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fix int overflow in flatten

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This commit is contained in:
John Cupitt 2019-08-02 10:17:57 +01:00
parent c361731693
commit 0a225314b9
1 changed files with 23 additions and 23 deletions
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46
libvips/conversion/flatten.c
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@ -99,6 +99,25 @@ G_DEFINE_TYPE( VipsFlatten, vips_flatten, VIPS_TYPE_CONVERSION );
} \
}
/* Same, but with float arithmetic. Necessary for short/int to prevent
* overflow.
*/
#define VIPS_FLATTEN_BLACK_FLOAT( TYPE ) { \
TYPE * restrict p = (TYPE *) in; \
TYPE * restrict q = (TYPE *) out; \
\
for( x = 0; x < width; x++ ) { \
TYPE alpha = p[bands - 1]; \
int b; \
\
for( b = 0; b < bands - 1; b++ ) \
q[b] = ((double) p[b] * alpha) / max_alpha; \
\
p += bands; \
q += bands - 1; \
} \
}
/* Flatten with any background.
*/
#define VIPS_FLATTEN( TYPE ) { \
@ -119,25 +138,6 @@ G_DEFINE_TYPE( VipsFlatten, vips_flatten, VIPS_TYPE_CONVERSION );
} \
}
/* Same, but with float arithmetic. Necessary for int/uint to prevent
* overflow.
*/
#define VIPS_FLATTEN_BLACK_FLOAT( TYPE ) { \
TYPE * restrict p = (TYPE *) in; \
TYPE * restrict q = (TYPE *) out; \
\
for( x = 0; x < width; x++ ) { \
TYPE alpha = p[bands - 1]; \
int b; \
\
for( b = 0; b < bands - 1; b++ ) \
q[b] = ((double) p[b] * alpha) / max_alpha; \
\
p += bands; \
q += bands - 1; \
} \
}
#define VIPS_FLATTEN_FLOAT( TYPE ) { \
TYPE * restrict p = (TYPE *) in; \
TYPE * restrict q = (TYPE *) out; \
@ -187,11 +187,11 @@ vips_flatten_black_gen( VipsRegion *or, void *vseq, void *a, void *b,
break;
case VIPS_FORMAT_USHORT:
VIPS_FLATTEN_BLACK( unsigned short );
VIPS_FLATTEN_BLACK_FLOAT( unsigned short );
break;
case VIPS_FORMAT_SHORT:
VIPS_FLATTEN_BLACK( signed short );
VIPS_FLATTEN_BLACK_FLOAT( signed short );
break;
case VIPS_FORMAT_UINT:
@ -252,11 +252,11 @@ vips_flatten_gen( VipsRegion *or, void *vseq, void *a, void *b,
break;
case VIPS_FORMAT_USHORT:
VIPS_FLATTEN( unsigned short );
VIPS_FLATTEN_FLOAT( unsigned short );
break;
case VIPS_FORMAT_SHORT:
VIPS_FLATTEN( signed short );
VIPS_FLATTEN_FLOAT( signed short );
break;
case VIPS_FORMAT_UINT: