I'm not sure exactly what platform limitations you're running into, since I don't have a FreeBSD box, but I seem to recall people using something like this to only use setreuid and the like: 

  ($GID,$EGID)=($g,$g);
  ($UID,$EUID)=($u,$u);

[download]

Might be worth a try.

In reply to Re: Problem switching UID + GID under FreeBSD by sgifford
in thread Problem switching UID + GID under FreeBSD by skx

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