Messages in this thread | | | Date | Wed, 18 Nov 2020 10:35:45 +0100 | From | Jiri Olsa <> | Subject | Re: [PATCH 06/24] perf tools: Add build_id__is_defined function |
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On Tue, Nov 17, 2020 at 08:33:13PM -0300, Arnaldo Carvalho de Melo wrote: > Em Tue, Nov 17, 2020 at 09:53:59PM +0100, Jiri Olsa escreveu: > > On Tue, Nov 17, 2020 at 11:00:37AM -0800, Ian Rogers wrote: > > > On Tue, Nov 17, 2020 at 3:01 AM Jiri Olsa <jolsa@kernel.org> wrote: > > > > > > > Adding build_id__is_defined helper to check build id > > > > is defined and is != zero build id. > > > > > > > > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > > > > --- > > > > tools/perf/util/build-id.c | 7 +++++++ > > > > tools/perf/util/build-id.h | 1 + > > > > 2 files changed, 8 insertions(+) > > > > > > > > diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c > > > > index 6b410c3d52dc..7d9ecc37849c 100644 > > > > --- a/tools/perf/util/build-id.c > > > > +++ b/tools/perf/util/build-id.c > > > > @@ -912,3 +912,10 @@ void build_id__init(struct build_id *bid, const u8 > > > > *data, size_t size) > > > > memcpy(bid->data, data, size); > > > > bid->size = size; > > > > } > > > > + > > > > +bool build_id__is_defined(const struct build_id *bid) > > > > +{ > > > > + static u8 zero[BUILD_ID_SIZE]; > > > > + > > > > + return bid && bid->size ? memcmp(bid->data, &zero, bid->size) : > > > > false; > > > > Fwiw, I find this method to test for zero a little hard to parse - I'm > > > > heh, it's controversial one, Namhyung commented > > on this one in previous version, so I changed it ;-) > > https://lore.kernel.org/lkml/CAM9d7cjjGjTN8sDgLZ1PoQZ-sUXWjnVaNdyOVE1yHxq46PrPkw@mail.gmail.com/ > > So, the kernel has an idiom for this in lib/string.c: > > /** > * memchr_inv - Find an unmatching character in an area of memory. > * @start: The memory area > * @c: Find a character other than c > * @bytes: The size of the area. > * > * returns the address of the first character other than @c, or %NULL > * if the whole buffer contains just @c. > */ > void *memchr_inv(const void *start, int c, size_t bytes) > > No need for any array of some particular size :-)
ok, will check
thanks, jirka
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