sdsMakeRoomFor() exposed as public API. sdsIncrLen() added. Both the changes make it possible to copy stuff from a system call to an sds buffer without the need of an additional buffer and copying overhead.

src/sds.h

@@ -88,4 +88,8 @@ sds *sdssplitargs(char *line, int *argc);
 void sdssplitargs_free(sds *argv, int argc);
 sds sdsmapchars(sds s, char *from, char *to, size_t setlen);
 
+/* Low level functions exposed to the user API */
+sds sdsMakeRoomFor(sds s, size_t addlen);
+void sdsIncrLen(sds s, int incr);
+
 #endif