avfilter/src_movie: fix how we check for overflows with seek_point
authorMarios Titas <redneb@gmx.com>
Sat, 2 Apr 2016 18:11:44 +0000 (21:11 +0300)
committerMichael Niedermayer <michael@niedermayer.cc>
Sun, 1 May 2016 03:00:45 +0000 (05:00 +0200)
commitdc751a55e5ae243630b18f3f6bedc49ee9656b38
tree2e817c4cf1c1a42e75342a57889013751ed09347
parenteae0a6582df3c658e9f32744c6c3252876db2570
avfilter/src_movie: fix how we check for overflows with seek_point

Currently, if the movie source filter is used and a seek_point is
specified on a file that has a negative start time, ffmpeg will fail.

An easy way to reproduce this is as follows:
$ ffmpeg -vsync passthrough -filter_complex 'color=d=10,setpts=PTS-1/TB' test.mp4
$ ffmpeg -filter_complex 'movie=filename=test.mp4:seek_point=2' -f null -

The problem is caused by checking for int64_t overflow the wrong way.
In general, to check whether a + b overflows, it is not enough to do:
    a > INT64_MAX - b
because b might be negative; the correct way is:
    b > 0 && > a > INT64_MAX - b

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit c1f9734f977f59bc0034096afbe8e43e40d93a5d)

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
libavfilter/src_movie.c