mirror of https://github.com/hslam/shm.git
71 lines
1.6 KiB
Go
71 lines
1.6 KiB
Go
// Copyright (c) 2020 Meng Huang (mhboy@outlook.com)
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// This package is licensed under a MIT license that can be found in the LICENSE file.
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// +build darwin linux dragonfly freebsd netbsd openbsd
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package shm
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import (
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"syscall"
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"unsafe"
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)
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const (
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// IPC_CREATE creates if key is nonexistent
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IPC_CREATE = 00001000
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//IPC_RMID removes identifier
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IPC_RMID = 0
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)
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// GetAt calls the shmget and shmat system call.
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func GetAt(key int, size int, shmFlg int) (uintptr, []byte, error) {
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if shmFlg == 0 {
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shmFlg = IPC_CREATE | 0600
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}
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shmid, _, errno := syscall.Syscall(SYS_SHMGET, uintptr(key), uintptr(validSize(int64(size))), uintptr(shmFlg))
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if int(shmid) < 0 {
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return 0, nil, syscall.Errno(errno)
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}
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shmaddr, _, errno := syscall.Syscall(SYS_SHMAT, shmid, 0, uintptr(shmFlg))
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if int(shmaddr) < 0 {
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Remove(shmid)
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return 0, nil, syscall.Errno(errno)
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}
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var sl = struct {
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addr uintptr
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len int
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cap int
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}{shmaddr, size, size}
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b := *(*[]byte)(unsafe.Pointer(&sl))
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return shmid, b, nil
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}
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// Dt calls the shmdt system call.
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func Dt(b []byte) error {
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r1, _, errno := syscall.Syscall(SYS_SHMDT, uintptr(unsafe.Pointer(&b[0])), 0, 0)
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if int(r1) < 0 {
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return syscall.Errno(errno)
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}
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return nil
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}
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// Remove removes the shm with the given id.
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func Remove(shmid uintptr) error {
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r1, _, errno := syscall.Syscall(SYS_SHMCTL, shmid, IPC_RMID, 0)
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if int(r1) < 0 {
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return syscall.Errno(errno)
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}
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return nil
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}
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// Ftruncate changes the file size of the fd.
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func Ftruncate(fd int, length int64) (err error) {
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return syscall.Ftruncate(fd, length)
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}
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// Close closes the fd.
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func Close(fd int) (err error) {
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return syscall.Close(fd)
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}
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