jas_image_t *jp2_decode(jas_stream_t *in, char *optstr)
{
	jp2_box_t *box;
	int found;
	jas_image_t *image;
	jp2_dec_t *dec;
	bool samedtype;
	int dtype;
	unsigned int i;
	jp2_cmap_t *cmapd;
	jp2_pclr_t *pclrd;
	jp2_cdef_t *cdefd;
	unsigned int channo;
	int newcmptno;
	int_fast32_t *lutents;
#if 0
	jp2_cdefchan_t *cdefent;
	int cmptno;
#endif
	jp2_cmapent_t *cmapent;
	jas_icchdr_t icchdr;
	jas_iccprof_t *iccprof;

	dec = 0;
	box = 0;
	image = 0;

	if (!(dec = jp2_dec_create())) {
		goto error;
	}

	/* Get the first box.  This should be a JP box. */
	if (!(box = jp2_box_get(in))) {
		jas_eprintf("error: cannot get box\n");
		goto error;
	}
	if (box->type != JP2_BOX_JP) {
		jas_eprintf("error: expecting signature box\n");
		goto error;
	}
	if (box->data.jp.magic != JP2_JP_MAGIC) {
		jas_eprintf("incorrect magic number\n");
		goto error;
	}
	jp2_box_destroy(box);
	box = 0;

	/* Get the second box.  This should be a FTYP box. */
	if (!(box = jp2_box_get(in))) {
		goto error;
	}
	if (box->type != JP2_BOX_FTYP) {
		jas_eprintf("expecting file type box\n");
		goto error;
	}
	jp2_box_destroy(box);
	box = 0;

	/* Get more boxes... */
	found = 0;
	while ((box = jp2_box_get(in))) {
		if (jas_getdbglevel() >= 1) {
			jas_eprintf("got box type %s\n", box->info->name);
		}
		switch (box->type) {
		case JP2_BOX_JP2C:
			found = 1;
			break;
		case JP2_BOX_IHDR:
			if (!dec->ihdr) {
				dec->ihdr = box;
				box = 0;
			}
			break;
		case JP2_BOX_BPCC:
			if (!dec->bpcc) {
				dec->bpcc = box;
				box = 0;
			}
			break;
		case JP2_BOX_CDEF:
			if (!dec->cdef) {
				dec->cdef = box;
				box = 0;
			}
			break;
		case JP2_BOX_PCLR:
			if (!dec->pclr) {
				dec->pclr = box;
				box = 0;
			}
			break;
		case JP2_BOX_CMAP:
			if (!dec->cmap) {
				dec->cmap = box;
				box = 0;
			}
			break;
		case JP2_BOX_COLR:
			if (!dec->colr) {
				dec->colr = box;
				box = 0;
			}
			break;
		}
		if (box) {
			jp2_box_destroy(box);
			box = 0;
		}
		if (found) {
			break;
		}
	}

	if (!found) {
		jas_eprintf("error: no code stream found\n");
		goto error;
	}

	if (!(dec->image = jpc_decode(in, optstr))) {
		jas_eprintf("error: cannot decode code stream\n");
		goto error;
	}

	/* An IHDR box must be present. */
	if (!dec->ihdr) {
		jas_eprintf("error: missing IHDR box\n");
		goto error;
	}
 
 	/* Does the number of components indicated in the IHDR box match
 	  the value specified in the code stream? */
	if (dec->ihdr->data.ihdr.numcmpts != JAS_CAST(jas_uint,
 	  jas_image_numcmpts(dec->image))) {
 		jas_eprintf("warning: number of components mismatch\n");
 	}

	/* At least one component must be present. */
	if (!jas_image_numcmpts(dec->image)) {
		jas_eprintf("error: no components\n");
		goto error;
	}

 	/* Determine if all components have the same data type. */
 	samedtype = true;
 	dtype = jas_image_cmptdtype(dec->image, 0);
	for (i = 1; i < JAS_CAST(jas_uint, jas_image_numcmpts(dec->image)); ++i) {
 		if (jas_image_cmptdtype(dec->image, i) != dtype) {
 			samedtype = false;
 			break;
		}
	}

