[FFmpeg-devel] [PATCH 1/2] avformat/aviobuf: Remove AVIOInternal and one level of indirection

Andreas Rheinhardt andreas.rheinhardt at gmail.com
Mon Jan 13 00:05:11 EET 2020


On Mon, Jan 6, 2020 at 3:51 PM Andreas Rheinhardt <
andreas.rheinhardt at gmail.com> wrote:

> In the Libav commit cae448cf, the opaque of every AVIOContext opened
> by ffio_fdopen() (which is used internally by avio_open() and avio_open2())
> changed: It was a simple pointer to an URLContext before, but now it was
> a structure (namely AVIOInternal) containing a pointer to an URLContext
> as its only member. The next commits (namely 8c0ceafb and ec4c4839) added
> members to AVIOInternal to allow white-/blacklisting of protocols.
>
> But these two commits were never merged into FFmpeg (they were only
> merged as no-ops in 510046c2 and 063b26d3), because FFmpeg chose
> a different way to implement this (in 93629735); and so our AVIOInternal
> still has exactly one member.
>
> This of course means that it is unnecessary to use AVIOInternal as
> opaque as it is just adding a level of indirection (not only pointer
> dereference, but also wrapper functions). Therefore this commit
> removes AVIOInternal entirely and essentially reverts cae448cf.
>
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
> ---
>  libavformat/aviobuf.c | 86 ++++++++-----------------------------------
>  1 file changed, 15 insertions(+), 71 deletions(-)
>
> diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
> index 70e1d2ca10..0e2f038988 100644
> --- a/libavformat/aviobuf.c
> +++ b/libavformat/aviobuf.c
> @@ -42,15 +42,10 @@
>   */
>  #define SHORT_SEEK_THRESHOLD 4096
>
> -typedef struct AVIOInternal {
> -    URLContext *h;
> -} AVIOInternal;
> -
>  static void *ff_avio_child_next(void *obj, void *prev)
>  {
>      AVIOContext *s = obj;
> -    AVIOInternal *internal = s->opaque;
> -    return prev ? NULL : internal->h;
> +    return prev ? NULL : s->opaque;
>  }
>
>  static const AVClass *ff_avio_child_class_next(const AVClass *prev)
> @@ -940,49 +935,8 @@ uint64_t ffio_read_varlen(AVIOContext *bc){
>      return val;
>  }
>
> -static int io_read_packet(void *opaque, uint8_t *buf, int buf_size)
> -{
> -    AVIOInternal *internal = opaque;
> -    return ffurl_read(internal->h, buf, buf_size);
> -}
> -
> -static int io_write_packet(void *opaque, uint8_t *buf, int buf_size)
> -{
> -    AVIOInternal *internal = opaque;
> -    return ffurl_write(internal->h, buf, buf_size);
> -}
> -
> -static int64_t io_seek(void *opaque, int64_t offset, int whence)
> -{
> -    AVIOInternal *internal = opaque;
> -    return ffurl_seek(internal->h, offset, whence);
> -}
> -
> -static int io_short_seek(void *opaque)
> -{
> -    AVIOInternal *internal = opaque;
> -    return ffurl_get_short_seek(internal->h);
> -}
> -
> -static int io_read_pause(void *opaque, int pause)
> -{
> -    AVIOInternal *internal = opaque;
> -    if (!internal->h->prot->url_read_pause)
> -        return AVERROR(ENOSYS);
> -    return internal->h->prot->url_read_pause(internal->h, pause);
> -}
> -
> -static int64_t io_read_seek(void *opaque, int stream_index, int64_t
> timestamp, int flags)
> -{
> -    AVIOInternal *internal = opaque;
> -    if (!internal->h->prot->url_read_seek)
> -        return AVERROR(ENOSYS);
> -    return internal->h->prot->url_read_seek(internal->h, stream_index,
> timestamp, flags);
> -}
> -
>  int ffio_fdopen(AVIOContext **s, URLContext *h)
>  {
