mirror of
https://github.com/linuxkit/linuxkit.git
synced 2025-07-19 09:16:29 +00:00
Convert rc.init and rc.shutdown to Go
This removes more shell scripts to improve maintainability. This now also works correctly in userspace, so it can be used for running LinuxKit images in Docker and other such use cases. It is a literal conversion of the shell scripts with a few small tweaks. Signed-off-by: Justin Cormack <justin.cormack@docker.com>
This commit is contained in:
Justin Cormack
parent
f88ac735ba
commit
bcfb760a1d
@ -9,6 +9,9 @@ ENV GOPATH=/go PATH=$PATH:/go/bin
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COPY cmd /go/src/cmd
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RUN go-compile.sh /go/src/cmd/init
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RUN go-compile.sh /go/src/cmd/rc.init
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# this makes sure that the multi stage build copies as a symlink
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RUN mkdir /tmp/bin && cd /tmp/bin/ && cp /go/bin/rc.init . && ln -s rc.init rc.shutdown
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RUN cd /go/src/cmd/service && ./skanky-vendor.sh $GOPATH/src/github.com/containerd/containerd
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RUN go-compile.sh /go/src/cmd/service
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@ -28,8 +31,8 @@ ENTRYPOINT []
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CMD []
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WORKDIR /
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COPY --from=build /go/bin/init /
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COPY --from=build /tmp/bin /bin/
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COPY --from=build /go/bin/service /usr/bin/
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COPY --from=build usermode-helper /sbin/
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COPY --from=mirror /out/ /
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COPY etc etc/
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COPY bin bin/
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@ -1,134 +0,0 @@
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#!/bin/sh
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# mount proc filesystem
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mount -n -t proc proc /proc -o nodev,nosuid,noexec,relatime
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# remount rootfs as readonly
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mount -o remount,ro /
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# mount tmpfs for /tmp and /run
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mount -n -t tmpfs tmpfs /run -o nodev,nosuid,noexec,relatime,size=10%,mode=755
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mount -n -t tmpfs tmpfs /tmp -o nodev,nosuid,noexec,relatime,size=10%,mode=1777
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# mount tmpfs for /var. This may be overmounted with a persistent filesystem later
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mount -n -t tmpfs tmpfs /var -o nodev,nosuid,noexec,relatime,size=50%,mode=755
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# add standard directories in /var
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mkdir -m 755 /var/cache
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mkdir -m 555 /var/empty
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mkdir -m 755 /var/lib
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mkdir -m 755 /var/local
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mkdir -m 755 /var/lock
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mkdir -m 755 /var/log
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mkdir -m 755 /var/opt
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ln -s /run /var/run
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mkdir -m 755 /var/spool
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mkdir -m 1777 /var/tmp
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# mount devfs
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mount -n -t devtmpfs dev /dev -o nosuid,noexec,relatime,size=10m,nr_inodes=248418,mode=755
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# devices
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[ -c /dev/console ] || mknod -m 600 /dev/console c 5 1
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[ -c /dev/tty1 ] || mknod -m 620 /dev/tty1 c 4 1
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[ -c /dev/tty ] || mknod -m 666 /dev/tty c 5 0
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[ -c /dev/null ] || mknod -m 666 /dev/null c 1 3
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[ -c /dev/kmsg ] || mknod -m 660 /dev/kmsg c 1 11
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# extra symbolic links not provided by default
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[ -e /dev/fd ] || ln -snf /proc/self/fd /dev/fd
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[ -e /dev/stdin ] || ln -snf /proc/self/fd/0 /dev/stdin
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[ -e /dev/stdout ] || ln -snf /proc/self/fd/1 /dev/stdout
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[ -e /dev/stderr ] || ln -snf /proc/self/fd/2 /dev/stderr
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[ -e /proc/kcore ] && ln -snf /proc/kcore /dev/core
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# devfs filesystems
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mkdir -p -m 1777 /dev/mqueue
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mkdir -p -m 1777 /dev/shm
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mkdir -p -m 0755 /dev/pts
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mount -n -t mqueue -o noexec,nosuid,nodev mqueue /dev/mqueue
