-uschar *code;
-uschar *p = (uschar *)clear;
-uschar *pp;
-int c = len;
-int count = 1;
-register int x;
-
-/* We have to do a prepass to find out how many specials there are,
-in order to get the right amount of store. */
-
-while (c -- > 0)
- count += ((x = *p++) < 33 || x > 127 || x == '+' || x == '=')? 3 : 1;
-
-pp = code = store_get(count);
-
-p = (uschar *)clear;
-c = len;
-while (c-- > 0)
- {
- if ((x = *p++) < 33 || x > 127 || x == '+' || x == '=')
- {
- sprintf(CS pp, "+%.02x", x); /* There's always room */
- pp += 3;
- }
- else *pp++ = x;
- }
-
-*pp = 0;
-return code;
+gstring * g = NULL;
+for(uschar ch; len > 0; len--, clear++)
+ g = (ch = *clear) < 33 || ch > 126 || ch == '+' || ch == '='
+ ? string_fmt_append(g, "+%.02X", ch)
+ : string_catn(g, clear, 1);
+gstring_release_unused(g);
+return string_from_gstring(g);