On Fri, Jan 09, 2015 at 10:33:00PM +0000, Al Viro wrote: > On Fri, Jan 09, 2015 at 05:17:28PM -0500, Rich Felker wrote: > > > Back then the procfs-free environments had been pushed as a serious argument > > > in favour of merging the damn thing. Now you guys turn around and say that > > > we not only need procfs mounted, we need a yet-to-be-added kludge in there > > > to cope with the actual intended uses. > > > > Reverting does not fix the problem. There is no way to make fexecve > > work for scripts without kernel support, and the needed kernel support > > without fexecve would be even nastier, since handling of /proc/self/fd > > magic-symlinks would need to be special-cased. The added fexecveat > > syscall supports fully /proc-less operation for non-scripts. > > Oh, yes it does. It's not *our* problem if it's out of tree and not > a part of ABI. That way if you need it, *you* get to come up with clean > implementation. If it's in-tree you get leverage to push ugly kludges > further in. And frankly, I don't trust you to abstain from using that > leverage in rather nasty ways. > > Out of curiosity, how would you expect that "open only once" to work? > All reliable variants I see are beyond sick... Here's a very simple way it could work -- it could put the O_PATH fd on a previously-unused fd number, and put a special flag on the fd, like FD_CLOEXEC, but that causes the kernel to close it whenever it's opened. The pathname passed could then simply be /dev/fd/%d or /proc/self/fd/%d, and although this is presently dependent on /proc being mounted, virtual /dev/fd/* could someday be something completely independent of procfs. The kernel keeps all the freedom to choose how to pass the name to the interpreter. I'm not proposing any kernel API/ABI lock-in and I'm with you in opposing such lock-in. Rich -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
