This fixes warnings generated for `-Wunused-result` when mpv is built
with `-O1 -D_FORTIFY_SOURCE=1` or higher on clang since read/write
functions are declared with the `warn_unused_result` attribute.
Cast to void to avoid these warnings.
During execve() ignored and blocked signals carry over to the child
process, though apparently for SIGCHLD (which the bug report was about)
this is implementation-defined.
fixes#9613
Make it possible to feed a string to stdin of a subprocess. Out of
laziness, it can't be an arbitrary byte string. (Would require adding an
option type that takes in a Lua byte string.)
Do not set stdin of a subprocess to fd 0 (i.e. mpv's stdin) anymore,
because it makes things more consistent. Enabling stdin didn't make too
much sense in the first place, so this behavior change seems
justifiable.
win32 support missing.
Fixes: #8003
This code runs posix_spawnp() within a fork() in some cases, in order to
"disown" processes which are meant as being started detached. But
posix_spawnp() is not marked as async-signal-safe, so what we do is not
allowed. It could for example cause deadlocks, depending on
implementation and luck at runtime. Turns out posix_spawnp() is useless
crap.
Replace it with "classic" fork() to ensure correctness.
We could probably use another mechanism to start a process "disowned"
than doing a double-fork(). The only problem with "disowning" a process
is calling setsid() (which posix_spawnp() didn't support, but maybe will
in newer revisions), and removing as as parent from the child process
(the double-fork() will make PID 1 the parent). But there is no good way
to either remove us as parent, or to "reap" the PID in a way that is
safe and less of a mess than the current code. This is because
POSIX/UNIX is a miserable heap of shit. (Less shit than "alternatives"
like win32, no doubt.)
Because POSIX/UNIX is a miserable heap of shit, execvp() is also not
specified as async-signal-safe. It's funny how you can run a full
fledged HTTP server in an async-signal-safe context, but not start a
shitty damn process. Unix is really, really, really extremely bad at
this process management stuff. So we reimplement execvp() in an
async-signal-safe way.
The new code assumes that CLOEXEC is a thing. Since POSIX/UNIX is such a
heap of shit, O_CLOEXEC and FD_CLOEXEC were (probably) added at
different times, but both must be present. io.h defines them to 0 if
they don't exist, and in this case the code will error out at runtime.
Surely we could do without CLOEXEC via fallback, but I'll do that only
if at least 1 bug is reported wrt. this issue.
The idea how to report exec() failure or success is from musl. The way
as_execvpe() is also inspired by musl (for example, the list of error
codes that should make it fail is the same as in musl's code).
The previous method for this sucked: for every launched detached
process, it started a thread, which then would leak if the launched
process didn't end before the player uninitialized. This was very racy
(although I bet the race condition wouldn't trigger in a 100 years), and
wasteful (threads aren't a cheap resource).
Implement it for POSIX directly. posix_spawn() has no direct support for
this, so we need to do it ourselves with fork(). We could probably do it
without fork(), and attempt to collect the PID in another thread. But
then we'd either have a waiting thread again, or we'd need to do an
unsafe waitpid(-1, ...) call. (POSIX process management sucks so badly,
how did they even manage this. Hopefully I'm just missing something, but
I'm not.) So now we depend on both posix_spawn() _and_ fork(), isn't it
fun?
Also call setsid(), to essentially detach the child process from the
terminal. (Otherwise it can receive various signals from the terminal,
which is probably not what you want.) posix_spawn() adds
POSIX_SPAWN_SETSID in newer POSIX releases, but we don't want to rely on
this yet.
The posix_spawnp() call is duplicated, but this is better than somehow
trying to unify the code paths.
Only somewhat tested, so enjoy the bugs.
Introduce mp_subprocess() and related definitions. This is a bit more
flexible than the old stuff. This may or may not be used for a more
complicated feature that involves starting processes, and which would
require more control.
Only port subprocess-posix.c to this API. The player still uses the
"old" API, so for win32 and dummy implementations, the new API is simply
not available, while for POSIX, the old APIs are emulated on top of the
new one. I'm hoping the win32 code can be ported as well, so the ifdefs
in subprocess.c can be dropped, and the player can (if convenient or
needed) use the new API.
It seems a bit inappropriate to have dumped this into stream.c, even if
it's roughly speaking its main user. At least it made its way somewhat
unfortunately to other components not related to the stream or demuxer
layer at all.
I'm too greedy to give this weird helper its own file, so dump it into
thread_tools.c.
Probably a somewhat pointless change.
While this is perfectly OK on Unix, it causes annoying valgrind
warnings, and might be otherwise confusing to others.
On Windows, the runtime can actually abort the process if this is
called.
push.c part taken from a patch by Pedro Pombeiro.
This covers source files which were added in mplayer2 and mpv times
only, and where all code is covered by LGPL relicensing agreements.
There are probably more files to which this applies, but I'm being
conservative here.
A file named ao_sdl.c exists in MPlayer too, but the mpv one is a
complete rewrite, and was added some time after the original ao_sdl.c
was removed. The same applies to vo_sdl.c, for which the SDL2 API is
radically different in addition (MPlayer supports SDL 1.2 only).
common.c contains only code written by me. But common.h is a strange
case: although it originally was named mp_common.h and exists in MPlayer
too, by now it contains only definitions written by uau and me. The
exceptions are the CONTROL_ defines - thus not changing the license of
common.h yet.
codec_tags.c contained once large tables generated from MPlayer's
codecs.conf, but all of these tables were removed.
From demux_playlist.c I'm removing a code fragment from someone who was
not asked; this probably could be done later (see commit 15dccc37).
misc.c is a bit complicated to reason about (it was split off mplayer.c
and thus contains random functions out of this file), but actually all
functions have been added post-MPlayer. Except get_relative_time(),
which was written by uau, but looks similar to 3 different versions of
something similar in each of the Unix/win32/OSX timer source files. I'm
not sure what that means in regards to copyright, so I've just moved it
into another still-GPL source file for now.
screenshot.c once had some minor parts of MPlayer's vf_screenshot.c, but
they're all gone.
We want to distinguish actual errors, and just aborting the program
intentionally.
Also be a bit more careful with handling the wait() exit status: do not
called WEXITSTATUS() without checking WIFEXITED() first.
It's useless, and creates a bogus warning in subprocess-posix.c.
Since I don't know which compilers might have it by default, just change
it to -Wno-redundant-decls.
It appears youtube-dl sometimes asks for a password on stdin. This won't
work, because mpv already uses the terminal.
(I wonder if this could be simpler, like simply closing FD 0, but let's
not. The FD would be reused by something random.)
If the stdout or stderr write callback is NULL, then don't redirect this
stream. Preparation for the next commit.
Not sure what to do on Windows; it seems STARTUPINFO doesn't allow
redirection only one of them. So just let them write nothing. For our
intended use-case (next commit), this is probably sensible.
The subprocess code was already split into fairly general functions,
separate from the Lua code. It's getting pretty big though, especially
the Windows-specific parts, so move it into its own files.
Kacper Michajłow
llyyr
sfan5
wm4
Kevin Mitchell
James Ross-Gowan