Writing Shared Libraries, first draft

[Stuart Anderson]

On Fri, 5 Nov 2004, Mike Hearn wrote:

> This sort of thing actually explains quite a few of the "linux binary
> portability is black magic" type posts you see on the net. An error like:
>
> foo: undefined reference to __ctype_b_loc at GLIBC_2.3
>
> when you never heard of that function can be quite mysterious. The problem
> is you used one of the ctype functions like isupper() and that was
> rewritten by a macro behind your back.

This involves more than just the header file stuff. In this case, both
the name and version of the underlying symbol changed. We've seen lots
of symbols change version without any other signature change, which is
just as fatal ABI-wise, but have nothing to do with the headers at all.

The whole concept of mangling symol in the headers has been a major pain
for years.

                                Stuart

Stuart R. Anderson                               anderson at netsweng.com
Network & Software Engineering                   http://www.netsweng.com/
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