mirror of
https://github.com/gnif/LookingGlass.git
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121 lines
4.0 KiB
C++
121 lines
4.0 KiB
C++
/**
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* Looking Glass
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* Copyright © 2017-2026 The Looking Glass Authors
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* https://looking-glass.io
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc., 59
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* Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "CClipboardRing.h"
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#include "Atomic.h"
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#include <string.h>
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void CClipboardRing::Initialize(
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ClipboardMapping& mapping, uint64_t epoch)
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{
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memset(&mapping, 0, sizeof(mapping));
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mapping.magic = LG_CLIPBOARD_MAPPING_MAGIC;
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mapping.version = LG_CLIPBOARD_MAPPING_VERSION;
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mapping.size = sizeof(mapping);
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mapping.slotBytes = KVMFR_CLIPBOARD_DATA_BYTES;
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mapping.slotCount = KVMFR_CLIPBOARD_SLOT_COUNT;
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mapping.epoch = epoch;
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}
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bool CClipboardRing::Valid(
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const ClipboardMapping& mapping, uint64_t epoch)
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{
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if (mapping.magic != LG_CLIPBOARD_MAPPING_MAGIC ||
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mapping.version != LG_CLIPBOARD_MAPPING_VERSION ||
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mapping.size != sizeof(mapping) ||
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mapping.slotBytes != KVMFR_CLIPBOARD_DATA_BYTES ||
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mapping.slotCount != KVMFR_CLIPBOARD_SLOT_COUNT ||
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!mapping.epoch || mapping.epoch != epoch)
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return false;
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ClipboardRing& helper =
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const_cast<ClipboardRing&>(mapping.helperToIdd);
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ClipboardRing& idd =
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const_cast<ClipboardRing&>(mapping.iddToHelper);
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const uint32_t helperProduced = Atomic::Load(helper.produced);
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const uint32_t helperConsumed = Atomic::Load(helper.consumed);
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const uint32_t iddProduced = Atomic::Load(idd.produced);
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const uint32_t iddConsumed = Atomic::Load(idd.consumed);
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return helperProduced - helperConsumed <= KVMFR_CLIPBOARD_SLOT_COUNT &&
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iddProduced - iddConsumed <= KVMFR_CLIPBOARD_SLOT_COUNT;
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}
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ClipboardRingSlot * CClipboardRing::BeginWrite(
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ClipboardRing& ring, uint32_t& ticket)
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{
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const uint32_t produced = Atomic::Load(ring.produced);
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const uint32_t consumed = Atomic::Load(ring.consumed);
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const uint32_t pending = produced - consumed;
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if (pending >= KVMFR_CLIPBOARD_SLOT_COUNT)
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return nullptr;
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ticket = produced;
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return &ring.slots[produced % KVMFR_CLIPBOARD_SLOT_COUNT];
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}
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bool CClipboardRing::EndWrite(ClipboardRing& ring, uint32_t ticket)
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{
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if (Atomic::Load(ring.produced) != ticket)
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return false;
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Atomic::Fence();
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Atomic::Store(ring.produced, ticket + 1U);
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return true;
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}
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ClipboardRingReadResult CClipboardRing::BeginRead(ClipboardRing& ring,
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uint32_t& ticket, const ClipboardRingSlot *& slot)
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{
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slot = nullptr;
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const uint32_t consumed = Atomic::Load(ring.consumed);
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const uint32_t pending = Atomic::Load(ring.produced) - consumed;
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if (!pending)
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return ClipboardRingReadResult::EMPTY;
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if (pending > KVMFR_CLIPBOARD_SLOT_COUNT)
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return ClipboardRingReadResult::CORRUPT;
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Atomic::Fence();
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ticket = consumed;
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slot = &ring.slots[consumed % KVMFR_CLIPBOARD_SLOT_COUNT];
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return ClipboardRingReadResult::READY;
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}
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bool CClipboardRing::EndRead(ClipboardRing& ring, uint32_t ticket)
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{
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if (Atomic::Load(ring.consumed) != ticket)
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return false;
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Atomic::Fence();
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Atomic::Store(ring.consumed, ticket + 1U);
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return true;
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}
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bool CClipboardRing::Valid(const ClipboardRingSlot& slot)
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{
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return slot.header.version == KVMFR_CLIPBOARD_VERSION &&
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slot.header.type >= KVMFR_CLIPBOARD_MESSAGE_CLAIM &&
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slot.header.type <= KVMFR_CLIPBOARD_MESSAGE_GRANT &&
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slot.header.length <= KVMFR_CLIPBOARD_DATA_BYTES &&
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(slot.header.type == KVMFR_CLIPBOARD_MESSAGE_DATA ||
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!slot.header.length);
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}
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