[FFmpeg-devel] [PATCH] lavf/aviobuf: add ff_get_line2() variant

[Michael Niedermayer]

On Tue, Oct 18, 2016 at 01:32:12PM +0200, Stefano Sabatini wrote:
> On date Thursday 2016-10-13 21:59:19 +0200, Michael Niedermayer encoded:
> > On Thu, Oct 13, 2016 at 07:40:59PM +0200, Stefano Sabatini wrote:
> > > This allows to probe if the read line was partially discarded.
> > > ---
> > >  libavformat/aviobuf.c  | 10 +++++++++-
> > >  libavformat/internal.h | 14 ++++++++++++++
> > >  2 files changed, 23 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
> > > index 134d627..28183b4 100644
> > > --- a/libavformat/aviobuf.c
> > > +++ b/libavformat/aviobuf.c
> > > @@ -764,18 +764,26 @@ unsigned int avio_rb32(AVIOContext *s)
> > >  
> > >  int ff_get_line(AVIOContext *s, char *buf, int maxlen)
> > >  {
> > > -    int i = 0;
> > > +    return ff_get_line2(s, buf, maxlen, NULL);
> > > +}
> > > +
> > > +int ff_get_line2(AVIOContext *s, char *buf, int maxlen, int *readlen)
> > > +{
> > > +    int i = 0, j = 0;
> > >      char c;
> > >  
> > >      do {
> > >          c = avio_r8(s);
> > >          if (c && i < maxlen-1)
> > >              buf[i++] = c;
> > > +        j++;
> > >      } while (c != '\n' && c != '\r' && c);
> > 
> 
> > "\n" and "\0" would i belive both have a j=1 but they would have
> > differig i
> > is that intended ? (seems to me that this would make truncation
> > detection more annoying)
> > or am i missing something that avoids this difference?
> 
> Improved version in attachment.
> -- 
> FFmpeg = Fascinating Foolish Mystic Puritan Egregious Gymnast

>  aviobuf.c  |   18 +++++++++++++++---
>  internal.h |   14 ++++++++++++++
>  2 files changed, 29 insertions(+), 3 deletions(-)
> 19b979c45f087997ac69fba2caf5504c933acfc8  0001-lavf-aviobuf-add-ff_get_line2-variant.patch
> From 58c1cad434447d48246e153e3a1a391d72d23c7b Mon Sep 17 00:00:00 2001
> From: Stefano Sabatini <stefasab at gmail.com>
> Date: Thu, 13 Oct 2016 16:36:30 +0200
> Subject: [PATCH] lavf/aviobuf: add ff_get_line2() variant
> 
> This allows to probe if the read line was partially discarded.
> ---
>  libavformat/aviobuf.c  | 18 +++++++++++++++---
>  libavformat/internal.h | 14 ++++++++++++++
>  2 files changed, 29 insertions(+), 3 deletions(-)
> 
> diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
> index 134d627..29bcf1e 100644
> --- a/libavformat/aviobuf.c
> +++ b/libavformat/aviobuf.c
> @@ -764,18 +764,30 @@ unsigned int avio_rb32(AVIOContext *s)
>  
>  int ff_get_line(AVIOContext *s, char *buf, int maxlen)
>  {
> -    int i = 0;
> +    return ff_get_line2(s, buf, maxlen, NULL);
> +}
> +
> +int ff_get_line2(AVIOContext *s, char *buf, int maxlen, int *readlen)
> +{
> +    int i = 0, j = 0;
>      char c;
>  
> +    while (1) {
>          c = avio_r8(s);
>          if (c && i < maxlen-1)
>              buf[i++] = c;
> +        if (c != '\n' && c != '\r' && c) {
> +            j++;
> +        } else {
> +            break;
> +        }
> +    }

a string like "\n"
would have a strlen of 1
but readlen of 0
while a string like "X" would have a strlen and readlen of 1

is this difference intended ?
or maybe i misread the code

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Those who are too smart to engage in politics are punished by being
governed by those who are dumber. -- Plato 
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