mirror of
https://github.com/LadybirdBrowser/ladybird.git
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94ca55cefd
As suggested by Joshua, this commit adds the 2-clause BSD license as a comment block to the top of every source file. For the first pass, I've just added myself for simplicity. I encourage everyone to add themselves as copyright holders of any file they've added or modified in some significant way. If I've added myself in error somewhere, feel free to replace it with the appropriate copyright holder instead. Going forward, all new source files should include a license header.
187 lines
6 KiB
C++
187 lines
6 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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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 met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (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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#include <Kernel/Process.h>
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#include <Kernel/SharedBuffer.h>
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Lockable<HashMap<int, NonnullOwnPtr<SharedBuffer>>>& shared_buffers()
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{
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static Lockable<HashMap<int, NonnullOwnPtr<SharedBuffer>>>* map;
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if (!map)
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map = new Lockable<HashMap<int, NonnullOwnPtr<SharedBuffer>>>;
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return *map;
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}
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void SharedBuffer::sanity_check(const char* what)
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{
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LOCKER(shared_buffers().lock());
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unsigned found_refs = 0;
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for (const auto& ref : m_refs)
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found_refs += ref.count;
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if (found_refs != m_total_refs) {
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dbgprintf("%s sanity -- SharedBuffer{%p} id: %d has total refs %d but we found %d\n", what, this, m_shared_buffer_id, m_total_refs, found_refs);
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for (const auto& ref : m_refs) {
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dbgprintf(" ref from pid %d: refcnt %d\n", ref.pid, ref.count);
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}
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ASSERT_NOT_REACHED();
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}
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}
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bool SharedBuffer::is_shared_with(pid_t peer_pid)
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{
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LOCKER(shared_buffers().lock());
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if (m_global)
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return true;
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for (auto& ref : m_refs) {
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if (ref.pid == peer_pid) {
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return true;
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}
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}
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return false;
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}
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void* SharedBuffer::ref_for_process_and_get_address(Process& process)
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{
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LOCKER(shared_buffers().lock());
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ASSERT(is_shared_with(process.pid()));
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if (m_global) {
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bool found = false;
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for (auto& ref : m_refs) {
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if (ref.pid == process.pid()) {
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found = true;
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break;
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}
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}
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if (!found)
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m_refs.append(Reference(process.pid()));
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}
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for (auto& ref : m_refs) {
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if (ref.pid == process.pid()) {
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ref.count++;
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m_total_refs++;
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if (ref.region == nullptr) {
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ref.region = process.allocate_region_with_vmobject(VirtualAddress(), size(), m_vmobject, 0, "SharedBuffer", PROT_READ | (m_writable ? PROT_WRITE : 0));
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ref.region->set_shared(true);
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}
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sanity_check("ref_for_process_and_get_address");
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return ref.region->vaddr().as_ptr();
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}
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}
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ASSERT_NOT_REACHED();
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}
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void SharedBuffer::share_with(pid_t peer_pid)
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{
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LOCKER(shared_buffers().lock());
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for (auto& ref : m_refs) {
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if (ref.pid == peer_pid) {
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// don't increment the reference count yet; let them get_shared_buffer it first.
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sanity_check("share_with (old ref)");
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return;
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}
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}
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m_refs.append(Reference(peer_pid));
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sanity_check("share_with (new ref)");
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}
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void SharedBuffer::deref_for_process(Process& process)
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{
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LOCKER(shared_buffers().lock());
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for (int i = 0; i < m_refs.size(); ++i) {
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auto& ref = m_refs[i];
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if (ref.pid == process.pid()) {
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ref.count--;
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m_total_refs--;
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if (ref.count == 0) {
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#ifdef SHARED_BUFFER_DEBUG
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dbgprintf("Releasing shared buffer reference on %d of size %d by PID %d\n", m_shared_buffer_id, size(), process.pid());
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#endif
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process.deallocate_region(*ref.region);
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m_refs.unstable_remove(i);
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#ifdef SHARED_BUFFER_DEBUG
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dbgprintf("Released shared buffer reference on %d of size %d by PID %d\n", m_shared_buffer_id, size(), process.pid());
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#endif
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sanity_check("deref_for_process");
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destroy_if_unused();
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return;
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}
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return;
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}
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}
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ASSERT_NOT_REACHED();
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}
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void SharedBuffer::disown(pid_t pid)
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{
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LOCKER(shared_buffers().lock());
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for (int i = 0; i < m_refs.size(); ++i) {
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auto& ref = m_refs[i];
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if (ref.pid == pid) {
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#ifdef SHARED_BUFFER_DEBUG
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dbgprintf("Disowning shared buffer %d of size %d by PID %d\n", m_shared_buffer_id, size(), pid);
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#endif
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m_total_refs -= ref.count;
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m_refs.unstable_remove(i);
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#ifdef SHARED_BUFFER_DEBUG
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dbgprintf("Disowned shared buffer %d of size %d by PID %d\n", m_shared_buffer_id, size(), pid);
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#endif
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destroy_if_unused();
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return;
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}
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}
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}
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void SharedBuffer::destroy_if_unused()
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{
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LOCKER(shared_buffers().lock());
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sanity_check("destroy_if_unused");
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if (m_total_refs == 0) {
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#ifdef SHARED_BUFFER_DEBUG
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kprintf("Destroying unused SharedBuffer{%p} id: %d\n", this, m_shared_buffer_id);
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#endif
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auto count_before = shared_buffers().resource().size();
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shared_buffers().resource().remove(m_shared_buffer_id);
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ASSERT(count_before != shared_buffers().resource().size());
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}
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}
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void SharedBuffer::seal()
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{
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LOCKER(shared_buffers().lock());
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m_writable = false;
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for (auto& ref : m_refs) {
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if (ref.region) {
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ref.region->set_writable(false);
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ref.region->remap();
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}
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}
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}
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