359 lines
7.9 KiB
C++
359 lines
7.9 KiB
C++
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/*
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* \brief Socket-based IPC implementation for Linux
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* \author Norman Feske
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* \author Christian Helmuth
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* \date 2011-10-11
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*
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* We create two sockets under lx_rpath() for each thread: client and server
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* role. The naming is 'ep-<thread id>-<role>'. The socket descriptors are
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* cached in Thread_base::_tid.
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*
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* Currently two socket files are needed, as the client does not send the reply
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* socket access-rights in a combined message with the payload. In the future,
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* only server sockets must be bound in lx_rpath().
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*
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* The current request message layout is:
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*
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* long server_local_name;
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* long client_thread_id;
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* int opcode;
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* ...payload...
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*
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* Response messages look like this:
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*
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* long scratch_word;
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* int exc_code;
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* ...payload...
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*
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* All fields are naturally aligned, i.e., aligend on 4 or 8 byte boundaries on
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* 32-bit resp. 64-bit systems.
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*/
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/*
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* Copyright (C) 2011 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 <base/ipc.h>
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#include <base/thread.h>
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#include <base/blocking.h>
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#include <base/snprintf.h>
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/* Linux includes */
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#include <sys/socket.h>
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#include <sys/un.h>
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#include <errno.h>
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#include <linux_syscalls.h>
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#include <linux_rpath.h>
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extern "C" void wait_for_continue(void);
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extern "C" int raw_write_str(const char *str);
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#define PRAW(fmt, ...) \
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do { \
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char str[128]; \
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snprintf(str, sizeof(str), \
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ESC_ERR fmt ESC_END "\n", ##__VA_ARGS__); \
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raw_write_str(str); \
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} while (0)
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using namespace Genode;
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/**
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* Utility: Create socket address for thread ID and role (client/server)
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*/
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static void lx_create_sockaddr(sockaddr_un *addr, long thread_id, char const *role)
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{
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addr->sun_family = AF_UNIX;
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Genode::snprintf(addr->sun_path, sizeof(addr->sun_path), "%s/ep-%ld-%s",
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lx_rpath(), thread_id, role);
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}
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/**
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* Utility: Create a socket descriptor and file for given thread and role
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*/
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static int create_socket(long thread_id, char const *role)
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{
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int sd = lx_socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0);
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if (sd < 0) return -1;
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sockaddr_un addr;
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lx_create_sockaddr(&addr, thread_id, role);
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/* make sure bind succeeds */
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lx_unlink(addr.sun_path);
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if (lx_bind(sd, (sockaddr *)&addr, sizeof(addr)) < 0)
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return -2;
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return sd;
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}
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/**
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* Utility: Unlink socket file and close descriptor
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*
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* XXX Currently, socket destruction is missing. The client socket could be
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* used from multiple Ipc_client objects. A safe destruction would need
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* reference counting.
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*/
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//static void destroy_socket(int sd, long thread_id, char const *role)
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//{
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// sockaddr_un addr;
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// lx_create_sockaddr(&addr, thread_id, role);
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//
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// lx_unlink(addr.sun_path);
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// lx_close(sd);
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//}
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/**
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* Get client-socket descriptor for main thread
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*/
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static int main_client_socket()
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{
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static int sd = create_socket(lx_gettid(), "client");
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return sd;
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}
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/**
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* Utility: Get server socket for given thread
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*/
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static int server_socket(Thread_base *thread)
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{
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/*
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* Main thread uses Ipc_server for sleep_forever() only.
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*/
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if (!thread)
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return lx_socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0);
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if (thread->tid().server == -1)
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thread->tid().server = create_socket(thread->tid().tid, "server");
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return thread->tid().server;
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}
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/**
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* Utility: Get client socket for given thread
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*/
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static int client_socket(Thread_base *thread)
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{
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if (!thread) return main_client_socket();
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if (thread->tid().client == -1)
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thread->tid().client = create_socket(thread->tid().tid, "client");
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return thread->tid().client;
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}
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/**
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* Utility: Send message to thread via given socket descriptor
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*/
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static void send_to(int sd, long thread_id, char const *target_role,
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void *msg, Genode::size_t msg_len)
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{
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sockaddr_un addr;
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lx_create_sockaddr(&addr, thread_id, target_role);
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int res = lx_sendto(sd, msg, msg_len, 0, (sockaddr *)&addr, sizeof(addr));
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if (res < 0) {
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PRAW("Send error: %d with %s in %d", res, addr.sun_path, lx_gettid());
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wait_for_continue();
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throw Ipc_error();
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}
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}
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/**
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* Utility: Receive message via given socket descriptor
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*/
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static void recv_from(int sd, void *buf, Genode::size_t buf_len)
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{
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socklen_t fromlen;
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int res = lx_recvfrom(sd, buf, buf_len, 0, 0, &fromlen);
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if (res < 0) {
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if ((-res) == EINTR)
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throw Blocking_canceled();
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else {
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PRAW("Recv error: %d in %d", res, lx_gettid());
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wait_for_continue();
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throw Ipc_error();
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}
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}
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}
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/*****************
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** Ipc_ostream **
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*****************/
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/*
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* XXX This class will be removed soon.
