On Tue, 2008-06-10 at 12:17 -0500, Sean C. Farley wrote: > >> I suggest reading the two paragraphs from Open Group's getenv()[1] > >> documentation starting at "Conforming applications are required not > >> to modify environ directly, ..." for the rationale in the new design. > >> Obviously, applications are not required to conform, but the > >> documentation talks about what an OS may be doing under the covers to > >> environ. > > > > How about implementing clearenv()? I'm using it now if it's available. > > It is a thought. It is not part of SUSv3, but there are many API calls > in our libc that are not part of that spec. > > Interestingly, clearenv() on Linux ends up setting environ=NULL. Also, > from the Linux man page: > > The DG/UX and Tru64 manpages write: If environ has been modified by > anything other than the putenv(), getenv(), or clearenv() functions, > then clearenv() will return an error and the process environment > will remain unchanged. > > Hopefully, no libraries on these systems are manipulating environ else > clearenv() will not work.
I don't think there's any other reason to do it than clearing it. > > BTW. I wonder if this change breaks any applications where not > > clearing environment could result in a security hole. As far as I know > > FreeBSD 7.0 is the only modern OS where environ[0]=NULL doesn't work. > > OpenSolaris also does not detect environ[0]=NULL. Haiku[1], like MacOS, > does not handle environ=NULL. *sigh* To support the most OS's I > recommend the environ replacement such as in the static environ above. Oh. I don't have OpenSolaris installed, but I would have thought that since it worked in Solaris 10 it would have worked in OpenSolaris too. > No guarantees, but I will do some research about detecting a NULL at > environ[0] as another means of clearing the environment and/or writing > an implementation of clearenv(). Of course, you will still have > problems on OpenSolaris. What are you planning to do there, or does it > support cleanenv()? I've changed my code now to do: > environ = calloc(1, sizeof(*environ)); should work on all assuming NULL > was not returned. Hopefully that'll work for a few years. (I also use clearenv() if detected by configure.) > Does anyone know why clearenv() was rejected? There is hardly a peep > on > the OpenGroup web site. No idea, but I don't really understand why it returns int instead of void. It shouldn't do more than free memory.
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