rem: if ((anchor = del_lump (&msg->add_rm, off, oldlen, 0)) == 0)
add: if ((anchor = del_lump (msg, off, oldlen, 0)) == 0)
context: patch (struct sip_msg *msg, char *oldstr, unsigned int oldlen, char *newstr,       unsigned int newlen){	int off;	struct lump *anchor;	if (oldstr == NULL)		return -1;	if (newstr == NULL)		return -2;	off = oldstr - msg->buf;	if (off < 0)		return -3;	if ((anchor = del_lump (&msg->add_rm, off, oldlen, 0)) == 0)	{		LOG (L_ERR, "ERROR: patch: error lumping with del_lump\n");		return -4;	}	if ((insert_new_lump_after (anchor, newstr, newlen, 0)) == 0)	{		LOG (L_ERR,		     "ERROR: patch: error lumping with insert_new_lump_after\n");		return -5;	}	return 0;}