Re: [Qemu-devel] [PATCH 2/3] XXX oslib-posix: Ignore fcntl("/dev/null", F_SETFL, O_NONBLOCK) failure

[Philippe Mathieu-Daudé]

On 1/28/19 10:47 AM, Alex Bennée wrote:
> 
> Philippe Mathieu-Daudé <address@hidden> writes:
> 
>> Previous to OpenBSD 6.3 [1], fcntl(F_SETFL) is not permitted on memory
>> devices. Do not assert fcntl failures on OpenBSD.
>> This fixes:
>>
>>   $ lm32-softmmu/qemu-system-lm32
>>   assertion "f != -1" failed: file "util/oslib-posix.c", line 247, function 
>> "qemu_set_nonblock"
>>   Abort trap (core dumped)
>>
>> [1] The fix seems https://github.com/openbsd/src/commit/c2a35b387f9d3c
>>   "fcntl(F_SETFL) invokes the FIONBIO and FIOASYNC ioctls internally, so
>>   the memory devices (/dev/null, /dev/zero, etc) need to permit them."
> 
> I assume set_nonblock is called on more than just these special devices?
> Is there anyway to check this on OpenBSD or is it just an anonymous fd
> at this point?

I'll let an OpenBSD expert to answer that.

I forgot to comment, the assert() was added one month ago (da93b82079d),
Michael said we can also revert this change.

>>
>> Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
>> ---
>>  util/oslib-posix.c | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/util/oslib-posix.c b/util/oslib-posix.c
>> index 4ce1ba9ca4..064c3ae2f7 100644
>> --- a/util/oslib-posix.c
>> +++ b/util/oslib-posix.c
>> @@ -244,7 +244,9 @@ void qemu_set_nonblock(int fd)
>>      f = fcntl(fd, F_GETFL);
>>      assert(f != -1);
>>      f = fcntl(fd, F_SETFL, f | O_NONBLOCK);
>> +#ifndef __OpenBSD__
>>      assert(f != -1);
>> +#endif
>>  }
>>
>>  int socket_set_fast_reuse(int fd)
> 
> 
> --
> Alex Bennée
>