Re: [PATCH v2 1/4] osdep: Make qemu_madvise() to set errno in all cases

[David Hildenbrand <david@redhat.com>]

On 31.05.24 09:57, Philippe Mathieu-Daudé wrote:
> Hi Michal,
> 
> On 31/5/24 09:28, Michal Privoznik wrote:
>> The unspoken premise of qemu_madvise() is that errno is set on
>> error. And it is mostly the case except for posix_madvise() which
>> is documented to return either zero (on success) or a positive
>> error number.
> 
> Watch out, Linux:
> 
>     RETURN VALUE
> 
>        On success, posix_madvise() returns 0.  On failure,
>        it returns a positive error number.
> 
> but on Darwin:
> 
>     RETURN VALUES
> 
>        Upon successful completion, a value of 0 is returned.
>        Otherwise, a value of -1 is returned and errno is set
>        to indicate the error.
> 
> (Haven't checked other POSIX OSes).
> 

... but it's supposed to follow the "posix standard" :D Maybe an issue 
in the docs?

FreeBSD seems to follow the standard: "The posix_madvise() interface is 
identical, except it returns an error number on error and does not 
modify errno, and is provided for standards conformance."

Same with OpenBSD: "The posix_madvise() interface has the same effect, 
but returns the error value instead of only setting errno."

-- 
Cheers,

David / dhildenb