[PATCH v4] Fix Linux fcntl OFD locks for non-LFS architectures (BZ#20251)

[Florian Weimer]

On 06/22/2018 02:20 PM, Adhemerval Zanella wrote:
>>> +Â Â Â Â Â  /* case F_OFD_GETLK:
>>> +Â Â Â Â Â Â Â Â  case F_OFD_GETLK64:
>>> +Â Â Â Â Â Â Â Â  case F_SETLK64:
>>> +Â Â Â Â Â Â Â Â  case F_GETOWN:Â  */
>>> +Â Â Â Â Â  default:
>>> +Â Â Â Â Â Â Â  return __fcntl64_nocancel_adjusted (fd, cmd, arg);
>>> +Â Â Â  }
>>>  Â  }
>>
>> The comment before the default case looks wrong to me.  F_OFD_GETLK is duplicated.  Maybe add comments for the cases where mapping is not needed, explaining why.
> 
> I changed to:
> 
>        /* Since only F_SETLKW{64}/F_OLD_SETLK are cancellation entrypoints and
>          only OFD locks requires LFS handling, all others flags are handled
>          unmodified by calling __NR_fcntl64.  */

Thanks.  I think it should read “only OFD locks require LFS handling”.

>>> +# include <shlib-compat.h>
>>> +# if SHLIB_COMPAT(libc, GLIBC_2_0, GLIBC_2_28)
>>> +int
>>> +__old_libc_fcntl64 (int fd, int cmd, ...)
>>> +{
>>> +Â  va_list ap;
>>> +Â  void *arg;
>>> +
>>> +Â  va_start (ap, cmd);
>>> +Â  arg = va_arg (ap, void *);
>>> +Â  va_end (ap);
>>> +
>>> +Â  return __libc_fcntl64 (fd, cmd, arg);
>>> +} > +compat_symbol (libc, __old_libc_fcntl64, fcntl, GLIBC_2_0);
>>
>> This should have a comment why you call it __old_libc_fcntl64, when there never was a fcntl64 before.
> 
> I added.
> 
>    /* Previous versions called __NR_fcntl64 for fcntl (which do not handle
>       OFD locks in LFS mode).  */

“which did not handle”?

Florian