[vlc-devel] [PATCH 1/2] demux: mkv: parse language codes with embedded country codes

[Filip Roséen]

Hi Shaleen,

On 2017-04-12 14:44, Shaleen Jain wrote:

> fixes bug: https://trac.videolan.org/vlc/ticket/11813
> ---
>  modules/demux/mkv/matroska_segment_parse.cpp | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/modules/demux/mkv/matroska_segment_parse.cpp b/modules/demux/mkv/matroska_segment_parse.cpp
> index f4d73613c9..94f54838f8 100644
> --- a/modules/demux/mkv/matroska_segment_parse.cpp
> +++ b/modules/demux/mkv/matroska_segment_parse.cpp
> @@ -80,6 +80,17 @@ static inline char * ToUTF8( const UTFstring &u )
>      return strdup( u.GetUTF8().c_str() );
>  }
>  
> +// https://www.matroska.org/technical/specs/index.html#languages
> +static inline char * parseLanguage(const char * lang)
> +{
> +    char* psz_lang = strdup(lang);
> +	if( strchr(psz_lang, '-' ) != NULL ) {

Potential *null-dereference* if `strdup` fails.

> +		return strtok(psz_lang, "-");
> +	} else {
> +		return psz_lang;
> +	}
> +}
> +
>  /*****************************************************************************
>   * ParseSeekHead:
>   *****************************************************************************/
> @@ -380,7 +391,7 @@ void matroska_segment_c::ParseTrackEntry( KaxTrackEntry *m )
>          E_CASE( KaxTrackLanguage, lang )
>          {
>              free( vars.tk->fmt.psz_language );
> -            vars.tk->fmt.psz_language = strdup( std::string( lang ).c_str() );
> +            vars.tk->fmt.psz_language = parseLanguage(std::string( lang ).c_str());

As you are currently in a context where utilities in the standard
library associated with C++ can be used, please do so. It is an
*anti-pattern* to declare a helper-function without linkage written in
C, in a translation-unit in C++.

**TLDR**: Make the argument to `parseLanguage` a `std::string const&`,
though it is certainly debatable if you really need this to be a
separate function as it only used once, and the functionality can
certainly be implemented directly in the relevant `E_CASE`.

>              debug( vars, "Track Language=`%s'", vars.tk->fmt.psz_language );
>          }
>          E_CASE( KaxCodecID, codecid )

Best Regards,\
Filip
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