#!/bin/sh

set -e
unset GREP_OPTIONS GPGHOMEDIR CURRENTTRAP
export IFS="$(printf "\n\b")"

MASTER_KEYRING=''
eval "$(apt-config shell MASTER_KEYRING APT::Key::MasterKeyring)"
ARCHIVE_KEYRING=''
eval "$(apt-config shell ARCHIVE_KEYRING APT::Key::ArchiveKeyring)"
REMOVED_KEYS=''
eval "$(apt-config shell REMOVED_KEYS APT::Key::RemovedKeys)"
ARCHIVE_KEYRING_URI=''
eval "$(apt-config shell ARCHIVE_KEYRING_URI APT::Key::ArchiveKeyringURI)"

aptkey_echo() { echo "$@"; }

find_gpgv_status_fd() {
   while [ -n "$1" ]; do
	if [ "$1" = '--status-fd' ]; then
		shift
		echo "$1"
		break
	fi
	shift
   done
}
GPGSTATUSFD="$(find_gpgv_status_fd "$@")"

apt_warn() {
    if [ -z "$GPGHOMEDIR" ]; then
	echo >&2 'W:' "$@"
    else
	echo 'W:' "$@" > "${GPGHOMEDIR}/aptwarnings.log"
    fi
    if [ -n "$GPGSTATUSFD" ]; then
	echo >&${GPGSTATUSFD} '[APTKEY:] WARNING' "$@"
    fi
}
apt_error() {
    if [ -z "$GPGHOMEDIR" ]; then
	echo >&2 'E:' "$@"
    else
	echo 'E:' "$@" > "${GPGHOMEDIR}/aptwarnings.log"
    fi
    if [ -n "$GPGSTATUSFD" ]; then
	echo >&${GPGSTATUSFD} '[APTKEY:] ERROR' "$@"
    fi
}

cleanup_gpg_home() {
    if [ -z "$GPGHOMEDIR" ]; then return; fi
    if [ -s "$GPGHOMEDIR/aptwarnings.log" ]; then
	cat >&2 "$GPGHOMEDIR/aptwarnings.log"
    fi
    if command_available 'gpgconf'; then
	GNUPGHOME="${GPGHOMEDIR}" gpgconf --kill all >/dev/null 2>&1 || true
    fi
    rm -rf "$GPGHOMEDIR"
}

# gpg needs (in different versions more or less) files to function correctly,
# so we give it its own homedir and generate some valid content for it later on
create_gpg_home() {
    # for cases in which we want to cache a homedir due to expensive setup
    if [ -n "$GPGHOMEDIR" ]; then
	return
    fi
    if [ -n "$TMPDIR" ]; then
	# tmpdir is a directory and current user has rwx access to it
	# same tests as in apt-pkg/contrib/fileutl.cc GetTempDir()
	if [ ! -d "$TMPDIR" ] || [ ! -r "$TMPDIR" ] || [ ! -w "$TMPDIR" ] || [ ! -x "$TMPDIR" ]; then
	    unset TMPDIR
	fi
    fi
    GPGHOMEDIR="$(mktemp --directory --tmpdir 'apt-key-gpghome.XXXXXXXXXX')"
    CURRENTTRAP="${CURRENTTRAP} cleanup_gpg_home;"
    trap "${CURRENTTRAP}" 0 HUP INT QUIT ILL ABRT FPE SEGV PIPE TERM
    if [ -z "$GPGHOMEDIR" ]; then
	apt_error "Could not create temporary gpg home directory in $TMPDIR (wrong permissions?)"
	exit 28
    fi
    chmod 700 "$GPGHOMEDIR"
}

requires_root() {
	if [ "$(id -u)" -ne 0 ]; then
		apt_error "This command can only be used by root."
		exit 1
	fi
}

command_available() {
    if [ -x "$1" ]; then return 0; fi
    command -v "$1" >/dev/null # required by policy, see #747320
}

escape_shell() {
    echo "$@" | sed -e "s#'#'\"'\"'#g"
}

get_fingerprints_of_keyring() {
    aptkey_execute "$GPG_SH" --keyring "$1" --with-colons --fingerprint | while read publine; do
	# search for a public key
	if [ "${publine%%:*}" != 'pub' ]; then continue; fi
	# search for the associated fingerprint (should be the very next line)
	while read fprline; do
	   if [ "${fprline%%:*}" = 'sub' ]; then break; # should never happen
	   elif [ "${fprline%%:*}" != 'fpr' ]; then continue; fi
	   echo "$fprline" | cut -d':' -f 10
	done
	# order in the keyring shouldn't be important
    done | sort
}

add_keys_with_verify_against_master_keyring() {
    ADD_KEYRING="$1"
    MASTER="$2"

    if [ ! -f "$ADD_KEYRING" ]; then
	apt_error "Keyring '$ADD_KEYRING' to be added not found"
	return
    fi
    if [ ! -f "$MASTER" ]; then
	apt_error "Master-Keyring '$MASTER' not found"
	return
    fi

