102 lines
2.2 KiB
C++
102 lines
2.2 KiB
C++
/*
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* \brief Jitterentropy based random file system
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* \author Josef Soentgen
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* \date 2014-08-19
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*/
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/*
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* Copyright (C) 2014 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 _JITTERENTROPY_FILE_SYSTEM_H_
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#define _JITTERENTROPY_FILE_SYSTEM_H_
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/* Genode includes */
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#include <util/xml_node.h>
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#include <vfs/single_file_system.h>
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/* jitterentropy includes */
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extern "C" {
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#include <jitterentropy.h>
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}
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class Jitterentropy_file_system : public Vfs::Single_file_system
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{
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private:
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struct rand_data *_ec_stir;
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bool _initialized;
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bool _init_jitterentropy()
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{
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int err = jent_entropy_init();
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if (err) {
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PERR("jitterentropy library could not be initialized!");
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return false;
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}
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/* use the default behaviour as specified in jitterentropy(3) */
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_ec_stir = jent_entropy_collector_alloc(0, 0);
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if (!_ec_stir) {
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PERR("jitterentropy could not allocate entropy collector!");
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return false;
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}
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return true;
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}
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public:
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Jitterentropy_file_system(Genode::Xml_node config)
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:
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Single_file_system(NODE_TYPE_CHAR_DEVICE, name(), config),
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_ec_stir(0),
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_initialized(_init_jitterentropy())
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{ }
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~Jitterentropy_file_system()
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{
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if (_initialized)
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jent_entropy_collector_free(_ec_stir);
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}
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static char const *name() { return "jitterentropy"; }
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/********************************
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** File I/O service interface **
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********************************/
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Write_result write(Vfs::Vfs_handle *, char const *, Genode::size_t count,
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Genode::size_t &count_out) override
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{
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return WRITE_ERR_IO;
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}
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Read_result read(Vfs::Vfs_handle *vfs_handle, char *dst, Genode::size_t count,
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Genode::size_t &out_count) override
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{
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if (!_initialized)
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return READ_ERR_IO;
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enum { MAX_BUF_LEN = 256 };
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char buf[MAX_BUF_LEN];
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size_t len = count > MAX_BUF_LEN ? MAX_BUF_LEN : count;
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if (jent_read_entropy(_ec_stir, buf, len) < 0)
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return READ_ERR_IO;
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Genode::memcpy(dst, buf, len);
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out_count = len;
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return READ_OK;
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}
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};
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#endif /* _JITTERENTROPY_FILE_SYSTEM_H_ */
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