> -    AVIOInternal *internal = NULL;
>      uint8_t *buffer = NULL;
>      int buffer_size, max_packet_size;
>
> @@ -996,14 +950,10 @@ int ffio_fdopen(AVIOContext **s, URLContext *h)
>      if (!buffer)
>          return AVERROR(ENOMEM);
>
> -    internal = av_mallocz(sizeof(*internal));
> -    if (!internal)
> -        goto fail;
> -
> -    internal->h = h;
> -
> -    *s = avio_alloc_context(buffer, buffer_size, h->flags &
> AVIO_FLAG_WRITE,
> -                            internal, io_read_packet, io_write_packet,
> io_seek);
> +    *s = avio_alloc_context(buffer, buffer_size, h->flags &
> AVIO_FLAG_WRITE, h,
> +                            (int (*)(void *, uint8_t *, int))  ffurl_read,
> +                            (int (*)(void *, uint8_t *, int))
> ffurl_write,
> +                            (int64_t (*)(void *, int64_t,
> int))ffurl_seek);
>      if (!*s)
>          goto fail;
>
> @@ -1023,30 +973,28 @@ int ffio_fdopen(AVIOContext **s, URLContext *h)
>      (*s)->max_packet_size = max_packet_size;
>      (*s)->min_packet_size = h->min_packet_size;
>      if(h->prot) {
> -        (*s)->read_pause = io_read_pause;
> -        (*s)->read_seek  = io_read_seek;
> +        (*s)->read_pause = (int (*)(void *, int))h->prot->url_read_pause;
> +        (*s)->read_seek  =
> +            (int64_t (*)(void *, int, int64_t,
> int))h->prot->url_read_seek;
>
>          if (h->prot->url_read_seek)
>              (*s)->seekable |= AVIO_SEEKABLE_TIME;
>      }
> -    (*s)->short_seek_get = io_short_seek;
> +    (*s)->short_seek_get = (int (*)(void *))ffurl_get_short_seek;
>      (*s)->av_class = &ff_avio_class;
>      return 0;
>  fail:
> -    av_freep(&internal);
>      av_freep(&buffer);
>      return AVERROR(ENOMEM);
>  }
>
>  URLContext* ffio_geturlcontext(AVIOContext *s)
>  {
> -    AVIOInternal *internal;
>      if (!s)
>          return NULL;
>
> -    internal = s->opaque;
> -    if (internal && s->read_packet == io_read_packet)
> -        return internal->h;
> +    if (s->opaque && s->read_packet == (int (*)(void *, uint8_t *,
> int))ffurl_read)
> +        return s->opaque;
>      else
>          return NULL;
>  }
> @@ -1216,17 +1164,15 @@ int avio_open2(AVIOContext **s, const char
> *filename, int flags,
>
>  int avio_close(AVIOContext *s)
>  {
> -    AVIOInternal *internal;
>      URLContext *h;
>
>      if (!s)
>          return 0;
>
>      avio_flush(s);
> -    internal = s->opaque;
> -    h        = internal->h;
> +    h         = s->opaque;
> +    s->opaque = NULL;
>
> -    av_freep(&s->opaque);
>      av_freep(&s->buffer);
>      if (s->write_flag)
>          av_log(s, AV_LOG_VERBOSE, "Statistics: %d seeks, %d writeouts\n",
> s->seek_count, s->writeout_count);
> @@ -1318,8 +1264,7 @@ int avio_read_to_bprint(AVIOContext *h, AVBPrint
> *pb, size_t max_size)
>  int avio_accept(AVIOContext *s, AVIOContext **c)
>  {
>      int ret;
> -    AVIOInternal *internal = s->opaque;
> -    URLContext *sc = internal->h;
> +    URLContext *sc = s->opaque;
>      URLContext *cc = NULL;
>      ret = ffurl_accept(sc, &cc);
>      if (ret < 0)
> @@ -1329,8 +1274,7 @@ int avio_accept(AVIOContext *s, AVIOContext **c)
>
>  int avio_handshake(AVIOContext *c)
>  {
> -    AVIOInternal *internal = c->opaque;
> -    URLContext *cc = internal->h;
> +    URLContext *cc = c->opaque;
>      return ffurl_handshake(cc);
>  }
>
> --
> 2.20.1
>
>
Ping.

- Andreas


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