genode/repos/os/include/os/child_policy_dynamic_rom.h
Norman Feske eaac3cc1bd Revised API documentation
This patch curates the API documentation to become suitable for the
functional specificaton, which is partially generated from the header
files.
2015-04-09 16:04:46 +02:00

179 lines
4.5 KiB
C++

/*
* \brief Child policy helper for supplying dynamic ROM modules
* \author Norman Feske
* \date 2012-04-04
*/
/*
* Copyright (C) 2012-2013 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU General Public License version 2.
*/
#ifndef _INCLUDE__OS__CHILD_POLICY_DYNAMIC_ROM_H_
#define _INCLUDE__OS__CHILD_POLICY_DYNAMIC_ROM_H_
#include <ram_session/ram_session.h>
#include <rom_session/rom_session.h>
#include <base/rpc_server.h>
#include <os/attached_ram_dataspace.h>
namespace Genode { class Child_policy_dynamic_rom_file; }
class Genode::Child_policy_dynamic_rom_file : public Rpc_object<Rom_session>,
public Service
{
private:
Ram_session *_ram;
/*
* The ROM module may be written and consumed by different threads,
* e.g., written by the main thread and consumed by the child's
* entrypoint that manages the local ROM service for handing out a
* dynamic config. Hence, the '_lock' is used to synchronize the
* 'load' and 'dataspace' methods.
*/
Lock _lock;
/*
* We keep two dataspaces around. The foreground ('_fg') dataspace
* is the one we present to the client. While the foreground
* dataspace is in use, we perform all modifications of the data
* in the background dataspace (which is invisible to the client).
* Once the client calls 'dataspace()', we promote the old
* background dataspace to the new foreground and thereby hand out
* the former background dataspace.
*/
Attached_ram_dataspace _fg;
Attached_ram_dataspace _bg;
bool _bg_has_pending_data;
Signal_context_capability _sigh_cap;
Rpc_entrypoint &_ep;
Rom_session_capability _rom_session_cap;
enum { FILENAME_MAX_LEN = 32 };
char _filename[FILENAME_MAX_LEN];
public:
/**
* Constructor
*
* \param ram RAM session used to allocate the backing store
* for buffering ROM module data
*
* If 'ram' is 0, the child policy is ineffective.
*/
Child_policy_dynamic_rom_file(const char *filename,
Rpc_entrypoint &ep,
Ram_session *ram)
:
Service("ROM"),
_ram(ram),
_fg(0, 0), _bg(0, 0),
_bg_has_pending_data(false),
_ep(ep),
_rom_session_cap(_ep.manage(this))
{
strncpy(_filename, filename, sizeof(_filename));
}
/**
* Destructor
*/
~Child_policy_dynamic_rom_file() { _ep.dissolve(this); }
/**
* Load new content into ROM module
*
* \throw Ram_session::Alloc_failed
* \throw Rm_session::Attach_failed
*/
void load(void const *data, size_t data_len)
{
Lock::Guard guard(_lock);
if (!_ram) {
PERR("Error: No backing store for loading ROM data");
return;
}
/* let background buffer grow if needed */
if (_bg.size() < data_len)
_bg.realloc(_ram, data_len);
memcpy(_bg.local_addr<void>(), data, data_len);
_bg_has_pending_data = true;
if (_sigh_cap.valid())
Signal_transmitter(_sigh_cap).submit();
}
/***************************
** ROM session interface **
***************************/
Rom_dataspace_capability dataspace()
{
Lock::Guard guard(_lock);
if (!_fg.size() && !_bg_has_pending_data) {
PERR("Error: no data loaded");
return Rom_dataspace_capability();
}
/*
* Keep foreground if no background exists. Otherwise, use
* old background as new foreground.
*/
if (_bg_has_pending_data) {
_fg.swap(_bg);
_bg_has_pending_data = false;
}
Dataspace_capability ds_cap = _fg.cap();
return static_cap_cast<Rom_dataspace>(ds_cap);
}
void sigh(Signal_context_capability cap) { _sigh_cap = cap; }
/***********************
** Service interface **
***********************/
Session_capability session(const char *, Affinity const &) {
return _rom_session_cap; }
void upgrade(Session_capability, const char *) { }
void close(Session_capability) { }
/**********************
** Policy interface **
**********************/
Service *resolve_session_request(const char *service_name,
const char *args)
{
if (!_ram) return 0;
/* ignore session requests for non-ROM services */
if (strcmp(service_name, "ROM")) return 0;
/* drop out if request refers to another file name */
char buf[FILENAME_MAX_LEN];
Arg_string::find_arg(args, "filename").string(buf, sizeof(buf), "");
return !strcmp(buf, _filename) ? this : 0;
}
};
#endif /* _INCLUDE__OS__CHILD_POLICY_DYNAMIC_ROM_H_ */