Re: [PATCH 2/2] qemu/osdep: handle sysconf(_SC_OPEN_MAX) return value == -1

[Clément Léger]

On 30/08/2024 13:31, Michael Tokarev wrote:
> 30.08.2024 14:14, Clément Léger wrote:
>> On some systems (MacOS for instance), sysconf(_SC_OPEN_MAX) can return
>> -1. In that case we should fallback to using the OPEN_MAX define.
>> According to "man sysconf", the OPEN_MAX define should be present and
>> provided by either unistd.h and/or limits.h so include them for that
>> purpose. For other OSes, just assume a maximum of 1024 files descriptors
>> as a fallback.
>>
>> Fixes: 4ec5ebea078e ("qemu/osdep: Move close_all_open_fds() to oslib-
>> posix")
>> Reported-by: Daniel P. Berrangé <berrange@redhat.com>
>> Signed-off-by: Clément Léger <cleger@rivosinc.com>
> 
> Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
> 
>> @@ -928,6 +933,13 @@ static void qemu_close_all_open_fd_fallback(const
>> int *skip, unsigned int nskip,
>>   void qemu_close_all_open_fd(const int *skip, unsigned int nskip)
>>   {
>>       int open_max = sysconf(_SC_OPEN_MAX);
>> +    if (open_max == -1) {
>> +#ifdef CONFIG_DARWIN
>> +        open_max = OPEN_MAX;
>> +#else
>> +        open_max = 1024;
>> +#endif
> 
> BTW, Can we PLEASE cap this to 1024 in all cases? :)
> (unrelated to this change but still).

Hi Michael,

Do you mean for all OSes or always using 1024 rather than using the
sysconf returned value ?

In any case, the code now uses close_range() or /proc/self/fd and is
handling that efficiently.

Thanks,

Clément

> 
> /mjt