[PATCH] selftests/ftrace: Use /bin/echo for backslash included command

From: Masami Hiramatsu
Date: Mon May 11 2020 - 08:01:15 EST


Since the built-in echo has different behavior in POSIX shell
(dash) and bash, kprobe_syntax_errors.tc can fail on dash which
interpret backslash escape automatically.

To fix this issue, we explicitly use /bin/echo -E (not interpret
backslash escapes) if the command string can include backslash.

Reported-by: Liu Yiding <yidingx.liu@xxxxxxxxx>
Suggested-by: Xiao Yang <yangx.jy@xxxxxxxxxxxxxx>
Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
---
tools/testing/selftests/ftrace/test.d/functions | 8 +++++---
.../ftrace/test.d/kprobe/kprobe_syntax_errors.tc | 4 +++-
2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/ftrace/test.d/functions b/tools/testing/selftests/ftrace/test.d/functions
index 61a3c7e2634d..69708830026f 100644
--- a/tools/testing/selftests/ftrace/test.d/functions
+++ b/tools/testing/selftests/ftrace/test.d/functions
@@ -119,12 +119,14 @@ yield() {
ping $LOCALHOST -c 1 || sleep .001 || usleep 1 || sleep 1
}

+# Since probe event command may include backslash, explicitly use /bin/echo -E
+# to NOT interpret it.
ftrace_errlog_check() { # err-prefix command-with-error-pos-by-^ command-file
- pos=$(echo -n "${2%^*}" | wc -c) # error position
- command=$(echo "$2" | tr -d ^)
+ pos=$(/bin/echo -En "${2%^*}" | wc -c) # error position
+ command=$(/bin/echo -E "$2" | tr -d ^)
echo "Test command: $command"
echo > error_log
- (! echo "$command" >> "$3" ) 2> /dev/null
+ (! /bin/echo -E "$command" >> "$3" ) 2> /dev/null
grep "$1: error:" -A 3 error_log
N=$(tail -n 1 error_log | wc -c)
# " Command: " and "^\n" => 13
diff --git a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc
index ef1e9bafb098..4cfcf9440a1a 100644
--- a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc
+++ b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc
@@ -91,7 +91,9 @@ esac
if grep -q "Create/append/" README && grep -q "imm-value" README; then
echo 'p:kprobes/testevent _do_fork' > kprobe_events
check_error '^r:kprobes/testevent do_exit' # DIFF_PROBE_TYPE
-echo 'p:kprobes/testevent _do_fork abcd=\1' > kprobe_events
+
+# Explicitly use /bin/echo -E to not interpret \1
+/bin/echo -E 'p:kprobes/testevent _do_fork abcd=\1' > kprobe_events
check_error 'p:kprobes/testevent _do_fork ^bcd=\1' # DIFF_ARG_TYPE
check_error 'p:kprobes/testevent _do_fork ^abcd=\1:u8' # DIFF_ARG_TYPE
check_error 'p:kprobes/testevent _do_fork ^abcd=\"foo"' # DIFF_ARG_TYPE