Re: [PATCH v2 2/4] Add fchmodat4(), a new syscall
flat view
From: Rich Felker <dalias@libc.org>
Date: 2019-07-17 02:51:04
Also in:
linux-alpha, linux-api, linux-arch, linux-fsdevel, linux-mips, linux-s390, linux-sh, lkml, sparclinux
On Tue, Jul 16, 2019 at 06:27:17PM -0700, Palmer Dabbelt wrote:
man 3p says that fchmodat() takes a flags argument, but the Linux syscall does not. There doesn't appear to be a good userspace workaround for this issue but the implementation in the kernel is pretty straight-forward. The specific use case where the missing flags came up was WRT a fuse filesystem implemenation, but the functionality is pretty generic so I'm assuming there would be other use cases.
Note that we do have a workaround in musl libc with O_PATH and /proc/self/fd, but a syscall that allows a proper fix with the ugly workaround only in the fallback path for old kernels will be much appreciated! What about also doing a new SYS_faccessat4 with working AT_EACCESS flag? The workaround we have to do for it is far worse. Rich