diff options
Diffstat (limited to 'bin/rotcheck')
| -rwxr-xr-x | bin/rotcheck | 353 |
1 files changed, 353 insertions, 0 deletions
diff --git a/bin/rotcheck b/bin/rotcheck new file mode 100755 index 0000000..c8a59fe --- /dev/null +++ b/bin/rotcheck @@ -0,0 +1,353 @@ +#!/bin/sh +set -uf +IFS="$(printf '\n\t')" +LC_ALL="C" + +# Copyright (C) 2019 Jamie Nguyen <j@jamielinux.com> +# +# A simple shell script to recursively generate, update and verify checksums +# for files you care about. It's useful for detecting bit rot. +# +# It's written in POSIX shell, but requires GNU coreutils, BusyBox or some +# other collection that includes similar checksum tools. + +VERSION=1.1.2 +COMMAND="sha512sum" +CHECKFILE="./.rotcheck" + +APPEND_MODE=0 +CHECK_MODE=0 +DELETE_MODE=0 +UPDATE_MODE=0 + +IGNORE_MISSING=0 +FOLLOW_SYMLINKS=1 +VERBOSE=0 +WARN_FORMATTING=0 +EXCLUDE_HIDDEN=0 +FORCE_UPDATE=0 + +usage() { + cat << EOF +rotcheck $VERSION +Usage: rotcheck MODE [OPTIONS] + or: rotcheck MODE [OPTIONS] -- [DIRECTORY]... [ARBITRARY FIND OPTION]... +Recursively generate, update and verify checksums. + +MODES: + -a APPEND mode: Record checksums for any files without a checksum + already. Never modify existing checksums. + -c CHECK mode: Check that files checksums are the same. + -d DELETE mode: Remove checksums for files that don't exist. + -u APPEND-AND-UPDATE mode: Like append-only mode, but also update + checksums for files with a modification date newer than the + the checksum file. (NB: Also see \`-M\`.) + +OPTIONS: + -b COMMAND Checksum command to use. Default: sha512sum + -f FILE File to store checksums. For relative paths, prefix with "./" + or the checksum file will be checksummed. Default: ./.rotcheck + -h Display this help. + -n Don't follow symlinks. The default is to follow symlinks. + -v Be more verbose when adding, deleting, changing or verifying + checksums. + -w Warn about improperly formatted checksum lines. + -x Exclude all hidden files and directories when generating + checksums. The default is to include them. + -M Use with \`-u\` to update checksums regardless of modification + time. This is very slow so avoid if possible; try \`touch\` + instead to bump the modification time of specific files. + WARNING: The checksums might have changed due to bit rot so + use this option with care! + + (specific to GNU coreutils >= 8.25) + -i Ignore missing files when verifying checksums. + + +Supported commands: + GNU coreutils: + md5sum, sha1sum, sha224sum, sha256sum, sha384sum, sha512sum, b2sum + + BusyBox (applets must be symlinked): + md5sum, sha1sum, sha256sum, sha512sum, sha3sum + + BSD & macOS (install GNU coreutils): + gmd5sum, gsha1sum, gsha224sum, gsha256sum, gsha384sum, gsha512sum, gb2sum + + +Examples: + # Create checksum file (located at "./.rotcheck"): + rotcheck -a + + # You've added some new files and need to append some checksums: + rotcheck -va + + # You've edited some files and need to update the checksums (for files with + # a modification time newer than the checksum file): + rotcheck -vu + + # Verify checksums: + rotcheck -c + + # Search other directories instead of the current directory. + # WARNING: checksums might get duplicated if mixing relative and absolute + # paths, or if you change the way you specify directory paths! + rotcheck -a -- /mnt/archive-2018/ /mnt/archive-2019/ + + # Exclude .git folders (these arguments are passed directly to find): + rotcheck -a -- ! -path '*/\\.git/*' + +EOF + exit 0 +} + +fail() { + printf '%s\n' "$@"; exit 1 +} + +# Curiously, I stumbled across a bug in bash-3.0.16 (c. 2004) or older +# where \0177 (DEL) isn't handled properly. See the `find_safe` function below. +# bash-3.1 (c. 2005), dash-0.5.2 (c. 2005), and zsh-3.1 (c. 2000) all work +# and probably others too. +if [ -n ${BASH+x} ] && [ -n ${BASH_VERSION+x} ]; then + if printf '%s' "${BASH_VERSION:-x}" | grep -qE '^[0-2]+|^3\.0'; then + fail "bash-3.0.16 and older are broken." \ + "Try bash>=3.1, dash, zsh, or another POSIX shell." + fi +fi + +# Command-line arguments. `getopts` is POSIX, while `getopt` is not. +[ $# -gt 0 ] && [ "$1" = "--help" ] && usage +while getopts ":acdub:f:hinvwxM" opt; do + case "$opt" in + a) APPEND_MODE=1;; + c) CHECK_MODE=1;; + d) DELETE_MODE=1;; + u) UPDATE_MODE=1;; + b) COMMAND="$OPTARG";; + f) CHECKFILE="$OPTARG";; + h) usage;; + i) IGNORE_MISSING=1;; + n) FOLLOW_SYMLINKS=0;; + v) VERBOSE=1;; + w) WARN_FORMATTING=1;; + x) EXCLUDE_HIDDEN=1;; + M) FORCE_UPDATE=1;; + \?) fail "-$OPTARG: Invalid argument";; + :) fail "-$OPTARG requires an argument";; + esac +done; shift $(($OPTIND - 1)) + + + +# A few sanity checks. +MODE=$(($APPEND_MODE + $CHECK_MODE + $DELETE_MODE + $UPDATE_MODE)) +if [ $MODE -eq 0 ]; then + fail "Please specify one of -a, -c, -d, or -u." \ + "See \`rotcheck -h\` for help with usage." +elif [ $MODE -gt 1 ]; then + fail "You can only use one of -a, -c, -d, or -u options." \ + "See \`rotcheck -h\` for help with usage." +elif [ $CHECK_MODE -eq 1 ] || [ $DELETE_MODE -eq 1 ]; then + if [ ! -f "$CHECKFILE" ]; then + fail "$CHECKFILE: No such file." \ + "Try running \`rotcheck -a\` first, or see \`rotcheck -h\`." + fi +elif ! command -v "$COMMAND" >/dev/null 2>/dev/null; then + fail "$COMMAND: command not found" \ + "Try specifying a supported command using \`rotcheck -b COMMAND\`." \ + "You may need to install GNU coreutils or BusyBox." \ + "On *BSD, GNU coreutils commands begin with 'g', like 'gsha512sum'." \ + "See \`rotcheck -h\` for help with usage." +fi + +# When printing text to terminal, make sure it won't do anything unexpected. +printf_sanitized() { + printf '%s' "$@" | tr -d '[:cntrl:]' | iconv -cs -f UTF-8 -t UTF-8 + printf '\n' +} + +verify_checksums() { + IGNORE="" ; [ $IGNORE_MISSING -eq 1 ] && IGNORE="--ignore-missing" + WARN="" ; [ $WARN_FORMATTING -eq 1 ] && WARN="-w" + $COMMAND -c $WARN $IGNORE -- "$CHECKFILE" +} + +# Just verify checksums. +if [ $CHECK_MODE -eq 1 ]; then + # Only GNU coreutils supports `--quiet`, so use `grep -v` instead. + # Unfortunately, pipefail isn't POSIX so to return the exit status from the + # checksum command, we have to be clever (aka crazy) with file descriptors + # and subshells instead. + if [ $VERBOSE -eq 1 ]; then + verify_checksums + exit $? + else + exec 4>&1 + ( + exec 3>&1 + ( + # 2>&1 preserves order of stdout/stderr. + verify_checksums 2>&1; printf '%d' $? 1>&3 + ) | grep -Ev ': OK$' 1>&4 + exec 3>&- + ) | ( read -r retval; exit $retval ); retval=$? + exec 4>&- + exit $retval + fi +fi + +# Delete checksums for files that no longer exist. +if [ $DELETE_MODE -eq 1 ]; then + i=1 + for file in $(cut -d ' ' -f 3- -- "$CHECKFILE"); do + # `sed -i` isn't POSIX (nor is `mktemp`), so use `ex` instead. + if [ ! -f "$file" ]; then + cat << EOF | ex -s -- "$CHECKFILE" +${i}d +x +EOF + # Print what checksums were deleted. + if [ $VERBOSE -eq 1 ]; then + printf '%s' "DELETED: " + printf_sanitized "$file" + fi + else + # Only increment the line number if we didn't delete a line. + i=$(($i + 1)) + fi + done + exit $? +fi + +# For safety and sanity, ignore all filenames that have control characters +# like newline, tab, delete etc. +find_safe() { + FIND_L="" + FIND_FOLLOW="" + if [ $FOLLOW_SYMLINKS -eq 1 ]; then + # Old versions of findutils don't have -L. Use it if available. + if find -L / -maxdepth 0 -type d >/dev/null 2>/dev/null; then + FIND_L="-L" + else + FIND_FOLLOW="-follow" + fi + fi + + # POSIX find requires that you specify the search path either first + # or immediately after -H/-L. Use current directory by default unless + # user has specified a path. + FIND_DOT="./" + if [ $# -gt 0 ]; then + first_char="$(printf '%s' "$1" | cut -c 1)" + # Replace search path unless first arg is a non-path `find` option. + if [ "$first_char" != "-" ] \ + && [ "$first_char" != "!" ] && [ "$first_char" != "(" ]; then + FIND_DOT="" + fi + fi + + HIDDEN="" + [ $EXCLUDE_HIDDEN -eq 1 ] && HIDDEN='*/\.