tests: remove reliance on buffer behaviour of stderr/stdout streams

In the test cases "rename::exit_codes" and "rename::exit_codes", we rely
on the flushing behaviour of stderr and stdout streams relative to each
other. Streams in glibc will not flush on newlines if stdout is pointing
to a non-TTY file descriptor, but relying on this is fragile and may
break on systems with a different behaviour like musl libc.

Fix this by introducing a new parameter "--unbuffered" to `ts_run`. If
this parameter is passed and stdbuf(1) from coreutils is available, then
it will use it to disable buffering of standard output completely. Like
this, we can selectively run tests with this if ordering of messages
from stdout and stderr is being checked.

Signed-off-by: Patrick Steinhardt <ps@pks.im>

x

tests/expected/misc/swaplabel

@@ -1,7 +1,7 @@
 mkswap: error: swap area needs to be at least 10 pages
 mkswap: <swapfile>: insecure permissions <perm>, 0600 suggested.
-mkswap: Label was truncated.
 Setting up swapspace version 1, size = 9 pages (9xPGSZ bytes)
+mkswap: Label was truncated.
 LABEL=1234567890abcde, UUID=12345678-abcd-abcd-abcd-1234567890ab
 LABEL: 1234567890abcde
 UUID:  12345678-abcd-abcd-abcd-1234567890ab

tests/expected/rename/exit_codes

@@ -2,6 +2,6 @@ RENAME_EXIT_NOTHING: 4
 `rename_exit_codes.1' -> `rename_exit_values.1'
 `rename_exit_codes.2' -> `rename_exit_values.2'
 EXIT_SUCCESS: 0
-rename: rename_exit_values.2: rename to rename_exit_codes.2 failed: Is a directory
 `rename_exit_values.1' -> `rename_exit_codes.1'
+rename: rename_exit_values.2: rename to rename_exit_codes.2 failed: Is a directory
 RENAME_EXIT_SOMEOK: 2

tests/functions.sh

@@ -420,26 +420,48 @@ function ts_init_py {
 }
 
 function ts_run {
+	local UNBUFFERED=
+
+	while true; do
+		case "$1" in
+			--unbuffered)
+				UNBUFFERED=1
+				shift;;
+			--)
+				shift
+				break;;
+			*)
+				break;;
+		esac
+	done
+
+	declare -a args
+
+	#
+	# ASAN mode
+	#
+	if [ "$TS_ENABLE_ASAN" == "yes" ]; then
+		args+=(ASAN_OPTIONS='detect_leaks=1')
+	fi
+
+	#
+	# Disable buffering of stdout
+	#
+	if [ -n "$UNBUFFERED" ]; then
+		if type stdbuf >/dev/null 2>&1; then
+			args+=(stdbuf --output=0)
+		fi
+	fi
+
 	#
 	# valgrind mode
 	#
 	if [ -n "$TS_VALGRIND_CMD" ]; then
-		libtool --mode=execute \
-		$TS_VALGRIND_CMD --tool=memcheck --leak-check=full \
-				 --leak-resolution=high --num-callers=20 \
-				 --log-file="$TS_VGDUMP" "$@"
-	#
-	# ASAN mode
-	#
-	elif [ "$TS_ENABLE_ASAN" == "yes" ]; then
-		ASAN_OPTIONS='detect_leaks=1' "$@"
-
-	#
-	# Default mode
-	#
-	else
-		"$@"
+		args+=(libtool --mode=execute "$TS_VALGRIND_CMD" --tool=memcheck --leak-check=full)
+		args+=(--leak-resolution=high --num-callers=20 --log-file="$TS_VGDUMP")
 	fi
+
+	"${args[@]}" "$@"
 }
 
 function ts_gen_diff {
@@ -977,4 +999,3 @@ function ts_has_ncurses_support {
 		echo "no"
 	fi
 }
-

tests/ts/misc/swaplabel

@@ -39,7 +39,7 @@ MIN_SWAP_SIZE_KB=$(( MIN_SWAP_SIZE / 1024 ))
 
 rm -f $IMAGE
 fallocate_or_skip $(( $MIN_SWAP_SIZE - 1 )) $IMAGE
-$TS_CMD_MKSWAP \
+ts_run --unbuffered $TS_CMD_MKSWAP \
 	--label 1234567890abcdef \
 	--uuid 12345678-abcd-abcd-abcd-1234567890ab \
 	$IMAGE 2>&1 |\
@@ -50,7 +50,7 @@ $TS_CMD_MKSWAP \
 
 rm -f $IMAGE
 fallocate_or_skip $MIN_SWAP_SIZE $IMAGE
-$TS_CMD_MKSWAP \
+ts_run --unbuffered $TS_CMD_MKSWAP \
 	--label 1234567890abcdef \
 	--uuid 12345678-abcd-abcd-abcd-1234567890ab \
 	$IMAGE 2>&1 |\

tests/ts/rename/exit_codes

@@ -32,7 +32,7 @@ $TS_CMD_RENAME -v codes values rename_exit_codes.? >> $TS_OUTPUT 2>&1
 echo "EXIT_SUCCESS: $?" >> $TS_OUTPUT
 
 mkdir rename_exit_codes.2
-$TS_CMD_RENAME -v values codes rename_exit_values.? >> $TS_OUTPUT 2>&1
+ts_run --unbuffered $TS_CMD_RENAME -v values codes rename_exit_values.? >> $TS_OUTPUT 2>&1
 echo "RENAME_EXIT_SOMEOK: $?" >> $TS_OUTPUT
 
 rmdir rename_exit_codes.2