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mount -n -t tmpfs -o noexec,nosuid,nodev,mode=1777 shm /dev/shm
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mount -n -t devpts -o noexec,nosuid,gid=5,mode=0620 devpts /dev/pts
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# mount sysfs
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sysfs_opts=nodev,noexec,nosuid
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mount -n -t sysfs -o ${sysfs_opts} sysfs /sys
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[ -d /sys/kernel/security ] && mount -n -t securityfs -o ${sysfs_opts} securityfs /sys/kernel/security
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[ -d /sys/kernel/debug ] && mount -n -t debugfs -o ${sysfs_opts} debugfs /sys/kernel/debug
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[ -d /sys/kernel/config ] && mount -n -t configfs -o ${sysfs_opts} configfs /sys/kernel/config
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[ -d /sys/fs/fuse/connections ] && mount -n -t fusectl -o ${sysfs_opts} fusectl /sys/fs/fuse/connections
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[ -d /sys/fs/selinux ] && mount -n -t selinuxfs -o nosuid,noexec selinuxfs /sys/fs/selinux
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[ -d /sys/fs/pstore ] && mount -n -t pstore pstore -o ${sysfs_opts} /sys/fs/pstore
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[ -d /sys/firmware/efi/efivars ] && mount -n -t efivarfs -o ro,${sysfs_opts} efivarfs /sys/firmware/efi/efivars
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# misc /proc mounted fs
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[ -d /proc/sys/fs/binfmt_misc ] && mount -t binfmt_misc -o nodev,noexec,nosuid binfmt_misc /proc/sys/fs/binfmt_misc
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# mount cgroups
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mount -n -t tmpfs -o nodev,noexec,nosuid,mode=755,size=10m cgroup_root /sys/fs/cgroup
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while read name hier groups enabled rest
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do
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case "${enabled}" in
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1) mkdir -p /sys/fs/cgroup/${name}
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mount -n -t cgroup -o ${sysfs_opts},${name} ${name} /sys/fs/cgroup/${name}
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;;
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esac
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done < /proc/cgroups
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# use hierarchy for memory
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echo 1 > /sys/fs/cgroup/memory/memory.use_hierarchy
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# for compatibility
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mkdir -p /sys/fs/cgroup/systemd
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mount -t cgroup -o none,name=systemd cgroup /sys/fs/cgroup/systemd
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# start mdev for hotplug
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echo "/sbin/mdev" > /proc/sys/kernel/hotplug
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# mdev -s will not create /dev/usb[1-9] devices with recent kernels
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# so we trigger hotplug events for usb for now
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for i in $(find /sys/devices -name 'usb[0-9]*'); do
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[ -e $i/uevent ] && echo add > $i/uevent
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done
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mdev -s
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# Load modules for cold-plugged devices (ie devices present on boot)
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grep -h MODALIAS /sys/bus/*/devices/*/uevent | cut -d= -f2 | xargs modprobe -abq 2> /dev/null
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# set hostname
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if [ -s /etc/hostname ]
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then
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hostname -F /etc/hostname
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fi
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if [ $(hostname) = "(none)" -a -f /sys/class/net/eth0/address ]
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then
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mac=$(cat /sys/class/net/eth0/address)
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hostname linuxkit-$(echo $mac | sed 's/://g')
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fi
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# set system clock from hwclock
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hwclock --hctosys --utc
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# bring up loopback interface
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ip addr add 127.0.0.1/8 dev lo brd + scope host
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ip route add 127.0.0.0/8 dev lo scope host
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ip link set lo up
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# for containerizing dhcpcd and other containers that need writable /etc/resolv.conf
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[ -L /etc/resolv.conf ] && mkdir -p $(dirname $(readlink -n /etc/resolv.conf)) && touch /etc/resolv.conf
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# make / rshared
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mount --make-rshared /
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# set global ulimits TODO move to /etc/limits.conf?
