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Re: [PATCH 1/6] Add INLINE_SYSCALL_ERROR_RETURN
- From: Florian Weimer <fweimer at redhat dot com>
- To: Andreas Schwab <schwab at suse dot de>
- Cc: "H.J. Lu" <hjl dot tools at gmail dot com>, GNU C Library <libc-alpha at sourceware dot org>
- Date: Tue, 13 Oct 2015 15:52:28 +0200
- Subject: Re: [PATCH 1/6] Add INLINE_SYSCALL_ERROR_RETURN
- Authentication-results: sourceware.org; auth=none
- References: <20151012231925 dot GB17339 at intel dot com> <561CFB56 dot 1050504 at redhat dot com> <CAMe9rOqQW4QJiTJkOp5zUfENeDNnxHiBG3OvjGJ867u4eG52cQ at mail dot gmail dot com> <mvmmvvmx4sb dot fsf at hawking dot suse dot de>
On 10/13/2015 03:43 PM, Andreas Schwab wrote:
> "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
This name is fine with me.
> 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.
Right.
Florian