# shellcheck shell=bash
#
# Copyright (C) 2017 Canonical Ltd
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 3 as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
# _complete_from_snap performs the tab completion request by calling the
# appropriate 'snap run --command=complete' with serialized args, and
# deserializes the response into the usual tab completion result.
#
# How snap command completion works is:
# 1. snapd's complete.sh is sourced into the user's shell environment
# 2. user performs '<command> <tab>'. If '<command>' is a snap command,
# proceed to step '3', otherwise perform normal bash completion
# 3. run 'snap run --command=complete ...', converting bash completion
# environment into serialized command line arguments
# 4. 'snap run --command=complete ...' exec()s 'etelpmoc.sh' within the snap's
# runtime environment and confinement
# 5. 'etelpmoc.sh' takes the serialized command line arguments from step '3'
# and puts them back into the bash completion environment variables
# 6. 'etelpmoc.sh' sources the snap's 'completer' script, performs the bash
# completion and serializes the resulting completion environment variables
# by printing to stdout the results in a format that snapd's complete.sh
# will understand, then exits
# 7. control returns to snapd's 'complete.sh' and it deserializes the output
# from 'etelpmoc.sh', validates the results and puts the validated results
# into the bash completion environment variables
# 8. bash displays the results to the user
type -t _complete_from_snap > /dev/null ||
_complete_from_snap() {
{
# De-serialize the output of 'snap run --command=complete ...' into the format
# bash expects:
read -r -a opts
# opts is expected to be a series of compopt options
if [[ ${#opts[@]} -gt 0 ]]; then
if [[ "${opts[0]}" == "cannot" ]]; then
# older snap-execs sent errors over stdout :-(
return 1
fi
for i in "${opts[@]}"; do
if ! [[ "$i" =~ ^[a-z]+$ ]]; then
# only lowercase alpha characters allowed
return 2
fi
done
fi
read -r bounced
case "$bounced" in
""|"alias"|"export"|"job"|"variable")
# OK
;;
*)
# unrecognised bounce
return 2
;;
esac
read -r sep
if [ -n "$sep" ]; then
# non-blank separator? madness!
return 2
fi
local oldIFS="$IFS"
if [ ! "$bounced" ]; then
local IFS=$'\n'
# Ignore any suspicious results that are uncommon in filenames and that
# might be used to trick the user. A whitelist approach would be better
# but is impractical with UTF-8 and common characters like quotes.
COMPREPLY=( $( command grep -v '[[:cntrl:];&?*{}]' ) )
IFS="$oldIFS"
fi
if [[ ${#opts[@]} -gt 0 ]]; then
# shellcheck disable=SC2046
# (we *want* word splitting to happen here)
compopt $(printf " -o %s" "${opts[@]}")
fi
if [ "$bounced" ]; then
# We validated '$bounced' above and '${COMP_WORDS[$COMP_CWORD]}' is
# coming from the user's session, not the snap so skip input
# validation: we aren't trying to protect the user from themselves.
COMPREPLY+=(compgen -A "$bounced" -- "${COMP_WORDS[$COMP_CWORD]}")
fi
} < <(
snap run --command=complete "$1" "$COMP_TYPE" "$COMP_KEY" "$COMP_POINT" "$COMP_CWORD" "$COMP_WORDBREAKS" "$COMP_LINE" "${COMP_WORDS[@]}" 2>/dev/null || return 1
)
}
# this file can be sourced directly as e.g. /usr/lib/snapd/complete.sh, or via
# a symlink from /var/lib/snapd/desktop/bash-completion/completions/. In the first case we
# want to load the default loader; in the second, the specific one.
#
if [[ "${BASH_SOURCE[0]}" =~ ^(/var/lib/snapd/desktop|/usr/share)/bash-completion/completions/ ]]; then
complete -F _complete_from_snap "$1"
else
# _complete_from_snap_maybe calls _complete_from_snap if the command is in
# bin/snap, and otherwise does bash-completion's _completion_loader (which is
# what -D would've done before).
type -t _complete_from_snap_maybe > /dev/null ||
_complete_from_snap_maybe() {
local etel=snap/core/current/usr/lib/snapd/etelpmoc.sh
# catch /snap/bin and /var/lib/snapd/snap/bin
if [[ "$(command -v "$1")" =~ ^(/var/lib/snapd)?/snap/bin/ && ( -e "/var/lib/snapd/$etel" || -e "/$etel" ) ]]; then
complete -F _complete_from_snap "$1"
return 124
fi
# fallback to the old -D
_completion_loader "$1"
}
complete -D -F _complete_from_snap_maybe
fi
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