Defining MPV_CPLUGIN_DYNAMIC_SYM during plugin compilation will replace mpv_*
functions with function pointers. Those pointer will be initialized when
loading the plugin.
It is recommended to use this symbol table when targeting Windows. The loader
does not have notion of global symbols. Loading cplugin into mpv process will
not allow this plugin to call any of the symbols that may be available in
other modules. Instead cplugin has to link explicitly to specific PE binary,
libmpv-2.dll/mpv.exe or any other binary that may have linked mpv statically.
This limits portability of cplugin as it would need to be compiled separately
for each of target PE binary that includes mpv's symbols. Which in practice
is unrealictis, as we want one cplugin to be loaded without those restrictions.
Instead of linking to any PE binary, we create function pointer for all mpv's
exported symbols. For convinience names of entrypoints are redefined to those
pointer so no changes are required in cplugin source code, except defining
MPV_CPLUGIN_DYNAMIC_SYM. Those function pointer are exported to make them
available for mpv to init with correct values during runtime, before calling
`mpv_open_cplugin`.
Note that those pointer are decorated with `selectany` attribute, so no need
to worry about multiple definitions, linker will keep only single instance.
This fixes cplugin usability on Windows. Without any API changes, only
recompilation with -DMPV_CPLUGIN_DYNAMIC_SYM is needed.
Discovered with:
find . -type f \( -name '*.md' -o -name '*.rst' \) -exec grep -n 'http://' {} +
All links to mpv.io or github.com/mpv-player that were http were
converted to https.
This basically reuses the scripting infrastructure.
Note that this needs to be explicitly enabled at compilation. For one,
enabling export for certain symbols from an executable seems to be quite
toolchain-specific. It might not work outside of Linux and cause random
problems within Linux.
If C plugins actually become commonly used and this approach is starting
to turn out as a problem, we can build mpv CLI as a wrapper for libmpv,
which would remove the requirement that plugins pick up host symbols.
I'm being lazy, so implementation/documentation are parked in existing
files, even if that stuff doesn't necessarily belong there. Sue me, or
better send patches.
And replace the sort-of duplicated explanations.
(It's a bit funny to use weblinks to the generated web version of itself
instead of proper RST links, but I think I don't care.)
Kacper Michajłow
25792431
LaserEyess
Érico Rolim
wm4