+static void *
+fgets_big_buffer(FILE *fp)
+{
+int len = 0;
+
+big_buffer[0] = 0;
+if (Ufgets(big_buffer, big_buffer_size, fp) == NULL) return NULL;
+
+while ((len = Ustrlen(big_buffer)) == big_buffer_size-1
+ && big_buffer[len-1] != '\n')
+ {
+ uschar *newbuffer;
+ int newsize;
+
+ if (big_buffer_size >= BIG_BUFFER_SIZE * 4) return NULL;
+ newsize = big_buffer_size * 2;
+ newbuffer = store_get_perm(newsize, GET_UNTAINTED);
+ memcpy(newbuffer, big_buffer, len);
+
+ big_buffer = newbuffer;
+ big_buffer_size = newsize;
+ if (Ufgets(big_buffer + len, big_buffer_size - len, fp) == NULL) return NULL;
+ }
+
+if (len <= 0 || big_buffer[len-1] != '\n') return NULL;
+return big_buffer;
+}
+
+