+static void command_pre_select(struct sched *s, struct task *t)
+{
+ struct command_task *ct = t->private_data;
+ t->ret = 1;
+ para_fd_set(ct->fd, &s->rfds, &s->max_fileno);
+}
+
+/*
+ * On errors, negative value is written to fd.
+ * On success: If query produced a result, the result_shmid is written to fd.
+ * Otherwise, zero is written.
+ */
+static int call_callback(int fd, int query_shmid)
+{
+ void *query_shm, *result_shm;
+ struct callback_query *cq;
+ struct callback_result *cr;
+ struct osl_object query, result = {.data = NULL};
+ int result_shmid = -1, ret, ret2;
+
+ ret = shm_attach(query_shmid, ATTACH_RW, &query_shm);
+ if (ret < 0)
+ goto out;
+ cq = query_shm;
+ query.data = (char *)query_shm + sizeof(*cq);
+ query.size = cq->query_size;
+ ret = cq->handler(&query, &result);
+ ret2 = shm_detach(query_shm);
+ if (ret2 < 0 && ret >= 0)
+ ret = ret2;
+ if (ret < 0)
+ goto out;
+ ret = 0;
+ if (!result.data || !result.size)
+ goto out;
+ ret = shm_new(result.size + sizeof(struct callback_result));
+ if (ret < 0)
+ goto out;
+ result_shmid = ret;
+ ret = shm_attach(result_shmid, ATTACH_RW, &result_shm);
+ if (ret < 0)
+ goto out;
+ cr = result_shm;
+ cr->result_size = result.size;
+ memcpy(result_shm + sizeof(*cr), result.data, result.size);
+ ret = shm_detach(result_shm);
+ if (ret < 0)
+ goto out;
+ ret = result_shmid;
+out:
+ free(result.data);
+ ret2 = send_bin_buffer(fd, (char *)&ret, sizeof(int));
+ if (ret < 0 || ret2 < 0) {
+ if (result_shmid >= 0)
+ if (shm_destroy(result_shmid) < 0)
+ PARA_ERROR_LOG("destroy result failed\n");
+ if (ret >= 0)
+ ret = ret2;
+ }
+ return ret;
+}
+
+static void command_post_select(struct sched *s, struct task *t)
+{
+ struct command_task *ct = t->private_data;
+ struct sockaddr_un unix_addr;
+ char buf[sizeof(uint32_t) + sizeof(int)];
+ uint32_t cookie;
+ int query_shmid, fd;
+
+ t->ret = 1;
+ if (!FD_ISSET(ct->fd, &s->rfds))
+ return;
+ t->ret = para_accept(ct->fd, &unix_addr, sizeof(unix_addr));
+ if (t->ret < 0)
+ return;
+ /*
+ * The following errors may be caused by a malicious local user. So do
+ * not return an error in this case as this would terminate para_afs
+ * and para_server.
+ */
+ fd = t->ret;
+ /* FIXME: This is easily dosable (peer doesn't send data) */
+ t->ret = recv_bin_buffer(fd, buf, sizeof(buf));
+ if (t->ret < 0) {
+ PARA_NOTICE_LOG("%s (%d)\n", PARA_STRERROR(-t->ret), t->ret);
+ t->ret = 1;
+ goto out;
+ }
+ if (t->ret != sizeof(buf)) {
+ PARA_NOTICE_LOG("short read (%d bytes, expected %lu)\n",
+ t->ret, sizeof(buf));
+ t->ret = 1;
+ goto out;
+ }
+ cookie = *(uint32_t *)buf;
+ if (cookie != ct->cookie) {
+ PARA_NOTICE_LOG("received invalid cookie(got %u, expected %u)\n",
+ (unsigned)cookie, (unsigned)ct->cookie);
+ t->ret = 1;
+ goto out;
+ }
+ query_shmid = *(int *)(buf + sizeof(cookie));
+ if (query_shmid < 0) {
+ PARA_WARNING_LOG("received invalid query shmid %d)\n",
+ query_shmid);
+ t->ret = 1;
+ goto out;
+ }
+ t->ret = call_callback(fd, query_shmid);
+ if (t->ret < 0) {
+ PARA_NOTICE_LOG("%s\n", PARA_STRERROR(-t->ret));
+ t->ret = 1;
+ goto out;
+ }
+out:
+ close(fd);
+}
+
+static void register_command_task(uint32_t cookie)
+{
+ static struct command_task command_task_struct;
+ struct command_task *ct = &command_task_struct;
+ ct->fd = setup_command_socket_or_die();
+ ct->cookie = cookie;
+
+ ct->task.pre_select = command_pre_select;
+ ct->task.post_select = command_post_select;
+ ct->task.private_data = ct;
+ sprintf(ct->task.status, "command task");
+ register_task(&ct->task);
+}
+
+void register_tasks(uint32_t cookie)