In article <[EMAIL PROTECTED]>,
Tony Finch <[EMAIL PROTECTED]> wrote:
> John Polstra <[EMAIL PROTECTED]> wrote:
> >The right way to do it on FreeBSD is like this:
> > gcc -fpic -c *.c
> > gcc -shared -o libshim.so *.o
>
> That works fine, thanks! Any idea why my clumsy success worked and why
> my clumsy failures didn't?
Nah, I didn't pay that much attention to what you did. I just
noticed that it wasn't right. :-)
The "gcc -fpic" makes the object code position-independent. I am not
sure, but probably you would also benefit (performance-wise) by using
that on Solaris.
The "gcc -shared" turns it into a shared library instead of a normal
object file. In the process it also links in some extra little .o
files which are necessary to hold it all together. You can use "gcc
-v" to get the gory details.
> >The names "_init" and "_fini" are "reserved for the implementation"
> >in ANSI/ISO-speak. You shouldn't use them.
>
> I don't have any choice on Solaris, unfortunately (and my code has to
> be portable between FreeBSD and Solaris). I suppose in that case
> Solaris is the implementation and they have reserved it for my use. I
> gather from the linker errors that FreeBSD has reserved the names for
> a different use?
The machinery that supports C++ constructors uses them.
> >Or, write it in C++ and use a global constructor.
>
> No. Never. No way. NO. :-)
I didn't mean write everything in C++ -- just the
initialization hook. It's not that bad. There's an example in
"src/lib/libc_r/uthread/uthread_autoinit.cc".
The advantage of using C++ for this is that you're using a portable
mechanism instead of a gcc extension.
> >> I also note a user-interface incompatibility between FreeBSD's
> >> implementation of LD_PRELOAD and Solaris's: on Solaris the filenames
> >> listed in LD_PRELOAD are space-separated, but on FreeBSD they are
> >> colon or semicolon separated.
> >
> >That could be a bug. You're probably the first person on earth to
> >have more than one library in LD_PRELOAD. :-) What does Linux do?
>
> According to the documentation I looked at it uses arbitrary
> whitespace as the separator. I haven't looked at the code to check.
I took a look. They accept white space or colons. I'll change ours
to be similarly tolerant. The semicolons are a vestige from SVR4.0,
and should probably be ditched.
John
--
John Polstra [EMAIL PROTECTED]
John D. Polstra & Co., Inc. Seattle, Washington USA
"Disappointment is a good sign of basic intelligence." -- Chögyam Trungpa
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