This supercedes my previous switch_root patches, and applies on top of davej's repo at git.kernel.org. Nash is gone. In its place we have a reasonable switch_root implementation. Of course, this switch_root is written in some rather hideous shell script, and relies on some rather dodgy hacks. Rewriting in C would help things out. However, it should be distro-independent, and it gets the job done. --- TODO | 9 +--- dracut.spec | 2 - init | 43 ++++++++++----------- modules/99base | 1 - switch_root | 115 ++++++++++++++++++++++++++++++++++++++++++++++++++++++- 5 files changed, 135 insertions(+), 35 deletions(-) diff --git a/TODO b/TODO index e04be3a..3ced6f7 100644 --- a/TODO +++ b/TODO @@ -4,12 +4,9 @@ are/should be marked with "FIXME" in the code INITRAMFS TODO -------------- -* Currently, our switch_root command uses nash's switchroot. Getting -a reasonable switchroot implementation into util-linux-ng is a -pre-condition for support on other distros. pjones has a basic -implementation at -http://pjones.fedorapeople.org/mkstart/usr/lib/mkstart/switchroot.c -and I've asked kzak about util-linux inclusion +* We have a horribly ugly switchroot implementation whose only + good point is that it gets rid of our dependency on nash. + It needs to be replaced by something nicer. * The hard-coded list of udev rules that we care about is kind of lame. See about getting /lib/udev/initrules.d or similar for storing the rules that we care about in the initramfs. These could be diff --git a/dracut.spec b/dracut.spec index 24f6513..04590cd 100644 --- a/dracut.spec +++ b/dracut.spec @@ -19,9 +19,7 @@ Requires: findutils Requires: grep Requires: mktemp Requires: mount -Requires: nash Requires: bash -Requires: /usr/bin/eu-readelf Obsoletes: mkinitrd < 7.0 Provides: mkinitrd = 7.0 BuildArch: noarch diff --git a/init b/init index c8ac4e5..ad6c06f 100755 --- a/init +++ b/init @@ -10,13 +10,12 @@ emergency_shell() echo ; echo echo "Bug in initramfs /init detected. Dropping to a shell. Good luck!" echo - sh -i 2>/dev/console + sh -i } getarg() { local o line - read -r line </proc/cmdline - for o in $line; do + for o in $CMDLINE; do [ "${o%%=*}" = "$1" ] && { echo $o; break; } done return 1 @@ -31,16 +30,15 @@ source_all() { echo "Starting initrd..." export PATH=/sbin:/bin:/usr/sbin:/usr/bin export TERM=linux - +CONSOLE=/dev/console +[ -c $CONSOLE ] && exec >$CONSOLE 2>&1 <$CONSOLE trap "emergency_shell" 0 -# /dev/console comes from the built-in initramfs crud in the kernel -# someday, we may need to mkdir /dev first here -# exec > /dev/console 2>&1 < /dev/console - # mount some important things mount -t proc /proc /proc mount -t sysfs /sys /sys mount -t tmpfs -omode=0755 udev /dev +read CMDLINE </proc/cmdline; + # FIXME: what device nodes does plymouth really _need_ ? mknod /dev/ptmx c 5 2 @@ -59,7 +57,7 @@ udevd --daemon udevadm trigger >/dev/null 2>&1 # mount the rootfs -NEWROOT="/sysroot" +export NEWROOT="/sysroot" # FIXME: there's got to be a better way ... # it'd be nice if we had a udev rule that just did all of the bits for @@ -85,22 +83,21 @@ echo "Trying to mount rootfs $root" ln -s "$root" /dev/root mount -o ro /dev/root $NEWROOT || emergency_shell -# now we need to prepare to switchroot -mount --bind /dev $NEWROOT/dev - -# FIXME: now for a bunch of boiler-plate mounts. really, we should have -# some like /etc/fstab.sys that's provided by filesystem/initscripts -# and then do mount -f /etc/fstab.sys -a -mount -t proc /proc $NEWROOT/proc -mount -t sysfs /sys $NEWROOT/sys - +INIT=$(getarg init) +[ "$INIT" ] || { + for i in /sbin/init /etc/init /init /bin/sh; do + [ -x "$NEWROOT$i" ] && { INIT="$i"; break; } + done + [ "$INIT" ] || { + echo "Cannot find init! Please check to make sure you passed" + echo "a valid root filesystem! Dropping to a shell." + emergency_shell + } +} + source_all pre-pivot -# kill off udev -kill $(pidof udevd) - -# FIXME: nash die die die -exec switch_root +exec switch_root "$NEWROOT" "$INIT" $CMDLINE # davej doesn't like initrd bugs echo "Something went very badly wrong in the initrd. Please " echo "file a bug against mkinitrd." diff --git a/modules/99base b/modules/99base index c746abc..4963beb 100755 --- a/modules/99base +++ b/modules/99base @@ -1,6 +1,5 @@ #!