Re: [gst-cvs] gst-plugins-bad: apexsink: Use a union to avoid type-punning strict aliasing compiler warning.

[Peter Kjellerstedt]

> -----Original Message-----
> From: Jan Schmidt [mailto:[hidden email]]
> Sent: den 27 februari 2009 13:04
> To: [hidden email]
> Subject: [gst-cvs] gst-plugins-bad: apexsink: Use a union to avoid
> type-punning strict aliasing compiler warning.
>
> Module: gst-plugins-bad
> Branch: master
> Commit: 4a046a08a336e1cde0105f40461f67491f5b22a1
> URL:    http://cgit.freedesktop.org/gstreamer/gst-plugins-bad/commit/?id=4a046a08a336e1cde0105f40461f67491f5b22a1
>
> Author: Jan Schmidt <[hidden email]>
> Date:   Fri Feb 27 10:16:57 2009 +0000
>
> apexsink: Use a union to avoid type-punning strict aliasing compiler warning.
>
> ---
>
>  ext/apexsink/gstapexraop.c |   24 +++++++++++++++++-------
>  1 files changed, 17 insertions(+), 7 deletions(-)
>
> diff --git a/ext/apexsink/gstapexraop.c b/ext/apexsink/gstapexraop.c
> index 42b707c..98b7d86 100644
> --- a/ext/apexsink/gstapexraop.c
> +++ b/ext/apexsink/gstapexraop.c
> @@ -231,7 +231,17 @@ gst_apexraop_connect (GstApExRAOP * con)
>        creq[GST_APEX_RAOP_SDP_DEFAULT_LENGTH],
>        hreq[GST_APEX_RAOP_HDR_DEFAULT_LENGTH], *req;
>    RSA *rsa;
> -  guchar *mod, *exp, buf[4 + 8 + 16], rsakey[512];
> +  guchar *mod, *exp, rsakey[512];
> +  union gst_randbytes
> +  {
> +    struct asvals
> +    {
> +      gulong url_key;
> +      guint64 conn_id;
> +      guchar challenge[16];
> +    } v;
> +    guchar buf[4 + 8 + 16];

Wouldn't it be better to use:

    guchar buf[sizeof (struct asvals)];

> +  } randbuf;
>    gsize size;
>    struct sockaddr_in ioaddr;
>    socklen_t iolen;

//Peter


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[Jan Schmidt-6]

On Tue, 2009-03-03 at 10:24 +0100, Peter Kjellerstedt wrote:
> > -----Original Message-----

> > ---
> >
> >  ext/apexsink/gstapexraop.c |   24 +++++++++++++++++-------
> >  1 files changed, 17 insertions(+), 7 deletions(-)
> >
> > diff --git a/ext/apexsink/gstapexraop.c b/ext/apexsink/gstapexraop.c
> > index 42b707c..98b7d86 100644
> > --- a/ext/apexsink/gstapexraop.c
> > +++ b/ext/apexsink/gstapexraop.c
> > @@ -231,7 +231,17 @@ gst_apexraop_connect (GstApExRAOP * con)
> >        creq[GST_APEX_RAOP_SDP_DEFAULT_LENGTH],
> >        hreq[GST_APEX_RAOP_HDR_DEFAULT_LENGTH], *req;
> >    RSA *rsa;
> > -  guchar *mod, *exp, buf[4 + 8 + 16], rsakey[512];
> > +  guchar *mod, *exp, rsakey[512];
> > +  union gst_randbytes
> > +  {
> > +    struct asvals
> > +    {
> > +      gulong url_key;
> > +      guint64 conn_id;
> > +      guchar challenge[16];
> > +    } v;
> > +    guchar buf[4 + 8 + 16];
>
> Wouldn't it be better to use:
>
>     guchar buf[sizeof (struct asvals)];
>
> > +  } randbuf;
> >    gsize size;
> >    struct sockaddr_in ioaddr;
> >    socklen_t iolen;
>

Easier to read maybe. It makes no difference in the end though - the
union will have the overall size of the larger structure anyway. The
buffer could be declared guchar buf[1], and it'd all be fine.

J.
--
Jan Schmidt <[hidden email]>


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-OSBC tackles the biggest issue in open source: Open Sourcing the Enterprise
-Strategies to boost innovation and cut costs with open source participation
-Receive a $600 discount off the registration fee with the source code: SFAD
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