06499edb90
What is done: * Add comments on decisions to not enable backup/restore $HOME directory. * Add informational messages on what backup/restore scripts are currently doing. * Disable possibility of using termux-restore script as root user due to risk of messing up access modes, ownership and SELinux labels in $PREFIX.
110 lines
3.3 KiB
Bash
Executable File
110 lines
3.3 KiB
Bash
Executable File
#!@TERMUX_PREFIX@/bin/bash
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##
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## Termux script for restoring $PREFIX (package installation dir).
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## For backup script, see "termux-backup".
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##
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## Why it doesn't implement support for restoring $HOME:
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##
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## * It can't selectively restore files due to tar option
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## --recursive-unlink, that will erase file tree before extracting.
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##
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## * It has to maintain support of piped input. Therefore we can't
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## allow optional backup of home by termux-backup. Here is why:
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## with piped input it is not possible to check contents of backup
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## file (you can't seek piped content twice). We must be sure that
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## all directories selected for restore are present inside archive
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## and this is possible only with hardcoded configuration
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## (e.g. backup only $PREFIX). Otherwise, restore procedure may
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## fail or even worse, erase all directories (potentially user
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## data) that are not present in backup.
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##
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## Considering the mentioned 2 major issues, should be obvious that
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## we have literally 2 choices: either backup/restore only $PREFIX
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## or backup/restore both $HOME and $PREFIX unconditionally, to
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## ensure consistency of data passed to termux-restore.
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##
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## However the current choice is to stick to backing up only $PREFIX,
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## to leave responsibility of managing files in $HOME to user (as said
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## above, termux-restore script ERASES DATA before restore).
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##
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## On side note, why data should be erased before restore:
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##
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## * Perform a complete rollback to state exactly as in archive.
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##
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## * Get rid of files that are not tracked by package manager.
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##
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set -e -u
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export PREFIX=@TERMUX_PREFIX@
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msg() {
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echo "$*" >&2
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}
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show_usage() {
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msg
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msg "Usage: termux-restore [input file]"
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msg
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msg "Script for restoring Termux installation directory (\$PREFIX)"
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msg "from the given TAR archive."
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msg
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msg "It is expected that backup file was made by 'termux-backup'."
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msg "Restoring procedure will erase all files in \$PREFIX directory"
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msg "that are not present in the given backup file. Be careful."
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msg
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msg "Backup contents may be supplied via stdin by specifying input"
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msg "file as '-'. Note that piped TAR archive must be uncompressed."
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msg
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}
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if [ "$(id -u)" = "0" ]; then
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msg "This script should not be used as root."
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exit 1
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fi
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if [ $# -lt 1 ]; then
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msg
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msg "[!] Input file path is not specified."
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show_usage
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exit 1
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fi
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if [ $# -gt 1 ]; then
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shift 1
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msg
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msg "[!] Got extra arguments: $*"
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show_usage
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exit 1
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fi
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case "$1" in
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-\?|-h|--help|--usage) show_usage; exit 0;;
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*) BACKUP_FILE_PATH=$1;;
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esac
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if [ "$BACKUP_FILE_PATH" != "-" ] && [ ! -e "$BACKUP_FILE_PATH" ]; then
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msg
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msg "[!] File '$BACKUP_FILE_PATH' does not exist."
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msg
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exit 1
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else
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if [ "$BACKUP_FILE_PATH" != "-" ] && [ ! -f "$BACKUP_FILE_PATH" ]; then
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msg
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msg "[!] Path '$BACKUP_FILE_PATH' is not a regular file."
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msg
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exit 1
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fi
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fi
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# Ensure that prefix doesn't contain read-only files.
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msg "Fixing read-write access to files where necessary..."
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find "@TERMUX_PREFIX@" -type d -print0 | xargs -0 -r chmod u+rwx
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find "@TERMUX_PREFIX@" -type f -print0 | xargs -0 -r chmod u+rw
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# --recursive-unlink is added intentionally to delete all orphan/extra files
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# in $PREFIX. It must be restored to a clean state as in backup tarball.
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msg "Erasing current \$PREFIX and restoring one from archive..."
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tar -x -C "@TERMUX_BASE_DIR@" -f "$BACKUP_FILE_PATH" \
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--recursive-unlink --preserve-permissions ./usr
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