From 34bffe1e2a70b4a117de65b552ffbddc34f1201b Mon Sep 17 00:00:00 2001 From: Michael Aldridge Date: Thu, 10 Aug 2017 23:28:26 -0700 Subject: [PATCH] Factor out chroot helpers to lib.sh This commit removes all of the chroot refactor to a seperate file. This paves the way to use these functions in all other scripts. --- lib.sh.in | 189 ++++++++++++++++++++++++++++++++++++++++++++++ mkrootfs.sh.in | 198 ++++--------------------------------------------- 2 files changed, 203 insertions(+), 184 deletions(-) create mode 100644 lib.sh.in diff --git a/lib.sh.in b/lib.sh.in new file mode 100644 index 0000000..6762d49 --- /dev/null +++ b/lib.sh.in @@ -0,0 +1,189 @@ +info_msg() { + # This function handles the printing that is bold within all + # scripts. This is a convenience function so that the rather ugly + # looking ASCII escape codes live in only one place. + printf "\033[1m%s\n\033[m" "$@" +} + +die() { + # This function is registered in all the scripts to make sure that + # the important mounts get cleaned up and the $ROOTFS location is + # removed. + printf "FATAL: %s\n" "$@" + umount_pseudofs + [ -d "$ROOTFS" ] && rm -rf "$ROOTFS" + exit 1 +} + +mount_pseudofs() { + # This function ensures that the psuedofs mountpoints are present + # in the chroot. Strictly they are not necessary to have for many + # commands, but bind-mounts are cheap and it isn't too bad to just + # mount them all the time. + for f in dev proc sys; do + # In a naked chroot there is nothing to bind the mounts to, so + # we need to create directories for these first. + [ ! -d "$ROOTFS/$f" ] && mkdir -p "$ROOTFS/$f" + if ! mountpoint -q "$ROOTFS/$f" ; then + # It is VERY important that this only happen if the + # pseudofs isn't already mounted. If it already is then + # this is virtually impossible to troubleshoot because it + # looks like the subsequent umount just isn't working. + mount -r --bind /$f "$ROOTFS/$f" + fi + done +} + +umount_pseudofs() { + # This function cleans up the mounts in the chroot. Failure to + # clean up these mounts will prevent the tmpdir from being + # deletable instead throwing the error "Device or Resource Busy". + # The '-f' option is passed to umount to account for the + # contingency where the psuedofs mounts are not present. + if [ -d "${ROOTFS}" ]; then + for f in dev proc sys; do + umount -f "$ROOTFS/$f" >/dev/null 2>&1 + done + fi +} + +run_cmd_target() { + info_msg "Running $* for target $XBPS_TARGET_ARCH ..." + if [ "$XBPS_TARGET_ARCH" = "$(xbps-uhelper arch)" ] ; then + # This is being run on the same architecture as the host, + # therefore we should set XBPS_ARCH. + if ! eval XBPS_ARCH="$XBPS_TARGET_ARCH" "$@" ; then + die "Could not run command $*" + fi + else + # This is being run on a foriegn arch, therefore we should set + # XBPS_TARGET_ARCH. In this case XBPS will not attempt + # certain actions and will require reconfiguration later. + if ! eval XBPS_TARGET_ARCH="$XBPS_TARGET_ARCH" "$@" ; then + die "Could not run command $*" + fi + fi +} + +run_cmd() { + # This is a general purpose function to run commands that a user + # may wish to see. For example its useful to see the tar/xz + # pipeline to not need to delve into the scripts to see what + # options its set up with. + info_msg "Running $*" + eval "$@" +} + +run_cmd_chroot() { + # General purpose chroot function which makes sure the chroot is + # prepared. This function takes 2 arguments, the location to + # chroot to and the command to run. + + # This is an idempotent function, it is safe to call every time + # before entering the chroot. This has the advantage of making + # execution in the chroot appear as though it "Just Works(tm)". + register_binfmt + + # Before we step into the chroot we need to make sure the + # pseudo-filesystems are ready to go. Not all commands will need + # this, but its still a good idea to call it here anyway. + mount_pseudofs + + # With assurance that things will run now we can jump into the + # chroot and run stuff! + chroot "$1" sh -c "$2" +} + +cleanup_chroot() { + # This function cleans up the chroot shims that are used by QEMU + # to allow builds on alien platforms. It takes no arguments but + # expects the global $ROOTFS variable to be set. + + # Un-Mount the pseudofs mounts if they were mounted + umount_pseudofs + + # If a QEMU binary was copied in, remove that as well + if [ -x "$ROOTFS/usr/bin/$QEMU_BIN" ] ; then + rm "$ROOTFS/usr/bin/$QEMU_BIN" + fi +} + +# TODO: Figure out how to register the binfmt for x86_64 and for i686 +# to facilitate building on alien build systems. +register_binfmt() { + # This function sets up everything that is needed to be able to + # chroot into a ROOTFS and be able to run commands there. This + # really matters on platforms where the host architecture is + # different from the target, and you wouldn't be able to run + # things like xbps-reconfigure -a. This function is idempotent + # (You can run it multiple times without modifying