New upstream version 25.upstream/25

1 files changed, 68 insertions, 35 deletions

diff --git a/arch-chroot.in b/arch-chroot.in
index fd6140e..bcb38df 100644
--- a/arch-chroot.in
+++ b/arch-chroot.in
@@ -4,11 +4,15 @@ shopt -s extglob
 
 m4_include(common)
 
+setup=chroot_setup
+unshare="$root_unshare"
+
 usage() {
   cat <<EOF
-usage: ${0##*/} chroot-dir [command]
+usage: ${0##*/} chroot-dir [command] [arguments...]
 
     -h                  Print this help message
+    -N                  Run in unshare mode as a regular user
     -u <user>[:group]   Specify non-root user and optional group to use
 
 If 'command' is unspecified, ${0##*/} will launch /bin/bash.
@@ -23,40 +27,63 @@ itself to make it a mountpoint, i.e. 'mount --bind /your/chroot /your/chroot'.
 EOF
 }
 
+resolve_link() {
+  local target=$1
+  local root=$2
+
+  # If a root was given, make sure it ends in a slash.
+  [[ -n $root && $root != */ ]] && root=$root/
+
+  while [[ -L $target ]]; do
+    target=$(readlink -m "$target")
+    # If a root was given, make sure the target is under it.
+    # Make sure to strip any leading slash from target first.
+    [[ -n $root && $target != $root* ]] && target=$root${target#/}
+  done
+
+  printf %s "$target"
+}
+
 chroot_add_resolv_conf() {
-  local chrootdir=$1 resolv_conf=$1/etc/resolv.conf
-
-  [[ -e /etc/resolv.conf ]] || return 0
-
-  # Handle resolv.conf as a symlink to somewhere else.
-  if [[ -L $chrootdir/etc/resolv.conf ]]; then
-    # readlink(1) should always give us *something* since we know at this point
-    # it's a symlink. For simplicity, ignore the case of nested symlinks.
-    resolv_conf=$(readlink "$chrootdir/etc/resolv.conf")
-    if [[ $resolv_conf = /* ]]; then
-      resolv_conf=$chrootdir$resolv_conf
-    else
-      resolv_conf=$chrootdir/etc/$resolv_conf
-    fi
-
-    # ensure file exists to bind mount over
-    if [[ ! -f $resolv_conf ]]; then
-      install -Dm644 /dev/null "$resolv_conf" || return 1
-    fi
-  elif [[ ! -e $chrootdir/etc/resolv.conf ]]; then
-    # The chroot might not have a resolv.conf.
-    return 0
+  local chrootdir=$1
+  local src=$(resolve_link /etc/resolv.conf)
+  local dest=$(resolve_link "$chrootdir/etc/resolv.conf" "$chrootdir")
+
+  # If we don't have a source resolv.conf file, there's nothing useful we can do.
+  [[ -e $src ]] || return 0
+
+  if [[ ! -e $dest ]]; then
+    # There are two reasons the destination might not exist:
+    #
+    #   1. There may be no resolv.conf in the chroot.  In this case, $dest won't exist,
+    #      and it will be equal to $1/etc/resolv.conf.  In this case, we'll just exit.
+    #      The chroot environment must not be concerned with DNS resolution.
+    #
+    #   2. $1/etc/resolv.conf is (or resolves to) a broken link.  The environment
+    #      clearly intends to handle DNS resolution, but something's wrong.  Maybe it
+    #      normally creates the target at boot time.  We'll (try to) take care of it by
+    #      creating a dummy file at the target, so that we have something to bind to.
+
+    # Case 1.
+    [[ $dest = $chrootdir/etc/resolv.conf ]] && return 0
+
+    # Case 2.
+    install -Dm644 /dev/null "$dest" || return 1
   fi
 
-  chroot_add_mount /etc/resolv.conf "$resolv_conf" --bind
+  chroot_add_mount "$src" "$dest" --bind
 }
 
-while getopts ':hu:' flag; do
+while getopts ':hNu:' flag; do
   case $flag in
     h)
       usage
       exit 0
       ;;
+    N)
+      setup=unshare_setup
+      unshare="$user_unshare"
+      ;;
     u)
       userspec=$OPTARG
       ;;
@@ -70,21 +97,27 @@ while getopts ':hu:' flag; do
 done
 shift $(( OPTIND - 1 ))
 
-(( EUID == 0 )) || die 'This script must be run with root privileges'
 (( $# )) || die 'No chroot directory specified'
 chrootdir=$1
 shift
 
-[[ -d $chrootdir ]] || die "Can't create chroot on non-directory %s" "$chrootdir"
+arch-chroot() {
+  (( EUID == 0 )) || die 'This script must be run with root privileges'
+
+  [[ -d $chrootdir ]] || die "Can't create chroot on non-directory %s" "$chrootdir"
 
-if ! mountpoint -q "$chrootdir"; then
-  warning "$chrootdir is not a mountpoint. This may have undesirable side effects."
-fi
+  $setup "$chrootdir" || die "failed to setup chroot %s" "$chrootdir"
+  chroot_add_resolv_conf "$chrootdir" || die "failed to setup resolv.conf"
 
-chroot_setup "$chrootdir" || die "failed to setup chroot %s" "$chrootdir"
-chroot_add_resolv_conf "$chrootdir" || die "failed to setup resolv.conf"
+  if ! mountpoint -q "$chrootdir"; then
+    warning "$chrootdir is not a mountpoint. This may have undesirable side effects."
+  fi
 
-chroot_args=()
-[[ $userspec ]] && chroot_args+=(--userspec "$userspec")
+  chroot_args=()
+  [[ $userspec ]] && chroot_args+=(--userspec "$userspec")
+
+  SHELL=/bin/bash chroot "${chroot_args[@]}" -- "$chrootdir" "${args[@]}"
+}
 
-SHELL=/bin/bash unshare --fork --pid chroot "${chroot_args[@]}" -- "$chrootdir" "$@"
+args=("$@")
+$unshare bash -c "$(declare_all); arch-chroot"