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package tsm1
import (
"errors"
"os"
"reflect"
"sync"
"syscall"
"unsafe"
)
// mmap implementation for Windows
// Based on: https://github.com/edsrzf/mmap-go
// Based on: https://github.com/boltdb/bolt/bolt_windows.go
// Ref: https://groups.google.com/forum/#!topic/golang-nuts/g0nLwQI9www
// We keep this map so that we can get back the original handle from the memory address.
var handleLock sync.Mutex
var handleMap = map[uintptr]syscall.Handle{}
var fileMap = map[uintptr]*os.File{}
func openSharedFile(f *os.File) (file *os.File, err error) {
var access, createmode, sharemode uint32
var sa *syscall.SecurityAttributes
access = syscall.GENERIC_READ
sharemode = uint32(syscall.FILE_SHARE_READ | syscall.FILE_SHARE_WRITE | syscall.FILE_SHARE_DELETE)
createmode = syscall.OPEN_EXISTING
fileName := f.Name()
pathp, err := syscall.UTF16PtrFromString(fileName)
if err != nil {
return nil, err
}
h, e := syscall.CreateFile(pathp, access, sharemode, sa, createmode, syscall.FILE_ATTRIBUTE_NORMAL, 0)
if e != nil {
return nil, e
}
//NewFile does not add finalizer, need to close this manually
return os.NewFile(uintptr(h), fileName), nil
}
func mmap(f *os.File, offset int64, length int) (out []byte, err error) {
// Open a file mapping handle.
sizelo := uint32(length >> 32)
sizehi := uint32(length) & 0xffffffff
sharedHandle, errno := openSharedFile(f)
if errno != nil {
return nil, os.NewSyscallError("CreateFile", errno)
}
h, errno := syscall.CreateFileMapping(syscall.Handle(sharedHandle.Fd()), nil, syscall.PAGE_READONLY, sizelo, sizehi, nil)
if h == 0 {
return nil, os.NewSyscallError("CreateFileMapping", errno)
}
// Create the memory map.
addr, errno := syscall.MapViewOfFile(h, syscall.FILE_MAP_READ, 0, 0, uintptr(length))
if addr == 0 {
return nil, os.NewSyscallError("MapViewOfFile", errno)
}
handleLock.Lock()
handleMap[addr] = h
fileMap[addr] = sharedHandle
handleLock.Unlock()
// Convert to a byte array.
hdr := (*reflect.SliceHeader)(unsafe.Pointer(&out))
hdr.Data = uintptr(unsafe.Pointer(addr))
hdr.Len = length
hdr.Cap = length
return
}
// munmap Windows implementation
// Based on: https://github.com/edsrzf/mmap-go
// Based on: https://github.com/boltdb/bolt/bolt_windows.go
func munmap(b []byte) (err error) {
handleLock.Lock()
defer handleLock.Unlock()
addr := (uintptr)(unsafe.Pointer(&b[0]))
if err := syscall.UnmapViewOfFile(addr); err != nil {
return os.NewSyscallError("UnmapViewOfFile", err)
}
handle, ok := handleMap[addr]
if !ok {
// should be impossible; we would've seen the error above
return errors.New("unknown base address")
}
delete(handleMap, addr)
e := syscall.CloseHandle(syscall.Handle(handle))
if e != nil {
return os.NewSyscallError("CloseHandle", e)
}
file, ok := fileMap[addr]
if !ok {
// should be impossible; we would've seen the error above
return errors.New("unknown base address")
}
delete(fileMap, addr)
e = file.Close()
if e != nil {
return errors.New("close file" + e.Error())
}
return nil
}
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