Commit 98a6f1fc02 (fs/cpio: make initramfs init script survive 'console='
kernel argument) dropped the explicit /dev/console execs for fd 0,1,2, as
they fail when booted with console= and aren't really needed as the kernel
will setup fd 0,1,2 from /dev/console before executing the initramfs anyway.
Not doing this unfortunately confuses glibc's ttyname_r(3) implementation
(used by E.G. busybox/coreutils 'tty'), causing it to fail with ENOENT as
it does a fstat on fd 0 and tries to match up st_ino / st_dev against the
entries in /dev (since glibc 2.26):
commit 15e9a4f378c8607c2ae1aa465436af4321db0e23
Author: Christian Brauner <christian.brauner@canonical.com>
Date: Fri Jan 27 15:59:59 2017 +0100
linux ttyname and ttyname_r: do not return wrong results
If a link (say /proc/self/fd/0) pointing to a device, say /dev/pts/2, in a
parent mount namespace is passed to ttyname, and a /dev/pts/2 exists (in a
different devpts) in the current namespace, then it returns /dev/pts/2.
But /dev/pts/2 is NOT the current tty, it is a different file and device.
Detect this case and return ENODEV. Userspace can choose to take this as a hint
that the fd points to a tty device but to act on the fd rather than the link.
Signed-off-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
The reason it fails is that we manually mount devtmpfs on /dev in /init, so
the /dev/console used by the kernel (in rootfs) is not the same file as
/dev/console at runtime (in devtmpfs).
Notice: Once logged in, tty does work correctly. Presumably login reopens
stdin/stdout/stderr.
To fix this, re-add the exec of /dev/console for fd 0,1,2, but only do so if
possible. Because of the above mentioned shell behaviour (specified by
POSIX [0]), perform this check in a subshell.
[0] https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_20_01
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
When booting with 'console=<empty>' in the kernel command line (as e.g.
U-Boot does with silent flags in effect), opening /dev/console fails.
As per POSIX [0], when iany redirection fails, the shell running exec
shal exit in error. So, when 'console=<empty>' is specified.
/dev/console can't be opened, and the redirection fails, and /init is
killed.
That behaviour was fixed on the kernel side with commit 2bd3a997befc2
(Open /dev/console from rootfs), present since 2.6.34, released in May
2010, so any [dr]ecent kernel will have that fix.
Furthermore, busybox will fix things up anyway (in bb_sanitize_stdio()),
falling back to opening /dev/null if no console is availble. systemd
does a similar thing (in make_console_stdio()), and sysvinit again has
a similar approach (in console_init()).
The archealogy search turned up those relevant commits:
2011-08-04 10a130f91e initramfs/init: make sure that 0, 1, 2 fds are available
introduces the three exec redirections in initramfs
2011-09-06 3fac21ef8d cpio: fix boot with dynamic /dev
introduces the three exec redirections in cpio
2011-09-06 13a3afc536 fs/initramfs: refactor with fs/cpio
dropped the initramfs tweaks to reuse the cpio ones
2012-11-04 e1ebae700a fs/common: Create initial console device
introduces the /dev/console char,5,1 pseudo device creation in
cpio
2018-03-31 dec061adce fs/cpio: don't extend packages' permissions table
switched from the permission-table to a manual mknod to create
/dev/console
The redirections were added before we could guarantee there was a
/dev/console in the rootfs.
We're now guaranteed to have /dev/console in an initramfs, and any recent
kernel will automatically open /dev/console before spawning /init.
The three redirections are useless now, and cause harm under certain
conditions. Drop them.
[0] https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_20_01
Signed-off-by: Timo Ketola <timo.ketola@exertus.fi>
Cc: Peter Korsgaard <peter@korsgaard.com>
[yann.morin.1998@free.fr:
- extend commit log with the analysis done with Peter
]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Use "$@" instead of $* to preserve arguments containing spaces.
The shell expands "$@" as "$1" "$2" "$3"... while it expands $@ as $1 $2
$3. With the second form, we loses spaces in positional parameters.
Signed-off-by: Gaël PORTAY <gael.portay@savoirfairelinux.com>
Reviewed-by: Adrian Perez de Castro <aperez@igalia.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Devtmpfs doesn't get automounted by the kernel when an initramfs is used.
Since cpio archives are used almost exclusively as an initramfs, the same
fix should be applied to it as for the initramfs.
Cfr. commit 424888e474 and
10a130f91e.
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