*' + + find $FIND_L $FIND_DOT "$@" $FIND_FOLLOW \ + -type f ! -path "$CHECKFILE" ! -path "$HIDDEN" \ + ! -name "$(printf '*%b*' '\0001')" ! -name "$(printf '*%b*' '\0002')" \ + ! -name "$(printf '*%b*' '\0003')" ! -name "$(printf '*%b*' '\0004')" \ + ! -name "$(printf '*%b*' '\0005')" ! -name "$(printf '*%b*' '\0006')" \ + ! -name "$(printf '*%b*' '\0007')" ! -name "$(printf '*%b*' '\0010')" \ + ! -name "$(printf '*%b*' '\0011')" ! -name "$(printf '*%b*' '\0012')" \ + ! -name "$(printf '*%b*' '\0013')" ! -name "$(printf '*%b*' '\0014')" \ + ! -name "$(printf '*%b*' '\0015')" ! -name "$(printf '*%b*' '\0016')" \ + ! -name "$(printf '*%b*' '\0017')" ! -name "$(printf '*%b*' '\0020')" \ + ! -name "$(printf '*%b*' '\0021')" ! -name "$(printf '*%b*' '\0022')" \ + ! -name "$(printf '*%b*' '\0023')" ! -name "$(printf '*%b*' '\0024')" \ + ! -name "$(printf '*%b*' '\0025')" ! -name "$(printf '*%b*' '\0026')" \ + ! -name "$(printf '*%b*' '\0027')" ! -name "$(printf '*%b*' '\0030')" \ + ! -name "$(printf '*%b*' '\0031')" ! -name "$(printf '*%b*' '\0032')" \ + ! -name "$(printf '*%b*' '\0033')" ! -name "$(printf '*%b*' '\0034')" \ + ! -name "$(printf '*%b*' '\0035')" ! -name "$(printf '*%b*' '\0036')" \ + ! -name "$(printf '*%b*' '\0037')" ! -name "$(printf '*%b*' '\0177')" +} + +find_updated_files() { + if [ $FORCE_UPDATE -eq 1 ]; then + find_safe "$@" + else + find_safe "$@" -newer "$CHECKFILE" + fi +} + +# This function could be replaced entirely with the much simpler: +# cut -d ' ' -f 3- "$CHECKFILE" | grep -Fxn -- "$file" | cut -d ':' -f 1 +# But this function is slightly faster as it avoids passing huge chunks of text +# (ie, the whole checksum file minus the first column) through a pipe. +get_line_number() { + # Avoid `grep -E` as filename characters might get interpreted (eg, $). + for l in $(grep -Fn -- "$file" "$CHECKFILE" | cut -d ':' -f 1); do + if sed -n -e "${l}p" -- "$CHECKFILE" \ + | cut -d ' ' -f 3- | grep -Fxq -- "$file" >/dev/null; then + printf '%d' "$l" + return 0 + fi + done + printf '%d' "0" +} + +umask 077 +# For files with a modification date newer than the checksum file, if there's +# an existing checksum then update it. Otherwise append a new checksum. +if [ $UPDATE_MODE -eq 1 ] && [ -f "$CHECKFILE" ]; then + for file in $(find_updated_files "$@"); do + line_num="$(get_line_number)" + if [ ${line_num:-0} -eq 0 ]; then + # No checksum yet, so append one. + $COMMAND -- "$file" >> "$CHECKFILE" + else + old="$(sed -n -e "${line_num}p" -- "$CHECKFILE" | cut -d ' ' -f 1)" + new="$($COMMAND -- "$file")" + # Should never happen, but double check these aren't empty: + if [ -z ${old:+x} ] || [ -z ${new:+x} ]; then + continue + fi + # `sed -i` isn't POSIX (nor is `mktemp`), so use `ex` instead. + if [ "$old" != "${new%% *}" ]; then + cat << EOF | ex -s -- "$CHECKFILE" +${line_num}c +$new +. +x +EOF + # Bail immediately if something went wrong. + [ $? -ne 0 ] && fail "Failed to update checksum file." + + # Print what checksums were changed. + if [ $VERBOSE -eq 1 ]; then + printf '%s' "CHANGED: " + printf_sanitized "$file" + fi + fi + fi + done +fi + +# Append checksums for files that have no checksum yet. +if [ $APPEND_MODE -eq 1 ] || [ $UPDATE_MODE -eq 1 ]; then + for file in $(find_safe "$@"); do + # Avoid `grep -E` as filename characters might get interpreted (eg, $). + # The first grep isn't strictly needed, but grep+cut+grep is faster + # than just cut+grep here. + if [ ! -f "$CHECKFILE" ] || ! grep -- "$file" "$CHECKFILE" \ + | cut -d ' ' -f 3- | grep -Fxq -- "$file"; then + if ! $COMMAND -- "$file" >> "$CHECKFILE"; then + fail "Failed to write to checksum file." + fi + + # Print what checksums were appended. + if [ $VERBOSE -eq 1 ]; then + printf '%s' "ADDED: " + printf_sanitized "$file" + fi + fi + done +fi |