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ulimit -n 1048576
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ulimit -p unlimited
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# execute other init processes
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INITS="$(find /etc/init.d ! -type d 2>/dev/null | sort)"
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for f in $INITS
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do
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$f
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done
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@ -1,20 +0,0 @@
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#!/bin/sh
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# execute other shutdown processes
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SHUTS="$(find /etc/shutdown.d ! -type d 2>/dev/null | sort)"
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for f in $SHUTS
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do
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$f
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done
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# kill all processes and unmount filesystems
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/usr/sbin/killall5 -15
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/bin/sleep 5
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/usr/sbin/killall5 -9
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/sbin/swapoff -a
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/bin/echo "Unmounting filesystems"
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/bin/umount -a -r
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# shutdown or reboot
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[ "$1" = "reboot" ] && exec /sbin/reboot -f
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/sbin/poweroff -f
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456
pkg/init/cmd/rc.init/main.go
Normal file
456
pkg/init/cmd/rc.init/main.go
Normal file
@ -0,0 +1,456 @@
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package main
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import (
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"bufio"
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"encoding/csv"
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"io/ioutil"
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"log"
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"os"
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"os/exec"
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"path/filepath"
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"strings"
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"time"
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"golang.org/x/sys/unix"
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)
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const (
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nodev = unix.MS_NODEV
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noexec = unix.MS_NOEXEC
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nosuid = unix.MS_NOSUID
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readonly = unix.MS_RDONLY
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rec = unix.MS_REC
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relatime = unix.MS_RELATIME
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remount = unix.MS_REMOUNT
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shared = unix.MS_SHARED
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)
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var (
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rliminf = unix.RLIM_INFINITY
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infinity = uint64(rliminf)
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)
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// set as a subreaper
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func subreaper() {
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err := unix.Prctl(unix.PR_SET_CHILD_SUBREAPER, uintptr(1), 0, 0, 0)
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if err != nil {
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log.Printf("error setting as a subreaper: %v", err)
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}
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}
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// nothing really to error to, so just warn
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func mount(source string, target string, fstype string, flags uintptr, data string) {
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err := unix.Mount(source, target, fstype, flags, data)
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if err != nil {
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log.Printf("error mounting %s to %s: %v", source, target, err)
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}
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}
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// in some cases, do not even log an error
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func mountSilent(source string, target string, fstype string, flags uintptr, data string) {
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_ = unix.Mount(source, target, fstype, flags, data)
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}
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// make a character device
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func mkchar(path string, mode, major, minor uint32) {
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// unix.Mknod only supports int dev numbers; this is ok for us
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dev := int(unix.Mkdev(major, minor))
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err := unix.Mknod(path, mode, dev)
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if err != nil {
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if err.Error() == "file exists" {
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return
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}
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log.Printf("error making device %s: %v", path, err)
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}
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}
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// symlink with error warning
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func symlink(oldpath string, newpath string) {
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err := unix.Symlink(oldpath, newpath)
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if err != nil {
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log.Printf("error making symlink %s: %v", newpath, err)
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}
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}
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// mkdirall with warning
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func mkdir(path string, perm os.FileMode) {
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err := os.MkdirAll(path, perm)
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if err != nil {
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log.Printf("error making directory %s: %v", path, err)
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}
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}
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// list of all enabled cgroups
