Re: [PATCH 0/5] Linux: lchmod and AT_SYMLINK_NOFOLLOW support for fchmodat

["Dmitry V. Levin" <ldv@altlinux.org>]

On Tue, Jul 21, 2020 at 11:54:38AM +0200, Florian Weimer via Libc-alpha wrote:
> * Andreas Schwab:
> > On Jan 22 2020, Florian Weimer wrote:
> >
> >> These patches use the O_PATH hack to implement a fairly close
> >> approximation of fchmodat in AT_SYMLINK_NOFOLLOW mode.
> >
> > This means that cp -a now fails when /proc is not mounted.
> >
> > <https://build.opensuse.org/package/live_build_log/home:Andreas_Schwab:glibc:rebuild/installation-images:openSUSE/f/x86_64>
> >
> > running "cp -a /var/lib/ca-certificates var/lib"
> > cp: setting permissions for 'var/lib/ca-certificates/pem': Operation not supported
> > cp: setting permissions for 'var/lib/ca-certificates/openssl': Operation not supported
> >
> > newfstatat(AT_FDCWD, "/var/lib/ca-certificates/pem", {st_mode=S_IFDIR|0500, st_size=4096, ...}, AT_SYMLINK_NOFOLLOW) = 0
> > mkdir("var/lib/ca-certificates/pem", 0500) = 0
> > lstat("var/lib/ca-certificates/pem", {st_mode=S_IFDIR|0500, st_size=4096, ...}) = 0
> > openat(AT_FDCWD, "var/lib/ca-certificates/pem", O_RDONLY|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 3
> > newfstatat(3, "", {st_mode=S_IFDIR|0500, st_size=4096, ...}, AT_EMPTY_PATH) = 0
> > chmod("/proc/self/fd/3", 040700)        = -1 ENOENT (No such file or directory)
> > close(3)                                = 0
> > write(2, "cp: ", 4)                     = 4
> > write(2, "setting permissions for 'var/lib"..., 53) = 53
> > write(2, ": Operation not supported", 25) = 25
> > write(2, "\n", 1)                       = 1
> 
> Yes, it's a known issue.

Sorry but this is a regression, we cannot assume that /proc is always mounted.


-- 
ldv