[FFmpeg-devel] [PATCH] fix MSVC compilation errors

[Hendrik Leppkes]

On Thu, Dec 7, 2017 at 2:02 AM, Mateusz <mateuszb at poczta.onet.pl> wrote:
> After commit 3701d49 'error_resilience: remove avpriv_atomic usage'
> we have included windows.h in much more files and we should
> avoid conflicts with defines/function declarations.
>
> We should declare compatible variables for atomic compat wrappers
> that expect fixed size variables in atomic_compare_exchange* macro.
>
> Signed-off-by: Mateusz Brzostek <mateuszb at poczta.onet.pl>
> ---
>  libavcodec/jpegls.h   |  2 ++
>  libavcodec/mjpegdec.h |  2 ++
>  libavcodec/mss2.c     |  6 +++---
>  libavcodec/utils.c    | 12 ++++++++++++
>  libavformat/mxfenc.c  |  2 +-
>  5 files changed, 20 insertions(+), 4 deletions(-)
>
> diff --git a/libavcodec/jpegls.h b/libavcodec/jpegls.h
> index c8997c7861..6b89b2afa3 100644
> --- a/libavcodec/jpegls.h
> +++ b/libavcodec/jpegls.h
> @@ -32,6 +32,8 @@
>  #include "avcodec.h"
>  #include "internal.h"
>
> +#undef near /* This file uses struct member 'near' which in windows.h is defined as empty. */
> +
>  typedef struct JpeglsContext {
>      AVCodecContext *avctx;
>  } JpeglsContext;
> diff --git a/libavcodec/mjpegdec.h b/libavcodec/mjpegdec.h
> index c84a40aa6e..c36fba5f22 100644
> --- a/libavcodec/mjpegdec.h
> +++ b/libavcodec/mjpegdec.h
> @@ -39,6 +39,8 @@
>  #include "hpeldsp.h"
>  #include "idctdsp.h"
>
> +#undef near /* This file uses struct member 'near' which in windows.h is defined as empty. */
> +
>  #define MAX_COMPONENTS 4
>
>  typedef struct MJpegDecodeContext {
> diff --git a/libavcodec/mss2.c b/libavcodec/mss2.c
> index 9e7cc466de..3180af1d60 100644
> --- a/libavcodec/mss2.c
> +++ b/libavcodec/mss2.c
> @@ -464,9 +464,9 @@ static int decode_wmv9(AVCodecContext *avctx, const uint8_t *buf, int buf_size,
>      return 0;
>  }
>
> -typedef struct Rectangle {
> +struct Rectangle {
>      int coded, x, y, w, h;
> -} Rectangle;
> +};
>
>  #define MAX_WMV9_RECTANGLES 20
>  #define ARITH2_PADDING 2
> @@ -485,7 +485,7 @@ static int mss2_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
>
>      int keyframe, has_wmv9, has_mv, is_rle, is_555, ret;
>
> -    Rectangle wmv9rects[MAX_WMV9_RECTANGLES], *r;
> +    struct Rectangle wmv9rects[MAX_WMV9_RECTANGLES], *r;
>      int used_rects = 0, i, implicit_rect = 0, av_uninit(wmv9_mask);
>
>      if ((ret = init_get_bits8(&gb, buf, buf_size)) < 0)
> diff --git a/libavcodec/utils.c b/libavcodec/utils.c
> index baf09119fe..70a0764714 100644
> --- a/libavcodec/utils.c
> +++ b/libavcodec/utils.c
> @@ -1943,7 +1943,13 @@ int av_lockmgr_register(int (*cb)(void **mutex, enum AVLockOp op))
>
>  int ff_lock_avcodec(AVCodecContext *log_ctx, const AVCodec *codec)
>  {
> +#if !defined(COMPAT_ATOMICS_DUMMY_STDATOMIC_H) && !defined(COMPAT_ATOMICS_PTHREAD_STDATOMIC_H) && \
> +    !defined(COMPAT_ATOMICS_SUNCC_STDATOMIC_H) && !defined(COMPAT_ATOMICS_WIN32_STDATOMIC_H)
>      _Bool exp = 0;
> +#else
> +    atomic_bool exp = 0;
> +#endif
> +
>      if (codec->caps_internal & FF_CODEC_CAP_INIT_THREADSAFE || !codec->init)
>          return 0;
>
> @@ -1969,7 +1975,13 @@ int ff_lock_avcodec(AVCodecContext *log_ctx, const AVCodec *codec)
>
>  int ff_unlock_avcodec(const AVCodec *codec)
>  {
> +#if !defined(COMPAT_ATOMICS_DUMMY_STDATOMIC_H) && !defined(COMPAT_ATOMICS_PTHREAD_STDATOMIC_H) && \
> +    !defined(COMPAT_ATOMICS_SUNCC_STDATOMIC_H) && !defined(COMPAT_ATOMICS_WIN32_STDATOMIC_H)
>      _Bool exp = 1;
> +#else
> +    atomic_bool exp = 1;
> +#endif
> +
>      if (codec->caps_internal & FF_CODEC_CAP_INIT_THREADSAFE || !codec->init)
>          return 0;
>

These ifdefs here are very ugly, and as mentioned in another mail, the
atomics in those two functions arent even required - all access to
those variables is supposed to be protected by the lockmgr anyway.
So it would be easier to just remove any atomic nature of those
variables (or at the very lease replace the compare_exchange with a
store to solve this problem at hand).

- Hendrik