[Spice-devel] [spice-server v6 7/9] reds: drop sscanf() in favour of g_strsplit()

Victor Toso victortoso at redhat.com
Tue Jan 31 14:13:05 UTC 2017


Hi,

On Tue, Jan 31, 2017 at 07:16:04AM -0500, Frediano Ziglio wrote:
> >
> > From: Victor Toso <me at victortoso.com>
> >
> > As there is a need to iterate over every encoder:codec pair and we do
> > a check for every encoder and every codec, g_strsplit() is less
> > complex and easier to follow.
> >
> > This change makes much easier to extend the input which is currently a
> > list of tuples encoder:video-codec.
> >
> > Signed-off-by: Victor Toso <victortoso at redhat.com>
>
> I had a though this morning about the syntax.
>
> We are moving from a set or "encoder:codec" separated with ";" to
> a set of "encoder:codec:priority". All this to allow same priority in
> the list. Why not having a "light" separator, something like
>
> "gstreamer:vp8 gstreamer:h264;gstreamer:h264;spice:mjpeg"
>
> (not the space). So the first 2 will have same "priority" while the

typo: s/not the space/note the space

> others less (but different) ?

At first I did not understand so I'll try to clarify slightly now that
I've talked with Frediano.

Current input that is supported by the API is like this:

[0] encoder1:codec1;encoder2:codec3;encoder2:codec2;

- We do have the priority set here, which is: codec1 > codec3 > codec2.

- We also have a way to disable values, for instance codec4 will never
  be used because it was not set.

- We don't have a way to say that a few codecs might have the *same*
  priority, which is addressed by Frediano's suggestions, such as:

[1] encoder1:codec1 encoder2:codec3;encoder2:codec2;

- The space means that both tuples have the same priority, meaning:
  codec1 == codec3 > codec2

---

Just for reference, what I have proposed is an additional (numeric and
optional) field, and following the example above it would be:

[2] encoder1:codec1:2;encoder2:codec3:2;encoder2:codec2:1;

I guess both have pros/cons and some discussion is needed!

