In nxt_kqueue_poll() error is declared as a nxt_bool_t aka unsigned int
(on x86-64 anyway).
It is used both as a boolean and as the return storage for a bitwise AND
operation.
This has potential to go awry.
If nxt_bool_t was changed to be a u8 then we would have the following
issue
gcc12 -c -pipe -fPIC -fvisibility=hidden -O -W -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wmissing-prototypes -Werror -g -O2 -I src -I build -I/usr/local/include -o build/src/nxt_kqueue_engine.o -MMD -MF build/src/nxt_kqueue_engine.dep -MT build/src/nxt_kqueue_engine.o src/nxt_kqueue_engine.c
src/nxt_kqueue_engine.c: In function 'nxt_kqueue_poll':
src/nxt_kqueue_engine.c:728:17: error: overflow in conversion from 'int' to 'nxt_bool_t' {aka 'unsigned char'} changes value from '(int)kev->flags & 16384' to '0' [-Werror=overflow]
728 | error = (kev->flags & EV_ERROR);
| ^
cc1: all warnings being treated as errors
EV_ERROR has the value 16384, after the AND operation error holds 16384,
however this overflows and wraps around (64 times) exactly to 0.
With nxt_bool_t defined as a u32, we would have a similar issue if
EV_ERROR ever became UINT_MAX + 1 (or a multiple thereof)...
Rather than conflating the use of error, keep error as a boolean (it is
used further down the function) but do the AND operation inside the
if ().
Reviewed-by: Alejandro Colomar <alx@nginx.com>
Signed-off-by: Andrew Clayton <a.clayton@nginx.com>
If kqueue reported both the EVFILT_READ and the EVFILT_WRITE events
for the socket but only the former had the EV_EOF flag set, the flag
was silently ignored.
