Re: [libvirt] [PATCH 3/4] Add a simple macro to check in which library dlopen() is, and use it.
According to Diego Elio “Flameeyes” Pettenò on 2/24/2010 8:27 AM:
> The shell expansion ${a#b} is not portable to Solaris /bin/sh.
Is that a
> problem for libvirt, or are we Linux-centric enough to not care?
That's definitely a problem I didn't think about, I was expecting POSIX
shell to support that, but I'll look for another way.
POSIX, yes. But Solaris /bin/sh is not POSIX.
> Underquoted; if the AC_MSG_ERROR were ever changed to contain a
comma,
> then this would be passing an unintentional extra argument to
> AC_SEARCH_LIBS.
I have to double check that one but I think that if I were to quote that
it wouldn't expand properly.
Maybe the alternative is to use m4_default_quoted (oops, not portable to
older autoconf), or m4_default([$2], [[AC_MSG_ERROR([])]]) in the
definition of action_if_not_found. The problem I'm trying to avoid is
that you should be sure that AC_SEARCH_LIBS sees [AC_MSG_ERROR([])], and
not the underquoted AC_MSG_ERROR([]), so that the contents of the error
message can safely be changed to have m4 metacharacters without any impact.
> Is this something that would be worth wrapping in an AC_CACHE_CHECK, to
> avoid repeating the check if config.cache exists?
The inner check is already cached, so I don't think there is much need
for adding one further cache…
Good point. All of the heavy lifting is already in AC_SEARCH_LIBS, so
adding another cache layer doesn't buy anything.
But this actually made me think that we might as well just use
AC_SEARCH_LIB and rely on the value stored in the cache to begin with so
I'll send a different version in a moment.
Which may render all of the above comments obsolete, depending on what you
come up with.
--
Eric Blake eblake(a)redhat.com +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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