in safe mode.

From what i understood, php *emulates* setuid scripts by checking ownership of a file before accessing it from another. This could theoritically be done by calling stat() on the file and checking the st_uid field but for some reason, it appears that if the user database is not in the chroot, php will fail the checks, to be more precise, the check will always appear to be valid (i suspect this from being the result of a comparison between two error values).

This means that:
<?
  include('someonesfile');  // will succeed

  echo getmyuid();          // the uid of owner of file
                            // not from apache's child
?>

since getmyuid() shows me the uid of owner of file, then it proves me that uid of owner of file is successfully detected (stat() ?) and since include() succeeds (unless i start copying all the user and group files in chroot) despite the fact that the owner of 'someonesfile' is not equal to value of getmyuid(), it makes me think that a getpw*() function call is being used for some reason that I couldnt figure out yet.

I didnt get a chance yet to look deep inside the source code since im ill, so the reasons of why this happens are plain suppositions but the problems occurs. Im sorry if I am not clear, mail me and I try explain in a more clear way. I will try to get some free time this week to figure this out since its quite annoying but maybe a developper could explain brievely how the checks are done ?