    # when adding new keys, make sure that the archive-master-keyring
    # is honored. so:
    #   all keys that are exported must have a valid signature
    #   from a key in the $distro-master-keyring
    add_keys="$(get_fingerprints_of_keyring "$ADD_KEYRING")"
    all_add_keys="$(aptkey_execute "$GPG_SH" --keyring "$ADD_KEYRING" --with-colons --list-keys | grep ^[ps]ub | cut -d: -f5)"
    master_keys="$(aptkey_execute "$GPG_SH" --keyring "$MASTER" --with-colons --list-keys | grep ^pub | cut -d: -f5)"

    # ensure there are no colisions LP: #857472
    for all_add_key in $all_add_keys; do
	for master_key in $master_keys; do
            if [ "$all_add_key" = "$master_key" ]; then
                echo >&2 "Keyid collision for '$all_add_key' detected, operation aborted"
                return 1
            fi
        done
    done

    for add_key in $add_keys; do
        # export the add keyring one-by-one
	local TMP_KEYRING="${GPGHOMEDIR}/tmp-keyring.gpg"
	aptkey_execute "$GPG_SH" --batch --yes --keyring "$ADD_KEYRING" --output "$TMP_KEYRING" --export "$add_key"
	if ! aptkey_execute "$GPG_SH" --batch --yes --keyring "$TMP_KEYRING" --import "$MASTER" > "${GPGHOMEDIR}/gpgoutput.log" 2>&1; then
	    cat >&2 "${GPGHOMEDIR}/gpgoutput.log"
	    false
	fi
	# check if signed with the master key and only add in this case
	ADDED=0
	for master_key in $master_keys; do
	    if aptkey_execute "$GPG_SH" --keyring "$TMP_KEYRING" --check-sigs --with-colons "$add_key" \
	       | grep '^sig:!:' | cut -d: -f5 | grep -q "$master_key"; then
		aptkey_execute "$GPG_SH" --batch --yes --keyring "$ADD_KEYRING" --export "$add_key" \
		   | aptkey_execute "$GPG" --batch --yes --import
		ADDED=1
	    fi
	done
	if [ $ADDED = 0 ]; then
	    echo >&2 "Key '$add_key' not added. It is not signed with a master key"
	fi
	rm -f "${TMP_KEYRING}"
    done
}

# update the current archive signing keyring from a network URI
# the archive-keyring keys needs to be signed with the master key
# (otherwise it does not make sense from a security POV)
net_update() {
    local APT_DIR='/'
    eval $(apt-config shell APT_DIR Dir)

    # Disabled for now as code is insecure (LP: #1013639 (and 857472, 1013128))
    APT_KEY_NET_UPDATE_ENABLED=""
    eval $(apt-config shell APT_KEY_NET_UPDATE_ENABLED APT::Key::Net-Update-Enabled)
    if [ -z "$APT_KEY_NET_UPDATE_ENABLED" ]; then
        exit 1
    fi

    if [ -z "$ARCHIVE_KEYRING_URI" ]; then
	apt_error 'Your distribution is not supported in net-update as no uri for the archive-keyring is set'
	exit 1
    fi
    # in theory we would need to depend on wget for this, but this feature
    # isn't usable in debian anyway as we have no keyring uri nor a master key
    if ! command_available 'wget'; then
	apt_error 'wget is required for a network-based update, but it is not installed'
	exit 1
    fi
    if [ ! -d "${APT_DIR}/var/lib/apt/keyrings" ]; then
	mkdir -p "${APT_DIR}/var/lib/apt/keyrings"
    fi
    keyring="${APT_DIR}/var/lib/apt/keyrings/$(basename "$ARCHIVE_KEYRING_URI")"
    old_mtime=0
    if [ -e $keyring ]; then
	old_mtime=$(stat -c %Y "$keyring")
    fi
    (cd  "${APT_DIR}/var/lib/apt/keyrings"; wget --timeout=90 -q -N "$ARCHIVE_KEYRING_URI")
    if [ ! -e "$keyring" ]; then
	return
    fi
    new_mtime=$(stat -c %Y "$keyring")
    if [ $new_mtime -ne $old_mtime ]; then
	aptkey_echo "Checking for new archive signing keys now"
	add_keys_with_verify_against_master_keyring "$keyring" "$MASTER_KEYRING"
    fi
}

update() {
    if [ -z "$APT_KEY_DONT_WARN_ON_DANGEROUS_USAGE" ]; then
	echo >&2 "Warning: 'apt-key update' is deprecated and should not be used anymore!"
	if [ -z "$ARCHIVE_KEYRING" ]; then
	    echo >&2 "Note: In your distribution this command is a no-op and can therefore be removed safely."
	    exit 0
	fi
    fi
    if [ ! -f "$ARCHIVE_KEYRING" ]; then
	apt_error "Can't find the archive-keyring (Is the debian-archive-keyring package installed?)"
	exit 1
    fi