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func cgroupList() []string {
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list := []string{}
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f, err := os.Open("/proc/cgroups")
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if err != nil {
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log.Printf("cannot open /proc/cgroups: %v", err)
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return list
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}
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defer f.Close()
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reader := csv.NewReader(f)
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// tab delimited
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reader.Comma = '\t'
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// four fields
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reader.FieldsPerRecord = 4
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cgroups, err := reader.ReadAll()
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if err != nil {
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log.Printf("cannot parse /proc/cgroups: %v", err)
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return list
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}
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for _, cg := range cgroups {
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// see if enabled
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if cg[3] == "1" {
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list = append(list, cg[0])
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}
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}
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return list
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}
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// write a file, eg sysfs
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func write(path string, value string) {
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err := ioutil.WriteFile(path, []byte(value), 0600)
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if err != nil {
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log.Printf("cannot write to %s: %v", path, err)
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}
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}
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// read a file, eg sysfs, strip whitespace, empty string if does not exist
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func read(path string) string {
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data, err := ioutil.ReadFile(path)
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if err != nil {
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return ""
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}
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return strings.TrimSpace(string(data))
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}
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// read a directory
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func readdir(path string) []string {
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names := []string{}
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files, err := ioutil.ReadDir(path)
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if err != nil {
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log.Printf("cannot read directory %s: %v", path, err)
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return names
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}
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for _, f := range files {
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names = append(names, f.Name())
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}
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return names
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}
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// glob logging errors
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func glob(pattern string) []string {
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files, err := filepath.Glob(pattern)
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if err != nil {
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log.Printf("error in glob %s: %v", pattern, err)
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return []string{}
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}
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return files
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}
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// test if a file exists
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func exists(path string) bool {
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_, err := os.Stat(path)
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return err == nil
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}
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// modalias runs modprobe on the modalias file contents
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func modalias(path string) {
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alias := read(path)
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cmd := exec.Command("/sbin/modprobe", "-abq", alias)
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// many of these error so do not report
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_ = cmd.Run()
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}
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func doMounts() {
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// mount proc filesystem
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mount("proc", "/proc", "proc", nodev|nosuid|noexec|relatime, "")
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// remount rootfs read only if it is not already
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mountSilent("", "/", "", remount|readonly, "")
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// mount tmpfs for /tmp and /run
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mount("tmpfs", "/run", "tmpfs", nodev|nosuid|noexec|relatime, "size=10%,mode=755")
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mount("tmpfs", "/tmp", "tmpfs", nodev|nosuid|noexec|relatime, "size=10%,mode=1777")
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// mount tmpfs for /var. This may be overmounted with a persistent filesystem later
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mount("tmpfs", "/var", "tmpfs", nodev|nosuid|noexec|relatime, "size=50%,mode=755")
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// add standard directories in /var
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mkdir("/var/cache", 0755)
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mkdir("/var/empty", 0555)
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mkdir("/var/lib", 0755)
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mkdir("/var/local", 0755)
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mkdir("/var/lock", 0755)
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mkdir("/var/log", 0755)
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mkdir("/var/opt", 0755)
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mkdir("/var/spool", 0755)
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mkdir("/var/tmp", 01777)
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symlink("/run", "/var/run")
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// mount devfs
