Bug#872577: debootstrap: Handle existing /dev
On Tue, Aug 22, 2017 at 10:23 AM, Dan Nicholson <nicholson@endlessm.com> wrote:
>
> That certainly helps, but it doesn't cover everything since the
> mkdir's and ln's could fail. Those are easier to handle by adding -p
> and -f, respectively, but that's a subtle change in behavior for ln
> relative to the mknod change. In the mknod case, an existing device is
> left as is. In the ln case, it would be forcefully overwritten.
Attached is a patch to handle all the potentially failing cases. I
tested this by running debootstrap once, wiping everything the target
except /dev, and running debootstrap again. It succeeded. As mentioned
above, an existing device is skipped while the symlinks are forcefully
overwritten. That seems inconsistent, but I'm not sure it matters. I
could easily change the mknod function to forcefully remove, too.
From 5e97c8d293764015fae25085cb884c5bf265207a Mon Sep 17 00:00:00 2001
From: Dan Nicholson <nicholson@endlessm.com>
Date: Fri, 25 Aug 2017 15:44:26 -0500
Subject: [PATCH] Handle existing /dev (Closes: #872577)
When devices.tar.gz was being used, the devices would be written into
place with tar. This has the effect that the devices would be merged
into an existing /dev in the target. setup_devices_simple() does not
handle this case and fails when /dev already exists.
Normally, the target would be empty and this wouldn't be an issue.
However, some tools that use debootstrap to initialize a target depended
on the old behavior. In particular, the obs-build package used for OBS
sets up a minimal /dev in the generic prep code before using debootstrap
to install packages needed for building debian packages.
Allow for existing devices, directories and symlinks by skipping
existing devices and directories and forcefully overwriting existing
symlinks.
---
functions | 39 ++++++++++++++++++++++++++-------------
1 file changed, 26 insertions(+), 13 deletions(-)
diff --git a/functions b/functions
index 3cfa0d4..877cdbd 100644
--- a/functions
+++ b/functions
@@ -1161,26 +1161,39 @@ setup_dynamic_devices () {
esac
}
+# Create a device node if it does not exist. By default, the mode is 666.
+mknod_if_needed () {
+ local device="$1"
+ local type="$2"
+ local major="$3"
+ local minor="$4"
+ local mode="${5:-666}"
+
+ if [ ! -e "$device" ]; then
+ mknod -m "$mode" "$device" "$type" "$major" "$minor"
+ fi
+}
+
setup_devices_simple () {
# The list of devices that can be created in a container comes from
# src/core/cgroup.c in the systemd source tree.
- mknod -m 666 $TARGET/dev/null c 1 3
- mknod -m 666 $TARGET/dev/zero c 1 5
- mknod -m 666 $TARGET/dev/full c 1 7
- mknod -m 666 $TARGET/dev/random c 1 8
- mknod -m 666 $TARGET/dev/urandom c 1 9
- mknod -m 666 $TARGET/dev/tty c 5 0
- mkdir $TARGET/dev/pts/ $TARGET/dev/shm/
+ mknod_if_needed $TARGET/dev/null c 1 3
+ mknod_if_needed $TARGET/dev/zero c 1 5
+ mknod_if_needed $TARGET/dev/full c 1 7
+ mknod_if_needed $TARGET/dev/random c 1 8
+ mknod_if_needed $TARGET/dev/urandom c 1 9
+ mknod_if_needed $TARGET/dev/tty c 5 0
+ mkdir -p $TARGET/dev/pts/ $TARGET/dev/shm/
# Inside a container, we might not be allowed to create /dev/ptmx.
# If not, do the next best thing.
- if ! mknod -m 666 $TARGET/dev/ptmx c 5 2; then
+ if ! mknod_if_needed $TARGET/dev/ptmx c 5 2; then
warning MKNOD "Could not create /dev/ptmx, falling back to symlink. This chroot will require /dev/pts mounted with ptmxmode=666"
- ln -s pts/ptmx $TARGET/dev/ptmx
+ ln -sf pts/ptmx $TARGET/dev/ptmx
fi
- ln -s /proc/self/fd $TARGET/dev/fd
- ln -s /proc/self/fd/0 $TARGET/dev/stdin
- ln -s /proc/self/fd/1 $TARGET/dev/stdout
- ln -s /proc/self/fd/2 $TARGET/dev/stderr
+ ln -sf /proc/self/fd $TARGET/dev/fd
+ ln -sf /proc/self/fd/0 $TARGET/dev/stdin
+ ln -sf /proc/self/fd/1 $TARGET/dev/stdout
+ ln -sf /proc/self/fd/2 $TARGET/dev/stderr
}
setup_devices_fakechroot () {
--
2.5.5
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