    # add new keys from the package;

    # we do not use add_keys_with_verify_against_master_keyring here,
    # because "update" is run on regular package updates.  A
    # attacker might as well replace the master-archive-keyring file
    # in the package and add his own keys. so this check wouldn't
    # add any security. we *need* this check on net-update though
    import_keyring_into_keyring "$ARCHIVE_KEYRING" '' && cat "${GPGHOMEDIR}/gpgoutput.log"

    if [ -r "$REMOVED_KEYS" ]; then
	# remove no-longer supported/used keys
	get_fingerprints_of_keyring "$(dearmor_filename "$REMOVED_KEYS")" | while read key; do
	    foreach_keyring_do 'remove_key_from_keyring' "$key"
	done
    else
	apt_warn "Removed keys keyring '$REMOVED_KEYS' missing or not readable"
    fi
}

remove_key_from_keyring() {
    local KEYRINGFILE="$1"
    shift
    # non-existent keyrings have by definition no keys
    if [ ! -e "$KEYRINGFILE" ]; then
       return
    fi

    local FINGERPRINTS="${GPGHOMEDIR}/keyringfile.keylst"
    local DEARMOR="$(dearmor_filename "$KEYRINGFILE")"
    get_fingerprints_of_keyring "$DEARMOR" > "$FINGERPRINTS"

    for KEY in "$@"; do
	# strip leading 0x, if present:
	KEY="$(echo "${KEY#0x}" | tr -d ' ')"

	# check if the key is in this keyring
	if ! grep -iq "^[0-9A-F]*${KEY}$" "$FINGERPRINTS"; then
	    continue
	fi
	if [ ! -w "$KEYRINGFILE" ]; then
	    apt_warn "Key ${KEY} is in keyring ${KEYRINGFILE}, but can't be removed as it is read only."
	    continue
	fi
	# check if it is the only key in the keyring and if so remove the keyring altogether
	if [ '1' = "$(uniq "$FINGERPRINTS" | wc -l)" ]; then
	    mv -f "$KEYRINGFILE" "${KEYRINGFILE}~" # behave like gpg
	    return
	fi
	# we can't just modify pointed to files as these might be in /usr or something
	local REALTARGET
	if [ -L "$DEARMOR" ]; then
	    REALTARGET="$(readlink -f "$DEARMOR")"
	    mv -f "$DEARMOR" "${DEARMOR}.dpkg-tmp"
	    cp -a "$REALTARGET" "$DEARMOR"
	fi
	# delete the key from the keyring
	aptkey_execute "$GPG_SH" --keyring "$DEARMOR" --batch --delete-keys --yes "$KEY"
	if [ -n "$REALTARGET" ]; then
	    # the real backup is the old link, not the copy we made
	    mv -f "${DEARMOR}.dpkg-tmp" "${DEARMOR}~"
	fi
	if [ "$DEARMOR" != "$KEYRINGFILE" ]; then
	    mv -f "$KEYRINGFILE" "${KEYRINGFILE}~"
	    create_new_keyring "$KEYRINGFILE"
	    aptkey_execute "$GPG_SH" --keyring "$DEARMOR" --armor --export > "$KEYRINGFILE"
	fi
	get_fingerprints_of_keyring "$DEARMOR" > "$FINGERPRINTS"
    done
}

accessible_file_exists() {
   if ! test -s "$1"; then
      return 1
   fi
   if test -r "$1"; then
      return 0
   fi
   apt_warn "The key(s) in the keyring $1 are ignored as the file is not readable by user '$USER' executing apt-key."
   return 1
}

is_supported_keyring() {
    # empty files are always supported
    if ! test -s "$1"; then
	return 0
    fi
    local FILEEXT="${1##*.}"
    if [ "$FILEEXT" = 'gpg' ]; then
	# 0x98, 0x99 and 0xC6 via octal as hex isn't supported by dashs printf
	if printf '\231' | cmp -s -n 1 - "$1"; then
	    true
	elif printf '\230' | cmp -s -n 1 - "$1"; then
	    true
	elif printf '\306' | cmp -s -n 1 - "$1"; then
	    true
	else
	    apt_warn "The key(s) in the keyring $1 are ignored as the file has an unsupported filetype."
	    return 1
	fi
    elif [ "$FILEEXT" = 'asc' ]; then
	true #dearmor_filename will deal with them
    else
	# most callers ignore unsupported extensions silently
	apt_warn "The key(s) in the keyring $1 are ignored as the file has an unsupported filename extension."
	return 1
    fi
    return 0
}

