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fe734272bc
This patch improves the config handling by falling back to a static string (empty "<config />") if no valid config ROM module could be found. This can happen initially, but also at runtime when the ROM module dissapears, e.g., a ROM module accessed via fs_rom where the corresponding file gets unlinked.
114 lines
2.5 KiB
C++
114 lines
2.5 KiB
C++
/*
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* \brief Access to process configuration
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* \author Norman Feske
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* \date 2010-05-04
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*/
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/*
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* Copyright (C) 2010-2013 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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#ifndef _INCLUDE__OS__CONFIG_H_
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#define _INCLUDE__OS__CONFIG_H_
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#include <util/xml_node.h>
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#include <dataspace/client.h>
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#include <rom_session/connection.h>
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#include <base/exception.h>
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namespace Genode {
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class Config
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{
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private:
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Rom_connection _config_rom;
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Dataspace_capability _config_ds;
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Xml_node _config_xml;
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Xml_node _config_xml_node()
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{
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if (_config_ds.valid())
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return Xml_node(env()->rm_session()->attach(_config_ds),
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Genode::Dataspace_client(_config_ds).size());
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else
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return Xml_node("<config/>");
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}
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public:
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/**
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* Exception class for configuration errors
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*/
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class Invalid : public Exception { };
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/**
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* Constructor
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*/
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Config() :
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_config_rom("config"),
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_config_ds(_config_rom.dataspace()),
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_config_xml(_config_xml_node())
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{ }
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Xml_node xml_node() { return _config_xml; }
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/**
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* Register signal handler for tracking config modifications
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*/
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void sigh(Signal_context_capability cap) { _config_rom.sigh(cap); }
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/**
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* Reload configuration
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*
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* \throw Invalid if the new configuration has an invalid syntax
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*
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* This function is meant to be called as response to a signal
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* received by the signal handler as registered via 'sigh()'.
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*/
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void reload()
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{
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try {
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/* re-acquire dataspace from ROM session */
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if (_config_ds.valid())
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env()->rm_session()->detach(_config_xml.addr());
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_config_ds = _config_rom.dataspace();
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/* re-initialize XML node with new config data */
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_config_xml = _config_xml_node();
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} catch (Genode::Xml_node::Invalid_syntax) {
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PERR("Config file has invalid syntax");
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throw Invalid();
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}
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}
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};
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/**
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* Return singleton instance of config
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*/
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static Config *config()
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{
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static bool config_failed = false;
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if (!config_failed) {
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try {
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static Config config_inst;
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return &config_inst;
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} catch (Genode::Rom_connection::Rom_connection_failed) {
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PERR("Could not obtain config file");
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} catch (Genode::Xml_node::Invalid_syntax) {
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PERR("Config file has invalid syntax");
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}
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}
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/* do not try again to construct 'config_inst' */
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config_failed = true;
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throw Config::Invalid();
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}
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}
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#endif /* _INCLUDE__OS__CONFIG_H_ */
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