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'Root::Unavailable', 'Service::Invalid_args', 'Service::Unavailable', and 'Local_service::Factory::Denied' types have been replaced by the single 'Service_denied' exception type defined in 'session/session.h'.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).
301 lines
7.4 KiB
C++
301 lines
7.4 KiB
C++
/*
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* \brief Service providing the 'Terminal_session' interface for a file
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* \author Josef Soentgen
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* \date 2013-10-08
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*/
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/*
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* Copyright (C) 2013-2017 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 <base/heap.h>
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#include <base/log.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 <root/component.h>
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#include <terminal_session/terminal_session.h>
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/* libc includes */
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/select.h>
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#include <stdio.h>
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#include <fcntl.h>
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class Open_file
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{
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private:
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/**
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* File descriptor for open file
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*/
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int _fd;
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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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public:
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Open_file(const char *filename) : _fd(-1)
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{
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_fd = ::open(filename, O_CREAT|O_RDWR);
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if (_fd == -1)
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::perror("open");
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}
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~Open_file() { close(_fd); }
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/**
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* Return file descriptor of the open file
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*/
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int fd() const { return _fd; }
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/**
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* Register signal handler to be notified once we openend the file
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*/
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void connected_sigh(Genode::Signal_context_capability sigh)
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{
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_connected_sigh = sigh;
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/* notify the client immediatly if we have already openend the file */
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if (file_opened() && _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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* 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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* Return true if the file was successfully openend
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*/
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bool file_opened() const { return _fd != -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 file */
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_read_buf_bytes_used = ::read(_fd, _read_buf, sizeof(_read_buf));
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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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* Flush internal read buffer into destination buffer
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*/
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Genode::size_t flush_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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Genode::memcpy(dst, _read_buf, num_bytes);
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_read_buf_bytes_used = 0;
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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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namespace Terminal {
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class Session_component : public Genode::Rpc_object<Session, Session_component>,
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public Open_file
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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,
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Genode::size_t io_buffer_size, const char *filename)
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:
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Open_file(filename),
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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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flush_read_buffer(_io_buffer.local_addr<char>(),
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Genode::min(_io_buffer.size(), dst_len));
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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 descriptor */
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ssize_t written_bytes = ::write(fd(),
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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_file::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_file::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 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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Genode::size_t io_buffer_size = 4096;
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try {
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Genode::Session_label label = Genode::label_from_args(args);
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Genode::Session_policy policy(label, _config);
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char filename[256];
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policy.attribute("filename").value(filename, sizeof(filename));
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if (policy.has_attribute("io_buffer_size"))
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policy.attribute("io_buffer_size").value(&io_buffer_size);
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return new (md_alloc())
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Session_component(_env, io_buffer_size, filename);
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}
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catch (Genode::Xml_node::Nonexistent_attribute) {
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Genode::error("missing \"filename\" attribute in policy definition");
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throw Genode::Service_denied();
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}
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catch (Genode::Session_policy::No_policy_defined) {
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Genode::error("invalid session request, no matching policy");
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throw Genode::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(), md_alloc),
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_env(env), _config(config)
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{ }
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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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using namespace Genode;
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Genode::log("--- file terminal started ---");
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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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