foreach_keyring_do() {
   local ACTION="$1"
   shift
   # if a --keyring was given, just work on this one
   if [ -n "$FORCED_KEYRING" ]; then
	$ACTION "$FORCED_KEYRING" "$@"
   else
	# otherwise all known keyrings are up for inspection
	if accessible_file_exists "$TRUSTEDFILE" && is_supported_keyring "$TRUSTEDFILE"; then
	    $ACTION "$TRUSTEDFILE" "$@"
	fi
	local TRUSTEDPARTS="/etc/apt/trusted.gpg.d"
	eval "$(apt-config shell TRUSTEDPARTS Dir::Etc::TrustedParts/d)"
	if [ -d "$TRUSTEDPARTS" ]; then
	    TRUSTEDPARTS="$(readlink -f "$TRUSTEDPARTS")"
	    local TRUSTEDPARTSLIST="$(cd /; find "$TRUSTEDPARTS" -mindepth 1 -maxdepth 1 \( -name '*.gpg' -o -name '*.asc' \))"
	    for trusted in $(echo "$TRUSTEDPARTSLIST" | sort); do
		if accessible_file_exists "$trusted" && is_supported_keyring "$trusted"; then
		    $ACTION "$trusted" "$@"
		fi
	    done
	fi
   fi
}

list_keys_in_keyring() {
    local KEYRINGFILE="$1"
    shift
    # fingerprint and co will fail if key isn't in this keyring
    aptkey_execute "$GPG_SH" --keyring "$(dearmor_filename "$KEYRINGFILE")" "$@" > "${GPGHOMEDIR}/gpgoutput.log" 2> "${GPGHOMEDIR}/gpgoutput.err" || true
    if [ ! -s "${GPGHOMEDIR}/gpgoutput.log" ]; then
	return
    fi
    # we fake gpg header here to refer to the real asc file rather than a temp file
    if [ "${KEYRINGFILE##*.}" = 'asc' ]; then
	if expr match "$(sed -n '2p' "${GPGHOMEDIR}/gpgoutput.log")" '^-\+$' >/dev/null 2>&1; then
	    echo "$KEYRINGFILE"
	    echo "$KEYRINGFILE" | sed 's#[^-]#-#g'
	    sed '1,2d' "${GPGHOMEDIR}/gpgoutput.log" || true
	else
	    cat "${GPGHOMEDIR}/gpgoutput.log"
	fi
    else
	cat "${GPGHOMEDIR}/gpgoutput.log"
    fi
    if [ -s "${GPGHOMEDIR}/gpgoutput.err" ]; then
	cat >&2 "${GPGHOMEDIR}/gpgoutput.err"
    fi
}

export_key_from_to() {
    local FROM="$1"
    local TO="$2"
    shift 2
    if ! aptkey_execute "$GPG_SH" --keyring "$(dearmor_filename "$FROM")" --export "$@" > "$TO" 2> "${GPGHOMEDIR}/gpgoutput.log"; then
	cat >&2 "${GPGHOMEDIR}/gpgoutput.log"
	false
    else
	chmod 0644 -- "$TO"
    fi
}

import_keyring_into_keyring() {
    local FROM="${1:-${GPGHOMEDIR}/pubring.gpg}"
    local TO="${2:-${GPGHOMEDIR}/pubring.gpg}"
    shift 2
    rm -f "${GPGHOMEDIR}/gpgoutput.log"
    # the idea is simple: We take keys from one keyring and copy it to another
    # we do this with so many checks in between to ensure that WE control the
    # creation, so we know that the (potentially) created $TO keyring is a
    # simple keyring rather than a keybox as gpg2 would create it which in turn
    # can't be read by gpgv.
    # BEWARE: This is designed more in the way to work with the current
    # callers, than to have a well defined it would be easy to add new callers to.
    if [ ! -s "$TO" ]; then
	if [ -s "$FROM" ]; then
	    if [ -z "$2" ]; then
		local OPTS
		if [ "${TO##*.}" = 'asc' ]; then
		    OPTS='--armor'
		fi
		export_key_from_to "$(dearmor_filename "$FROM")" "$TO" $OPTS ${1:+"$1"}
	    else
		create_new_keyring "$TO"
	    fi
	else
	    create_new_keyring "$TO"
	fi
    elif [ -s "$FROM" ]; then
	local EXPORTLIMIT="$1"
	if [ -n "$1$2" ]; then shift; fi
	local DEARMORTO="$(dearmor_filename "$TO")"
	if ! aptkey_execute "$GPG_SH" --keyring "$(dearmor_filename "$FROM")" --export ${EXPORTLIMIT:+"$EXPORTLIMIT"} \
	   | aptkey_execute "$GPG_SH" --keyring "$DEARMORTO" --batch --import "$@" > "${GPGHOMEDIR}/gpgoutput.log" 2>&1; then
	    cat >&2 "${GPGHOMEDIR}/gpgoutput.log"
	    false
	fi
	if [ "$DEARMORTO" != "$TO" ]; then
	    export_key_from_to "$DEARMORTO" "${DEARMORTO}.asc" --armor
	    if ! cmp -s "$TO" "${DEARMORTO}.asc" 2>/dev/null; then
		cp -a "$TO" "${TO}~"
		mv -f "${DEARMORTO}.asc" "$TO"
	    fi
	fi
    fi
}

