selfstrap: debootstrap using local /var/cache/apt/archives

1 files changed, 302 insertions, 0 deletions

diff --git a/multistrap/selfstrap b/multistrap/selfstrap
new file mode 100755
index 0000000..265049b
--- /dev/null
+++ b/multistrap/selfstrap
@@ -0,0 +1,302 @@
+#!/bin/bash
+debian_mirror=http://httpredir.debian.org/debian
+
+if [ $# = 1 ]; then
+    rootfs=$1
+else
+    echo "Usage: $0 <target directory>" >&2
+    exit 1
+fi
+
+die() { printf 'Error: %s\n' "$*"; exit 1; }
+
+am_root() { [ "$(id -u)" = 0 ]; }
+
+current_debian_codename()
+{
+    # lsb_release -cs
+    sed -ne 's/^VERSION=.* (\(.*\)).*/\1/p' /etc/os-release
+}
+
+sanity_checks()
+{
+    am_root || die 'you are not root'
+    rootfs=$(realpath "$rootfs") || die 'realpath failed'
+    [ "$rootfs" ] || die 'no $rootfs'
+    [ -d "$rootfs" ] || mkdir "$rootfs" || die 'could not mkdir($rootfs)'
+}
+
+generate_apt_config()
+{
+    APT_CONFIG=$(mktemp) || exit
+    chmod 644 "$APT_CONFIG"
+    cat > "$APT_CONFIG" <<EOF
+Dir::Etc "${rootfs}/etc/apt/";
+Dir::Etc::Parts "${rootfs}/etc/apt/apt.conf.d/";
+Dir::Etc::PreferencesParts "${rootfs}/etc/apt/preferences.d/";
+EOF
+    export APT_CONFIG
+}
+
+apt_get()
+{
+    [ "$rootfs" ] || die 'no $rootfs'
+    [ "$APT_CONFIG" ] || die 'no $APT_CONFIG'
+
+    set  --  -o  Apt::Install-Recommends=false                                "$@"
+
+    # Set various paths to within the created system.
+    set  --  -o  Apt::Architecture="$rootfs_arch"                             "$@"
+    set  --  -o  Apt::Default-Release="$release"                              "$@"
+    set  --  -o  Dir="$rootfs"                                                "$@"
+    set  --  -o  Dir::Cache="$rootfs"/var/cache/apt/                          "$@"
+    set  --  -o  Dir::Etc::Parts="$rootfs"/etc/apt/apt.conf.d/                "$@"
+    set  --  -o  Dir::Etc::PreferencesParts="$rootfs"/etc/apt/preferences.d/  "$@"
+    set  --  -o  Dir::Etc="$rootfs"/etc/apt/                                  "$@"
+    set  --  -o  Dir::State="$rootfs"/var/lib/apt/                            "$@"
+    set  --  -o  Dir::State::Status="$rootfs"/var/lib/dpkg/status             "$@"
+
+    # We must also set dpkg to use the created system.
+    # Dpkg::options requires undocumented apt CLI magic.
+    if [ "$DEBUG_DPKG" ]; then
+        [ "$DEBUG_DPKG" -gt 0 ] 2>/dev/null || DEBUG_DPKG=013
+        set  --  -o  DPkg::options::arg0=--debug="${DEBUG_DPKG}"              "$@"
+    fi
+    # This is the important one:
+    set  --  -o  DPkg::options::arg1=--root="$rootfs"                         "$@"
+    set  --  -o  DPkg::options::arg2=--force-unsafe-io                        "$@"
+
+    # Use the calling system for these.  This is an optimization.
+    set  --  -o  Dir::Cache::archives=/var/cache/apt/archives                 "$@"
+    set  --  -o  Dir::Etc::Trusted=/etc/apt/trusted.gpg                       "$@"
+    set  --  -o  Dir::Etc::TrustedParts=/etc/apt/trusted.gpg.d                "$@"
+    set  --  -o  Dir::State::Lists=/var/lib/apt/lists                         "$@"
+
+    # Avoid deleting lists on the calling system.
