Clean up code for widget_in() and widget_out().

Given syntactically wrong input, widget_in() could call atof() with an
indeterminate pointer argument, typically leading to a crash; or if it
didn't do that, it might return a NULL pointer, which again would lead
to a crash since old-style C functions aren't supposed to do things
that way.  Fix that by correcting the off-by-one syntax test and
throwing a proper error rather than just returning NULL.

Also, since widget_in and widget_out have been marked STRICT for a
long time, their tests for null inputs are just dead code; remove 'em.
In the oldest branches, also improve widget_out to use snprintf not
sprintf, just to be sure.

In passing, get rid of a long-since-useless sprintf into a local buffer
that nothing further is done with, and make some other minor coding
style cleanups.

In the intended regression-testing usage of these functions, none of
this is very significant; but if the regression test database were
left around in a production installation, these bugs could amount
to a minor security hazard.

Piotr Stefaniak, Michael Paquier, and Tom Lane

src/test/regress/regress.c

@@ -249,34 +249,33 @@ WIDGET *
 widget_in(char *str)
 {
 	char	   *p,
-			   *coord[NARGS],
-				buf2[1000];
+			   *coord[NARGS];
 	int			i;
 	WIDGET	   *result;
 
-	if (str == NULL)
-		return NULL;
 	for (i = 0, p = str; *p && i < NARGS && *p != RDELIM; p++)
-		if (*p == ',' || (*p == LDELIM && !i))
+	{
+		if (*p == DELIM || (*p == LDELIM && i == 0))
 			coord[i++] = p + 1;
-	if (i < NARGS - 1)
-		return NULL;
+	}
+
+	if (i < NARGS)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
+				 errmsg("invalid input syntax for type widget: \"%s\"",
+						str)));
+
 	result = (WIDGET *) palloc(sizeof(WIDGET));
 	result->center.x = atof(coord[0]);
 	result->center.y = atof(coord[1]);
 	result->radius = atof(coord[2]);
 
-	snprintf(buf2, sizeof(buf2), "widget_in: read (%f, %f, %f)\n",
-			 result->center.x, result->center.y, result->radius);
 	return result;
 }
 
 char *
 widget_out(WIDGET *widget)
 {
-	if (widget == NULL)
-		return NULL;
-
 	return psprintf("(%g,%g,%g)",
 					widget->center.x, widget->center.y, widget->radius);
 }