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sanity-check PNG read line size

This commit is contained in:
John Cupitt 2012-03-15 12:53:38 +00:00
parent 8126d48717
commit 2e7f4b2900
2 changed files with 21 additions and 22 deletions
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2
ChangeLog
View File

@ -1,4 +1,6 @@
13/3/12 started 7.28.2
- better PNG alpha handling
- sanity-check PNG read geometry
13/3/12 started 7.28.1
- add ICC profile read/write for png files

41
libvips/foreign/vipspng.c
View File

@ -40,6 +40,9 @@
* - add a longjmp() to our error handler to stop the default one running
* 13/3/12
* - add ICC profile read/write
* 15/3/12
* - better alpha handling
* - sanity check pixel geometry before allowing read
*/
/*
@ -213,32 +216,22 @@ png2vips_header( Read *read, VipsImage *out )
/* png_get_channels() gives us 1 band for palette images ... so look
* at colour_type for output bands.
*
* Ignore alpha, we detect that separately below.
*/
switch( color_type ) {
case PNG_COLOR_TYPE_PALETTE:
bands = 3;
/* If there's transparency in the palette, we make an alpha.
*/
if( png_get_valid( read->pPng, read->pInfo, PNG_INFO_tRNS ) )
bands = 4;
break;
case PNG_COLOR_TYPE_GRAY_ALPHA:
case PNG_COLOR_TYPE_GRAY:
bands = 1;
break;
case PNG_COLOR_TYPE_GRAY_ALPHA:
bands = 2;
break;
case PNG_COLOR_TYPE_RGB:
bands = 3;
break;
case PNG_COLOR_TYPE_RGB_ALPHA:
bands = 4;
bands = 3;
break;
default:
@ -264,17 +257,11 @@ png2vips_header( Read *read, VipsImage *out )
if( color_type == PNG_COLOR_TYPE_PALETTE )
png_set_palette_to_rgb( read->pPng );
/* Expand transparency images too.
/* Expand transparency.
*/
if( png_get_valid( read->pPng, read->pInfo, PNG_INFO_tRNS ) ) {
png_set_tRNS_to_alpha( read->pPng );
/* Some PNGs have an alpha but do not set color_type correctly
* .. make sure we add space for an alpha.
*/
if( color_type == PNG_COLOR_TYPE_GRAY ||
color_type == PNG_COLOR_TYPE_RGB )
bands += 1;
bands += 1;
}
/* Expand <8 bit images to full bytes.
@ -345,6 +332,16 @@ png2vips_header( Read *read, VipsImage *out )
(VipsCallbackFn) vips_free, profile_copy, proflen );
}
/* Sanity-check lines sizes.
*/
png_read_update_info( read->pPng, read->pInfo );
if( png_get_rowbytes( read->pPng, read->pInfo ) !=
VIPS_IMAGE_SIZEOF_LINE( out ) ) {
vips_error( "vipspng",
"%s", _( "unable to read PNG header" ) );
return( -1 );
}
return( 0 );
}