4d442bca30
This patch reduces the number of exception types by facilitating globally defined exceptions for common usage patterns shared by most services. In particular, RPC functions that demand a session-resource upgrade not longer reflect this condition via a session-specific exception but via the 'Out_of_ram' or 'Out_of_caps' types. Furthermore, the 'Parent::Service_denied', 'Parent::Unavailable', 'Root::Invalid_args', 'Root::Unavailable', 'Service::Invalid_args', 'Service::Unavailable', and 'Local_service::Factory::Denied' types have been replaced by the single 'Service_denied' exception type defined in 'session/session.h'. This consolidation eases the error handling (there are fewer exceptions to handle), alleviates the need to convert exceptions along the session-creation call chain, and avoids possible aliasing problems (catching the wrong type with the same name but living in a different scope).
580 lines
13 KiB
C++
580 lines
13 KiB
C++
/*
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* \brief Service providing the 'Terminal_session' interface via TCP
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* \author Norman Feske
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* \date 2011-09-07
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*/
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/*
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* Copyright (C) 2011-2017 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 Affero General Public License version 3.
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*/
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/* Genode includes */
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#include <util/list.h>
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#include <util/misc_math.h>
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#include <base/log.h>
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#include <base/rpc_server.h>
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#include <base/heap.h>
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#include <root/component.h>
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#include <terminal_session/terminal_session.h>
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#include <base/attached_ram_dataspace.h>
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#include <base/attached_rom_dataspace.h>
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#include <os/session_policy.h>
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#include <libc/component.h>
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#include <pthread.h>
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/* socket API */
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <sys/select.h>
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#include <arpa/inet.h>
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#include <netinet/in.h>
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#include <sys/ioctl.h>
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static bool const verbose = true;
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class Open_socket : public Genode::List<Open_socket>::Element
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{
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private:
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/**
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* Socket descriptor for listening to a new TCP connection
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*/
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int _listen_sd;
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/**
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* Socket descriptor for open TCP connection
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*/
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int _sd;
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/**
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* Signal handler to be informed about the established connection
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*/
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Genode::Signal_context_capability _connected_sigh;
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/**
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* Signal handler to be informed about data available to read
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*/
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Genode::Signal_context_capability _read_avail_sigh;
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/**
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* Buffer for incoming data
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*
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* This buffer is used for synchronizing the reception of data in the
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* main thread ('watch_sockets_for_incoming_data') and the entrypoint
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* thread ('read'). The main thread fills the buffer if its not already
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* occupied and the entrypoint thread consumes the buffer. When the
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* buffer becomes occupied, the corresponding socket gets removed from
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* the 'rfds' set of 'select()' until a read request from the terminal
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* client comes in.
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*/
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enum { READ_BUF_SIZE = 4096 };
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char _read_buf[READ_BUF_SIZE];
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Genode::size_t _read_buf_bytes_used;
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Genode::size_t _read_buf_bytes_read;
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/**
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* Establish remote connection
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*
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* \return socket descriptor used for the remote TCP connection
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*/
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static int _remote_listen(int tcp_port)
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{
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int listen_sd = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
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if (listen_sd == -1) {
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Genode::error("socket creation failed");
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return -1;
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}
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sockaddr_in sockaddr;
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sockaddr.sin_family = PF_INET;
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sockaddr.sin_port = htons (tcp_port);
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sockaddr.sin_addr.s_addr = INADDR_ANY;
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if (bind(listen_sd, (struct sockaddr *)&sockaddr, sizeof(sockaddr))) {
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Genode::error("bind to port ", tcp_port, " failed");
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return -1;
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}
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if (listen(listen_sd, 1)) {
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Genode::error("listen failed");
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return -1;
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}
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Genode::log("listening on port ", tcp_port, "...");
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return listen_sd;
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}
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public:
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Open_socket(int tcp_port);
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~Open_socket();
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/**
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* Return socket descriptor for listening to new connections
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*/
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int listen_sd() const { return _listen_sd; }
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/**
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* Return true if all steps of '_remote_listen' succeeded
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*/
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bool listen_sd_valid() const { return _listen_sd != -1; }
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/**
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* Return socket descriptor of the connection
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*/
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int sd() const { return _sd; }
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/**
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* Register signal handler to be notified once we accepted the TCP
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* connection
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*/
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void connected_sigh(Genode::Signal_context_capability sigh) { _connected_sigh = sigh; }
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/**
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* Register signal handler to be notified when data is available for
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* reading
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*/
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void read_avail_sigh(Genode::Signal_context_capability sigh)
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{
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_read_avail_sigh = sigh;
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/* if read data is available right now, deliver signal immediately */
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if (!read_buffer_empty() && _read_avail_sigh.valid())
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Genode::Signal_transmitter(_read_avail_sigh).submit();
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}
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/**
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* Accept new connection, defining the connection's socket descriptor
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*
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* This function is called by the 'select()' thread when a new
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* connection is pending.
