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

[Frediano Ziglio]

> 
> On 07/24/2017 01:22 PM, Christophe Fergeau wrote:
> > 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.
> 
> Why is that ? if (!allocated) then io.buf is not freed.
> 

Yes, is used for reading from a buffer you don't own

> Note that man 3 realloc says:
> "If realloc() fails, the original block is left untouched; it
>   is not freed or moved."
> 
> Uri.
> 
> > (though I might
> > try to use a std::vector in this codepath?)
> > Christophe
> 
> 

Frediano