Alex Converse <[email protected]> writes:

> 2011/6/18 Måns Rullgård <[email protected]>:
>> Yusuke Nakamura <[email protected]> writes:
>>
>>> 2011/6/18 Måns Rullgård <[email protected]>
>>>
>>>> Yusuke Nakamura <[email protected]> writes:
>>>>
>>>> > This patch fixes my 10L of following.
>>>> >
>>>> http://git.libav.org/?p=libav.git;a=commitdiff;h=5f0bb0baefd506d684adfa1ad4259c65973b455e
>>>> >
>>>> > From f3c030ebedabc9a17e377c6f91dc417e6578712b Mon Sep 17 00:00:00 2001
>>>> > From: Yusuke Nakamura <[email protected]>
>>>> > Date: Sun, 5 Jun 2011 01:28:43 +0900
>>>> > Subject: [PATCH] mov: Fix empty edit detection.
>>>> >
>>>> > ---
>>>> >  libavformat/mov.c |    2 +-
>>>> >  1 files changed, 1 insertions(+), 1 deletions(-)
>>>> >
>>>> > diff --git a/libavformat/mov.c b/libavformat/mov.c
>>>> > index e6ada4e..2d1d726 100644
>>>> > --- a/libavformat/mov.c
>>>> > +++ b/libavformat/mov.c
>>>> > @@ -2230,7 +2230,7 @@ static int mov_read_elst(MOVContext *c, AVIOContext
>>>> *pb, MOVAtom atom)
>>>> >              time     = avio_rb64(pb);
>>>> >          } else {
>>>> >              duration = avio_rb32(pb); /* segment duration */
>>>> > -            time     = avio_rb32(pb); /* media time */
>>>> > +            time     = (int32_t)avio_rb32(pb); /* media time */
>>>>
>>>> This cast is invalid if the value is >INT_MAX.
>>>
>>> What's wrong? If I get 0x80000000 from avio_rb32(pb), then I want to set
>>> 0xffffffff80000000 to int64_t time.
>>
>> The cast is not guaranteed to do that.
>
> On GCC it is...

Are you sure about that?  What about all those cases where it optimises
assuming signed integer arithmetic will never overflow since the results
are undefined/unspecified if it does?

> Do you know a compiler we support where it isn't? We do this all over
> the code base.

We should not be doing that then.

-- 
Måns Rullgård
[email protected]
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