avutil/frame: Rename av_frame_side_data_get and add wrapper for it

av_frame_side_data_get() has a const AVFrameSideData * const *sd
parameter; so calling it with an AVFramesSideData **sd like
AVCodecContext.decoded_side_data (or with a AVFramesSideData * const
*sd) is safe, but the conversion is not performed automatically
in C. All users of this function therefore resort to a cast.

This commit changes this: av_frame_side_data_get() is renamed
to av_frame_side_data_get_c(); furthermore, a static inline
wrapper for it name av_frame_side_data_get() is added
that accepts an AVFramesSideData * const * and converts this
to const AVFramesSideData * const * in a Wcast-qual safe way.

This also allows to remove the casts from the current users.

Reviewed-by: Jan Ekström <jeebjp@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

2 files changed, 21 insertions, 6 deletions

diff --git a/libavutil/frame.c b/libavutil/frame.c
index 8598aa98a2..7dd37e5490 100644
--- a/libavutil/frame.c
+++ b/libavutil/frame.c
@@ -813,9 +813,9 @@ int av_frame_side_data_clone(AVFrameSideData ***sd, int *nb_sd,
     return 0;
 }
 
-const AVFrameSideData *av_frame_side_data_get(const AVFrameSideData * const *sd,
-                                              const int nb_sd,
-                                              enum AVFrameSideDataType type)
+const AVFrameSideData *av_frame_side_data_get_c(const AVFrameSideData * const *sd,
+                                                const int nb_sd,
+                                                enum AVFrameSideDataType type)
 {
     for (int i = 0; i < nb_sd; i++) {
         if (sd[i]->type == type)
@@ -828,7 +828,7 @@ AVFrameSideData *av_frame_get_side_data(const AVFrame *frame,
                                         enum AVFrameSideDataType type)
 {
     return (AVFrameSideData *)av_frame_side_data_get(
-        (const AVFrameSideData **)frame->side_data, frame->nb_side_data,
+        frame->side_data, frame->nb_side_data,
         type
     );
 }
diff --git a/libavutil/frame.h b/libavutil/frame.h
index cf9ffe1ba9..373866c600 100644
--- a/libavutil/frame.h
+++ b/libavutil/frame.h
@@ -1051,9 +1051,24 @@ int av_frame_side_data_clone(AVFrameSideData ***sd, int *nb_sd,
  * @return a pointer to the side data of a given type on success, NULL if there
  *         is no side data with such type in this set.
  */
-const AVFrameSideData *av_frame_side_data_get(const AVFrameSideData * const *sd,
+const AVFrameSideData *av_frame_side_data_get_c(const AVFrameSideData * const *sd,
+                                                const int nb_sd,
+                                                enum AVFrameSideDataType type);
+
+/**
+ * Wrapper around av_frame_side_data_get_c() to workaround the limitation
+ * that for any type T the conversion from T * const * to const T * const *
+ * is not performed automatically in C.
+ * @see av_frame_side_data_get_c()
+ */
+static inline
+const AVFrameSideData *av_frame_side_data_get(AVFrameSideData * const *sd,
                                               const int nb_sd,
-                                              enum AVFrameSideDataType type);
+                                              enum AVFrameSideDataType type)
+{
+    return av_frame_side_data_get_c((const AVFrameSideData * const *)sd,
+                                    nb_sd, type);
+}
 
 /**
  * @}