/bin/bash dracut_install mount mknod mkdir modprobe pidof sleep chroot echo sed sh ls - # install our scripts and hooks inst "$initfile" "/init" inst "$switchroot" "/sbin/switch_root" diff --git a/switch_root b/switch_root dissimilarity index 96% index 2f0b8fa..1cc80e9 100755 --- a/switch_root +++ b/switch_root @@ -1,3 +1,112 @@ -#!/sbin/nash - -nash-switchroot +#!/bin/sh +# Copyright (c) Victor Lowther <victor.lowther@xxxxxxxxx> +# Licensed under the terms of the GNU GPL v2 or later. + +# some utility functions first +# this is so we can scroll back. + +die() { echo "${1}, dying horribly."; while :;do read line; done } + +# jsut enough to get the job done +simple_find() { + # $1 = file to look for + # $rest = places to look for it + local file=$1 + shift + for loc in "$@"; do + [ -f "$NEWROOT$loc/$file" ] && { echo "$loc/$file"; return 0; } + done + return 1 +} + +# We really should not be doing this from here, but... +find_interp() { + local ldso=$("$NEWROOT$CHROOT" "$NEWROOT" "$LDD" "$1" | + while read interp rest; do + [ -f "${NEWROOT}$interp" ] || continue + echo "$interp" + break + done); + [ "$ldso" ] && echo $ldso +} + +# this makes it easier to run a command entirely from newroot +# $1 = elf interpreter (must pass empty string if none) +# $2 = command or "exec" +# $3 = command if exec was passed +run_from_newroot() { + local ldso="$1" cmd="$2"; shift; shift + if [ "$cmd" = "exec" ]; then + cmd="$1"; shift + if [ "$ldso" ]; then + exec "$NEWROOT$ldso" --library-path "$LIBPATH" "$NEWROOT$cmd" "$@" + else + exec "$NEWROOT$cmd" "$@" + fi + else + if [ "$ldso" ]; then + "$NEWROOT$ldso" --library-path "$LIBPATH" "$NEWROOT$cmd" "$@" + else + "$NEWROOT$cmd" "$@" + fi + fi +} +# update the path to find our dynamic libraries on newroot +update_newroot_libpath() { + local x + LIBPATH=":" + LIBDIRS="$(echo $NEWROOT/lib* $NEWROOT/usr/lib*)" + for x in $LIBDIRS; do + [ -d "$x" ] && LIBPATH="${LIBPATH}${x}:" + done + LIBPATH="${LIBPATH%:}"; LIBPATH="${LIBPATH#:}" + [ "$LIBPATH" ] || die "Cannot find shared library diectories on $NEWROOT" +} +NEWROOT="$1" +INIT="$2" +[ -d "$NEWROOT" ] || die "$NEWROOT is not a directory" +[ -x "$NEWROOT$INIT" ] || die "$NEWROOT/$INIT is not executable." +shift; shift + +update_newroot_libpath + +# start looking for required binaries and bits of infrastructure +BINDIRS="/bin /sbin /usr/bin /usr/sbin" +INITDIRS="/sbin /etc /" +RM=$(simple_find rm $BINDIRS) || die "Cannnot find rm on $NEWROOT" +CHROOT=$(simple_find chroot $BINDIRS) || die "Cannot find chroot on $NEWROOT" +LDD=$(simple_find ldd $BINDIRS) || die "Cannot find ldd on $NEWROOT" +MOUNT=$(simple_find mount $BINDIRS) || die "Cannot find mount on $NEWROOT" + +# now, start the real process of switching the root +cd / + +# kill udevd, move all our mounts over to the new root +kill $(pidof udevd) +mount --move /proc $NEWROOT/proc +mount --move /sys $NEWROOT/sys +mount --move /dev $NEWROOT/dev + +# Find the binary interpreter for our three required binaries. +# We do it here so that ldd does not complain about a missing /dev/null. +CHROOT_LDSO=$(find_interp "$CHROOT") +RM_LDSO=$(find_interp "$RM") +MOUNT_LDSO=$(find_interp "$MOUNT") + +# redirect to new console. Our old initramfs will not be freed otherwise +CONSOLE=$NEWROOT/dev/console +[ -c $CONSOLE ] && exec >$CONSOLE 2>&1 <$CONSOLE +for x in *; do + [ "/$x" = "$NEWROOT" ] || run_from_newroot "$RM_LDSO" "$RM" -rf -- "$x" +done +# switch to our new root dir +cd "$NEWROOT" +# this moves rootfs to the actual root... +run_from_newroot "$MOUNT_LDSO" "$MOUNT" -n --move . / +# but does not update where / is in directory lookups. +# Therefore, newroot is now ".". Update things accordingly, then chroot and +# exec init. +NEWROOT="." +update_newroot_libpath +run_from_newroot "$CHROOT_LDSO" exec "$CHROOT" "$NEWROOT" "$INIT" "$@" +die "The chroot did not take for some reason" -- 1.6.0.6 -- To unsubscribe from this list: send the line "unsubscribe initramfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
