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From: ka@felix.UUCP (Kenneth Almquist)
Newsgroups: comp.unix.internals
Subject: Re: Shared Lib Question (ISC)
Message-ID: <162950@felix.UUCP>
Date: 18 May 91 01:33:46 GMT
References: <276@rwing.UUCP> <162@titccy.cc.titech.ac.jp> <19252@rpp386.cactus.org> <kre.673798776@mundamutti.cs.mu.OZ.AU> <19255@rpp386.cactus.org>
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jfh@rpp386.cactus.org (John F Haugh II) writes:
>>>Were the code in the C library pure, shared libraries would
>>>be extremely simple to implement.

and later challenges:
> Name a single library function which cannot be implemented well
> without global variables.  Justify your answer.

How about:

1)  getpwent and relatives -- needs global variables to hold the current
    state and the returned passwd structure.  (Placing these in a structure
    which is passed to getpwent would complicate the calling program,
    especially if the passwd file is examined in several places.)

2)  malloc/realloc/free -- requires a global data structure to keep track
    of which areas of memory are free.

3)  stdio/exit -- needs a global variable so that exit can locate and close
    all open files.
					Kenneth Almquist