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*/
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void accept_remote_connection()
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{
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struct sockaddr addr;
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socklen_t len = sizeof(addr);
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_sd = accept(_listen_sd, &addr, &len);
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if (_sd != -1)
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Genode::log("connection established");
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/*
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* Inform client about the finished initialization of the terminal
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* session
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*/
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if (_connected_sigh.valid())
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Genode::Signal_transmitter(_connected_sigh).submit();
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}
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/**
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* Return true if TCP connection is established
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*
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* If the return value is false, we are still in listening more
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* and have not yet called 'accept()'.
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*/
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bool connection_established() const { return _sd != -1; }
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/**
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* Fetch data from socket into internal read buffer
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*/
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void fill_read_buffer_and_notify_client()
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{
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if (_read_buf_bytes_used) {
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Genode::warning("read buffer already in use");
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return;
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}
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/* read from socket */
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_read_buf_bytes_used = ::read(_sd, _read_buf, sizeof(_read_buf));
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if (_read_buf_bytes_used == 0) {
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close(_sd);
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_sd = -1;
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return;
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}
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/* notify client about bytes available for reading */
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if (_read_avail_sigh.valid())
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Genode::Signal_transmitter(_read_avail_sigh).submit();
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}
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/**
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* Read out internal read buffer and copy into destination buffer.
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*/
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Genode::size_t read_buffer(char *dst, Genode::size_t dst_len)
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{
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Genode::size_t num_bytes = Genode::min(dst_len, _read_buf_bytes_used -
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_read_buf_bytes_read);
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Genode::memcpy(dst, _read_buf + _read_buf_bytes_read, num_bytes);
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_read_buf_bytes_read += num_bytes;
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if (_read_buf_bytes_read >= _read_buf_bytes_used)
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_read_buf_bytes_used = _read_buf_bytes_read = 0;
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/* notify client if there are still bytes available for reading */
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if (_read_avail_sigh.valid() && !read_buffer_empty())
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Genode::Signal_transmitter(_read_avail_sigh).submit();
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return num_bytes;
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}
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/**
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* Return true if the internal read buffer is ready to receive data
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*/
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bool read_buffer_empty() const { return _read_buf_bytes_used == 0; }
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};
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class Open_socket_pool
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{
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private:
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/**
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* Protection for '_list'
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*/
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Genode::Lock _lock;
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/**
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* List of open sockets
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*/
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Genode::List<Open_socket> _list;
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/**
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* Thread doing the select
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*/
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pthread_t _select;
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/**
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* Number of currently open sockets
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*/
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int _count;
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/**
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* Pipe used to synchronize 'select()' loop with the entrypoint thread
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*/
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int sync_pipe_fds[2];
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/**
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* Intercept the blocking state of the current 'select()' call
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*/
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void _wakeup_select()
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{
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char c = 0;
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::write(sync_pipe_fds[1], &c, sizeof(c));
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}
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static void * entry(void *arg) {
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Open_socket_pool * pool = reinterpret_cast<Open_socket_pool *>(arg);
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for (;;)
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pool->watch_sockets_for_incoming_data();
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return nullptr;
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}
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public:
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Open_socket_pool(Genode::Env &env)
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: _count(0)
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{
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pipe(sync_pipe_fds);
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if (pthread_create(&_select, nullptr, entry, this)) {
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class Startup_select_thread_failed : Genode::Exception { };
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throw Startup_select_thread_failed();
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}
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}
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void insert(Open_socket *s)
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{
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Genode::Lock::Guard guard(_lock);
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_list.insert(s);
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_count++;
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_wakeup_select();
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}
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void remove(Open_socket *s)
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{
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Genode::Lock::Guard guard(_lock);
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_list.remove(s);