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mount("dev", "/dev", "devtmpfs", nosuid|noexec|relatime, "size=10m,nr_inodes=248418,mode=755")
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// make minimum necessary devices
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mkchar("/dev/console", 0600, 5, 1)
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mkchar("/dev/tty1", 0620, 4, 1)
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mkchar("/dev/tty", 0666, 5, 0)
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mkchar("/dev/null", 0666, 1, 3)
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mkchar("/dev/kmsg", 0660, 1, 11)
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// make standard symlinks
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symlink("/proc/self/fd", "/dev/fd")
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symlink("/proc/self/fd/0", "/dev/stdin")
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symlink("/proc/self/fd/1", "/dev/stdout")
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symlink("/proc/self/fd/2", "/dev/stderr")
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symlink("/proc/kcore", "/dev/kcore")
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// dev mountpoints
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mkdir("/dev/mqueue", 01777)
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mkdir("/dev/shm", 01777)
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mkdir("/dev/pts", 0755)
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// mounts on /dev
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mount("mqueue", "/dev/mqueue", "mqueue", noexec|nosuid|nodev, "")
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mount("shm", "/dev/shm", "tmpfs", noexec|nosuid|nodev, "mode=1777")
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mount("devpts", "/dev/pts", "devpts", noexec|nosuid, "gid=5,mode=0620")
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// sysfs
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mount("sysfs", "/sys", "sysfs", noexec|nosuid|nodev, "")
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// some of the subsystems may not exist, so ignore errors
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mountSilent("securityfs", "/sys/kernel/security", "securityfs", noexec|nosuid|nodev, "")
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mountSilent("debugfs", "/sys/kernel/debug", "debugfs", noexec|nosuid|nodev, "")
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mountSilent("configfs", "/sys/kernel/config", "configfs", noexec|nosuid|nodev, "")
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mountSilent("fusectl", "/sys/fs/fuse/connections", "fusectl", noexec|nosuid|nodev, "")
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mountSilent("selinuxfs", "/sys/fs/selinux", "selinuxfs", noexec|nosuid, "")
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mountSilent("pstore", "/sys/fs/pstore", "pstore", noexec|nosuid|nodev, "")
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mountSilent("efivarfs", "/sys/firmware/efi/efivars", "efivarfs", noexec|nosuid|nodev, "")
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// misc /proc mounted fs
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mountSilent("binfmt_misc", "/proc/sys/fs/binfmt_misc", "binfmt_misc", noexec|nosuid|nodev, "")
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// mount cgroup root tmpfs
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mount("cgroup_root", "/sys/fs/cgroup", "tmpfs", nodev|noexec|nosuid, "mode=755,size=10m")
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// mount cgroups filesystems for all enabled cgroups
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for _, cg := range cgroupList() {
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path := filepath.Join("/sys/fs/cgroup", cg)
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mkdir(path, 0555)
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mount(cg, path, "cgroup", noexec|nosuid|nodev, cg)
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}
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// use hierarchy for memory
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write("/sys/fs/cgroup/memory/memory.use_hierarchy", "1")
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// many things assume systemd
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mkdir("/sys/fs/cgroup/systemd", 0555)
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mount("cgroup", "/sys/fs/cgroup/systemd", "cgroup", 0, "none,name=systemd")
|
||||
|
||||
// make / rshared
|
||||
mount("", "/", "", rec|shared, "")
|
||||
}
|
||||
|
||||
func doHotplug() {
|
||||
mdev := "/sbin/mdev"
|
||||
// start mdev for hotplug
|
||||
write("/proc/sys/kernel/hotplug", mdev)
|
||||
|
||||
devices := "/sys/devices"
|
||||
files := readdir(devices)
|
||||
for _, f := range files {
|
||||
uevent := filepath.Join(devices, f, "uevent")
|
||||
if strings.HasPrefix(f, "usb") && exists(uevent) {
|
||||
write(uevent, "add")
|
||||
}
|
||||
}
|
||||
|
||||
cmd := exec.Command(mdev, "-s")
|
||||
if err := cmd.Run(); err != nil {
|
||||
log.Printf("Failed to run %s -s: %v", mdev, err)
|
||||
}
|
||||
|
||||
// mdev only supports hot plug, so also add all existing cold plug devices
|
||||
for _, df := range glob("/sys/bus/*/devices/*/modalias") {
|
||||
modalias(df)
|
||||
}
|
||||
}
|
||||
|
||||
func doClock() {
|
||||
cmd := exec.Command("/sbin/hwclock", "--hctosys", "--utc")
|
||||
if err := cmd.Run(); err != nil {
|
||||
log.Printf("Failed to run hwclock: %v", err)
|
||||
}
|
||||
}
|
||||
|
||||
func rlimit(resource int, cur, max uint64) {
|
||||
lim := unix.Rlimit{Cur: cur, Max: max}
|
||||
err := unix.Setrlimit(resource, &lim)
|
||||
if err != nil {
|
||||
log.Printf("Failed to set rlimit %s: %v", resource, err)
|
||||
}
|
||||
}
|
||||
|
||||
func doLimits() {
|
||||
rlimit(unix.RLIMIT_NOFILE, 1048576, 1048576)
|
||||
rlimit(unix.RLIMIT_NPROC, infinity, infinity)
|
||||
}
|
||||
|
||||
func doHostname() {
|
||||
hostname := read("/etc/hostname")
|
||||
if hostname != "" {
|
||||
if err := unix.Sethostname([]byte(hostname)); err != nil {
|
||||
log.Printf("Setting hostname failed: %v", err)
|
||||
}
|
||||
}
|
||||
hostname, err := os.Hostname()
|
||||
if err != nil {
|
||||
log.Printf("Cannot read hostname: %v", err)
|
||||
return
|
||||
}
|
||||
|
||||
if hostname != "(none)" && hostname != "" {
|
||||
return
|
||||
}
|
||||
|
||||
mac := read("/sys/class/net/eth0/address")
|
||||
if mac == "" {
|
||||
return
|
||||
}
|
||||
|
||||
mac = strings.Replace(mac, ":", "", -1)
|
||||
if err := unix.Sethostname([]byte("linuxkit-" + mac)); err != nil {
|
||||
log.Printf("Setting hostname failed: %v", err)
|
||||
}
|
||||
}
|
||||
|
||||
func doResolvConf() {
|
||||
// for containerizing dhcpcd and other containers that need writable /etc/resolv.conf
|
||||
// if it is a symlink (usually to /run) make the directory and empty file
|
||||
link, err := os.Readlink("/etc/resolv.conf")
|
||||
if err != nil {
|
||||
return
|
||||
}
|
||||
mkdir(filepath.Dir(link), 0755)
|
||||
write(link, "")
|
||||
}
|
||||
|
||||
func doLoopback() {
|
||||
// TODO use netlink instead
|
||||
cmd := exec.Command("/sbin/ip", "addr", "add", "127.0.0.1/8", "dev", "lo", "brd", "+", "scope", "host")
|
||||
_ = cmd.Run()
|
||||
cmd = exec.Command("/sbin/ip", "route", "add", "127.0.0.0/8", "dev", "lo", "scope", "host")
|
||||
_ = cmd.Run()
|
||||
cmd = exec.Command("/sbin/ip", "link", "set", "lo", "up")
|
||||
_ = cmd.Run()
|
||||
}
|
||||
|
||||
// execute scripts in /etc/init.d/ or /etc/shutdown.d. These should not block.
