Pekka Enberg wrote: > > On 8/7/06, Edgar Toernig <froese@xxxxxx> wrote: > > Why do we need [f]revoke at all? As it doesn't implement the > > BSD semantic I can't see why it's better than fuser -k. > > Which part of the BSD semantics is that? That which talks about character devices, in particular ttys. NetBSD revoke(2): | | ... a read() from a character device file which has been revoked | returns a count of zero (end of file), and a close() call will | succeed. |... | revoke is normally used to prepare a terminal device for a new | login session, preventing any access by a previous user of the | terminal. Irix revoke(2) even mentions: | | ERRORS: | ... | [EINVAL] The named file is not a character-special file. It seems, revoke was intended to disable access to tty devices from old processes in a controlled way. Sounds sane. Your implementation is much cruder - it simply takes the fd away from the app; any future use gives EBADF. As a bonus, it works for regular files and even goes as far as destroying all mappings of the file from all processes (even root processes). IMVHO this is a disaster from a security and reliability point of view. So, the behaviour regarding ttys is completely different to other implementations and for other types of fds the Linux semantic seems unique (the man-pages of the other systems are pretty silent about that). A serious question: What do you need this feature of revoking regular files (or block devices) for? Maybe my imagination is lacking, but I can't find a use where fuser(1) (or similar tools) wouldn't be as good or even better than revoke(2). Ciao, ET. - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