dearmor_keyring() {
    # https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=831409#67
    # The awk script is more complex through to skip surrounding garbage and
    # to support multiple keys in one file (old gpgs generate version headers
    # which get printed with the original and hence result in garbage input for base64
    awk '/^-----BEGIN/{ x = 1; }
/^$/{ if (x == 1) { x = 2; }; }
/^[^=-]/{ if (x == 2) { print $0; }; }
/^-----END/{ x = 0; }' | base64 -d
}
dearmor_filename() {
    if [ "${1##*.}" = 'asc' ]; then
	local trusted="${GPGHOMEDIR}/${1##*/}.gpg"
	if [ -s "$1" ]; then
	    dearmor_keyring < "$1" > "$trusted"
	fi
	echo "$trusted"
    elif [ "${1##*.}" = 'gpg' ]; then
	echo "$1"
    elif [ "$(head -n 1 "$1" 2>/dev/null)" = '-----BEGIN PGP PUBLIC KEY BLOCK-----' ]; then
	local trusted="${GPGHOMEDIR}/${1##*/}.gpg"
	dearmor_keyring < "$1" > "$trusted"
	echo "$trusted"
    else
	echo "$1"
    fi
}
catfile() {
    cat "$(dearmor_filename "$1")" >> "$2"
}

merge_all_trusted_keyrings_into_pubring() {
    # does the same as:
    # foreach_keyring_do 'import_keys_from_keyring' "${GPGHOMEDIR}/pubring.gpg"
    # but without using gpg, just cat and find
    local PUBRING="$(readlink -f "${GPGHOMEDIR}")/pubring.gpg"
    rm -f "$PUBRING"
    touch "$PUBRING"
    foreach_keyring_do 'catfile' "$PUBRING"
}

import_keys_from_keyring() {
    import_keyring_into_keyring "$1" "$2"
}

merge_keys_into_keyrings() {
    import_keyring_into_keyring "$2" "$1" '' --import-options 'merge-only'
}

merge_back_changes() {
    if [ -n "$FORCED_KEYRING" ]; then
	# if the keyring was forced merge is already done
	if [ "$FORCED_KEYRING" != "$TRUSTEDFILE" ]; then
	    mv -f "$FORCED_KEYRING" "${FORCED_KEYRING}~"
	    export_key_from_to "$TRUSTEDFILE" "$FORCED_KEYRING" --armor
	fi
	return
    fi
    if [ -s "${GPGHOMEDIR}/pubring.gpg" ]; then
	# merge all updated keys
	foreach_keyring_do 'merge_keys_into_keyrings' "${GPGHOMEDIR}/pubring.gpg"
    fi
    # look for keys which were added or removed
    get_fingerprints_of_keyring "${GPGHOMEDIR}/pubring.orig.gpg" > "${GPGHOMEDIR}/pubring.orig.keylst"
    get_fingerprints_of_keyring "${GPGHOMEDIR}/pubring.gpg" > "${GPGHOMEDIR}/pubring.keylst"
    comm -3 "${GPGHOMEDIR}/pubring.keylst" "${GPGHOMEDIR}/pubring.orig.keylst" > "${GPGHOMEDIR}/pubring.diff"
    # key isn't part of new keyring, so remove
    cut -f 2 "${GPGHOMEDIR}/pubring.diff" | while read key; do
	if [ -z "$key" ]; then continue; fi
	foreach_keyring_do 'remove_key_from_keyring' "$key"
    done
    # key is only part of new keyring, so we need to import it
    cut -f 1 "${GPGHOMEDIR}/pubring.diff" | while read key; do
	if [ -z "$key" ]; then continue; fi
	import_keyring_into_keyring '' "$TRUSTEDFILE" "$key"
    done
}