|
||||
func runInit(path string) {
|
||||
for _, f := range readdir(path) {
|
||||
file := filepath.Join(path, f)
|
||||
fi, err := os.Stat(file)
|
||||
if err != nil {
|
||||
log.Printf("Cannot stat %s: %v", file, err)
|
||||
continue
|
||||
}
|
||||
if !fi.Mode().IsRegular() {
|
||||
continue
|
||||
}
|
||||
cmd := exec.Command(file)
|
||||
cmd.Stdout = os.Stdout
|
||||
cmd.Stderr = os.Stderr
|
||||
_ = cmd.Run()
|
||||
}
|
||||
}
|
||||
|
||||
func doReap() {
|
||||
// now reap all children
|
||||
// if we are running in a real system, init does this, but in a container it would terminate when we exit
|
||||
for {
|
||||
_, err := unix.Wait4(-1, nil, 0, nil)
|
||||
if err != nil {
|
||||
// ECHILD means no children left
|
||||
if e, ok := err.(*os.SyscallError); ok && e.Err == unix.ECHILD {
|
||||
return
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
func unmountAll() {
|
||||
mounts, err := os.Open("/proc/mounts")
|
||||
if err != nil {
|
||||
log.Printf("Cannot open /proc/mounts: %v", err)
|
||||
return
|
||||
}
|
||||
defer mounts.Close()
|
||||
scanner := bufio.NewScanner(mounts)
|
||||
for scanner.Scan() {
|
||||
line := scanner.Text()
|
||||
parts := strings.Split(line, " ")
|
||||
if len(parts) > 3 {
|
||||
dest := parts[1]
|
||||
tp := parts[2]
|
||||
switch tp {
|
||||
// do not unmount tmpfs or virtual filesystems, just ones that need to write data
|
||||
case "ext2", "ext3", "ext4", "btrfs", "xfs", "vfat", "msdos", "overlay":
|
||||
if err := unix.Unmount(dest, 0); err != nil {
|
||||
log.Printf("error unmounting %s: %v", dest, err)
|
||||
}
|
||||
case "nfs", "nfs4", "cifs":
|
||||
// lazy unmount as we do not want to block on network mounts
|
||||
if err := unix.Unmount(dest, unix.MNT_DETACH); err != nil {
|
||||
log.Printf("error unmounting %s: %v", dest, err)
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
func doShutdown(action string) {
|
||||
runInit("/etc/shutdown.d")
|
||||
_ = unix.Kill(-1, unix.SIGTERM)
|
||||
time.Sleep(5 * time.Second)
|
||||
_ = unix.Kill(-1, unix.SIGKILL)
|
||||
unix.Sync()
|
||||
unmountAll()
|
||||
switch action {
|
||||
case "poweroff":
|
||||
// TODO use syscall
|
||||
cmd := exec.Command("/sbin/poweroff", "-f")
|
||||
_ = cmd.Run()
|
||||
case "reboot":
|
||||
// TODO use syscall
|
||||
cmd := exec.Command("/sbin/reboot", "-f")
|
||||
_ = cmd.Run()
|
||||
}
|
||||
// if this failed, init will try again
|
||||
os.Exit(0)
|
||||
}
|
||||
|
||||
func main() {
|
||||
if filepath.Base(os.Args[0]) == "rc.shutdown" {
|
||||
action := "poweroff"
|
||||
if len(os.Args) > 1 {
|
||||
action = os.Args[1]
|
||||
}
|
||||
doShutdown(action)
|
||||
}
|
||||
// see if we are on a real system or in userspace
|
||||
// assume in userspace if /proc already mounted
|
||||
userspace := exists("/proc/self")
|
||||
|
||||
if userspace {
|
||||
subreaper()
|
||||
} else {
|
||||
doMounts()
|
||||
doHotplug()
|
||||
doClock()
|
||||
doLoopback()
|
||||
}
|
||||
|
||||
doLimits()
|
||||
doHostname()
|
||||
doResolvConf()
|
||||
|
||||
runInit("/etc/init.d")
|
||||
|
||||
if userspace {
|
||||
doReap()
|
||||
}
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user