Let's try this. It's BUGGERED.

src/cmd/tbl/te.c

@@ -0,0 +1,75 @@
+/* te.c: error message control, input line count */
+# include "t.h"
+
+void
+error(char *s)
+{
+	fprint(2, "\n%s:%d: %s\n", ifile, iline, s);
+	fprint(2, "tbl quits\n");
+	exits(s);
+}
+
+
+char	*
+gets1(char *s, int size)
+{
+	char	*p, *ns;
+	int	nbl;
+
+	iline++;
+	ns = s;
+	p = Brdline(tabin, '\n');
+	while (p == 0) {
+		if (swapin() == 0)
+			return(0);
+		p = Brdline(tabin, '\n');
+	}
+	nbl = Blinelen(tabin)-1;
+	if(nbl >= size)
+		error("input buffer too small");
+	p[nbl] = 0;
+	strcpy(s, p);
+	s += nbl;
+	for (nbl = 0; *s == '\\' && s > ns; s--)
+		nbl++;
+	if (linstart && nbl % 2) /* fold escaped nl if in table */
+		gets1(s + 1, size - (s-ns));
+
+	return(p);
+}
+
+
+# define BACKMAX 500
+char	backup[BACKMAX];
+char	*backp = backup;
+
+void
+un1getc(int c)
+{
+	if (c == '\n')
+		iline--;
+	*backp++ = c;
+	if (backp >= backup + BACKMAX)
+		error("too much backup");
+}
+
+
+int
+get1char(void)
+{
+	int	c;
+	if (backp > backup)
+		c = *--backp;
+	else
+		c = Bgetc(tabin);
+	if (c == 0) /* EOF */ {
+		if (swapin() == 0)
+			error("unexpected EOF");
+		c = Bgetc(tabin);
+	}
+	if (c == '\n')
+		iline++;
+	return(c);
+}
+
+