On 11/24/2015 10:52 AM, Marc-André Lureau wrote: > Hi > > ----- Original Message ----- >> On 11/24/2015 09:34 AM, marcandre.lur...@redhat.com wrote: >>> From: Marc-André Lureau <marcandre.lur...@redhat.com> >> >> In the subject: s/implicitely/implicitly/ if you are fixing the typo, or >> s/implicitely/explicitly/ if you are trying to make it match what the >> patch actually does. >> > > ok, I'll switch to explicitely (it depends on the point of view, I was > commenting from the qga API user pov, but I get your point)
I was trying to point out not only the 2 points of view, but also the
typo (it's explicitly, not explicitely) :)
>>> fh = gfh->fh;
>>> +
>>> + if (!gfh->writing) {
>>> + int ret = fseek(fh, 0, SEEK_CUR);
>>
>> Seems a bit odd to use fflush() in one place and fseek() in the other,
>> but the net result is the same either way.
>
> "and input is not directly followed by output without an intervening call to
> a file positioning function, unless the input operation encounters
> end-of-file."
>
> so I tried to follow what the spec said.
POSIX currently specifies the behavior of fflush() on seekable input
files, but did not always do so; and it has been a source of bugs on
several libc implementations (it is still undefined to use fflush() on a
non-seekable file, but I don't know if anyone is using qga guest-file-*
on non-seekable files, at least in a situation where they are both
reading and writing to the same file handle). So on further thought, I
actually prefer avoiding fflush() after input when possible, to avoid
confusing older libc, and as a result, your asymmetry is probably the
best choice after all.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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