decomp: input thread re-enters access

Typically, the input thread call stack looks like: input -> demux -> stream -> access.

If however, we have a threaded stream filter, it looks like: input -> demux -> stream filter. And then the extra stream filter thread looks like: stream filter -> stream -> access. In this case, the input thread cannot invoke access callbacks directly, lest it trigger re-entrancy bugs.

Affected call paths are located in src/input/input.c:

ControlPause(),
ControlUnpause(),
Control() at case INPUT_CONTROL_ADD_SLAVE,
UpdateGenericFromAccess(),
and InputSourceInit() after the stream_FilterChainNew() call.

Regarding ControlPause() and ControlUnpause(), the following access plugins are concerned: avio, dv, ftp, mmsh and mmstu; they implement the ACCESS_SET_PAUSE_STATE control. And regarding UpdateGenericFromAccess(), the following access plugins are concerned: http (for INPUT_UPDATE_META) and dtv (for INPUT_UPDATE_SIGNAL).

This bug mainly affects the decompression filter. Nevertheless it might also concern any of the 3 HTTP streaming filter (also threaded stream filters).

Edited Apr 13, 2013 by Rémi Denis-Courmont

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