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https://github.com/rwinkhart/sys.git
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Dustin Spicuzza
969570ce7c
Implements proposed API from https://golang.org/issue/46084. I chose `SysvShmDesc` since it's a clearer name than `SysvShm`. Initially supports Darwin and Linux. Solaris support has a blocker (https://golang.org/issue/46084#issuecomment-836980018) For golang/go#46084 Change-Id: Ied0f768a74c448254adc3315348417825a7ec63e GitHub-Last-Rev: befbd7af6b2f838753ac163ef387cebdb7957467 GitHub-Pull-Request: golang/sys#110 Reviewed-on: https://go-review.googlesource.com/c/sys/+/327830 Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com> Reviewed-by: Ian Lance Taylor <iant@golang.org> Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com> TryBot-Result: Go Bot <gobot@golang.org>
62 lines
1.6 KiB
Go
62 lines
1.6 KiB
Go
// Copyright 2021 The Go Authors. 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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//go:build (darwin && amd64) || linux
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// +build darwin,amd64 linux
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package unix
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import (
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"unsafe"
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"golang.org/x/sys/internal/unsafeheader"
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)
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// SysvShmAttach attaches the Sysv shared memory segment associated with the
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// shared memory identifier id.
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func SysvShmAttach(id int, addr uintptr, flag int) ([]byte, error) {
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addr, errno := shmat(id, addr, flag)
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if errno != nil {
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return nil, errno
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}
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// Retrieve the size of the shared memory to enable slice creation
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var info SysvShmDesc
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_, err := SysvShmCtl(id, IPC_STAT, &info)
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if err != nil {
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// release the shared memory if we can't find the size
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// ignoring error from shmdt as there's nothing sensible to return here
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shmdt(addr)
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return nil, err
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}
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// Use unsafe to convert addr into a []byte.
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// TODO: convert to unsafe.Slice once we can assume Go 1.17
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var b []byte
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hdr := (*unsafeheader.Slice)(unsafe.Pointer(&b))
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hdr.Data = unsafe.Pointer(addr)
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hdr.Cap = int(info.Segsz)
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hdr.Len = int(info.Segsz)
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return b, nil
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}
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// SysvShmDetach unmaps the shared memory slice returned from SysvShmAttach.
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//
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// It is not safe to use the slice after calling this function.
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func SysvShmDetach(data []byte) error {
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if len(data) == 0 {
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return EINVAL
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}
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return shmdt(uintptr(unsafe.Pointer(&data[0])))
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}
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// SysvShmGet returns the Sysv shared memory identifier associated with key.
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// If the IPC_CREAT flag is specified a new segment is created.
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func SysvShmGet(key, size, flag int) (id int, err error) {
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return shmget(key, size, flag)
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}
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