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*/
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void Ipc_ostream::_prepare_next_send()
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{
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PRAW("unexpected call to %s (%p)", __PRETTY_FUNCTION__, this);
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}
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void Ipc_ostream::_send()
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{
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PRAW("unexpected call to %s (%p)", __PRETTY_FUNCTION__, this);
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}
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Ipc_ostream::Ipc_ostream(Native_capability dst, Msgbuf_base *snd_msg):
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Ipc_marshaller(snd_msg->buf, snd_msg->size()), _snd_msg(snd_msg), _dst(dst)
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{ }
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/*****************
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** Ipc_istream **
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*****************/
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/*
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* XXX This class will be removed soon.
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*/
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void Ipc_istream::_prepare_next_receive()
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{
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PRAW("unexpected call to %s (%p)", __PRETTY_FUNCTION__, this);
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}
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void Ipc_istream::_wait()
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{
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PRAW("unexpected call to %s (%p)", __PRETTY_FUNCTION__, this);
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}
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Ipc_istream::Ipc_istream(Msgbuf_base *rcv_msg)
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: Ipc_unmarshaller(rcv_msg->buf, rcv_msg->size()),
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Native_capability(lx_gettid(), 0),
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_rcv_msg(rcv_msg), _rcv_cs(-1)
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{ }
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Ipc_istream::~Ipc_istream() { }
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/****************
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** Ipc_client **
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****************/
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void Ipc_client::_prepare_next_call()
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{
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/* prepare next request in buffer */
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long local_name = _dst.local_name();
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long tid = Native_capability::tid();
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_write_offset = 0;
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_write_to_buf(local_name);
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_write_to_buf(tid);
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/* prepare response buffer */
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_read_offset = sizeof(long);
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}
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void Ipc_client::_call()
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{
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if (_dst.valid()) {
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send_to(_rcv_cs, _dst.tid(), "server",
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_snd_msg->buf, _write_offset);
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recv_from(_rcv_cs, _rcv_msg->buf, _rcv_msg->size());
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}
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_prepare_next_call();
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}
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Ipc_client::Ipc_client(Native_capability const &srv,
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Msgbuf_base *snd_msg, Msgbuf_base *rcv_msg)
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: Ipc_istream(rcv_msg), Ipc_ostream(srv, snd_msg), _result(0)
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{
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_rcv_cs = client_socket(Thread_base::myself());
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_prepare_next_call();
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}
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/****************
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** Ipc_server **
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****************/
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void Ipc_server::_prepare_next_reply_wait()
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{
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/* skip server-local name */
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_read_offset = sizeof(long);
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/* read client thread id from request buffer */
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long tid;
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if (_reply_needed) {
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_read_from_buf(tid);
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_dst = Native_capability(tid, 0); /* only _tid member is used */
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}
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/* prepare next reply */
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_write_offset = 0;
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long local_name = _dst.local_name();
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_write_to_buf(local_name); /* XXX unused, needed by de/marshaller */
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/* leave space for exc code at the beginning of the msgbuf */
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_write_offset += align_natural(sizeof(int));
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}
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void Ipc_server::_wait()
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{
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/* wait for new server request */
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try {
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recv_from(_rcv_cs, _rcv_msg->buf, _rcv_msg->size());
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} catch (Blocking_canceled) { }
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/* now we have a request to reply, determine reply destination */
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_reply_needed = true;
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_prepare_next_reply_wait();
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}
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void Ipc_server::_reply()
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{
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try {
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send_to(_rcv_cs, _dst.tid(), "client", _snd_msg->buf, _write_offset);
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} catch (Ipc_error) { }
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_prepare_next_reply_wait();
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}
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void Ipc_server::_reply_wait()
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{
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/* when first called, there was no request yet */
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if (_reply_needed)
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send_to(_rcv_cs, _dst.tid(), "client", _snd_msg->buf, _write_offset);
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_wait();
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}
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Ipc_server::Ipc_server(Msgbuf_base *snd_msg, Msgbuf_base *rcv_msg)
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: Ipc_istream(rcv_msg),
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Ipc_ostream(Native_capability(), snd_msg), _reply_needed(false)
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{
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_rcv_cs = server_socket(Thread_base::myself());
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_prepare_next_reply_wait();
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}
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