	/* Is the component data type indicated in the IHDR box consistent
	  with the data in the code stream? */
	if ((samedtype && dec->ihdr->data.ihdr.bpc != JP2_DTYPETOBPC(dtype)) ||
	  (!samedtype && dec->ihdr->data.ihdr.bpc != JP2_IHDR_BPCNULL)) {
		jas_eprintf("warning: component data type mismatch\n");
	}

	/* Is the compression type supported? */
	if (dec->ihdr->data.ihdr.comptype != JP2_IHDR_COMPTYPE) {
		jas_eprintf("error: unsupported compression type\n");
		goto error;
	}

 	if (dec->bpcc) {
 		/* Is the number of components indicated in the BPCC box
 		  consistent with the code stream data? */
		if (dec->bpcc->data.bpcc.numcmpts != JAS_CAST(jas_uint, jas_image_numcmpts(
 		  dec->image))) {
 			jas_eprintf("warning: number of components mismatch\n");
 		}
 		/* Is the component data type information indicated in the BPCC
 		  box consistent with the code stream data? */
 		if (!samedtype) {
			for (i = 0; i < JAS_CAST(jas_uint, jas_image_numcmpts(dec->image));
 			  ++i) {
 				if (jas_image_cmptdtype(dec->image, i) !=
 				  JP2_BPCTODTYPE(dec->bpcc->data.bpcc.bpcs[i])) {
					jas_eprintf("warning: component data type mismatch\n");
				}
			}
		} else {
			jas_eprintf("warning: superfluous BPCC box\n");
		}
	}

	/* A COLR box must be present. */
	if (!dec->colr) {
		jas_eprintf("error: no COLR box\n");
		goto error;
	}

	switch (dec->colr->data.colr.method) {
	case JP2_COLR_ENUM:
		jas_image_setclrspc(dec->image, jp2_getcs(&dec->colr->data.colr));
		break;
	case JP2_COLR_ICC:
		iccprof = jas_iccprof_createfrombuf(dec->colr->data.colr.iccp,
		  dec->colr->data.colr.iccplen);
		if (!iccprof) {
			jas_eprintf("error: failed to parse ICC profile\n");
			goto error;
		}
		jas_iccprof_gethdr(iccprof, &icchdr);
		jas_eprintf("ICC Profile CS %08x\n", icchdr.colorspc);
		jas_image_setclrspc(dec->image, fromiccpcs(icchdr.colorspc));
		dec->image->cmprof_ = jas_cmprof_createfromiccprof(iccprof);
		assert(dec->image->cmprof_);
		jas_iccprof_destroy(iccprof);
		break;
	}

	/* If a CMAP box is present, a PCLR box must also be present. */
	if (dec->cmap && !dec->pclr) {
		jas_eprintf("warning: missing PCLR box or superfluous CMAP box\n");
		jp2_box_destroy(dec->cmap);
		dec->cmap = 0;
	}

	/* If a CMAP box is not present, a PCLR box must not be present. */
	if (!dec->cmap && dec->pclr) {
		jas_eprintf("warning: missing CMAP box or superfluous PCLR box\n");
		jp2_box_destroy(dec->pclr);
		dec->pclr = 0;
	}

 	/* Determine the number of channels (which is essentially the number
 	  of components after any palette mappings have been applied). */
 	dec->numchans = dec->cmap ? dec->cmap->data.cmap.numchans :
	  JAS_CAST(jas_uint, jas_image_numcmpts(dec->image));
 
 	/* Perform a basic sanity check on the CMAP box if present. */
 	if (dec->cmap) {
 		for (i = 0; i < dec->numchans; ++i) {
 			/* Is the component number reasonable? */
			if (dec->cmap->data.cmap.ents[i].cmptno >= JAS_CAST(jas_uint,
 			  jas_image_numcmpts(dec->image))) {
 				jas_eprintf("error: invalid component number in CMAP box\n");
 				goto error;
			}
			/* Is the LUT index reasonable? */
			if (dec->cmap->data.cmap.ents[i].pcol >=
			  dec->pclr->data.pclr.numchans) {
				jas_eprintf("error: invalid CMAP LUT index\n");
				goto error;
			}
		}
	}

