[vlc-devel] [vlc-commits] decoder: add Destroy helper function for decoder owners

[Thomas Guillem]

On Mon, Feb 18, 2019, at 16:11, Steve Lhomme wrote:
> vlc | branch: master | Steve Lhomme <robux4 at ycbcr.xyz> | Mon Feb 18 
> 14:50:21 2019 +0100| [4a79e6a4929085cd78024e0c0367c2bc01ab11b4] | 
> committer: Steve Lhomme
> 
> decoder: add Destroy helper function for decoder owners
> 
> > http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=4a79e6a4929085cd78024e0c0367c2bc01ab11b4
> ---
> 
>  include/vlc_codec.h         |  7 +++++++
>  src/input/decoder_helpers.c | 29 +++++++++++++++++++++++++++++
>  src/libvlccore.sym          |  1 +
>  3 files changed, 37 insertions(+)
> 
> diff --git a/include/vlc_codec.h b/include/vlc_codec.h
> index c287953ba7..2042ad2424 100644
> --- a/include/vlc_codec.h
> +++ b/include/vlc_codec.h
> @@ -320,6 +320,13 @@ VLC_API void decoder_AbortPictures( decoder_t 
> *dec, bool b_abort );
>  VLC_API void decoder_Init( decoder_t *dec, const es_format_t * );
>  
>  /**
> + * Destroy a decoder and reset the structure.
> + *
> + * To be used by decoder owners.
> + */
> +VLC_API void decoder_Destroy( decoder_t **p_dec );
> +
> +/**
>   * This function queues a single picture to the video output.
>   *
>   * \note
> diff --git a/src/input/decoder_helpers.c b/src/input/decoder_helpers.c
> index 51f7ce8f6d..b60b830123 100644
> --- a/src/input/decoder_helpers.c
> +++ b/src/input/decoder_helpers.c
> @@ -28,6 +28,8 @@
>  
>  #include <vlc_common.h>
>  #include <vlc_codec.h>
> +#include <vlc_meta.h>
> +#include <vlc_modules.h>
>  
>  void decoder_Init( decoder_t *p_dec, const es_format_t *restrict p_fmt 
> )
>  {
> @@ -43,3 +45,30 @@ void decoder_Init( decoder_t *p_dec, const 
> es_format_t *restrict p_fmt )
>      es_format_Copy( &p_dec->fmt_in, p_fmt );
>      es_format_Init( &p_dec->fmt_out, p_fmt->i_cat, 0 );
>  }
> +
> +static void decoder_Clean( decoder_t *p_dec )
> +{
> +    es_format_Clean( &p_dec->fmt_in );
> +    es_format_Clean( &p_dec->fmt_out );
> +
> +    if ( p_dec->p_description )
> +    {
> +        vlc_meta_Delete(p_dec->p_description);
> +        p_dec->p_description = NULL;
> +    }
> +    if ( p_dec->p_module != NULL )
> +    {
> +        module_unneed(p_dec, p_dec->p_module);
> +        p_dec->p_module = NULL;
> +    }
> +}
> +
> +void decoder_Destroy( decoder_t **p_dec )
> +{
> +    if (*p_dec != NULL)
> +    {
> +        decoder_Clean( *p_dec );
> +        vlc_object_release( *p_dec );
> +        *p_dec = NULL;
> +    }

I really prefer to use a decoder_t * here.
There is not many functions in VLC that set the pointer to NULL. This will add more confusion.

I really prefer having a crash (via assert/ASAN) when a client is misusing an API (calling Destroy with a freed pointer) instead of ignoring it.

> +}
> diff --git a/src/libvlccore.sym b/src/libvlccore.sym
> index 09b5936180..906a449f2b 100644
> --- a/src/libvlccore.sym
> +++ b/src/libvlccore.sym
> @@ -74,6 +74,7 @@ date_Decrement
>  date_Increment
>  date_Init
>  decoder_Init
> +decoder_Destroy
>  decoder_AbortPictures
>  decoder_NewAudioBuffer
>  demux_PacketizerDestroy
> 
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