extra validations and improved error handlingHEADmaster

1 files changed, 77 insertions, 32 deletions

diff --git a/backomp b/backomp
index f653621..2fdd219 100755
--- a/backomp
+++ b/backomp
@@ -1,8 +1,6 @@
 #!/usr/bin/env bash
 
-set -e
-
-! read -rd '' AWK_PREFILTER <<'EOF'
+read -rd '' AWK_PREFILTER <<'EOF'
 /(\/|^)[0-9]{4}-[0-9]{2}-[0-9]{2}-[0-9]{6}$/ {
 	a[$0]
 }
@@ -14,7 +12,7 @@ END {
 }
 EOF
 
-! read -rd '' AWK_FILTER <<'EOF'
+read -rd '' AWK_FILTER <<'EOF'
 function flr(n, s) {
 	return int(n / s) * s
 }
@@ -93,9 +91,16 @@ END {
 }
 EOF
 
+err() {
+	echo "${0##*/}: error: $*" >&2
+}
+
 run() {
-	echo "* ${@}"
-	"${@}"
+	echo "* $*"
+	if ! "$@"; then
+		err "command failed: $*"
+		return 1
+	fi
 }
 
 current() {
@@ -119,43 +124,67 @@ current() {
 	(($(date -u +%s) / s == $(date -ud "${d}" +%s) / s))
 }
 
+filter() {
+	local -n _f_src="${1}" _f_dest="${2}"
+	local _f_dest_name="${2}" _f_label="${3}" _f_script="${4}"
+	shift 4
+
+	mapfile -td $'\0' "${_f_dest_name}" < <(
+		printf '%s\0' "${_f_src[@]}" | awk -v 'RS=\0' -v 'ORS=\0' \
+			"${@}" -- "${_f_script}")
+	wait "$!"
+	if [[ "$?" -ne 0 ]]; then
+		err "${_f_label} failed"
+		return 1
+	fi
+	if [[ ${#_f_src[@]} -gt 0 && ! -d "${_f_dest[0]}" ]]; then
+		err "${_f_label} returned empty or invalid list"
+		return 1
+	fi
+}
+
 backup() {
-	local dest_dir="${1}" src_path="${2}"
+	local src_path="${1}" dest_dir="${2}"
 	local retain="${3}" interval="${4}" week_start="${5}"
 	local dest_path snaps keep skip i ki
 
-	mapfile -td $'\0' snaps < <(shopt -s nullglob;
-		printf '%s\0' "${dest_dir}/"* | awk -v 'RS=\0' -v 'ORS=\0' \
-			-- "${AWK_PREFILTER}")
-	[[ -n "${snaps}" ]] && current "${snaps[0]##*/}" "${interval}" && \
-		skip=1
-	printf '[%d] [%s] %s => %s%s\n' "$((++dcount))" "${retain}" \
-		"${src_path}" "${dest_dir}" "${skip:+ [SKIPPED]}"
-	[[ -n "${skip}" ]] && return
+	if [[ ! -e "${src_path}" ]]; then
+		err "source does not exist: ${src_path}"
+		return 1
+	fi
+
+	mapfile -td $'\0' snaps < \
+		<(shopt -s nullglob; printf '%s\0' "${dest_dir}/"*)
+	filter snaps snaps 'pre-snapshot awk prefilter' "${AWK_PREFILTER}" \
+		|| return 1
+	[[ -n "${snaps}" ]] && current "${snaps[0]##*/}" "${interval}" \
+		&& return
 
 	dest_path="${dest_dir}/$(date -u '+%Y-%m-%d-%H%M%S')"
+	if [[ -e "${dest_path}" || -e "${dest_path}.tmp" ]]; then
+		err "destination already exists: ${dest_path}"
+		return 1
+	fi
 	run rsync -ac --mkpath ${snaps[0]:+"--link-dest=${snaps[0]}"} \
-		"${src_path}" "${dest_path}"
-	snaps+=("${dest_path}")
-	mapfile -td $'\0' snaps < <(
-		printf '%s\0' "${snaps[@]}" | awk -v 'RS=\0' -v 'ORS=\0' \
-			-- "${AWK_PREFILTER}")
-
-	mapfile -td $'\0' keep < <(
-		printf '%s\0' "${snaps[@]}" | awk -v 'RS=\0' -v 'ORS=\0' \
-			-v "opt_retain=${retain}" \
-			-v "opt_week_start=${week_start}" \
-			-- "${AWK_FILTER}")
-	if [[ -z "${keep}" ]]; then
-		echo "WARNING: dirs to keep shouldn't be empty; skipping" >&2
-		return
+		"${src_path}" "${dest_path}.tmp/" || return 1
+	run mv -T "${dest_path}.tmp" "${dest_path}" || return 1
+
+	if [[ ! "${retain}" =~ ^( *([0-9]+|\*)\^?[hdwM] *)+$ ]]; then
+		err "invalid \$retain setting: ${retain}"
+		return 1
 	fi
+	snaps+=("${dest_path}")
+	filter snaps snaps 'post-snapshot awk prefilter' "${AWK_PREFILTER}" \
+		|| return 1
+	filter snaps keep 'awk filter' "${AWK_FILTER}" \
+		-v "opt_retain=${retain}" -v "opt_week_start=${week_start}" \
+		|| return 1
 
 	for ((i = ${#snaps[@]} - 1, ki = 0; i >= 0; --i)); do
 		if [[ "${snaps[i]}" == "${keep[ki]}" ]]; then
 			((++ki))
 		else
-			run rm -r "${snaps[i]}"
+			run rm -rf "${snaps[i]}"
 		fi
 	done
 }
@@ -167,6 +196,7 @@ declare -A def_opts=(
 )
 declare -A opts
 
+declare -A seen
 while IFS='=' read -r f1 f2; do
 	[[ -z "${f1}" ]] || [[ "${f1}" == '#'* ]] && continue
 
@@ -178,9 +208,24 @@ while IFS='=' read -r f1 f2; do
 		[[ "${f2}" == '-' ]] && opts["${opt}"]= ||
 			opts["${opt}"]="${f2:-"${def_opts["${opt}"]}"}"
 	else
-		backup "${base_path}/${f1}" "${f2}" \
+		dest="${base_path}/${f1}"
+		printf '[%d] [%s] %s => %s%s\n' "$((++dcount))" \
+			"${opts['retain']}" "${f2}" "${dest}"
+
+		dest_rp="$(realpath -m "${dest}")"
+		if [[ -v "seen["${dest_rp}"]" ]]; then
+			err "destination already seen: ${dest}"
+			((++errors))
+			continue
+		fi
+		seen["${dest_rp}"]=
+
+		backup "${f2}" "${dest}" \
 			"${opts['retain']}" \
 			"${opts['interval']}" \
-			"${opts['week_start']}"
+			"${opts['week_start']}" \
+			|| ((++errors))
 	fi
 done < "${1}"
+
+((!errors))