a928a438b8
Used cppclean to help identify useless includes and removed them. This involved erroneously included headers, but also cases where forward declarations could have been used rather than a full include.
117 lines
3.9 KiB
C++
117 lines
3.9 KiB
C++
/*
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* Copyright (c) 2003-2005 The Regents of The University of Michigan
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met: redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer;
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* redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution;
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* neither the name of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Authors: Gabe Black
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*/
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#ifndef __SIM_SYSCALLRETURN_HH__
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#define __SIM_SYSCALLRETURN_HH__
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#include <inttypes.h>
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/**
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* This class represents the return value from an emulated system call,
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* including any errno setting.
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*
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* On some platforms, the return value and errno are encoded in a
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* single signed integer. A value less than zero but greater than
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* -4096 indicates an error, and the value is the negation of the
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* errno value. Otherwise, the call was successful and the integer is
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* the return value. (Large negative numbers are considered
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* successful to allow syscalls to return pointers to high memory,
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* e.g., stack addresses.) See, for example, Appendix A of the AMD64
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* ABI spec at http://www.x86-64.org/documentation/abi.pdf.
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*
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* Other platforms use a more complex interface, returning a value and
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* an error code in separate registers.
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*
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* This class is designed to support both types of interfaces.
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*/
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class SyscallReturn
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{
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public:
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/// For simplicity, allow the object to be initialized with a
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/// single signed integer using the same positive=success,
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/// negative=-errno convention described above.
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///
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/// Typically this constructor is used as a default type
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/// conversion, so a bare integer is used where a SyscallReturn
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/// value is expected, e.g., as the return value from a system
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/// call emulation function ('return 0;' or 'return -EFAULT;').
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SyscallReturn(int64_t v)
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: value(v), retryFlag(false)
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{}
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/// Pseudo-constructor to create an instance with the retry flag set.
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static SyscallReturn retry()
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{
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SyscallReturn s(0);
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s.retryFlag = true;
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return s;
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}
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~SyscallReturn() {}
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/// Was the system call successful?
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bool successful() const
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{
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return (value >= 0 || value <= -4096);
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}
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/// Does the syscall need to be retried?
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bool needsRetry() const { return retryFlag; }
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/// The return value
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int64_t returnValue() const
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{
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assert(successful());
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return value;
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}
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/// The errno value
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int errnoValue() const
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{
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assert(!successful());
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return -value;
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}
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/// The encoded value (as described above)
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int64_t encodedValue() const
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{
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return value;
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}
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private:
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int64_t value;
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bool retryFlag;
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};
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#endif
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