Hi, guys, I need to acess shared memory, so I write some code like this:
```go
func shmget(key int, size int, mode int) (int, error) {
shmId, _, ret := syscall.Syscall(syscall.SYS_SHMGET, uintptr(key),
uintptr(size), uintptr(mode))
if ret != 0 {
return 0, fmt.Errorf("shmget ret: %d", ret)
}
return int(shmId), nil
}
// shmat 映射共享内存地址到当前进程空间
func shmat(shmId int, addr unsafe.Pointer, flags int) (unsafe.Pointer,
error) {
shmAddr, _, ret := syscall.Syscall(syscall.SYS_SHMAT, uintptr(shmId),
uintptr(addr), uintptr(flags))
if ret != 0 {
return nil, fmt.Errorf("shmat ret: %d", ret)
}
*return unsafe.Pointer(shmAddr), nil // => possible misuse of
unsafe.Pointer*
}
func GetShm(iKey, iSize, iFlag int) (unsafe.Pointer, error) {
iShmID, err := shmget(iKey, iSize, iFlag)
if err != nil {
return nil, err
}
sShmPtr, err := shmat(iShmID, nil, iFlag)
if err != nil {
return nil, err
}
return sShmPtr, nil
}
```
When I run go vet to check this code, it reports "possible misuse of
unsafe.Pointer" for the bold line "*return unsafe.Pointer(shmaddr), nil*" .
And I have read the Pointer rules. I see this case isn't listed in the
rules.
I want to know :
- is it safe to use pointer like this? I think syscall `shmat` returns the
attached memory address that doesn't controlled by GC. I think it's safe.
- if it's safe, how could I work around this check? just neglect it or do
we have some directives to prevent go vet checking?
Thanks.
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