if (ch == '0') {

		if (ch >= '1' && ch <= '9') {

			unsigned char i;

			/* Filter \1...\9; let \0 fall to conv_escape(). */

			i = 3;

			ch = '\\';

			ch = 0;

			--str;

			do {

				unsigned k = octtobin(*str);

				if (k > 7)

					break;

				str++;

				ch <<= 3;

				ch += k;

			} while (--i);