Thanks!
  toso

>
> > ---
> >  server/reds.c                      | 63
> >  ++++++++++++++++++--------------------
> >  server/tests/test-codecs-parsing.c |  8 ++---
> >  2 files changed, 33 insertions(+), 38 deletions(-)
> > 
> > diff --git a/server/reds.c b/server/reds.c
> > index fb58bd0..d20edee 100644
> > --- a/server/reds.c
> > +++ b/server/reds.c
> > @@ -3527,34 +3527,15 @@ static const int video_codec_caps[] = {
> >  };
> >  
> >  
> > -/* Expected string:  encoder:codec;encoder:codec */
> > -static const char* parse_video_codecs(const char *codecs, char **encoder,
> > -                                      char **codec)
> > -{
> > -    if (!codecs) {
> > -        return NULL;
> > -    }
> > -    while (*codecs == ';') {
> > -        codecs++;
> > -    }
> > -    if (!*codecs) {
> > -        return NULL;
> > -    }
> > -    int n;
> > -    *encoder = *codec = NULL;
> > -    if (sscanf(codecs, "%m[0-9a-zA-Z_]:%m[0-9a-zA-Z_]%n", encoder, codec,
> > &n) != 2) {
> > -        while (*codecs != '\0' && *codecs != ';') {
> > -            codecs++;
> > -        }
> > -        return codecs;
> > -    }
> > -    return codecs + n;
> > -}
> > -
> > +/*
> > + * @codecs should be described in a semi-colon separated list of
> > encoder:codec.
> > + * e.g: "gstreamer:vp8;spice:mjpeg"
> > + */
> >  static void reds_set_video_codecs_from_string(RedsState *reds, const char
> >  *codecs)
> >  {
> > -    char *encoder_name, *codec_name;
> >      GArray *video_codecs;
> > +    gchar **preferences;
> > +    gint i;
> >  
> >      g_return_if_fail(codecs != NULL);
> >  
> > @@ -3563,13 +3544,29 @@ static void
> > reds_set_video_codecs_from_string(RedsState *reds, const char *codec
> >      }
> >  
> >      video_codecs = g_array_new(FALSE, FALSE, sizeof(RedVideoCodec));
> > -    const char *c = codecs;
> > -    while ( (c = parse_video_codecs(c, &encoder_name, &codec_name)) ) {
> > +    preferences = g_strsplit(codecs, ";", -1);
> > +    for (i = 0; preferences[i] != NULL; i++) {
> > +        const gchar *encoder_name, *codec_name;
> >          uint32_t encoder_index, codec_index;
> > -        if (!encoder_name || !codec_name) {
> > -            spice_warning("spice: invalid encoder:codec value at %s",
> > codecs);
> > +        gchar **pref;
> > +
> > +        /* Don't bother with empty strings that would be an extra ';'
> > somewhere */
> > +        if (g_str_equal(preferences[i], "")) {
> > +            continue;
> > +        }
> > +
> > +        pref = g_strsplit(preferences[i], ":", 2);
> >  
> > -        } else if (!get_name_index(video_encoder_names, encoder_name,
> > &encoder_index)){
> > +        if (pref[0] == NULL || pref[1] == NULL) {
> > +            spice_warning("spice: invalid encoder:codec value at '%s'",
> > preferences[i]);
> > +            g_strfreev(pref);
> > +            continue;
> > +        }
> > +
> > +        encoder_name = pref[0];
> > +        codec_name = pref[1];
> > +
> > +        if (!get_name_index(video_encoder_names, encoder_name,
> > &encoder_index)){
> >              spice_warning("spice: unknown video encoder %s", encoder_name);
> >  
> >          } else if (!get_name_index(video_codec_names, codec_name,
> >          &codec_index)) {
> > @@ -3585,11 +3582,9 @@ static void
> > reds_set_video_codecs_from_string(RedsState *reds, const char *codec
> >              new_codec.cap = video_codec_caps[codec_index];
> >              g_array_append_val(video_codecs, new_codec);
> >          }
> > -
> > -        free(encoder_name);
> > -        free(codec_name);
> > -        codecs = c;
> > +        g_strfreev(pref);
> >      }
> > +    g_strfreev(preferences);
> >  
> >      if (video_codecs->len == 0) {
> >          spice_warning("Failed to set video codecs, input string: '%s'",
> >          codecs);
> > diff --git a/server/tests/test-codecs-parsing.c
> > b/server/tests/test-codecs-parsing.c
> > index 5af2e5d..16fab24 100644
> > --- a/server/tests/test-codecs-parsing.c
> > +++ b/server/tests/test-codecs-parsing.c
> > @@ -84,12 +84,12 @@ static void codecs_bad(void)
> >          },{
> >              ";:;",
> >              G_LOG_LEVEL_WARNING,
> > -            "*spice: invalid encoder:codec value*",
> > +            "*spice: unknown video encoder*",
> >              TRUE,
> >          },{
> >              "::::",
> >              G_LOG_LEVEL_WARNING,
> > -            "*spice: invalid encoder:codec value*",
> > +            "*spice: unknown video encoder*",
> >              TRUE,
> >          },{
> >              "missingcolon",
> > @@ -99,12 +99,12 @@ static void codecs_bad(void)
> >          },{
> >              ":missing_encoder",
> >              G_LOG_LEVEL_WARNING,
> > -            "*spice: invalid encoder:codec value*",
> > +            "*spice: unknown video encoder*",
> >              TRUE,
> >          },{
> >              "missing_value:;",
> >              G_LOG_LEVEL_WARNING,
> > -            "*spice: invalid encoder:codec value*",
> > +            "*spice: unknown video encoder*",
> >              TRUE,
> >          },{
> >              "unknown_encoder:mjpeg",
> > --
> > 2.9.3
> > 
> > _______________________________________________
> > Spice-devel mailing list
> > Spice-devel at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/spice-devel
> > 
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