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_count--;
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_wakeup_select();
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}
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void update_sockets_to_watch()
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{
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_wakeup_select();
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}
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void watch_sockets_for_incoming_data()
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{
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/* prepare arguments for 'select()' */
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fd_set rfds;
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int nfds = 0;
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{
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Genode::Lock::Guard guard(_lock);
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/* collect file descriptors of all open sessions */
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FD_ZERO(&rfds);
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for (Open_socket *s = _list.first(); s; s = s->next()) {
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/*
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* If one of the steps of creating the listen socket
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* failed, skip the session.
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*/
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if (!s->listen_sd_valid())
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continue;
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/*
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* If the connection is not already established, tell
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* 'select' to notify us about a new connection.
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*/
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if (!s->connection_established()) {
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nfds = Genode::max(nfds, s->listen_sd());
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FD_SET(s->listen_sd(), &rfds);
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continue;
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}
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/*
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* The connection is established. We watch the connection's
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* file descriptor for reading, but only if our buffer can
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* take new data. Otherwise, we let the incoming data queue
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* up in the TCP/IP stack.
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*/
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nfds = Genode::max(nfds, s->sd());
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if (s->read_buffer_empty())
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FD_SET(s->sd(), &rfds);
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}
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/* add sync pipe to set of file descriptors to watch */
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FD_SET(sync_pipe_fds[0], &rfds);
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nfds = Genode::max(nfds, sync_pipe_fds[0]);
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}
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/* block for incoming data or sync-pipe events */
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select(nfds + 1, &rfds, NULL, NULL, NULL);
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/* check if we were woken up via the sync pipe */
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if (FD_ISSET(sync_pipe_fds[0], &rfds)) {
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char c = 0;
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::read(sync_pipe_fds[0], &c, 1);
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return;
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}
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/* read pending data from sockets */
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{
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Genode::Lock::Guard guard(_lock);
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for (Open_socket *s = _list.first(); s; s = s->next()) {
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/* look for new connection */
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if (!s->connection_established()) {
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if (FD_ISSET(s->listen_sd(), &rfds))
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s->accept_remote_connection();
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continue;
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}
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/* connection is established, look for incoming data */
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if (FD_ISSET(s->sd(), &rfds))
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s->fill_read_buffer_and_notify_client();
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}
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}
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}
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};
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Open_socket_pool *open_socket_pool(Genode::Env * env = nullptr)
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{
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static Open_socket_pool inst(*env);
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return &inst;
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}
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Open_socket::Open_socket(int tcp_port)
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:
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_listen_sd(_remote_listen(tcp_port)), _sd(-1),
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_read_buf_bytes_used(0), _read_buf_bytes_read(0)
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{
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open_socket_pool()->insert(this);
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}
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Open_socket::~Open_socket()
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{
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if (_sd != -1) close(_sd);
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open_socket_pool()->remove(this);
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}
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namespace Terminal {
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class Session_component;
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class Root_component;
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};
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class Terminal::Session_component : public Genode::Rpc_object<Session, Session_component>,
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public Open_socket
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{
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private:
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Genode::Attached_ram_dataspace _io_buffer;
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public:
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Session_component(Genode::Env &env, Genode::size_t io_buffer_size, int tcp_port)
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:
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Open_socket(tcp_port),
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_io_buffer(env.ram(), env.rm(), io_buffer_size)
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{ }
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/********************************
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** Terminal session interface **
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********************************/
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Size size() { return Size(0, 0); }
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bool avail()
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{
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return !read_buffer_empty();
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}
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Genode::size_t _read(Genode::size_t dst_len)
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{
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Genode::size_t num_bytes =
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read_buffer(_io_buffer.local_addr<char>(),
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Genode::min(_io_buffer.size(), dst_len));
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/*
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* If read buffer was in use, look if more data is buffered in
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* the TCP/IP stack.
