[FFmpeg-devel] [PATCH 1/5] w32pthreads: always use Vista+ API, drop XP support

[wm4]

On Thu, 21 Dec 2017 21:31:37 -0300
James Almer <jamrial at gmail.com> wrote:

> On 12/21/2017 7:22 PM, wm4 wrote:
> > This removes the XP compatibility code, and switches entirely to SWR
> > locks, which are available starting at Windows Vista.
> > 
> > This removes CRITICAL_SECTION use, which allows us to add
> > PTHREAD_MUTEX_INITIALIZER, which will be useful later.
> > 
> > Windows XP is hereby not a supported build target anymore. It was
> > decided in a project vote that this is OK. (Technically, it could still
> > be built for Windows XP using an external pthread lib as of this
> > commit.)
> > 
> > Windows Vista adds WSAPoll(), and for some reason struct pollfd. Since
> > we raise the Windows API level globally when enabling w32threads, we
> > need to move it before configure checks for struct pollfd to avoid that
> > the compatibility ifdef mess redefines it.
> > ---
> > Not sure if there's a better way to do the things configure does.
> > ---
> >  Changelog                  |   2 +
> >  compat/w32pthreads.h       | 269 ++-------------------------------------------
> >  configure                  |  93 ++++++++--------
> >  libavcodec/pthread_frame.c |   4 -
> >  libavcodec/pthread_slice.c |   4 -
> >  libavfilter/pthread.c      |   4 -
> >  libavutil/slicethread.c    |   4 -
> >  7 files changed, 60 insertions(+), 320 deletions(-)  
> 
> [...]
> 
> > --- a/configure
> > +++ b/configure
> > @@ -2089,7 +2089,6 @@ TOOLCHAIN_FEATURES="
> >  "
> >  
> >  TYPES_LIST="
> > -    CONDITION_VARIABLE_Ptr
> >      kCMVideoCodecType_HEVC
> >      socklen_t
> >      struct_addrinfo
> > @@ -5163,8 +5162,8 @@ probe_libc(){
> >          add_${pfx}cppflags -U__STRICT_ANSI__ -D__USE_MINGW_ANSI_STDIO=1
> >          check_${pfx}cpp_condition _mingw.h "__MSVCRT_VERSION__ < 0x0700" &&
> >              add_${pfx}cppflags -D__MSVCRT_VERSION__=0x0700
> > -        check_${pfx}cpp_condition windows.h "defined(_WIN32_WINNT) && _WIN32_WINNT < 0x0502" &&
> > -            add_${pfx}cppflags -D_WIN32_WINNT=0x0502
> > +        check_${pfx}cpp_condition windows.h "defined(_WIN32_WINNT) && _WIN32_WINNT < 0x0600" &&
> > +            add_${pfx}cppflags -D_WIN32_WINNT=0x0600  
> 
> This same check should now also be added to the mingw-w64 part of this
> function.
> Until now, this was done this way because mingw32 defaults to Win98,
> whereas mingw-w64 to WinXP. Now we need Vista in both.

Oh, I didn't even notice that was mingw32 only.

> It would be a good idea for that matter to make sure all the required
> Vista API is actually supported by Mingw32 3.15, or if we need to bump
> that (or just drop mingw32 support, which wouldn't really hurt).

The code already checks for CONDITION_VARIABLE. Any other things I
should check for? Maybe a representative function? (I don't think I'm
going to add checks for _all_ the symbols.)

> >          eval test \$${pfx_no_}cc_type = "gcc" &&
> >              add_${pfx}cppflags -D__printf__=__gnu_printf__
> >      elif check_${pfx}cpp_condition crtversion.h "defined _VC_CRT_MAJOR_VERSION"; then
> > @@ -5184,14 +5183,14 @@ probe_libc(){
> >          # 0x601 by default unless something else is set by the user.
> >          # This can easily lead to us detecting functions only present
> >          # in such new versions and producing binaries requiring windows 7.0.
> > -        # Therefore explicitly set the default to XP unless the user has
> > +        # Therefore explicitly set the default to Vista unless the user has
> >          # set something else on the command line.
> >          # Don't do this if WINAPI_FAMILY is set and is set to a non-desktop
> >          # family. For these cases, configure is free to use any functions
> >          # found in the SDK headers by default. (Alternatively, we could force
> >          # _WIN32_WINNT to 0x0602 in that case.)
> >          check_${pfx}cpp_condition stdlib.h "defined(_WIN32_WINNT)" ||
> > -            { check_${pfx}cpp <<EOF && add_${pfx}cppflags -D_WIN32_WINNT=0x0502; }
> > +            { check_${pfx}cpp <<EOF && add_${pfx}cppflags -D_WIN32_WINNT=0x0600; }
> >  #ifdef WINAPI_FAMILY
> >  #include <winapifamily.h>
> >  #if !WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)
> > @@ -5564,6 +5563,51 @@ check_code cc arm_neon.h "int16x8_t test = vdupq_n_s16(0)" && enable intrinsics_
> >  check_ldflags -Wl,--as-needed
> >  check_ldflags -Wl,-z,noexecstack
> >  
> > +if ! disabled w32threads && ! enabled pthreads; then
> > +    check_func_headers "windows.h process.h" _beginthreadex &&
> > +        check_type "windows.h" CONDITION_VARIABLE &&
> > +        enable w32threads || disable w32threads
> > +    if ! enabled w32threads && enabled winrt; then
> > +        check_func_headers "windows.h" CreateThread &&
> > +            enable w32threads || disable w32threads
> > +    fi
> > +fi
> > +
> > +if enabled w32threads; then
> > +    if check_cpp_condition windows.h "!defined(_WIN32_WINNT) || _WIN32_WINNT < 0x0600" ; then
> > +        add_cppflags -D_WIN32_WINNT=0x0600  
> 
> Win Vista should be forced regardless of w32threads being enabled or
> not, so this should be done in probe_libc().

OK, sounds good. So this means we always set _WIN32_WINNT
unconditionally (unless it's already set to something higher than
Vista). This will probably simplify the configure changes.