Курнат Андрей
58 lines
1.5 KiB
Go
58 lines
1.5 KiB
Go
//go:build !arm64
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// +build !arm64
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/*
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* Copyright 2020 Dgraph Labs, Inc. and Contributors
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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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*/
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package z
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import (
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"fmt"
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"reflect"
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"unsafe"
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"golang.org/x/sys/unix"
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)
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// mremap is a Linux-specific system call to remap pages in memory. This can be used in place of munmap + mmap.
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func mremap(data []byte, size int) ([]byte, error) {
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//nolint:lll
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// taken from <https://github.com/torvalds/linux/blob/f8394f232b1eab649ce2df5c5f15b0e528c92091/include/uapi/linux/mman.h#L8>
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const MREMAP_MAYMOVE = 0x1
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header := (*reflect.SliceHeader)(unsafe.Pointer(&data))
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mmapAddr, mmapSize, errno := unix.Syscall6(
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unix.SYS_MREMAP,
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header.Data,
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uintptr(header.Len),
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uintptr(size),
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uintptr(MREMAP_MAYMOVE),
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0,
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0,
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)
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if errno != 0 {
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return nil, errno
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}
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if mmapSize != uintptr(size) {
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return nil, fmt.Errorf("mremap size mismatch: requested: %d got: %d", size, mmapSize)
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}
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header.Data = mmapAddr
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header.Cap = size
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header.Len = size
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return data, nil
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}
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