perf build: Add shellcheck to tools/perf scripts

Address shell check errors/warnings in perf-archive.sh and
perf-completion.sh.

Reviewed-by: James Clark <[e-mail]>
Signed-off-by: Ian Rogers <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Athira Rajeev <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Kajol Jain <[e-mail]>
Cc: Kan Liang <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Oliver Upton <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Ravi Bangoria <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/Build

···
 perf-y += scripts/
 
 gtk-y += ui/gtk/
+
+ifdef SHELLCHECK
+  SHELL_TESTS := $(wildcard *.sh)
+  TEST_LOGS := $(SHELL_TESTS:%=%.shellcheck_log)
+else
+  SHELL_TESTS :=
+  TEST_LOGS :=
+endif
+
+$(OUTPUT)%.shellcheck_log: %
+	$(call rule_mkdir)
+	$(Q)$(call echo-cmd,test)shellcheck -s bash -a -S warning "$<" > $@ || (cat $@ && rm $@ && false)
+
+perf-y += $(TEST_LOGS)

tools/perf/perf-archive.sh

···
 		TARGET=`find . -regex "\./perf.*\.tar\.bz2"`
 		TARGET_NUM=`echo -n "$TARGET" | grep -c '^'`
 
-		if [ -z "$TARGET" -o $TARGET_NUM -gt 1 ]; then
+		if [ -z "$TARGET" ] || [ $TARGET_NUM -gt 1 ]; then
 			echo -e "Error: $TARGET_NUM files found for unpacking:\n$TARGET"
 			echo "Provide the requested file as an argument"
 			exit 1

tools/perf/perf-completion.sh

···
 
 __perfcomp ()
 {
+	# Expansion of spaces to array is deliberate.
+	# shellcheck disable=SC2207
 	COMPREPLY=( $( compgen -W "$1" -- "$2" ) )
 }
 
···
 
 	let i=cword-1
 	cmds_=$($cmd $1 --list-cmds)
-	prev_skip_opts=()
+	prev_skip_opts=""
 	while [ $i -ge 0 ]; do
-		if [[ ${words[i]} == $1 ]]; then
+		if [[ ${words[i]} == "$1" ]]; then
 			return
 		fi
 		for cmd_ in $cmds_; do
-			if [[ ${words[i]} == $cmd_ ]]; then
+			if [[ ${words[i]} == "$cmd_" ]]; then
 				prev_skip_opts=${words[i]}
 				return
 			fi
···
 		$prev_skip_opts == @(record|stat|top) ]]; then
 
 		local cur1=${COMP_WORDS[COMP_CWORD]}
-		local raw_evts=$($cmd list --raw-dump hw sw cache tracepoint pmu sdt)
+		local raw_evts
 		local arr s tmp result cpu_evts
 
+		raw_evts=$($cmd list --raw-dump hw sw cache tracepoint pmu sdt)
 		# aarch64 doesn't have /sys/bus/event_source/devices/cpu/events
 		if [[ `uname -m` != aarch64 ]]; then
 			cpu_evts=$(ls /sys/bus/event_source/devices/cpu/events)
···
 		if [[ "$cur1" == */* && ${cur1#*/} =~ ^[A-Z] ]]; then
 			OLD_IFS="$IFS"
 			IFS=" "
+			# Expansion of spaces to array is deliberate.
+			# shellcheck disable=SC2206
 			arr=($raw_evts)
 			IFS="$OLD_IFS"
 
-			for s in ${arr[@]}
+			for s in "${arr[@]}"
 			do
 				if [[ "$s" == *cpu/* ]]; then
 					tmp=${s#*cpu/}
···
 		fi
 	elif [[ $prev == @("--pfm-events") &&
 		$prev_skip_opts == @(record|stat|top) ]]; then
-	        local evts=$($cmd list --raw-dump pfm)
+		local evts
+		evts=$($cmd list --raw-dump pfm)
 		__perfcomp "$evts" "$cur"
 	elif [[ $prev == @("-M"|"--metrics") &&
 		$prev_skip_opts == @(stat) ]]; then
-	        local metrics=$($cmd list --raw-dump metric metricgroup)
+		local metrics
+		metrics=$($cmd list --raw-dump metric metricgroup)
 		__perfcomp "$metrics" "$cur"
 	else
 		# List subcommands for perf commands
···
 		let cword=CURRENT-1
 		emulate ksh -c __perf_main
 		let _ret && _default && _ret=0
+		# _ret is only assigned 0 or 1, disable inaccurate analysis.
+		# shellcheck disable=SC2152
 		return _ret
 	}