This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: [PATCH 2/6] Use 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 15:51:50 +0200
- Subject: Re: [PATCH 2/6] Use INLINE_SYSCALL_ERROR_RETURN
- Authentication-results: sourceware.org; auth=none
- References: <20151012231944 dot GA27441 at intel dot com> <561D0388 dot 8030206 at redhat dot com> <CAMe9rOqC+Bar9XVrTutMJuo15qtiwts8AL-UMpaPQPc+WxXqNw at mail dot gmail dot com> <mvmfv1ex4iq dot fsf at hawking dot suse dot de>
On 10/13/2015 03:49 PM, Andreas Schwab wrote:
> "H.J. Lu" <hjl.tools@gmail.com> writes:
>
>> diff --git a/sysdeps/unix/sysv/linux/mmap64.c b/sysdeps/unix/sysv/linux/mmap64.c
>> index 1c9d3c1..8d5b0a4 100644
>> --- a/sysdeps/unix/sysv/linux/mmap64.c
>> +++ b/sysdeps/unix/sysv/linux/mmap64.c
>> @@ -46,7 +46,7 @@ __mmap64 (void *addr, size_t len, int prot, int
>> flags, int fd, off64_t offset)
>> }
>> #endif
>> if (offset & ((1 << page_shift) - 1))
>> - return (void *) INLINE_SYSCALL_ERROR_RETURN (EINVAL);
>> + return (void *) (ptrdiff_t) INLINE_SYSCALL_ERROR_RETURN (EINVAL);
>
> That's doesn't look like a good change, since you lose the warning if
> INLINE_SYSCALL_ERROR_RETURN returns something different from the size of
> a pointer.
INLINE_SYSCALL_ERROR_RETURN (EINVAL) is of type int, so we definitely do
not want a warning here.
The problem here is that the cast is implementation-defined, and I think
we want sign extension here (although the manual pages are unclear about
this).
Florian