+    set  --  -o  APT::Get::List-Cleanup=false                                 "$@"
+
+    apt-get "$@"
+}
+
+write_lines_once()
+{
+    local output="$1"
+    shift
+    [ -e "$output" ] || printf '%s\n' "$@" > "$output"
+}
+
+populate_rootfs()
+{
+    [ "$rootfs" ] || die 'no $rootfs'
+    set -B
+    mkdir -p \
+          "$rootfs"/etc/apt/{preferences.d,apt.conf.d,trusted.gpg.d,sources.list.d} \
+          "$rootfs"/var/{lib/{apt/lists/partial,dpkg/{info,parts,triggers,alternatives,updates}},cache/apt} \
+          "$rootfs"/var/log/apt
+
+    touch "$rootfs"/var/lib/dpkg/status
+
+    write_lines_once "$rootfs"/var/lib/dpkg/arch "$rootfs_arch"
+    write_lines_once "$rootfs"/etc/apt/sources.list \
+                     "deb $debian_mirror $release main contrib non-free" \
+                     "deb http://security.debian.org $release/updates main contrib non-free"
+}
+
+parse_apt_noact_line()
+{
+    set -- $*
+    action=$1
+    package=$2
+    version=${3#\(}
+    shift 3
+
+    while [ "$1" ]; do
+        case "$1" in
+            *\))
+                arch=${1%\)}
+                arch=${arch#\[}
+                arch=${arch%\]}
+                return
+                ;;
+            *) shift ;;
+        esac
+    done
+    return 1
+}
+
+extract_dpkg_info()
+{
+    local deb="$1" TARGET="$2" multiarch="$3" command PKG
+    PKG=${deb##*/}
+    PKG=${PKG%%_*}
+    PKG=$PKG$multiarch
+
+    command='
+[ "$TAR_FILENAME" = ./control ] && exit
+f=$TARGET/var/lib/dpkg/info/$PKG.${TAR_FILENAME#./}
+cat > "$f"
+chmod $TAR_MODE "$f"
+'
+    (export PKG TARGET
+     dpkg --ctrl-tarfile "$deb" | tar -x --to-command "$command")
+    dpkg --fsys-tarfile "$deb" | tar -t | sed 's?^\.??; s?^/$?/.?; s?/$??' > "$TARGET/var/lib/dpkg/info/$PKG.list"
+
+}
+
+apt_run_inst()
+{
+    apt_get -s -yqq install "$@" | while read line; do
+        parse_apt_noact_line "$line" || die "unexpected output from apt-get: $line"
+        export DPKG_MAINTSCRIPT_PACKAGE="$package" DPKG_MAINTSCRIPT_ARCH="$arch"
+        if is_multiarch_same "$package"; then
+            multiarch=":$arch"
+        else
+            multiarch=
+        fi
+        case "$action" in
+            Inst)
+                export DPKG_MAINTSCRIPT_NAME=preinst
+                preinst=/var/lib/dpkg/info/${package}${multiarch}.preinst
+                if [ -x "$rootfs"/"$preinst" ]; then
+                    (set -x; chroot "$rootfs" "$preinst" install)
+                fi
+                ;;
+            Conf)
+                export DPKG_MAINTSCRIPT_NAME=postinst
+                postinst=/var/lib/dpkg/info/${package}${multiarch}.postinst
+                if [ -x "$rootfs"/"$postinst" ]; then
+                    (set -x; chroot "$rootfs" "$postinst" configure)
+                fi
+                ;;
+            Remv) ;;
+            *) die "impossible" ;;
+        esac
+    done
+}
+
+apt_extract()
+{
+    apt_get -d -yqq install "$@"
+    apt_get -s -yqq install "$@" | while read line; do
+        parse_apt_noact_line "$line" || die "unexpected output from apt-get: $line"
+
+        deb=/var/cache/apt/archives/${package}_${version//:/%3a}_${arch}.deb
+        [ -f "$deb" ] || {
+            echo "line=$line" >&2
+            printf '%s\n' "$action" "$package" "$version" "$arch" >&2
