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HandleToInt() and IntToHandle() use int, a signed type, for the 32-bit integer representation of HANDLE values. For opaque values, an unsigned type would normally be used, but in this case, signed was chosen for sign extension to work correctly. INVALID_HANDLE_VALUE is defined as ((HANDLE)(LONG_PTR)-1), and this needs to round-trip through the chosen integer representation back to the same HANDLE value. Sign extension is also recommended by https://msdn.microsoft.com/en-us/library/windows/desktop/aa384203. As suggested in https://codereview.chromium.org/1422503015/diff/1/util/win/handle.cc#newcode24 R=scottmg@chromium.org Review URL: https://codereview.chromium.org/1422023010 .
66 lines
2.5 KiB
C++
66 lines
2.5 KiB
C++
// Copyright 2015 The Crashpad Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef CRASHPAD_UTIL_WIN_HANDLE_TO_INT_H_
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#define CRASHPAD_UTIL_WIN_HANDLE_TO_INT_H_
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#include <windows.h>
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namespace crashpad {
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//! \brief Converts a `HANDLE` to an `int`.
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//!
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//! `HANDLE` is a `typedef` for `void *`, but kernel `HANDLE` values aren’t
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//! pointers to anything. Only 32 bits of kernel `HANDLE`s are significant, even
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//! in 64-bit processes on 64-bit operating systems. See <a
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//! href="https://msdn.microsoft.com/en-us/library/windows/desktop/aa384203">Interprocess
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//! Communication Between 32-bit and 64-bit Applications</a>.
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//!
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//! This function safely converts a kernel `HANDLE` to an `int` similarly to a
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//! cast operation. It checks that the operation can be performed safely, and
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//! aborts execution if it cannot.
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//!
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//! \param[in] handle The kernel `HANDLE` to convert.
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//!
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//! \return An equivalent `int`, truncated (if necessary) from \a handle. If
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//! truncation would have resulted in an `int` that could not be converted
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//! back to \a handle, aborts execution.
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//!
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//! \sa IntToHandle()
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int HandleToInt(HANDLE handle);
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//! \brief Converts an `int` to an `HANDLE`.
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//!
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//! `HANDLE` is a `typedef` for `void *`, but kernel `HANDLE` values aren’t
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//! pointers to anything. Only 32 bits of kernel `HANDLE`s are significant, even
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//! in 64-bit processes on 64-bit operating systems. See <a
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//! href="https://msdn.microsoft.com/en-us/library/windows/desktop/aa384203">Interprocess
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//! Communication Between 32-bit and 64-bit Applications</a>.
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//!
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//! This function safely convert an `int` to a kernel `HANDLE` similarly to a
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//! cast operation.
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//!
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//! \param[in] handle_int The `int` to convert. This must have been produced by
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//! HandleToInt(), possibly in a different process.
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//!
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//! \return An equivalent kernel `HANDLE`, sign-extended (if necessary) from \a
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//! handle_int.
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//!
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//! \sa HandleToInt()
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HANDLE IntToHandle(int handle_int);
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} // namespace crashpad
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#endif // CRASHPAD_UTIL_WIN_HANDLE_TO_INT_H_
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