236 lines
4.8 KiB
C++
236 lines
4.8 KiB
C++
/*
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* \brief Backend for end points of synchronous interprocess communication
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* \author Martin Stein
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* \date 2012-11-30
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*/
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/*
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* Copyright (C) 2012-2013 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU General Public License version 2.
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*/
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/* Genode includes */
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#include <util/string.h>
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/* core includes */
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#include <kernel/ipc_node.h>
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#include <assert.h>
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using namespace Kernel;
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void Ipc_node::_receive_request(Message_buf * const r)
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{
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/* FIXME: invalid requests should be discarded */
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if (r->size > _inbuf.size) {
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PWRN("oversized request");
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r->size = _inbuf.size;
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}
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/* fetch message */
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Genode::memcpy(_inbuf.base, r->base, r->size);
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_inbuf.size = r->size;
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_inbuf.src = r->src;
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/* update state */
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_state = PREPARE_REPLY;
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}
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void Ipc_node::_receive_reply(void * const base, size_t const size)
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{
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/* FIXME: when discard awaited replies userland must get a hint */
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if (size > _inbuf.size) {
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PDBG("discard invalid IPC reply");
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return;
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}
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/* receive reply */
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Genode::memcpy(_inbuf.base, base, size);
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_inbuf.size = size;
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/* update state */
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if (_state != PREPARE_AND_AWAIT_REPLY) { _state = INACTIVE; }
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else { _state = PREPARE_REPLY; }
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_send_request_succeeded();
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}
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void Ipc_node::_announce_request(Message_buf * const r)
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{
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/* directly receive request if we've awaited it */
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if (_state == AWAIT_REQUEST) {
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_receive_request(r);
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_await_request_succeeded();
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return;
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}
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/* cannot receive yet, so queue request */
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_request_queue.enqueue(r);
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}
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void Ipc_node::_cancel_request_queue()
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{
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while (1) {
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Message_buf * const r = _request_queue.dequeue();
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if (!r) { return; }
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r->src->_outbuf_request_cancelled();
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}
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}
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void Ipc_node::_cancel_outbuf_request()
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{
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if (_outbuf_dst) {
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_outbuf_dst->_announced_request_cancelled(&_outbuf);
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_outbuf_dst = 0;
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}
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}
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void Ipc_node::_cancel_inbuf_request()
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{
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if (_inbuf.src) {
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_inbuf.src->_outbuf_request_cancelled();
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_inbuf.src = 0;
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}
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}
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void Ipc_node::_announced_request_cancelled(Message_buf * const r)
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{
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if (_inbuf.src == r->src) {
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_inbuf.src = 0;
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return;
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}
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_request_queue.remove(r);
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}
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void Ipc_node::_outbuf_request_cancelled()
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{
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if (_outbuf_dst) {
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_outbuf_dst = 0;
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if (!_inbuf.src) { _state = INACTIVE; }
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else { _state = PREPARE_REPLY; }
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_send_request_failed();
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}
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}
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bool Ipc_node::_helps_outbuf_dst()
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{
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return (_state == PREPARE_AND_AWAIT_REPLY ||
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_state == AWAIT_REPLY) && _outbuf_dst_help;
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}
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void Ipc_node::send_request(Ipc_node * const dst, void * const buf_base,
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size_t const buf_size, size_t const msg_size,
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bool help)
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{
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/* assertions */
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assert(_state == INACTIVE || _state == PREPARE_REPLY);
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/* prepare transmission of request message */
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_outbuf.base = buf_base;
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_outbuf.size = msg_size;
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_outbuf.src = this;
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_outbuf_dst = dst;
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_outbuf_dst_help = 0;
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/*
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* Prepare reception of reply message but don't clear
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* '_inbuf.origin' because we might also prepare a reply.
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*/
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_inbuf.base = buf_base;
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_inbuf.size = buf_size;
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/* update state */
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if (_state != PREPARE_REPLY) { _state = AWAIT_REPLY; }
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else { _state = PREPARE_AND_AWAIT_REPLY; }
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/* announce request */
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dst->_announce_request(&_outbuf);
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/* set help relation after announcement to simplify scheduling */
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_outbuf_dst_help = help;
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}
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Ipc_node * Ipc_node::helping_sink() {
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return _helps_outbuf_dst() ? _outbuf_dst->helping_sink() : this; }
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bool Ipc_node::await_request(void * const buf_base,
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size_t const buf_size)
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{
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/* assertions */
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assert(_state == INACTIVE);
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/* prepare receipt of request */
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_inbuf.base = buf_base;
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_inbuf.size = buf_size;
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_inbuf.src = 0;
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/* if anybody already announced a request receive it */
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if (!_request_queue.empty()) {
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_receive_request(_request_queue.dequeue());
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return true;
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}
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/* no request announced, so wait */
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_state = AWAIT_REQUEST;
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return false;
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}
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void Ipc_node::send_reply(void * const msg_base,
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size_t const msg_size)
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{
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/* reply to the last request if we have to */
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if (_state == PREPARE_REPLY) {
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if (_inbuf.src) {
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_inbuf.src->_receive_reply(msg_base, msg_size);
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_inbuf.src = 0;
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}
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_state = INACTIVE;
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}
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}
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void Ipc_node::cancel_waiting()
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{
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switch (_state) {
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case AWAIT_REPLY:
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_cancel_outbuf_request();
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_state = INACTIVE;
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_send_request_failed();
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return;
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case AWAIT_REQUEST:
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_state = INACTIVE;
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_await_request_failed();
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return;
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case PREPARE_AND_AWAIT_REPLY:
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_cancel_outbuf_request();
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_state = PREPARE_REPLY;
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_send_request_failed();
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return;
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default: return;
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}
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}
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Ipc_node::Ipc_node() : _state(INACTIVE)
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{
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_inbuf.src = 0;
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_outbuf_dst = 0;
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}
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Ipc_node::~Ipc_node()
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{
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_cancel_request_queue();
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_cancel_inbuf_request();
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_cancel_outbuf_request();
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}
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