src/dawn/utils/SystemHandle.cpp

// Copyright 2025 The Dawn & Tint Authors
//
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// 2. Redistributions in binary form must reproduce the above copyright notice,
//    this list of conditions and the following disclaimer in the documentation
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#include "src/dawn/utils/SystemHandle.h"

#include <utility>

#include "src/utils/assert.h"
#include "src/utils/log.h"

#if DAWN_PLATFORM_IS(WINDOWS)
#include "src/utils/windows_with_undefs.h"
#elif DAWN_PLATFORM_IS(FUCHSIA)
#include <zircon/syscalls.h>
#elif DAWN_PLATFORM_IS(POSIX)
#include <unistd.h>
#endif

namespace dawn::utils {

namespace {

#if DAWN_PLATFORM_IS(WINDOWS)

constexpr inline HANDLE kInvalidHandle = nullptr;

inline bool IsHandleValid(HANDLE handle) {
    return handle != nullptr;
}

inline HANDLE DuplicateHandle(HANDLE handle) {
    HANDLE currentProcess = ::GetCurrentProcess();
    HANDLE outHandle;
    bool success = ::DuplicateHandle(currentProcess, handle, currentProcess, &outHandle, 0, FALSE,
                                     DUPLICATE_SAME_ACCESS);
    DAWN_CHECK(success);
    return outHandle;
}

inline void CloseHandle(HANDLE handle) {
    bool success = ::CloseHandle(handle);
    DAWN_CHECK(success);
}

#elif DAWN_PLATFORM_IS(FUCHSIA)

constexpr inline zx_handle_t kInvalidHandle = 0;

inline bool IsHandleValid(zx_handle_t handle) {
    return handle > 0;
}

inline zx_handle_t DuplicateHandle(zx_handle_t handle) {
    zx_handle_t outHandle = ZX_HANDLE_INVALID;
    auto status = zx_handle_duplicate(handle, ZX_RIGHT_SAME_RIGHTS, &outHandle);
    DAWN_CHECK(status == ZX_OK);
    return outHandle;
}

inline void CloseHandle(zx_handle_t handle) {
    auto status = zx_handle_close(handle);
    DAWN_CHECK(status == ZX_OK);
}

#elif DAWN_PLATFORM_IS(POSIX)

constexpr inline int kInvalidHandle = -1;

inline bool IsHandleValid(int handle) {
    return handle >= 0;
}

inline int DuplicateHandle(int handle) {
    int outHandle = dup(handle);
    DAWN_CHECK(outHandle >= 0);
    return outHandle;
}

inline void CloseHandle(int handle) {
    int status = close(handle);
    DAWN_CHECK(status >= 0);
}

#endif

}  // anonymous namespace

SystemHandle::SystemHandle() : mHandle(kInvalidHandle) {}
SystemHandle::SystemHandle(Handle handle) : mHandle(handle) {}

SystemHandle::SystemHandle(ErrorTag tag) : SystemHandle() {
    dawn::ErrorLog() << "SystemHandle constructed from incorrect handle type.";
    DAWN_UNREACHABLE();
}

bool SystemHandle::IsValid() const {
    return IsHandleValid(mHandle);
}

SystemHandle::SystemHandle(SystemHandle&& rhs) {
    mHandle = rhs.mHandle;
    rhs.mHandle = kInvalidHandle;
}

SystemHandle& SystemHandle::operator=(SystemHandle&& rhs) {
    if (this != &rhs) {
        if (IsValid()) {
            Close();
        }
        mHandle = rhs.mHandle;
        rhs.mHandle = kInvalidHandle;
    }
    return *this;
}

SystemHandle::Handle SystemHandle::Get() const {
    return mHandle;
}

SystemHandle::Handle* SystemHandle::GetMut() {
    if (IsValid()) {
        Close();
    }
    return &mHandle;
}

SystemHandle::Handle SystemHandle::Detach() {
    Handle handle = mHandle;
    mHandle = kInvalidHandle;
    return handle;
}

SystemHandle SystemHandle::Duplicate() const {
    DAWN_CHECK(IsValid());

    Handle handle = DuplicateHandle(mHandle);
    return SystemHandle(handle);
}

void SystemHandle::Close() {
    DAWN_ASSERT(IsValid());
    CloseHandle(mHandle);
    // Invalidate the handle after closing.
    mHandle = kInvalidHandle;
}

SystemHandle::~SystemHandle() {
    if (IsValid()) {
        Close();
    }
}

}  // namespace dawn::utils