setup_merged_keyring() {
    if [ -n "$FORCED_KEYID" ]; then
	merge_all_trusted_keyrings_into_pubring
	FORCED_KEYRING="${GPGHOMEDIR}/forcedkeyid.gpg"
	TRUSTEDFILE="${FORCED_KEYRING}"
	echo "#!/bin/sh
exec sh '($(escape_shell "${GPG}")' --keyring '$(escape_shell "${TRUSTEDFILE}")' \"\$@\"" > "${GPGHOMEDIR}/gpg.1.sh"
	GPG="${GPGHOMEDIR}/gpg.1.sh"
	# ignore error as this "just" means we haven't found the forced keyid and the keyring will be empty
	import_keyring_into_keyring '' "$TRUSTEDFILE" "$FORCED_KEYID" || true
    elif [ -z "$FORCED_KEYRING" ]; then
	merge_all_trusted_keyrings_into_pubring
	if [ -r "${GPGHOMEDIR}/pubring.gpg" ]; then
	    cp -a "${GPGHOMEDIR}/pubring.gpg" "${GPGHOMEDIR}/pubring.orig.gpg"
	else
	   touch "${GPGHOMEDIR}/pubring.gpg" "${GPGHOMEDIR}/pubring.orig.gpg"
	fi
	echo "#!/bin/sh
exec sh '$(escape_shell "${GPG}")' --keyring '$(escape_shell "${GPGHOMEDIR}/pubring.gpg")' \"\$@\"" > "${GPGHOMEDIR}/gpg.1.sh"
	GPG="${GPGHOMEDIR}/gpg.1.sh"
    else
	TRUSTEDFILE="$(dearmor_filename "$FORCED_KEYRING")"
	create_new_keyring "$TRUSTEDFILE"
	echo "#!/bin/sh
exec sh '$(escape_shell "${GPG}")' --keyring '$(escape_shell "${TRUSTEDFILE}")' \"\$@\"" > "${GPGHOMEDIR}/gpg.1.sh"
	GPG="${GPGHOMEDIR}/gpg.1.sh"
    fi
}

create_new_keyring() {
    # gpg defaults to mode 0600 for new keyrings. Create one with 0644 instead.
    if ! [ -e "$1" ]; then
	if [ -w "$(dirname "$1")" ]; then
	    touch -- "$1"
	    chmod 0644 -- "$1"
	fi
    fi
}

aptkey_execute() { sh "$@"; }

usage() {
    echo "Usage: apt-key [--keyring file] [command] [arguments]"
    echo
    echo "Manage apt's list of trusted keys"
    echo
    echo "  apt-key add <file>          - add the key contained in <file> ('-' for stdin)"
    echo "  apt-key del <keyid>         - remove the key <keyid>"
    echo "  apt-key export <keyid>      - output the key <keyid>"
    echo "  apt-key exportall           - output all trusted keys"
    echo "  apt-key update              - update keys using the keyring package"
    echo "  apt-key net-update          - update keys using the network"
    echo "  apt-key list                - list keys"
    echo "  apt-key finger              - list fingerprints"
    echo "  apt-key adv                 - pass advanced options to gpg (download key)"
    echo
    echo "If no specific keyring file is given the command applies to all keyring files."
}

while [ -n "$1" ]; do
   case "$1" in
      --keyring)
	 shift
	 if [ -z "$FORCED_KEYRING" -o "$FORCED_KEYRING" = '/dev/null' ]; then
	     TRUSTEDFILE="$1"
	     FORCED_KEYRING="$1"
	 elif [ "$TRUSTEDFILE" = "$FORCED_KEYRING" ]; then
	     create_gpg_home
	     FORCED_KEYRING="${GPGHOMEDIR}/mergedkeyrings.gpg"
	     echo -n '' > "$FORCED_KEYRING"
	     chmod 0644 -- "$FORCED_KEYRING"
	     catfile "$TRUSTEDFILE" "$FORCED_KEYRING"
	     catfile "$1" "$FORCED_KEYRING"
	 else
	     catfile "$1" "$FORCED_KEYRING"
	 fi
	 ;;
      --keyid)
	 shift
	 if [ -n "$FORCED_KEYID" ]; then
	     apt_error 'Specifying --keyid multiple times is not supported'
	     exit 1
	 fi
	 FORCED_KEYID="$1"
	 ;;
      --secret-keyring)
	 shift
	 FORCED_SECRET_KEYRING="$1"
	 ;;
      --readonly)
	 merge_back_changes() { true; }
	 create_new_keyring() { if [ ! -r "$FORCED_KEYRING" ]; then TRUSTEDFILE='/dev/null'; FORCED_KEYRING="$TRUSTEDFILE"; fi; }
	 ;;
      --fakeroot)
	 requires_root() { true; }
	 ;;
      --quiet)
	 aptkey_echo() { true; }
	 ;;
      --debug1)
	 # some cmds like finger redirect stderr to /dev/null …
	aptkey_execute() { echo 'EXEC:' "$@"; sh "$@"; }
	;;
      --debug2)
	 # … other more complicated ones pipe gpg into gpg.
	aptkey_execute() { echo >&2 'EXEC:' "$@"; sh "$@"; }
	;;
      --homedir)
	 # force usage of a specific homedir instead of creating a temporary
	 shift
	 GPGHOMEDIR="$1"
	;;
      --*)
	 echo >&2 "Unknown option: $1"
	 usage
	 exit 1;;
      *)
	 break;;
   esac
   shift
done

