[BUG] sof-test output is messy when run test case locally

[aiChaoSONG]

Describe the bug
When run test case locally, the output of the test case is messy. Log doesn't start from the beginning of a line. This makes the log hard to follow.

To Reproduce
Just run a test case, say check-playback.sh on any device, and check the output.

EDIT, duplicate of:

• [BUG] check-playback.sh log output is broken #945

[aiChaoSONG]

comment out this line, issue could not be reproduced

sof-test/case-lib/lib.sh

Line 377 in bc3ced5

sudo "${mtraceCmd[@]}" >& "$clogfile" &

not sure why a redirect break the current shell.

[aiChaoSONG]

sudo bash -c "${mtraceCmd[@]} >& $clogfile &", this will workaround the issue

[marc-hb]

Let's leave open as low priority because it's just a workaround and we have no idea why it works.

[marc-hb]

I've just observed the same effect in a totally different (build) context. I think it happens when multiple processes write to the same terminal concurrently and one of them uses control codes (e.g. color). I suspect control codes are not "atomic" which means another problem can insert characters in the middle and break them.

Maybe the workaround #1154 disables control codes by hiding the terminal.

This would also explains why CI results are not affected: they don't use a terminal.

EDIT: | cat could be a simpler workaround than sudo

[marc-hb]

The workaround in #1154 works for Zephyr but not stable-v2.2

I got tired of this and I tested further. This is a problem only when using sudo + &

/bin/sudo      sleep 1 &   # garbage
/bin/sudo -b   sleep 1     # clean
/bin/sudo      sleep 1     # clean
/bin/sudo -C 2 sleep 1     # clean
/bin/sudo -C 3 sleep 1     # garbage
2>&- /bin/sudo sleep 1 &   # garbage

--- a/case-lib/lib.sh
+++ b/case-lib/lib.sh
@@ -463,7 +463,7 @@ func_sof_logger_collect()
     dlogi "Starting ${loggerCmd[*]} > $logfile &"
     # Cleaned up by func_exit_handler() in hijack.sh
     # shellcheck disable=SC2024
-    sudo "${loggerCmd[@]}" > "$logfile" &
+    /bin/sudo sleep 1 &
 }

Backgrounding sudo is a bad idea anyway:
https://stackoverflow.com/questions/26109878/running-a-program-in-the-background-as-sudo

-b looks great but we can't use it because we have the crazy "sudo hijack" stuff in 1a4ea98