+            die "unexpected output from apt-get"
+        }
+        case "$action" in
+            Inst)
+                printf 'Extracting %s\n' "${deb##*/}" >&2
+                dpkg-deb --extract "$deb" "$rootfs"
+
+                if [ "$EXTRACT_DPKG_INFO" ]; then
+                    is_multiarch_same "$package" && multiarch=":$arch" || multiarch=
+                    extract_dpkg_info "$deb" "$rootfs" "$multiarch"
+                fi
+                ;;
+            Conf)
+                ;;
+            Remv) ;;
+            *) die "impossible" ;;
+        esac
+    done
+}
+
+install_etc_passwd()
+{
+    [ -e "$rootfs"/etc/passwd ] || cp "$rootfs"//usr/share/base-passwd/passwd.master "$rootfs"/etc/passwd
+    [ -e "$rootfs"/etc/group  ] || cp "$rootfs"//usr/share/base-passwd/group.master  "$rootfs"/etc/group
+}
+
+main_packages_file()
+{
+    local uri_part="${debian_mirror#*/}"
+    while [ "${uri_part:0:1}" = / ]; do
+        uri_part=${uri_part#?}
+    done
+    uri_part=${uri_part//\//_}
+    printf '/var/lib/apt/lists/%s_dists_%s_main_binary-%s_Packages\n' "$uri_part" "$release" "$rootfs_arch"
+}
+
+required_packages()
+{
+    perl -00 -ne \
+         '/^Priority: required/m || next; /^Package: (.*)$/m && print "$1\n"' \
+         "$(main_packages_file)" | sort -u
+}
+
+multiarch_same_packages()
+{
+    [ "$multiarch_same_packages" ] || multiarch_same_packages=$(multiarch_same_packages_)
+    echo "$multiarch_same_packages"
+}
+
+multiarch_same_packages_()
+{
+    perl -00 -ne \
+         '/^Multi-Arch: same/mi || next; /^Package: (.*)$/m && print "$1\n"' \
+         "$(main_packages_file)" | sort -u
+}
+
+is_multiarch_same()
+{
+    local p
+    for p in $(multiarch_same_packages); do
+        [ "$1" = "$p" ] && return
+    done
+    return 1
+}
+
+set -e
+
+rootfs_arch=$(dpkg-architecture -q DEB_HOST_ARCH) || die 'dpkg-architecture failed'
+release=$(current_debian_codename) && [ "$release" ] || die 'could not determine Debian release name'
+
+if [ "$FAST_MODE" ]; then
+    SKIP_INSTALL=y
+    EXTRACT_DPKG_INFO=y
+    RUN_INST_SCRIPTS=y
+fi
+
+# Set things up so apt-get update works.
+sanity_checks
+generate_apt_config
+populate_rootfs
+
+
+# Initial apt-get update will determine what we shall install.
+[ "$SKIP_UPDATE" ] || apt_get update
+packages=$(required_packages) && [ "$packages" ] || die 'failed to determine list of required packages'
+extra_packages='apt debian-archive-keyring locales'
+
+
+# Extract files from downloaded packages.
+#
+# Some files need to be present before 'apt-get install' can install anything.
+# In particular:
+#
+#   1. binaries used by dpkg 'inst' scripts.
+#   2. /etc/passwd and /etc/group so that 'chown' works
+
+# Rather than fuss about (1), extract everything from all packages.
+apt_extract $packages
+# This handles (2).
+install_etc_passwd
+
+
+# Finally we are ready to run apt-get install.
+export LC_ALL=C
+export DEBIAN_FRONTEND=noninteractive
+if [ "$SKIP_INSTALL" ]; then
+    apt_extract $extra_packages
+    if [ "$RUN_INST_SCRIPTS" ]; then
+        apt_run_inst $packages $extra_packages
+    fi
+else
+    if [ "$FIX_BROKEN" ]; then
+        dpkg --root="$rootfs" --configure -a
+    fi
+    apt_get install -y $packages $extra_packages
+fi