Exiv2

        long toRead = 0;

        while (readTotal < colorDataLength) {

            toRead =   static_cast<long>(colorDataLength - readTotal) < lbuf.size_

            if (io_->read(lbuf.pData_, toRead) != toRead) throw Error(3, "Photoshop");

            readTotal += toRead;

            if (outIo.write(lbuf.pData_, toRead) != toRead) throw Error(21);

                resourceSize = (resourceSize + 1) & ~1;        // pad to even

                while (readTotal < resourceSize) {

                    toRead =   static_cast<long>(resourceSize - readTotal) < lbuf.size_

                    if (io_->read(lbuf.pData_, toRead) != toRead) {

                        throw Error(3, "Photoshop");

                    }