游俊德 wrote:
> Hello,
>
> I have a question about source code of shm_open and sem_open functions.
>
> int
> shm_open(const char *path, int flags, mode_t mode)
> {
> ........ (skipped) ....
>
> if (sb,st_uid != getuid()) {
> close(fd);
> errno = EPERM;
> return -1;
> }
>
> ........ (skipped) ....
> }
>
> I know the UID comparison is used to avoid share memory accessed by
> different user. Similar code also existed in sem_open function.
>
> My question is, why it is getuid(), why not use geteuid()?
> I am not sure if it is bug or not, but I think it is more reasonable
> if it checked
> by effective user id,
geteuid may be better. though i would hope the difference doesn't matter.
