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| // Copyright 2016 Tom Thorogood. All rights reserved.
| // Use of this source code is governed by a
| // Modified BSD License license that can be found in
| // the LICENSE file.
|
| package shm
|
| import (
| "sync/atomic"
| "unsafe"
|
| "golang.org/x/sys/unix"
| )
|
| func OpenSimplex(name string) (*ReadWriteCloser, error) {
| file, err := Open(name, unix.O_RDWR, 0)
| if err != nil {
| return nil, err
| }
|
| defer file.Close()
|
| data, err := unix.Mmap(int(file.Fd()), 0, sharedHeaderSize, unix.PROT_READ, unix.MAP_SHARED)
| if err != nil {
| return nil, err
| }
|
| shared := (*sharedMem)(unsafe.Pointer(&data[0]))
|
| if atomic.LoadUint32((*uint32)(&shared.Version)) != version {
| return nil, ErrInvalidSharedMemory
| }
|
| blockCount, blockSize := uint64(shared.BlockCount), uint64(shared.BlockSize)
|
| if err = unix.Munmap(data); err != nil {
| return nil, err
| }
|
| size := sharedHeaderSize + (blockHeaderSize+blockSize)*blockCount
|
| data, err = unix.Mmap(int(file.Fd()), 0, int(size), unix.PROT_READ|unix.PROT_WRITE, unix.MAP_SHARED)
| if err != nil {
| return nil, err
| }
|
| shared = (*sharedMem)(unsafe.Pointer(&data[0]))
| return &ReadWriteCloser{
| name: name,
|
| data: data,
| readShared: shared,
| writeShared: shared,
| size: size,
| fullBlockSize: blockHeaderSize + blockSize,
|
| Flags: (*[len(shared.Flags)]uint32)(unsafe.Pointer(&shared.Flags[0])),
| }, nil
| }
|
| func OpenDuplex(name string) (*ReadWriteCloser, error) {
| file, err := Open(name, unix.O_RDWR, 0)
| if err != nil {
| return nil, err
| }
|
| defer file.Close()
|
| data, err := unix.Mmap(int(file.Fd()), 0, sharedHeaderSize, unix.PROT_READ, unix.MAP_SHARED)
| if err != nil {
| return nil, err
| }
|
| shared := (*sharedMem)(unsafe.Pointer(&data[0]))
|
| if atomic.LoadUint32((*uint32)(&shared.Version)) != version {
| return nil, ErrInvalidSharedMemory
| }
|
| blockCount, blockSize := uint64(shared.BlockCount), uint64(shared.BlockSize)
|
| if err = unix.Munmap(data); err != nil {
| return nil, err
| }
|
| sharedSize := sharedHeaderSize + (blockHeaderSize+blockSize)*blockCount
| size := 2 * sharedSize
|
| data, err = unix.Mmap(int(file.Fd()), 0, int(size), unix.PROT_READ|unix.PROT_WRITE, unix.MAP_SHARED)
| if err != nil {
| return nil, err
| }
|
| writeShared := (*sharedMem)(unsafe.Pointer(&data[0]))
| return &ReadWriteCloser{
| name: name,
|
| data: data,
| readShared: (*sharedMem)(unsafe.Pointer(&data[sharedSize])),
| writeShared: writeShared,
| size: size,
| fullBlockSize: blockHeaderSize + blockSize,
|
| Flags: (*[len(writeShared.Flags)]uint32)(unsafe.Pointer(&writeShared.Flags[0])),
| }, nil
| }
|
|
