86 lines
1.8 KiB
Go
86 lines
1.8 KiB
Go
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// +build windows,!appengine
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package maxminddb
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// Windows support largely borrowed from mmap-go.
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//
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// Copyright 2011 Evan Shaw. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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import (
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"errors"
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"os"
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"reflect"
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"sync"
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"unsafe"
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"golang.org/x/sys/windows"
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)
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type memoryMap []byte
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// Windows
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var handleLock sync.Mutex
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var handleMap = map[uintptr]windows.Handle{}
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func mmap(fd int, length int) (data []byte, err error) {
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h, errno := windows.CreateFileMapping(windows.Handle(fd), nil,
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uint32(windows.PAGE_READONLY), 0, uint32(length), nil)
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if h == 0 {
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return nil, os.NewSyscallError("CreateFileMapping", errno)
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}
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addr, errno := windows.MapViewOfFile(h, uint32(windows.FILE_MAP_READ), 0,
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0, uintptr(length))
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if addr == 0 {
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return nil, os.NewSyscallError("MapViewOfFile", errno)
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}
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handleLock.Lock()
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handleMap[addr] = h
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handleLock.Unlock()
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m := memoryMap{}
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dh := m.header()
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dh.Data = addr
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dh.Len = length
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dh.Cap = dh.Len
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return m, nil
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}
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func (m *memoryMap) header() *reflect.SliceHeader {
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return (*reflect.SliceHeader)(unsafe.Pointer(m))
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}
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func flush(addr, len uintptr) error {
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errno := windows.FlushViewOfFile(addr, len)
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return os.NewSyscallError("FlushViewOfFile", errno)
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}
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func munmap(b []byte) (err error) {
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m := memoryMap(b)
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dh := m.header()
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addr := dh.Data
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length := uintptr(dh.Len)
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flush(addr, length)
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err = windows.UnmapViewOfFile(addr)
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if err != nil {
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return err
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}
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handleLock.Lock()
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defer handleLock.Unlock()
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handle, ok := handleMap[addr]
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if !ok {
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// should be impossible; we would've errored above
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return errors.New("unknown base address")
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}
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delete(handleMap, addr)
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e := windows.CloseHandle(windows.Handle(handle))
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return os.NewSyscallError("CloseHandle", e)
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}
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