147 lines
2.6 KiB
C++
147 lines
2.6 KiB
C++
/*
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* \brief IPC message buffer layout
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* \author Norman Feske
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* \date 2015-05-10
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*/
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/*
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* Copyright (C) 2015 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__BASE__IPC_MSGBUF_H_
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#define _INCLUDE__BASE__IPC_MSGBUF_H_
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#include <base/native_types.h>
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namespace Genode {
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class Msgbuf_base;
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template <unsigned> struct Msgbuf;
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}
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class Genode::Msgbuf_base
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{
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public:
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enum { MAX_CAPS_PER_MSG = 3 };
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protected:
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/*
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* Resolve ambiguity if the header is included from a libc-using
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* program.
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*/
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typedef Genode::size_t size_t;
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/*
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* Capabilities to be transferred
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*/
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Native_capability _caps[MAX_CAPS_PER_MSG];
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size_t _used_caps = 0;
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size_t _read_cap_index = 0;
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/**
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* Maximum size of plain-data message payload
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*/
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size_t const _size;
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/**
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* Actual size of plain-data message payload
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*/
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size_t _used_size = 0;
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char _msg_start[]; /* symbol marks start of message buffer data */
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/*
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* No member variables are allowed beyond this point!
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*/
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Msgbuf_base(size_t size) : _size(size) { }
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public:
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char buf[];
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/**
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* Return size of message buffer
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*/
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size_t size() const { return _size; };
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void reset_caps()
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{
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for (Genode::size_t i = 0; i < _used_caps; i++)
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_caps[i] = Native_capability();
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_used_caps = 0;
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}
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void reset_read_cap_index()
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{
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_read_cap_index = 0;
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}
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/**
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* Return pointer to start of message-buffer content
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*/
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void const *data() const { return &_msg_start[0]; };
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void *data() { return &_msg_start[0]; };
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/**
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* Exception type
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*/
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class Too_many_caps : public Exception { };
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/**
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* Called from '_marshal_capability'
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*/
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void append_cap(Native_capability const &cap)
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{
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if (_used_caps == MAX_CAPS_PER_MSG)
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throw Too_many_caps();
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_caps[_used_caps++] = cap;
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}
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/**
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* Called from '_unmarshal_capability'
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*/
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Native_capability extract_cap()
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{
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if (_read_cap_index == _used_caps)
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return Native_capability();
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return _caps[_read_cap_index++];
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}
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/**
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* Return number of marshalled capabilities
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*/
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size_t used_caps() const { return _used_caps; }
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Native_capability &cap(unsigned index)
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{
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return _caps[index];
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}
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};
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template <unsigned BUF_SIZE>
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struct Genode::Msgbuf : Msgbuf_base
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{
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/**
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* Pump up IPC message buffer to specified buffer size
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*
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* XXX remove padding of 16
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*/
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char buf[BUF_SIZE + 16];
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Msgbuf() : Msgbuf_base(BUF_SIZE) { }
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};
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#endif /* _INCLUDE__BASE__IPC_MSGBUF_H_ */
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