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better handling of GIFs with out of bounds frames 

The recent reworking of gifload did not check for out of bounds frames
before setting DISPOSE_BACKGROUND.
This commit is contained in:
John Cupitt 2020-02-10 17:34:45 +00:00
parent 3285ef152a
commit 3ad3c30ab4
1 changed files with 26 additions and 21 deletions
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47
libvips/foreign/gifload.c
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@ -846,14 +846,14 @@ vips_foreign_load_gif_build_cmap( VipsForeignLoadGif *gif )
static void
vips_foreign_load_gif_render_line( VipsForeignLoadGif *gif,
int width, VipsPel * restrict dst )
int width, VipsPel * restrict dst, VipsPel * restrict src )
{
guint32 *idst = (guint32 *) dst;
guint32 * restrict idst = (guint32 *) dst;
int x;
for( x = 0; x < width; x++ ) {
VipsPel v = gif->line[x];
VipsPel v = src[x];
if( v != gif->transparent_index )
idst[x] = gif->cmap[v];
@ -873,19 +873,6 @@ vips_foreign_load_gif_render( VipsForeignLoadGif *gif )
return( -1 );
}
/* Update the colour map for this frame.
*/
vips_foreign_load_gif_build_cmap( gif );
/* PREVIOUS means we init the frame with the last un-disposed frame.
* So the last un-disposed frame is used as a backdrop for the new
* frame.
*/
if( gif->dispose == DISPOSE_PREVIOUS )
memcpy( VIPS_IMAGE_ADDR( gif->scratch, 0, 0 ),
VIPS_IMAGE_ADDR( gif->previous, 0, 0 ),
VIPS_IMAGE_SIZEOF_IMAGE( gif->scratch ) );
/* giflib does not check that the Left / Top / Width / Height for this
* Image is inside the canvas.
*
@ -906,8 +893,26 @@ vips_foreign_load_gif_render( VipsForeignLoadGif *gif )
"out of bounds frame of %d x %d pixels at %d x %d\n",
file->Image.Width, file->Image.Height,
file->Image.Left, file->Image.Top );
/* Don't flag an error -- many GIFs have this problem.
*/
return( 0 );
}
else if( file->Image.Interlace ) {
/* Update the colour map for this frame.
*/
vips_foreign_load_gif_build_cmap( gif );
/* PREVIOUS means we init the frame with the last un-disposed frame.
* So the last un-disposed frame is used as a backdrop for the new
* frame.
*/
if( gif->dispose == DISPOSE_PREVIOUS )
memcpy( VIPS_IMAGE_ADDR( gif->scratch, 0, 0 ),
VIPS_IMAGE_ADDR( gif->previous, 0, 0 ),
VIPS_IMAGE_SIZEOF_IMAGE( gif->scratch ) );
if( file->Image.Interlace ) {
int i;
VIPS_DEBUG_MSG( "vips_foreign_load_gif_render: "
@ -931,7 +936,7 @@ vips_foreign_load_gif_render( VipsForeignLoadGif *gif )
}
vips_foreign_load_gif_render_line( gif,
file->Image.Width, dst );
file->Image.Width, dst, gif->line );
}
}
}
@ -954,14 +959,14 @@ vips_foreign_load_gif_render( VipsForeignLoadGif *gif )
}
vips_foreign_load_gif_render_line( gif,
file->Image.Width, dst );
file->Image.Width, dst, gif->line );
}
}
/* Copy the result to frame, which then is picked up from outside
*/
memcpy( VIPS_IMAGE_ADDR( gif->frame, 0, 0 ),
VIPS_IMAGE_ADDR(gif->scratch, 0, 0 ),
VIPS_IMAGE_ADDR( gif->scratch, 0, 0 ),
VIPS_IMAGE_SIZEOF_IMAGE( gif->frame ) );
if( gif->dispose == DISPOSE_BACKGROUND ) {
@ -996,7 +1001,7 @@ vips_foreign_load_gif_render( VipsForeignLoadGif *gif )
* DISPOSE_PREVIOUS is specified in a later frame.
*/
memcpy( VIPS_IMAGE_ADDR( gif->previous, 0, 0 ),
VIPS_IMAGE_ADDR(gif->frame, 0, 0 ),
VIPS_IMAGE_ADDR( gif->frame, 0, 0 ),
VIPS_IMAGE_SIZEOF_IMAGE( gif->previous ) );
/* Reset values, as Graphic Control Extension is optional