	/* Allocate space for the channel-number to component-number LUT. */
	if (!(dec->chantocmptlut = jas_alloc2(dec->numchans,
	  sizeof(uint_fast16_t)))) {
		jas_eprintf("error: no memory\n");
		goto error;
	}

	if (!dec->cmap) {
		for (i = 0; i < dec->numchans; ++i) {
			dec->chantocmptlut[i] = i;
		}
	} else {
		cmapd = &dec->cmap->data.cmap;
		pclrd = &dec->pclr->data.pclr;
		cdefd = &dec->cdef->data.cdef;
		for (channo = 0; channo < cmapd->numchans; ++channo) {
			cmapent = &cmapd->ents[channo];
			if (cmapent->map == JP2_CMAP_DIRECT) {
				dec->chantocmptlut[channo] = channo;
			} else if (cmapent->map == JP2_CMAP_PALETTE) {
				lutents = jas_alloc2(pclrd->numlutents, sizeof(int_fast32_t));
				for (i = 0; i < pclrd->numlutents; ++i) {
					lutents[i] = pclrd->lutdata[cmapent->pcol + i * pclrd->numchans];
				}
				newcmptno = jas_image_numcmpts(dec->image);
				jas_image_depalettize(dec->image, cmapent->cmptno,
				  pclrd->numlutents, lutents,
				  JP2_BPCTODTYPE(pclrd->bpc[cmapent->pcol]), newcmptno);
				dec->chantocmptlut[channo] = newcmptno;
				jas_free(lutents);
#if 0
				if (dec->cdef) {
					cdefent = jp2_cdef_lookup(cdefd, channo);
					if (!cdefent) {
						abort();
					}
				jas_image_setcmpttype(dec->image, newcmptno, jp2_getct(jas_image_clrspc(dec->image), cdefent->type, cdefent->assoc));
				} else {
				jas_image_setcmpttype(dec->image, newcmptno, jp2_getct(jas_image_clrspc(dec->image), 0, channo + 1));
				}
#endif
			}
		}
	}
 
 	/* Mark all components as being of unknown type. */
 
	for (i = 0; i < JAS_CAST(jas_uint, jas_image_numcmpts(dec->image)); ++i) {
 		jas_image_setcmpttype(dec->image, i, JAS_IMAGE_CT_UNKNOWN);
 	}
 
	/* Determine the type of each component. */
	if (dec->cdef) {
		for (i = 0; i < dec->numchans; ++i) {
			/* Is the channel number reasonable? */
			if (dec->cdef->data.cdef.ents[i].channo >= dec->numchans) {
				jas_eprintf("error: invalid channel number in CDEF box\n");
				goto error;
			}
			jas_image_setcmpttype(dec->image,
			  dec->chantocmptlut[dec->cdef->data.cdef.ents[i].channo],
			  jp2_getct(jas_image_clrspc(dec->image),
			  dec->cdef->data.cdef.ents[i].type,
			  dec->cdef->data.cdef.ents[i].assoc));
		}
	} else {
		for (i = 0; i < dec->numchans; ++i) {
			jas_image_setcmpttype(dec->image, dec->chantocmptlut[i],
			  jp2_getct(jas_image_clrspc(dec->image), 0, i + 1));
		}
	}

	/* Delete any components that are not of interest. */
	for (i = jas_image_numcmpts(dec->image); i > 0; --i) {
		if (jas_image_cmpttype(dec->image, i - 1) == JAS_IMAGE_CT_UNKNOWN) {
			jas_image_delcmpt(dec->image, i - 1);
		}
	}

	/* Ensure that some components survived. */
	if (!jas_image_numcmpts(dec->image)) {
		jas_eprintf("error: no components\n");
		goto error;
	}
#if 0
jas_eprintf("no of components is %d\n", jas_image_numcmpts(dec->image));
#endif

	/* Prevent the image from being destroyed later. */
	image = dec->image;
	dec->image = 0;

	jp2_dec_destroy(dec);

	return image;

error:
	if (box) {
		jp2_box_destroy(box);
	}
	if (dec) {
		jp2_dec_destroy(dec);
	}
	return 0;
}

The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.