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relax GIF parse rules again

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lots of GIFs are very badly structured :(
This commit is contained in:
John Cupitt 2019-08-26 10:54:45 +01:00
parent db6e6a0076
commit 25e4577361
1 changed files with 10 additions and 15 deletions
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25
libvips/foreign/gifload.c
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@ -404,7 +404,7 @@ vips_foreign_load_gif_code_next( VipsForeignLoadGif *gif,
/* Quickly scan an image record. /* Quickly scan an image record.
*/ */
static int static int
vips_foreign_load_gif_scan_image_record( VipsForeignLoadGif *gif ) vips_foreign_load_gif_scan_image( VipsForeignLoadGif *gif )
{ {
VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( gif ); VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( gif );
GifFileType *file = gif->file; GifFileType *file = gif->file;
@ -413,6 +413,11 @@ vips_foreign_load_gif_scan_image_record( VipsForeignLoadGif *gif )
GifByteType *extension; GifByteType *extension;
if( DGifGetImageDesc( gif->file ) == GIF_ERROR ) {
vips_foreign_load_gif_error( gif );
return( -1 );
}
/* Check that the frame looks sane. Perhaps giflib checks /* Check that the frame looks sane. Perhaps giflib checks
* this for us. * this for us.
*/ */
@ -587,6 +592,8 @@ vips_foreign_load_gif_set_header( VipsForeignLoadGif *gif, VipsImage *image )
/* Attempt to quickly scan a GIF and discover what we need for our header. We /* Attempt to quickly scan a GIF and discover what we need for our header. We
* need to scan the whole file to get n_pages, transparency and colour. * need to scan the whole file to get n_pages, transparency and colour.
*
* Don't flag errors during header scan. Many GIFs do not follow spec.
*/ */
static int static int
vips_foreign_load_gif_header( VipsForeignLoad *load ) vips_foreign_load_gif_header( VipsForeignLoad *load )
@ -604,23 +611,12 @@ vips_foreign_load_gif_header( VipsForeignLoad *load )
gif->n_pages = 0; gif->n_pages = 0;
do { do {
/* Don't flag errors during header scan. Some corrupt GIFs
* will fail.
*/
if( DGifGetRecordType( gif->file, &record ) == GIF_ERROR ) if( DGifGetRecordType( gif->file, &record ) == GIF_ERROR )
continue; continue;
switch( record ) { switch( record ) {
case IMAGE_DESC_RECORD_TYPE: case IMAGE_DESC_RECORD_TYPE:
if( DGifGetImageDesc( gif->file ) == GIF_ERROR ) { (void) vips_foreign_load_gif_scan_image( gif );
vips_foreign_load_gif_error( gif );
return( -1 );
}
/* Read in the image record.
*/
if( vips_foreign_load_gif_scan_image_record( gif ) )
return( -1 );
gif->n_pages += 1; gif->n_pages += 1;
@ -630,8 +626,7 @@ vips_foreign_load_gif_header( VipsForeignLoad *load )
/* We will need to fetch the extensions to check for /* We will need to fetch the extensions to check for
* cmaps and transparency. * cmaps and transparency.
*/ */
if( vips_foreign_load_gif_scan_extension( gif ) ) (void) vips_foreign_load_gif_scan_extension( gif );
return( -1 );
break; break;
case TERMINATE_RECORD_TYPE: case TERMINATE_RECORD_TYPE: