278 lines
7.4 KiB
C++
278 lines
7.4 KiB
C++
/*
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* \brief Provide a rom-file as block device (aka loop devices)
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* \author Stefan Kalkowski
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* \date 2010-07-07
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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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#include <base/exception.h>
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#include <base/printf.h>
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#include <base/sleep.h>
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#include <base/semaphore.h>
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#include <base/allocator_avl.h>
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#include <root/component.h>
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#include <os/config.h>
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#include <cap_session/connection.h>
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#include <rom_session/connection.h>
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#include <block_session/rpc_object.h>
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using namespace Genode;
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namespace Block {
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class Session_component : public Session_rpc_object
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{
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private:
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/**
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* Thread handling the requests of an open block session.
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*/
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class Tx_thread : public Thread<8192>
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{
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private:
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Session_component *_session; /* corresponding session object */
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addr_t _dev_addr; /* rom-file address */
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size_t _dev_size; /* rom-file size */
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size_t _blk_size; /* block size */
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public:
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/**
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* Constructor
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*/
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Tx_thread(Session_component *session,
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addr_t dev_addr,
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size_t dev_size,
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size_t blk_size)
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: Thread("block_session_tx"),
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_session(session),
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_dev_addr(dev_addr),
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_dev_size(dev_size),
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_blk_size(blk_size) { }
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/**
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* Thread's entry function.
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*/
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void entry()
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{
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Session_component::Tx::Sink *tx_sink =
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_session->tx_sink();
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Block::Packet_descriptor packet;
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/* signal preparedness to server activation */
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_session->tx_ready();
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/* handle requests */
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while (true) {
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/* blocking-get packet from client */
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packet = tx_sink->get_packet();
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if (!packet.valid()) {
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PWRN("received invalid packet");
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continue;
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}
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/* sanity check block number */
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if ((packet.block_number() + packet.block_count()
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> _dev_size / _blk_size)
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|| packet.block_number() < 0) {
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PWRN("requested blocks %zd-%zd out of range!",
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packet.block_number(),
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packet.block_number() + packet.block_count());
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continue;
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}
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size_t offset = packet.block_number() * _blk_size;
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size_t size = packet.block_count() * _blk_size;
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switch (packet.operation()) {
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case Block::Packet_descriptor::READ:
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{
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/* copy file content to packet payload */
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memcpy(tx_sink->packet_content(packet),
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(void*)(_dev_addr + offset),
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size);
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packet.succeeded(true);
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break;
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}
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case Block::Packet_descriptor::WRITE:
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{
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PWRN("write attempt on read-only device");
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packet.succeeded(false);
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break;
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}
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default:
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PWRN("unsupported operation");
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packet.succeeded(false);
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continue;
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}
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/* acknowledge packet to the client */
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if (!tx_sink->ready_to_ack())
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PDBG("need to wait until ready-for-ack");
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tx_sink->acknowledge_packet(packet);
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}
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}
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friend class Session_component;
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};
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private:
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Dataspace_capability _tx_ds; /* buffer for tx channel */
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Semaphore _startup_sema; /* thread startup sync */
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Tx_thread _tx_thread; /* thread handling block requests */
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size_t _block_count; /* count of blocks of this session */
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size_t _block_size; /* size of a block */
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public:
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/**
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* Constructor
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*
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* \param tx_buf_size buffer size for tx channel
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* \param dev_addr address of attached file
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* \param dev_size size of attached file
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*/
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Session_component(size_t tx_buf_size,
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addr_t dev_addr,
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size_t dev_size,
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size_t blk_size,
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Genode::Rpc_entrypoint &ep)
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: Session_rpc_object(env()->ram_session()->alloc(tx_buf_size), ep),
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_startup_sema(0),
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_tx_thread(this, dev_addr, dev_size, blk_size),
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_block_count(dev_size / blk_size),
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_block_size(blk_size)
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{
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_tx_thread.start();
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/* block until thread is ready to handle requests */
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_startup_sema.down();
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}
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/**
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* Signal indicating that transmit thread is ready
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*/
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void tx_ready() { _startup_sema.up(); }
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/*****************************
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** Block session interface **
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*****************************/
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void info(size_t *blk_count, size_t *blk_size, Operations *ops)
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{
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*blk_count = _block_count;
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*blk_size = _block_size;
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ops->set_operation(Block::Packet_descriptor::READ);
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}
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void sync() {}
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};
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/**
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* Root component, handling new session requests
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*/
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class Root : public Root_component<Session_component>
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{
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private:
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Dataspace_capability _file_cap; /* rom-file capability */
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addr_t _file_addr; /* start address of attached file */
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size_t _file_sz; /* file size */
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size_t _blk_sz; /* block size */
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Genode::Rpc_entrypoint &_channel_ep;
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protected:
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Session_component *_create_session(const char *args)
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{
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size_t ram_quota =
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Arg_string::find_arg(args, "ram_quota" ).ulong_value(0);
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size_t tx_buf_size =
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Arg_string::find_arg(args, "tx_buf_size").ulong_value(0);
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/*
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* Check if donated ram quota suffices for session data,
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* and communication buffer.
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*/
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size_t session_size = sizeof(Session_component) + tx_buf_size;
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if (max((size_t)4096, session_size) > ram_quota) {
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PERR("insufficient 'ram_quota', got %zd, need %zd",
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ram_quota, session_size);
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throw Root::Quota_exceeded();
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}
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return new (md_alloc())
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Session_component(tx_buf_size, _file_addr, _file_sz, _blk_sz, _channel_ep);
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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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* \param session_ep session entrypoint
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* \param md_alloc meta-data allocator
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* \param file_cap capabilty of file to use as block-device
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*/
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Root(Rpc_entrypoint *session_ep, Allocator *md_alloc,
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Dataspace_capability file_cap, size_t blk_size)
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: Root_component<Session_component>(session_ep, md_alloc),
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_file_cap(file_cap),
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_file_addr(env()->rm_session()->attach(file_cap)),
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_file_sz(Dataspace_client(file_cap).size()),
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_blk_sz(blk_size),
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_channel_ep(*session_ep) { }
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~Root() { env()->rm_session()->detach((void*)_file_addr); }
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};
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}
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/**
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* Get name of the file we want to provide as block device,
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* and the block_size.
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*/
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static void process_config(char *file, size_t size, size_t *blk_size)
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{
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try {
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config()->xml_node().attribute("file").value(file, size);
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config()->xml_node().attribute("block_size").value(blk_size);
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}
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catch (...) { }
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}
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int main()
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{
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static char file[64];
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static size_t block_size = 512;
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process_config(file, sizeof(file), &block_size);
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PINF("Using file=%s as device with block size %zx.", file, block_size);
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try {
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enum { STACK_SIZE = 8192 };
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static Cap_connection cap;
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static Rpc_entrypoint ep(&cap, STACK_SIZE, "rom_loop_ep");
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static Rom_connection rom(file);
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static Block::Root blk_root(&ep, env()->heap(), rom.dataspace(), block_size);
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env()->parent()->announce(ep.manage(&blk_root));
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sleep_forever();
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} catch (Rom_connection::Rom_connection_failed) {
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PERR("Cannot open file %s.", file);
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}
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return 0;
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}
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