On Sun, Jun 20, 2004 at 08:50:24PM -0700, Rob Hudson wrote:
> I discovered elmo, not the cartoon character, but the mail client:
> http://elmo.sourceforge.net/ I thought it might make a nice replacement to
> mutt, which I've been using on my server for years.
>
> I wanted to try it on my FreeBSD server but it dies on the linking stage
> saying:
> /usr/local/src/elmo-1.2.0/src/str.c(.text+0x28d): undefined reference to `va_copy'
>
> Do you know what va_copy does? Is it part of C?
va_copy is C99. If your libc provides C99 compliance (gcc 3.3 would do
it) then you have it with the right thing enabled.
va_copy
An obvious implementation would have a va_list a pointer to the
stack frame of the variadic function. In such a setup (by far the
most common) there seems nothing against an assignment
va_list aq = ap;
Unfortunately, there are also systems that make it an array of
pointers (of length 1), and there one needs
va_list aq;
*aq = *ap;
Finally, on systems where parameters are passed in registers, it
may be necessary for va_start to allocate memory, store the
parameters there, and also an indication of which parameter is
next, so that va_arg can step through the list. Now va_end can free
the allocated memory again.
To accommodate this situation, C99 adds a macro va_copy, so that
the above assignment can be replaced by
va_list aq;
va_copy(aq, ap);
...
va_end(aq);
Each invocation of va_copy must be matched by a corresponding
invocation of va_end in the same function. Some systems that do
not supply va_copy have __va_copy instead, since that was the name
used in the draft proposal.
This is from a Linux system's manpage on the varargs functions. My Mac
lacks the manpage, but features the function protected by the explicit
need to require C99 be enabled.
_______________________________________________
EUGLUG mailing list
[EMAIL PROTECTED]
http://www.euglug.org/mailman/listinfo/euglug
