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https://github.com/RGBCube/serenity
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2d4d465206
It's a very bad idea to increment the refcount on behalf of another process. That process may (for either benign or evil reasons) not reference the SharedBuffer, and then we'll be stuck with loads of SharedBuffers until we OOM. Instead, increment the refcount when the buffer is mapped. That way, a buffer is only kept if *someone* has explicitly requested it via get_shared_buffer. Fixes #341
51 lines
1.2 KiB
C++
51 lines
1.2 KiB
C++
#pragma once
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#include <Kernel/VM/MemoryManager.h>
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#include <AK/OwnPtr.h>
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struct SharedBuffer {
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private:
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struct Reference {
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Reference(pid_t pid)
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: pid(pid)
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{
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}
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pid_t pid;
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unsigned count { 0 };
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Region* region { nullptr };
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};
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public:
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SharedBuffer(int id, int size)
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: m_shared_buffer_id(id)
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, m_vmo(VMObject::create_anonymous(size))
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{
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#ifdef SHARED_BUFFER_DEBUG
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dbgprintf("Created shared buffer %d of size %d\n", m_shared_buffer_id, size);
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#endif
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}
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~SharedBuffer()
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{
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#ifdef SHARED_BUFFER_DEBUG
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dbgprintf("Destroyed shared buffer %d of size %d\n", m_shared_buffer_id, size());
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#endif
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}
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bool is_shared_with(pid_t peer_pid);
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void* ref_for_process_and_get_address(Process& process);
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void share_with(pid_t peer_pid);
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void deref_for_process(Process& process);
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void disown(pid_t pid);
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size_t size() const { return m_vmo->size(); }
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void destroy_if_unused();
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void seal();
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int m_shared_buffer_id { -1 };
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bool m_writable { true };
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NonnullRefPtr<VMObject> m_vmo;
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Vector<Reference, 2> m_refs;
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unsigned m_total_refs { 0 };
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};
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Lockable<HashMap<int, OwnPtr<SharedBuffer>>>& shared_buffers();
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