if [ -z "$TRUSTEDFILE" ]; then
   TRUSTEDFILE="/etc/apt/trusted.gpg"
   eval $(apt-config shell TRUSTEDFILE Apt::GPGV::TrustedKeyring)
   eval $(apt-config shell TRUSTEDFILE Dir::Etc::Trusted/f)
   if [ "$APT_KEY_NO_LEGACY_KEYRING" ]; then
        TRUSTEDFILE="/dev/null"
   fi
fi

command="$1"
if [ -z "$command" ]; then
    usage
    exit 1
fi
shift

prepare_gpg_home() {
    # crude detection if we are called from a maintainerscript where the
    # package depends on gnupg or not. We accept recommends here as
    # well as the script hopefully uses apt-key optionally then like e.g.
    # debian-archive-keyring for (upgrade) cleanup did
    if [ -n "$DPKG_MAINTSCRIPT_PACKAGE" ] && [ -z "$APT_KEY_DONT_WARN_ON_DANGEROUS_USAGE" ]; then
	if ! dpkg-query --show --showformat '${Pre-Depends}${Depends}${Recommends}\n' "$DPKG_MAINTSCRIPT_PACKAGE" 2>/dev/null | grep -E -q 'gpg|gnupg'; then
	    cat >&2 <<EOF
Warning: The $DPKG_MAINTSCRIPT_NAME maintainerscript of the package $DPKG_MAINTSCRIPT_PACKAGE
Warning: seems to use apt-key (provided by apt) without depending on gpg, gnupg, or gnupg2.
Warning: This will BREAK in the future and should be fixed by the package maintainer(s).
Note: Check first if apt-key functionality is needed at all - it probably isn't!
EOF
	fi
    fi
    eval "$(apt-config shell GPG_EXE Apt::Key::gpgcommand)"
    if [ -n "$GPG_EXE" ] && command_available "$GPG_EXE"; then
	true
    elif command_available 'gpg'; then
	GPG_EXE="gpg"
    elif command_available 'gpg2'; then
	GPG_EXE="gpg2"
    elif command_available 'gpg1'; then
	GPG_EXE="gpg1"
    else
	apt_error 'gnupg, gnupg2 and gnupg1 do not seem to be installed, but one of them is required for this operation'
	exit 255
    fi

    create_gpg_home

    # now tell gpg that it shouldn't try to maintain this trustdb file
    echo "#!/bin/sh
exec '$(escape_shell "${GPG_EXE}")' --ignore-time-conflict --no-options --no-default-keyring \\
--homedir '$(escape_shell "${GPGHOMEDIR}")' --no-auto-check-trustdb --trust-model always \"\$@\"" > "${GPGHOMEDIR}/gpg.0.sh"
    GPG_SH="${GPGHOMEDIR}/gpg.0.sh"
    GPG="$GPG_SH"

    # create the trustdb with an (empty) dummy keyring
    # older gpgs required it, newer gpgs even warn that it isn't needed,
    # but require it nonetheless for some commands, so we just play safe
    # here for the foreseeable future and create a dummy one
    touch "${GPGHOMEDIR}/empty.gpg"
    if ! "$GPG_EXE" --ignore-time-conflict --no-options --no-default-keyring \
       --homedir "$GPGHOMEDIR" --quiet --check-trustdb --keyring "${GPGHOMEDIR}/empty.gpg" >"${GPGHOMEDIR}/gpgoutput.log" 2>&1; then
       cat >&2 "${GPGHOMEDIR}/gpgoutput.log"
       false
    fi

