Re: [PATCH 1/6] Add INLINE_SYSCALL_ERROR_RETURN

[Andreas Schwab <schwab at suse dot de>]

"H.J. Lu" <hjl.tools@gmail.com> writes:

> On Tue, Oct 13, 2015 at 5:38 AM, Florian Weimer <fweimer@redhat.com> wrote:
>> On 10/13/2015 01:19 AM, H.J. Lu wrote:
>>> +/* Set error number and return -1.  A target may choose to return the
>>> +   internal function, __syscall_error, which sets errno and returns -1.  */
>>> +#define INLINE_SYSCALL_ERROR_RETURN(err) \
>>> +  ({                                         \
>>> +    __set_errno (err);                               \
>>> +    -1;                                              \
>>> +  })
>>
>> I think the name is unfortunate because it the macro does not contain a
>> return statement.
>>
>> Perhaps INLINE_SYSCALL_SET_ERRNO would be a better name?
>>
>> Florian
>
> i386 defines it as
>
> /* Set error number and return -1.  Return the internal function,
>    __syscall_error, which sets errno from the negative error number
>    and returns -1, to avoid PIC.  */
> #undef INLINE_SYSCALL_ERROR_RETURN
> #define INLINE_SYSCALL_ERROR_RETURN(resultvar) \
>   __syscall_error (-(resultvar))
>
> This macro should only be used with "return".
> INLINE_SYSCALL_SET_ERRNO may be misleading.
> How about INLINE_SYSCALL_SET_ERRNO_AND_RETURN?

INLINE_SYSCALL_ERROR_RETURN_VALUE

It doesn't really matter whether the value is directly passed to return,
as long as the control flow leads to the end of the function without
making a detour.

Andreas.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
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"And now for something completely different."