On Tue, 21 May 2019 00:37:48 +0200, Kees Cook wrote:
As it turns out, the "stdbuf" command will actually force all subprocesses into unbuffered output, and some implementations of "echo" turn into single-character writes, which utterly wrecks writes to /sys and /proc files.
Instead, drop the "stdbuf" usage, and for any tests that want explicit flushing between newlines, they'll have to add "fflush(stdout);" as needed.
Reported-by: Takashi Iwai tiwai@suse.de Fixes: 5c069b6dedef ("selftests: Move test output to diagnostic lines") Signed-off-by: Kees Cook keescook@chromium.org
Tested-by: Takashi Iwai tiwai@suse.de
BTW, this might be specific to shell invocation. As in the original discussion thread, it starts working when I replace "echo" with "/usr/bin/echo".
Still it's not easy to control in a script itself, so dropping the unbuffered mode is certainly safer, yes.
Thanks!
Takashi
tools/testing/selftests/kselftest/runner.sh | 12 +----------- 1 file changed, 1 insertion(+), 11 deletions(-)
diff --git a/tools/testing/selftests/kselftest/runner.sh b/tools/testing/selftests/kselftest/runner.sh index eff3ee303d0d..00c9020bdda8 100644 --- a/tools/testing/selftests/kselftest/runner.sh +++ b/tools/testing/selftests/kselftest/runner.sh @@ -24,16 +24,6 @@ tap_prefix() fi } -# If stdbuf is unavailable, we must fall back to line-at-a-time piping. -tap_unbuffer() -{
- if ! which stdbuf >/dev/null ; then
"$@"- else
stdbuf -i0 -o0 -e0 "$@"- fi
-}
run_one() { DIR="$1" @@ -54,7 +44,7 @@ run_one() echo "not ok $test_num $TEST_HDR_MSG" else cd `dirname $TEST` > /dev/null
(((((tap_unbuffer ./$BASENAME_TEST 2>&1; echo $? >&3) |
(((((./$BASENAME_TEST 2>&1; echo $? >&3) | tap_prefix >&4) 3>&1) | (read xs; exit $xs)) 4>>"$logfile" &&-- 2.17.1