[Spice-devel] [vdagent-win PATCH v10 4/6] Support encoding PNG images

[Frediano Ziglio]

> 
> On Fri, Jul 21, 2017 at 02:51:39PM +0100, Frediano Ziglio wrote:
> > Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
> > Acked-by: Christophe Fergeau <cfergeau at redhat.com>
> > ---
> >  vdagent/imagepng.cpp | 110
> >  +++++++++++++++++++++++++++++++++++++++++++++++++--
> >  1 file changed, 106 insertions(+), 4 deletions(-)
> > 
> > diff --git a/vdagent/imagepng.cpp b/vdagent/imagepng.cpp
> > index 5642cc9..8a759f7 100644
> > --- a/vdagent/imagepng.cpp
> > +++ b/vdagent/imagepng.cpp
> > @@ -19,6 +19,7 @@
> >  
> >  #include <png.h>
> >  #include <algorithm>
> > +#include <vector>
> >  
> >  #include "imagepng.h"
> >  
> > @@ -36,9 +37,13 @@ private:
> >  struct BufferIo {
> >      uint8_t *buf;
> >      uint32_t pos, size;
> > +    bool allocated;
> >      BufferIo(uint8_t *_buf, uint32_t _size):
> > -        buf(_buf), pos(0), size(_size)
> > +        buf(_buf), pos(0), size(_size),
> > +        allocated(false)
> >      {}
> > +    ~BufferIo() { if (allocated) free(buf); }
> > +    uint8_t *release() { allocated = false; return buf; }
> >  };
> >  
> >  static void read_from_bufio(png_structp png, png_bytep out, png_size_t
> >  size)
> > @@ -50,6 +55,29 @@ static void read_from_bufio(png_structp png, png_bytep
> > out, png_size_t size)
> >      io.pos += size;
> >  }
> >  
> > +static void write_to_bufio(png_structp png, png_bytep in, png_size_t size)
> > +{
> > +    BufferIo& io(*(BufferIo*)png_get_io_ptr(png));
> > +    if (io.pos + size > io.size) {
> > +        uint32_t new_size = io.size ? io.size * 2 : 4096;
> > +        while (io.pos + size >= new_size) {
> > +            new_size *= 2;
> > +        }
> > +        uint8_t *p = (uint8_t*) realloc(io.buf, new_size);
> 
> you are missing a if (!allocated) io.buf = NULL; here. (though I might
> try to use a std::vector in this codepath?)
> 

You want a buffer to return (for the release() case).

> Christophe
> 

Maybe would be easier to define 2 classes, one for read and another for
write, they are quite different.

Frediano