    # We don't usually need a secret keyring, of course, but
    # for advanced operations, we might really need a secret keyring after all
    if [ -n "$FORCED_SECRET_KEYRING" ] && [ -r "$FORCED_SECRET_KEYRING" ]; then
	if ! aptkey_execute "$GPG" -v --batch --import "$FORCED_SECRET_KEYRING" >"${GPGHOMEDIR}/gpgoutput.log" 2>&1; then
	    # already imported keys cause gpg1 to fail for some reason… ignore this error
	    if ! grep -q 'already in secret keyring' "${GPGHOMEDIR}/gpgoutput.log"; then
		cat >&2 "${GPGHOMEDIR}/gpgoutput.log"
		false
	    fi
	fi
    else
       # and then, there are older versions of gpg which panic and implode
       # if there isn't one available - and writeable for imports
       # and even if not output is littered with the creation of a secring,
       # so lets call import once to have it create what it wants in silence
       echo -n | aptkey_execute "$GPG" --batch --import >/dev/null 2>&1 || true
    fi
}

warn_on_script_usage() {
    if [ -n "$APT_KEY_DONT_WARN_ON_DANGEROUS_USAGE" ]; then
	return
    fi
    # (Maintainer) scripts should not be using apt-key
    if [ -n "$DPKG_MAINTSCRIPT_PACKAGE" ]; then
	echo >&2 "Warning: apt-key should not be used in scripts (called from $DPKG_MAINTSCRIPT_NAME maintainerscript of the package ${DPKG_MAINTSCRIPT_PACKAGE})"
    fi

    echo >&2 "Warning: apt-key is deprecated. Manage keyring files in trusted.gpg.d instead (see apt-key(8))."
}

warn_outside_maintscript() {
    # In del, we want to warn in interactive use, but not inside maintainer
    # scripts, so as to give people a chance to migrate keyrings.
    #
    # FIXME: We should always warn starting in 2022.
    if [ -z "$DPKG_MAINTSCRIPT_PACKAGE" ]; then
	echo >&2 "Warning: apt-key is deprecated. Manage keyring files in trusted.gpg.d instead (see apt-key(8))."
    fi
}

if [ "$command" != 'help' ] && [ "$command" != 'verify' ]; then
    prepare_gpg_home
fi

case "$command" in
    add)
	warn_on_script_usage
	requires_root
	setup_merged_keyring
	aptkey_execute "$GPG" --quiet --batch --import "$@"
	merge_back_changes
	aptkey_echo "OK"
        ;;
    del|rm|remove)
	# no script warning here as removing 'add' usage needs 'del' for cleanup
	warn_outside_maintscript
	requires_root
	foreach_keyring_do 'remove_key_from_keyring' "$@"
	aptkey_echo "OK"
        ;;
    update)
	warn_on_script_usage
	requires_root
	setup_merged_keyring
	update
	merge_back_changes
	;;
    net-update)
	warn_on_script_usage
	requires_root
	setup_merged_keyring
	net_update
	merge_back_changes
	;;
    list|finger*)
	warn_on_script_usage
	foreach_keyring_do 'list_keys_in_keyring' --fingerprint "$@"
	;;
    export|exportall)
	warn_on_script_usage
	merge_all_trusted_keyrings_into_pubring
	aptkey_execute "$GPG_SH" --keyring "${GPGHOMEDIR}/pubring.gpg" --armor --export "$@"
	;;
    adv*)
	warn_on_script_usage
	setup_merged_keyring
	aptkey_echo "Executing: $GPG" "$@"
	aptkey_execute "$GPG" "$@"
	merge_back_changes
	;;
    verify)
	GPGV=''
	eval $(apt-config shell GPGV Apt::Key::gpgvcommand)
	if [ -n "$GPGV" ] && command_available "$GPGV"; then true;
	elif command_available 'gpgv'; then GPGV='gpgv';
	elif command_available 'gpgv2'; then GPGV='gpgv2';
	elif command_available 'gpgv1'; then GPGV='gpgv1';
	else
	   apt_error 'gpgv, gpgv2 or gpgv1 required for verification, but neither seems installed'
	   exit 29
	fi
	# for a forced keyid we need gpg --export, so full wrapping required
	if [ -n "$FORCED_KEYID" ]; then
	    prepare_gpg_home
	else
	    create_gpg_home
	fi
	setup_merged_keyring
	if [ -n "$FORCED_KEYRING" ]; then
	    "$GPGV" --homedir "${GPGHOMEDIR}" --keyring "$(dearmor_filename "${FORCED_KEYRING}")" --ignore-time-conflict "$@"
	else
	    "$GPGV" --homedir "${GPGHOMEDIR}" --keyring "${GPGHOMEDIR}/pubring.gpg" --ignore-time-conflict "$@"
	fi
	;;
    help)
        usage
        ;;
    *)
        usage
        exit 1
        ;;
esac