On Fri, Aug 04, 2017 at 06:13:42PM +0100, Daniel P. Berrange wrote:
Currently any mockable functions are marked with attributes noinline, noclone and weak. This prevents the compiler from optimizing away the impl of these functions.
It has an unfortunate side effect with the libtool convenience libraries, if executables directly link to them. For example virlockd, virlogd both link to libvirt_util.la When this is done, the linker does not consider weak symbols as being undefined, so it never copies them into the final executable.
In this new approach, we stop annotating the headers entirely. Instead we create a weak function alias in the source.
int fooImpl(void) { ..the real code.. }
int foo(void) __attribute__((noinline, noclone, weak, alias("fooImpl"))
If any functions in the same file call "foo", this prevents the optimizer from inlining any part of fooImpl. When linking to the libtool convenience static library, we also get all the symbols present. Finally the test suite can just directly define a 'foo' function in its source, removing the need to use LD_PRELOAD (though removal of LD_PRELOADS is left for a future patch).
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Self-NACK. This breaks on OS-X because the linker doesn't support 'alias' or 'weak'. For that matter it doesn't support LD_PRELOAD either, so we need to avoid wrapping the functions on this platform. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|