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*/
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if (num_bytes)
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open_socket_pool()->update_sockets_to_watch();
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return num_bytes;
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}
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Genode::size_t _write(Genode::size_t num_bytes)
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{
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/* sanitize argument */
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num_bytes = Genode::min(num_bytes, _io_buffer.size());
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/* write data to socket, assuming that it won't block */
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ssize_t written_bytes = ::write(sd(),
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_io_buffer.local_addr<char>(),
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num_bytes);
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if (written_bytes < 0) {
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Genode::error("write error, dropping data");
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return 0;
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}
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return written_bytes;
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}
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Genode::Dataspace_capability _dataspace()
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{
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return _io_buffer.cap();
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}
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void read_avail_sigh(Genode::Signal_context_capability sigh)
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{
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Open_socket::read_avail_sigh(sigh);
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}
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void connected_sigh(Genode::Signal_context_capability sigh)
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{
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Open_socket::connected_sigh(sigh);
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}
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Genode::size_t read(void *buf, Genode::size_t) { return 0; }
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Genode::size_t write(void const *buf, Genode::size_t) { return 0; }
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};
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class Terminal::Root_component : public Genode::Root_component<Session_component>
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{
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private:
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Genode::Env &_env;
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Genode::Xml_node _config;
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protected:
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Session_component *_create_session(const char *args)
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{
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using namespace Genode;
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/*
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* XXX read I/O buffer size from args
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*/
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Genode::size_t io_buffer_size = 4096;
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try {
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Session_label const label = label_from_args(args);
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Session_policy policy(label, _config);
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unsigned tcp_port = 0;
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policy.attribute("port").value(&tcp_port);
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return new (md_alloc())
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Session_component(_env, io_buffer_size, tcp_port);
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}
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catch (Xml_node::Nonexistent_attribute) {
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error("Missing \"port\" attribute in policy definition");
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throw Service_denied();
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}
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catch (Session_policy::No_policy_defined) {
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error("Invalid session request, no matching policy");
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throw Service_denied();
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}
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}
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public:
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/**
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* Constructor
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*/
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Root_component(Genode::Env &env,
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Genode::Xml_node config,
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Genode::Allocator &md_alloc)
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:
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Genode::Root_component<Session_component>(&env.ep().rpc_ep(),
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&md_alloc),
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_env(env), _config(config)
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{ }
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};
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struct Main
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{
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Genode::Env &_env;
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Genode::Attached_rom_dataspace _config_rom { _env, "config" };
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Genode::Xml_node _config { _config_rom.xml() };
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Genode::Sliced_heap _sliced_heap { _env.ram(), _env.rm() };
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/* create root interface for service */
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Terminal::Root_component _root { _env, _config, _sliced_heap };
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Main(Genode::Env &env) : _env(env)
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{
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Genode::log("--- TCP terminal started ---");
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/* start thread blocking in select */
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open_socket_pool(&_env);
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/* announce service at our parent */
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_env.parent().announce(env.ep().manage(_root));
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}
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};
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void Libc::Component::construct(Libc::Env &env) { static Main main(env); }
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