It turns out the glibc people are very clever and return an error if the
thread name exceeds the maximum supported kernel length, instead of
truncating the name. So everyone has to hardcode the currently allowed
Linux kernel name length limit, even if it gets extended later.
Also the Lua script filenames could get too long; use the client name
instead.
Another strange thing is that on Linux, unrelated threads "inherit" the
name by the thread they were created. This leads to random thread names,
because there's not necessarily a strong relation between these threads
(e.g. script command leads to filter recreation -> the filter's threads
are tagged with the script's thread name). Unfortunate.
On win32, open() is a function-like macro. The line of code changed
with this commit accidentally expanded the macro. Prevent this macro
expansion. Not sure why that happened now. Since as far as I remember
system functions can be defined as macros, this affects in theory not
only win32.
Especially with other components (libavcodec, OSX stuff), the thread
list can get quite populated. Setting the thread name helps when
debugging.
Since this is not portable, we check the OS variants in waf configure.
old-configure just gets a special-case for glibc, since doing a full
check here would probably be a waste of effort.
Windows doesn't have unix domain sockets, and can't handle sockets and
pipes in an uniform way. Only the libwaio fallback code is available,
which doesn't do JSON.
This is not realy obvious, so I assume this is a helpful hint.
Although the usefulness of such an approach is probably influenced by
the fact that the player might send events that arrive in the short
window while the socket is connected.
The ipc_thread can exit any time, and will free the mp_ipc_ctx when
doing this, leaving a dangling pointer. This was somewhat handled in the
original commit by setting mpctx->ipc_ctx to NULL when the thread
exited, but that was still a race condition.
Handle it by freeing most things after joining the ipc_thread. This
means some resources will not be freed until player exit, but that
should be ok (it's an exceptional error situation).
Also, actually close the pipe FDs in mp_init_ipc() on another error
path.
Thanks to the recently introduced mp_lua_PITA(), this is "simple" now.
It fixes leaks on Lua errors. The hack to avoid stack overflows
manually isn't needed anymore, and the Lua error handler will take
care of this.
The JSON parser was introduced for the IPC protocol, but I guess it's
useful here too.
The motivation for this commit is the same as with 8e4fa5fc (again).
Because 1) Lua is terrible, and 2) popen() is terrible. Unfortunately,
since Unix is also terrible, this turned out more complicated than I
hoped. As a consequence and to avoid that this code has to be maintained
forever, add a disclaimer that any function in Lua's utils module can
disappear any time. The complexity seems a bit ridiculous, especially
for a feature so far removed from actual video playback, so if it turns
out that we don't really need this function, it will be dropped again.
The motivation for this commit is the same as with 8e4fa5fc.
Note that there is an "#ifndef __GLIBC__". The GNU people are very
special people and thought it'd be convenient to actually declare
"environ", even though the POSIX people, which are also very special
people, state that no header declares this and that the user has to
declare this manually. Since the GNU people overtook the Unix world with
their very clever "embrace, extend, extinguish" strategy, but not 100%,
and trying to build without _GNU_SOURCE is hopeless; but since there
might be Unix environments which support _GNU_SOURCE features partially,
this means that in practice "environ" will be randomly declared or not
declared by system headers. Also, gcc was written by very clever people
too, and prints a warning if an external variable is declared twice (I
didn't check, but I suppose redeclaring is legal C, and not even the gcc
people are clever enough to only warn against a definitely not legal C
construct, although sometimes they do this), ...and since we at mpv hate
compiler warnings, we seek to silence them all. Adding a configure test
just for a warning seems too radical, so we special-case this against
__GLIBC__, which is hopefully not defined on other libcs, especially not
libcs which don't implement all aspects of _GNU_SOURCE, and redefine
"environ" on systems even if the headers define it already (because they
support _GNU_SOURCE - as I mentioned before, the clever GNU people wrote
software THAT portable that other libcs just gave up and implemented
parts of _GNU_SOURCE, although probably not all), which means that
compiling mpv will print a warning about "environ" being redefined, but
at least this won't happen on my system, so all is fine. However, should
someone complain about this warning, I will force whoever complained
about this warning to read this ENTIRE commit message, and if possible,
will also force them to eat a printed-out copy of the GNU Manifesto, and
if that is not enough, maybe this person could even be forced to
convince the very clever POSIX people of not doing crap like this:
having the user to manually declare somewhat central symbols - but I
doubt it's possible, because the POSIX people are too far gone and only
care about maintaining compatibility with old versions of AIX and HP-UX.
Oh, also, this code contains some subtle and obvious issues, but writing
about this is not fun.
Using the Lua API is a big PITA because it uses longjmp() error
handling. That is, a Lua API function could any time raise an error and
longjmp() to a lower part of the stack. This kind of "exception
handling" is completely foreign to C, and there are no proper ways to
clean up the "skipped" stack frames.
Other than avoiding such situations entirely, the only way to deal with
this is using Lua "userdata", which is basically a malloc'ed data block
managed by the Lua GC, and which can have a destructor function
associated (__gc metamethod).
This requires an awful lot of code (because the Lua API is just so
terrible), so I avoided this utnil now. But it looks like this will make
some of the following commits much easier, so here we go.
After removing synchronous libdispatch calls, this looks like it doesn't
deadlock anymore. I also experimented with pthread_mutex_trylock liek wm4
suggested, but it leads to some annoying black flickering. I will fallback to
that only if some new deadlocks are discovered.
It's kind of obvious, since the protocol by design has to allow you to
read (loadfile) and write (screenshot_to) random files, but better
make it explicit so that nobody accidentally does something insecure.
As I understand, otherwise, the code will try to destroy the same
window again in the cleanup part of the gui_thread(), which makes no
sense and is potentially dangerous.
mp_stat() instead of stat() was used in the normal code (i.e. even
on Unix), because MinGW-w64 has an unbelievable macro-mess in place,
which prevents solving this elegantly.
Add some dirty workarounds to hide mp_stat() from the normal code
properly. This now requires replacing all functions that use the
struct stat type. This includes fstat, lstat, fstatat, and possibly
others. (mpv currently uses stat and fstat only.)
Now requires newest libass git. Since this feature wasn't part of a
libass release yet, I'm not bothering making the mpv code compatible
with as how it was previously implemented (it will just be disabled
with any older libass).
CC: @mpv-player/stable (because mpv-build uses libass git, and this
breaks the feature)
It possibly goes to sleep without actually starting to decode audio.
Possibly fixes a problem with --no-osc --no-video reported on IRC.
CC: @mpv-player/stable
The previous commit was actually incorrect, and the change had
absolutely no effect. The two formats are (fortunately) the same. I'm
probably too tired.
