[Asterisk-code-review] jitterbuffer: Correct signed/unsigned mismatch causing assert (asterisk[18])

[George Joseph]

Hello Friendly Automation, 

I'd like you to reexamine a change. Please visit

    https://gerrit.asterisk.org/c/asterisk/+/16110

to look at the new patch set (#2).

Change subject: jitterbuffer:  Correct signed/unsigned mismatch causing assert
......................................................................

jitterbuffer:  Correct signed/unsigned mismatch causing assert

If the system time has stepped backwards because of a time
adjustment between the time a frame is timestamped and the
time we check the timestamps in abstract_jb:hook_event_cb(),
we get a negative interval, but we don't check for that there.
abstract_jb:hook_event_cb() then calls
fixedjitterbuffer:fixed_jb_get() (via abstract_jb:jb_get_fixed)
and the first thing that does is assert(interval >= 0).

There are several issues with this...

 * abstract_jb:hook_event_cb() saves the interval in a variable
   named "now" which is confusing in itself.

 * "now" is defined as an unsigned int which converts the negative
   value returned from ast_tvdiff_ms() to a large positive value.

 * fixed_jb_get()'s parameter is defined as a signed int so the
   interval gets converted back to a negative value.

 * fixed_jb_get()'s assert is NOT an ast_assert but a direct define
   that points to the system assert() so it triggers even in
   production mode.

So...

 * hook_event_cb()'s "now" was renamed to "relative_frame_start" and
   changed to an int64_t.
 * hook_event_cb() now checks for a negative value right after
   retrieving both the current and framedata timestamps and just
   returns the frame if the difference is negative.
 * fixed_jb_get()'s local define of ASSERT() was changed to call
   ast_assert() instead of the system assert().

ASTERISK-29480
Reported by: Dan Cropp

Change-Id: Ic469dec73c2edc3ba134cda6721a999a9714f3c9
---
M main/abstract_jb.c
M main/fixedjitterbuf.c
2 files changed, 19 insertions(+), 9 deletions(-)


  git pull ssh://gerrit.asterisk.org:29418/asterisk refs/changes/10/16110/2
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Gerrit-Project: asterisk
Gerrit-Branch: 18
Gerrit-Change-Id: Ic469dec73c2edc3ba134cda6721a999a9714f3c9
Gerrit-Change-Number: 16110
Gerrit-PatchSet: 2
Gerrit-Owner: George Joseph <gjoseph at digium.com>
Gerrit-Reviewer: Friendly Automation
Gerrit-MessageType: newpatchset
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