diff options
| author | Fangrui Song <i@maskray.me> | 2019-11-22 09:00:39 +0100 |
|---|---|---|
| committer | Markus Armbruster <armbru@redhat.com> | 2019-11-25 06:00:05 +0100 |
| commit | 25f74087c695364dfaa87443b1040a3aa5c29008 (patch) | |
| tree | b887c91b7bf15b6bef1e614004c9c0b078347b41 /contrib | |
| parent | 2061735ff09f9d5e67c501a96227b470e7de69b1 (diff) | |
| download | qemu-25f74087c695364dfaa87443b1040a3aa5c29008.zip qemu-25f74087c695364dfaa87443b1040a3aa5c29008.tar.gz qemu-25f74087c695364dfaa87443b1040a3aa5c29008.tar.bz2 | |
util/cutils: Fix incorrect integer->float conversion caught by clang
Clang does not like do_strtosz()'s code to guard against overflow:
qemu/util/cutils.c:245:23: error: implicit conversion from 'unsigned long' to 'double' changes value from 18446744073709550592 to 18446744073709551616 [-Werror,-Wimplicit-int-float-conversion]
The warning will be enabled by default in clang 10. It is not
available for clang <= 9.
val * mul >= 0xfffffffffffffc00 is indeed wrong. 0xfffffffffffffc00
is not representable exactly as double. It's half-way between the
representable values 0xfffffffffffff800 and 0x10000000000000000.
Which one we get is implementation-defined. Bad.
We want val * mul > (the largest uint64_t exactly representable as
double). That's 0xfffffffffffff800. Write it as nextafter(0x1p64, 0)
with a suitable comment.
Signed-off-by: Fangrui Song <i@maskray.me>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[Patch split, commit message improved]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20191122080039.12771-3-armbru@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Diffstat (limited to 'contrib')
0 files changed, 0 insertions, 0 deletions