state). This + # function takes no arguments, but does expect the global variable + # $XBPS_TARGET_ARCH to be set. + + # This select sets up the "magic" bytes in /proc that let the + # kernel select an alternate interpreter. More values for this + # map can be obtained from here: + # https://github.com/qemu/qemu/blob/master/scripts/qemu-binfmt-conf.sh + case "${XBPS_TARGET_ARCH}" in + armv*) + _cpu=arm + _magic="\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x28\x00" + _mask="\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff" + QEMU_BIN=qemu-arm-static + ;; + aarch64*) + _cpu=aarch64 + _magic="\x7fELF\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\xb7" + _mask="\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff" + QEMU_BIN=qemu-aarch64-static + ;; + mipsel*) + _cpu=mipsel + _magic="\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x08\x00" + _mask="\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff" + QEMU_BIN=qemu-mipsel-static + ;; + *86*) + info_msg "FIXME: Assuming that x86 instructions are native" + QEMU_BIN=NATIVE + ;; + *) + die "Unknown target architecture!" + ;; + esac + + # In the special case where the build is native we can return + # without doing anything else + if [ "$QEMU_BIN" = "NATIVE" ] ; then + return + fi + + # For builds that do not match the host architecture, the correct + # qemu binary will be required. + if ! $QEMU_BIN -version >/dev/null 2>&1; then + die "$QEMU_BIN binary is missing in your system, exiting." + fi + + # In order to use the binfmt system the binfmt_misc mountpoint + # must exist inside of proc + if ! mountpoint -q /proc/sys/fs/binfmt_misc ; then + modprobe -q binfmt_misc + mount -t binfmt_misc binfmt_misc /proc/sys/fs/binfmt_misc 2>/dev/null + fi + + # Only register if the map is incomplete + if [ ! -f /proc/sys/fs/binfmt_misc/qemu-$_cpu ] ; then + echo ":qemu-$_cpu:M::$_magic:$_mask:$QEMU_BIN:" > /proc/sys/fs/binfmt_misc/register 2>/dev/null + fi + + # If the static binary isn't in the chroot then the chroot will + # fail. The kernel knows about the map but without the static + # version there's no interpreter in the chroot, only the + # dynamically linked one in the host. To simplify things we just + # use the static one always and make sure it shows up at the same + # place in the host and the chroot. + if [ ! -x "$ROOTFS/usr/bin/$QEMU_BIN" ] ; then + cp -f "$(which "$QEMU_BIN")" "$ROOTFS/usr/bin" || + die "Could not install $QEMU_BIN to $ROOTFS/usr/bin/" + fi +} diff --git a/mkrootfs.sh.in b/mkrootfs.sh.in index 261ec22..7754465 100644 --- a/mkrootfs.sh.in +++ b/mkrootfs.sh.in @@ -28,21 +28,17 @@ readonly PROGNAME=$(basename "$0") readonly ARCH=$(uname -m) +# This source pulls in all the functions from lib.sh. This set of +# functions makes it much easier to work with chroots and abstracts +# away all the problems with running binaries with QEMU. +# shellcheck source=./lib.sh +. ./lib.sh + +# Die is a function provided in lib.sh which handles the cleanup of +# the mounts and removal of temporary directories if the running +# program exists unexpectedly. trap 'die "Interrupted! exiting..."' INT TERM HUP - -info_msg() { - printf "\033[1m%s\n\033[m" "$@" -} - -die() { - printf "FATAL: %s\n" "$@" - umount_pseudofs - [ -d "$ROOTFS" ] && rm -rf "$ROOTFS" - exit 1 -} - - # Even though we only support really one target for most of these # architectures this lets us refer to these quickly and easily by # XBPS_ARCH. This makes it a lot more obvious what is happening later @@ -68,178 +64,12 @@ Options _EOF } -mount_pseudofs() { - # This function ensures that the psuedofs mountpoints are present - # in the chroot. Strictly they are not necessary to have for many - # commands, but bind-mounts are cheap and it isn't too bad to just - # mount them all the time. - for f in dev proc sys; do - # In a naked chroot there is nothing to bind the mounts to, so - # we need to create directories for these first. - [ ! -d "$ROOTFS/$f" ] && mkdir -p "$ROOTFS/$f" - if ! mountpoint -q "$ROOTFS/$f" ; then - # It is VERY important that this only happen if the - # pseudofs isn't already mounted. If it already is then - # this is virtually impossible to troubleshoot because it - # looks like the subsequent umount just isn't working. - mount -r --bind /$f "$ROOTFS/$f" - fi - done -} +# ######################################## +# SCRIPT EXECUTION STARTS HERE +# ######################################## -umount_pseudofs() { - # This function cleans up the mounts in the chroot. Failure to - # clean up these mounts will prevent the tmpdir from being - # deletable instead throwing the error "Device or Resource Busy". - # The '-f' option is passed to umount to account for the - # contingency where the psuedofs mounts are not present. - if [ -d "${ROOTFS}" ]; then - for f in dev proc sys; do - umount -f "$ROOTFS/$f" >/dev/null 2>&1 - done - fi -} - -run_cmd_target() { - info_msg "Running $* for target $XBPS_TARGET_ARCH ..." - if [ "$XBPS_TARGET_ARCH" = "$(xbps-uhelper arch)" ] ; then - # This is being run on the same architecture as the host, - # therefore we should set XBPS_ARCH. - if ! eval XBPS_ARCH="$XBPS_TARGET_ARCH" "$@" ; then - die "Could not run command $*" - fi - else - # This is being run on a foriegn arch, therefore we should set - # XBPS_TARGET_ARCH. In this case XBPS will not attempt - # certain actions and will require reconfiguration later. - if ! eval XBPS_TARGET_ARCH="$XBPS_TARGET_ARCH" "$@" ; then - die "Could not run command $*" - fi - fi -} - -run_cmd() { - info_msg "Running $*" - eval "$@" -} - -run_cmd_chroot() { - # General purpose chroot function which makes sure the chroot is - # prepared. This function takes 2 arguments, the location to - # chroot to and the command to run. - - # This is an idempotent function, it is safe to call every time - # before entering the chroot. This has the advantage of making - # execution in the chroot appear as though it "Just Works(tm)". - register_binfmt - - # Before we step into the chroot we need to make sure the - # pseudo-filesystems are ready to go. Not all commands will need - # this, but its still a good idea to call it here anyway. - mount_pseudofs - - # With assurance that things will run now we can jump into the - # chroot and run stuff! - chroot "$1" sh -c "$2" -} - -cleanup_chroot() { - # This function cleans up the chroot shims that are used by QEMU - # to allow builds on alien platforms. It takes no arguments but - # expects the global $ROOTFS variable to be set. - - # Un-Mount the pseudofs mounts if they were mounted - umount_pseudofs - - # If a QEMU binary was copied in, remove that as well - if [ -x "$ROOTFS/usr/bin/$QEMU_BIN" ] ; then - rm "$ROOTFS/usr/bin/$QEMU_BIN" - fi -} - -# TODO: Figure out how to register the binfmt for x86_64 and for i686 -# to facilitate building on alien build systems. -register_binfmt() { - # This function sets up everything that is needed to be able to - # chroot into a ROOTFS and be able to run commands there. This - # really matters on platforms where the host architecture is - # different from the target, and you wouldn't be able to run - # things like xbps-reconfigure -a. This function is idempotent - # (You can run it multiple times without modifying state). This - # function takes no arguments, but does expect the global variable - # $XBPS_TARGET_ARCH to be set. - - # This select sets up the "magic" bytes in /proc that let the - # kernel select an alternate interpreter. More values for this - # map can be obtained from here: - # https://github.com/qemu/qemu/blob/master/scripts/qemu-binfmt-conf.sh - case "${XBPS_TARGET_ARCH}" in - armv*) - _cpu=arm - _magic="\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x28\x00" - _mask="\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff" - QEMU_BIN=qemu-arm-static - ;; - aarch64*) - _cpu=aarch64 - _magic="\x7fELF\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\xb7" - _mask="\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff" - QEMU_BIN=qemu-aarch64-static - ;; - mipsel*) - _cpu=mipsel - _magic="\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x08\x00" - _mask="\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff" - QEMU_BIN=qemu-mipsel-static - ;; - *86*) - info_msg "FIXME: Assuming that x86 instructions are native" - QEMU_BIN=NATIVE - ;; - *) - die "Unknown target architecture!" - ;; - esac - - # In the special case where the build is native we can return - # without doing anything else - if [ "$QEMU_BIN" = "NATIVE" ] ; then - return - fi - - # For builds that do not match the host architecture, the correct - # qemu binary will be required. - if ! $QEMU_BIN -version >/dev/null 2>&1; then - die "$QEMU_BIN binary is missing in your system, exiting." - fi - - # In order to use the binfmt system the binfmt_misc mountpoint - # must exist inside of proc - if ! mountpoint -q /proc/sys/fs/binfmt_misc ; then - modprobe -q binfmt_misc - mount -t binfmt_misc binfmt_misc /proc/sys/fs/binfmt_misc 2>/dev/null - fi - - # Only register if the map is incomplete - if [ ! -f /proc/sys/fs/binfmt_misc/qemu-$_cpu ] ; then - echo ":qemu-$_cpu:M::$_magic:$_mask:$QEMU_BIN:" > /proc/sys/fs/binfmt_misc/register 2>/dev/null - fi - - # If the static binary isn't in the chroot then the chroot will - # fail. The kernel knows about the map but without the static - # version there's no interpreter in the chroot, only the - # dynamically linked one in the host. To simplify things we just - # use the static one always and make sure it shows up at the same - # place in the host and the chroot. - if [ ! -x "$ROOTFS/usr/bin/$QEMU_BIN" ] ; then - cp -f "$(which "$QEMU_BIN")" "$ROOTFS/usr/bin" || - die "Could not install $QEMU_BIN to $ROOTFS/usr/bin/" - fi -} - -# -# main() -# +# Boilerplate option parsing. This script supports the bare minimum +# needed to build an image. while getopts "C:c:h:r:V" opt; do case $opt in C) XBPS_CONFFILE="-C $OPTARG";;