Re: UID width

Theodore Y. Ts'o (tytso@mit.edu)
Thu, 14 Jan 1999 23:02:23 -0500 (EST)


From: smurf@noris.de (Matthias Urlichs)
Date: 15 Jan 1999 00:23:19 +0100

Note that this includes all the _IO_* functions because the layout of
FILE has changed. This in fact demonstrates the one major problem with
symbol versioning -- suppose we have a glibc-2.1 program which passes
a FILE* to a shared library which was compiled with glibc 2.0...

There's an obvious solution to this problem, given that FILE *'s are
allocated by the library and the internal structure is completely opaque
to the calling application --- put a magic/version number at a standard
location in the structure, so you can distinguish old FILE*'s from New
*'s.

Actually --- given that FILE *'s are supposed to be a black-box
abstraction --- why did you have to version the interfaces just because
the layout of FILE * is changed?

- Ted

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