genode/repos/base/include/base/attached_rom_dataspace.h
Norman Feske d70cf314d8 Never throw in 'Attached_rom_dataspace::size'
If the ROM service returned in invalid dataspace, reflect this condition
via a size of zero instead of triggering an exception of type
'Reconstructible<Attached_dataspace>::Deref_unconstructed_object'.

Issue #3606
2020-02-04 15:51:10 +01:00

140 lines
3.8 KiB
C++

/*
* \brief Utility to open a ROM session and locally attach its content
* \author Norman Feske
* \date 2012-01-09
*/
/*
* Copyright (C) 2012-2017 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU Affero General Public License version 3.
*/
#ifndef _INCLUDE__BASE__ATTACHED_ROM_DATASPACE_H_
#define _INCLUDE__BASE__ATTACHED_ROM_DATASPACE_H_
#include <util/reconstructible.h>
#include <util/xml_node.h>
#include <base/attached_dataspace.h>
#include <rom_session/connection.h>
namespace Genode { class Attached_rom_dataspace; }
class Genode::Attached_rom_dataspace
{
private:
Region_map &_rm;
Rom_connection _rom;
/*
* A ROM module may change or disappear over the lifetime of a ROM
* session. In contrast to the plain 'Attached_dataspace', which is
* always be valid once constructed, a 'Attached_rom_dataspace' has
* to handle the validity of the dataspace.
*/
Constructible<Attached_dataspace> _ds { };
/**
* Try to attach the ROM module, ignore invalid dataspaces
*/
void _try_attach()
{
/*
* Normally, '_ds.construct()' would implicitly destruct an
* existing dataspace upon re-construction. However, we have to
* explicitly destruct the original dataspace prior calling
* '_rom.dataspace()'.
*
* The ROM server may destroy the original dataspace when the
* 'dataspace()' method is called. In this case, all existing
* mappings of the dataspace will be flushed by core. A destruction
* of 'Attached_dataspace' after this point will attempt to detach
* the already flushed mappings, thereby producing error messages
* at core.
*/
_ds.destruct();
try { _ds.construct(_rm, _rom.dataspace()); }
catch (Attached_dataspace::Invalid_dataspace) { }
}
public:
/**
* Constructor
*
* \throw Rom_connection::Rom_connection_failed
* \throw Region_map::Region_conflict
* \throw Region_map::Invalid_dataspace
* \throw Out_of_ram
* \throw Out_of_caps
*/
Attached_rom_dataspace(Env &env, char const *name)
: _rm(env.rm()), _rom(env, name) { _try_attach(); }
/**
* Return capability of the used dataspace
*/
Dataspace_capability cap() const { return _ds->cap(); }
template <typename T> T *local_addr() {
return _ds->local_addr<T>(); }
template <typename T> T const *local_addr() const {
return _ds->local_addr<T const>(); }
size_t size() const { return _ds.constructed() ? _ds->size() : 0; }
/**
* Register signal handler for ROM module changes
*/
void sigh(Signal_context_capability sigh) { _rom.sigh(sigh); }
/**
* Update ROM module content, re-attach if needed
*/
void update()
{
/*
* If the dataspace is already attached and the update fits into
* the existing dataspace, we can keep everything in place. The
* dataspace content gets updated by the call of '_rom.update'.
*/
if (_ds.constructed() && _rom.update() == true)
return;
/*
* If there was no valid dataspace attached beforehand or the
* new data size exceeds the capacity of the existing dataspace,
* replace the current dataspace by a new one.
*/
_try_attach();
}
/**
* Return true of content is present
*/
bool valid() const { return _ds.constructed(); }
/**
* Return dataspace content as XML node
*
* This method always returns a valid XML node. It never throws an
* exception. If the dataspace is invalid or does not contain properly
* formatted XML, the returned XML node has the form "<empty/>".
*/
Xml_node xml() const
{
try {
if (valid() && local_addr<void const>())
return Xml_node(local_addr<char>(), size());
} catch (Xml_node::Invalid_syntax) { }
return Xml_node("<empty/>");
}
};
#endif /* _INCLUDE__BASE__ATTACHED_ROM_DATASPACE_H_ */