[FFmpeg-devel] [RFC][PATCH 1/2] lavf/avio: Introduce avio_find_protocol

[Stefano Sabatini]

On date Sunday 2014-01-05 03:29:35 +0100, Alexander Strasser encoded:
> Make it possible to find out what protocol will be chosen
> for a given URL.
> 
> TODO: version bump
> 
> Signed-off-by: Alexander Strasser <eclipse7 at gmx.net>
> ---
>  libavformat/avio.c | 39 +++++++++++++++++++++++++++++----------
>  libavformat/avio.h |  9 +++++++++
>  2 files changed, 38 insertions(+), 10 deletions(-)
> 
> diff --git a/libavformat/avio.c b/libavformat/avio.c
> index 225d982..309b854 100644
> --- a/libavformat/avio.c
> +++ b/libavformat/avio.c
> @@ -215,18 +215,12 @@ int ffurl_connect(URLContext *uc, AVDictionary **options)
>      "ABCDEFGHIJKLMNOPQRSTUVWXYZ"                \
>      "0123456789+-."
>  
> -int ffurl_alloc(URLContext **puc, const char *filename, int flags,
> -                const AVIOInterruptCB *int_cb)
> +static struct URLProtocol *url_find_protocol(const char *filename)
>  {
>      URLProtocol *up = NULL;
>      char proto_str[128], proto_nested[128], *ptr;
>      size_t proto_len = strspn(filename, URL_SCHEME_CHARS);
>  
> -    if (!first_protocol) {
> -        av_log(NULL, AV_LOG_WARNING, "No URL Protocols are registered. "
> -                                     "Missing call to av_register_all()?\n");
> -    }
> -
>      if (filename[proto_len] != ':' &&
>          (filename[proto_len] != ',' || !strchr(filename + proto_len + 1, ':')) ||
>          is_dos_path(filename))
> @@ -243,13 +237,31 @@ int ffurl_alloc(URLContext **puc, const char *filename, int flags,
>  
>      while (up = ffurl_protocol_next(up)) {
>          if (!strcmp(proto_str, up->name))
> -            return url_alloc_for_protocol(puc, up, filename, flags, int_cb);
> +            break;
>          if (up->flags & URL_PROTOCOL_FLAG_NESTED_SCHEME &&
>              !strcmp(proto_nested, up->name))
> -            return url_alloc_for_protocol(puc, up, filename, flags, int_cb);
> +            break;
>      }
> +
> +    return up;
> +}
> +
> +int ffurl_alloc(URLContext **puc, const char *filename, int flags,
> +                const AVIOInterruptCB *int_cb)
> +{
> +    URLProtocol *p = NULL;
> +
> +    if (!first_protocol) {
> +        av_log(NULL, AV_LOG_WARNING, "No URL Protocols are registered. "
> +                                     "Missing call to av_register_all()?\n");
> +    }
> +
> +    p = url_find_protocol(filename);
> +    if (p)
> +       return url_alloc_for_protocol(puc, p, filename, flags, int_cb);
> +
>      *puc = NULL;
> -    if (!strcmp("https", proto_str))
> +    if (av_strstart("https:", filename, NULL))
>          av_log(NULL, AV_LOG_WARNING, "https protocol not found, recompile with openssl or gnutls enabled.\n");
>      return AVERROR_PROTOCOL_NOT_FOUND;
>  }
> @@ -376,6 +388,13 @@ int ffurl_close(URLContext *h)
>  }
>  
>  

Nit++: remove superfluous empty line

> +const char *avio_find_protocol(const char *url)
> +{
> +    URLProtocol *p = url_find_protocol(url);
> +
> +    return p ? p->name : "";
> +}

return p ? p->name : NULL;
?

> +
>  int avio_check(const char *url, int flags)
>  {
>      URLContext *h;
> diff --git a/libavformat/avio.h b/libavformat/avio.h
> index 4f4ac3c..737dc40 100644
> --- a/libavformat/avio.h
> +++ b/libavformat/avio.h
> @@ -151,6 +151,15 @@ typedef struct AVIOContext {
>  /* unbuffered I/O */
>  
>  /**
> + * Return the name of the protocol that will handle the passed URL.
> + * 
> + * An empty string is returned if no protocol could be found for the given URL.
> + *
> + * @return Name of the protocol or an empty string.
> + */
> +const char *avio_find_protocol(const char *url);

I'd prefer if this would return NULL in case no protocol was
found, so you can do if (!protocol_str).

LGTM otherwise (but I'm no avio maintainer).
-- 
FFmpeg = Free & Fantastic Mournful Pitiful Erroneous Gem