termux-packages/packages/termux-tools/termux-restore

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#!@TERMUX_PREFIX@/bin/bash
##
## Termux script for restoring $PREFIX (package installation dir).
## For backup script, see "termux-backup".
##
## Why it doesn't implement support for restoring $HOME:
##
## * It can't selectively restore files due to tar option
## --recursive-unlink, that will erase file tree before extracting.
##
## * It has to maintain support of piped input. Therefore we can't
## allow optional backup of home by termux-backup. Here is why:
## with piped input it is not possible to check contents of backup
## file (you can't seek piped content twice). We must be sure that
## all directories selected for restore are present inside archive
## and this is possible only with hardcoded configuration
## (e.g. backup only $PREFIX). Otherwise, restore procedure may
## fail or even worse, erase all directories (potentially user
## data) that are not present in backup.
##
## Considering the mentioned 2 major issues, should be obvious that
## we have literally 2 choices: either backup/restore only $PREFIX
## or backup/restore both $HOME and $PREFIX unconditionally, to
## ensure consistency of data passed to termux-restore.
##
## However the current choice is to stick to backing up only $PREFIX,
## to leave responsibility of managing files in $HOME to user (as said
## above, termux-restore script ERASES DATA before restore).
##
## On side note, why data should be erased before restore:
##
## * Perform a complete rollback to state exactly as in archive.
##
## * Get rid of files that are not tracked by package manager.
##
set -e -u
export PREFIX=@TERMUX_PREFIX@
msg() {
echo "$*" >&2
}
show_usage() {
msg
msg "Usage: termux-restore [input file]"
msg
msg "Script for restoring Termux installation directory (\$PREFIX)"
msg "from the given TAR archive."
msg
msg "It is expected that backup file was made by 'termux-backup'."
msg "Restoring procedure will erase all files in \$PREFIX directory"
msg "that are not present in the given backup file. Be careful."
msg
msg "Backup contents may be supplied via stdin by specifying input"
msg "file as '-'. Note that piped TAR archive must be uncompressed."
msg
}
if [ "$(id -u)" = "0" ]; then
msg "This script should not be used as root."
exit 1
fi
if [ $# -lt 1 ]; then
msg
msg "[!] Input file path is not specified."
show_usage
exit 1
fi
if [ $# -gt 1 ]; then
shift 1
msg
msg "[!] Got extra arguments: $*"
show_usage
exit 1
fi
case "$1" in
-\?|-h|--help|--usage) show_usage; exit 0;;
*) BACKUP_FILE_PATH=$1;;
esac
if [ "$BACKUP_FILE_PATH" != "-" ] && [ ! -e "$BACKUP_FILE_PATH" ]; then
msg
msg "[!] File '$BACKUP_FILE_PATH' does not exist."
msg
exit 1
else
if [ "$BACKUP_FILE_PATH" != "-" ] && [ ! -f "$BACKUP_FILE_PATH" ]; then
msg
msg "[!] Path '$BACKUP_FILE_PATH' is not a regular file."
msg
exit 1
fi
fi
# Ensure that prefix doesn't contain read-only files.
msg "Fixing read-write access to files where necessary..."
find "@TERMUX_PREFIX@" -type d -print0 | xargs -0 -r chmod u+rwx
find "@TERMUX_PREFIX@" -type f -print0 | xargs -0 -r chmod u+rw
# --recursive-unlink is added intentionally to delete all orphan/extra files
# in $PREFIX. It must be restored to a clean state as in backup tarball.
msg "Erasing current \$PREFIX and restoring one from archive..."
tar -x -C "@TERMUX_BASE_DIR@" -f "$BACKUP_FILE_PATH" \
--recursive-unlink --preserve-permissions ./usr