Quite a few of the tests have a need to mock the stat() / lstat()
functions and they are taking somewhat different & inconsistent
approaches none of which are actually fully correct. This is shown
by fact that 'make check' fails on 32-bit hosts. Investigation
revealed that the code was calling into the native C library impl,
not getting intercepted by our mocks.
The POSIX stat() function might resolve to any number of different
symbols in the C library.
The may be an additional stat64() function exposed by the headers
too.
On 64-bit hosts the stat & stat64 functions are identical, always
refering to the 64-bit ABI.
On 32-bit hosts they refer to the 32-bit & 64-bit ABIs respectively.
Libvirt uses _FILE_OFFSET_BITS=64 on 32-bit hosts, which causes the
C library to transparently rewrite stat() calls to be stat64() calls.
Libvirt will never see the 32-bit ABI from the traditional stat()
call. We cannot assume this rewriting is done using a macro. It might
be, but on GLibC it is done with a magic __asm__ statement to apply
the rewrite at link time instead of at preprocessing.
In GLibC there may be two additional functions exposed by the headers,
__xstat() and __xstat64(). When these exist, stat() and stat64() are
transparently rewritten to call __xstat() and __xstat64() respectively.
The former symbols will not actally exist in the library at all, only
the header. The leading "__" indicates the symbols are a private impl
detail of the C library that applications should not care about.
Unfortunately, because we are trying to mock replace the C library,
we need to know about this internal impl detail.
With all this in mind the list of functions we have to mock will depend
on several factors
- If _FILE_OFFSET_BITS is set, then we are on a 32-bit host, and we
only need to mock stat64 and __xstat64. The other stat / __xstat
functions exist, but we'll never call them so they can be ignored
for mocking.
- If _FILE_OFFSET_BITS is not set, then we are on a 64-bit host and
we should mock stat, stat64, __xstat & __xstat64. Either may be
called by app code.
- If __xstat & __xstat64 exist, then stat & stat64 will not exist
as symbols in the library, so the latter should not be mocked.
The same all applies to lstat()
These rules are complex enough that we don't want to duplicate them
across every mock file, so this centralizes all the logic in a helper
file virmockstathelper.c that should be #included when needed. The
code merely need to provide a filename rewriting callback called
virMockStatRedirect(). Optionally VIR_MOCK_STAT_HOOK can be defined
as a macro if further processing is needed inline.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
It may happen that both symbols are present. Especially when
chaining mocks. For instance if a test is using virpcimock and
then both stat and __xstat would be present in the address space
as virpcimock implements both. Then, if the test would try to use
say virfilewrapper (which again uses VIR_MOCK_REAL_INIT_ALT() to
init real_stat and real___xstat) it would find stat() from
virpcimock and stop there. The virfilewrapper.c:real___xstat
wouldn't be initialized and thus it may result in a segfault.
The reason for segfault is that sys/stat.h may redefine stat() to
call __xstat().
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Require that all headers are guarded by a symbol named
LIBVIRT_$FILENAME
where $FILENAME is the uppercased filename, with all characters
outside a-z changed into '_'.
Note we do not use a leading __ because that is technically a
namespace reserved for the toolchain.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
All of the ones being removed are pulled in by internal.h. The only
exception is sanlock which expects the application to include <stdint.h>
before sanlock's headers, because sanlock prototypes use fixed width
int, but they don't include stdint.h themselves, so we have to leave
that one in place.
Signed-off-by: Erik Skultety <eskultet@redhat.com>
Acked-by: Michal Privoznik <mprivozn@redhat.com>
It doesn't really make sense for us to have stdlib.h and string.h but
not stdio.h in the internal.h header.
Signed-off-by: Erik Skultety <eskultet@redhat.com>
Acked-by: Michal Privoznik <mprivozn@redhat.com>
Right-aligning backslashes when defining macros or using complex
commands in Makefiles looks cute, but as soon as any changes is
required to the code you end up with either distractingly broken
alignment or unnecessarily big diffs where most of the changes
are just pushing all backslashes a few characters to one side.
Generated using
$ git grep -El '[[:blank:]][[:blank:]]\\$' | \
grep -E '*\.([chx]|am|mk)$$' | \
while read f; do \
sed -Ei 's/[[:blank:]]*[[:blank:]]\\$/ \\/g' "$f"; \
done
Signed-off-by: Andrea Bolognani <abologna@redhat.com>
It wasn't as great idea as I thought. Thing around stat() are
more complicated than that. Therefore we need to revert
86d1705a8a plus drop use of the macro as introduced in
later patches.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
There is some magic going on when it comes to stat() or lstat().
Basically, stat() can either be a regular function, an inline
function that calls __xstat(_STAT_VER, ...) or a macro that does
the same as the inline func. Don't ask why is that, just read the
documentation in sys/stat.h and make sure you have a bucket next
to you. Anyway, currently there will not be both stat and __xstat
symbols at the same time, as one of them gets overwritten to the
other one during compilation. But this is not true anymore once
we start chaining our mocking libraries. Therefore we need a
wrapper that calls desired function from glibc.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
It looks like it was copy-pasted, so in case anyone wonders what some of
those methods do without looking at them, and for the sake of
completeness, fix them.
Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
Rename the VIR_MOCK_IMPL* macros to VIR_MOCK_WRAP*
and add new VIR_MOCK_IMPL macros which let you directly
implement overrides in the preloaded source.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Introduce virmock.h which provides some macros to assist in
creation of LD_PRELOAD overrides. When these are used, the
LD_PRELOAD code simply has some stubs which forward to a
wrapper function inside the main test case. This means that
logic for the test no longer has to be split between the
virXXXtest.c and virXXXmock.c files. It will also make it
possible to provide some common reusable modules for mocking
code like DBus.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
