[RFC PATCH v3 1/2] perf/kselftest: convert prefix.pl to Python

[Breno Rodrigues Alves <breno3011alves@gmail.com>]

Faithful re-implementation of tools/testing/selftests/kselftest/
prefix.pl in Python 3 (stdlib only). Same unbuffered stdin-to-stdout
processing, same "# " prefix behavior.

Update runner.sh to invoke prefix.py instead of prefix.pl, update
the install target to install prefix.py, and remove the old
prefix.pl.

Verified byte-for-byte identical to the Perl version.

Signed-off-by: Breno Rodrigues Alves <breno3011alves@gmail.com>
---
 tools/testing/selftests/Makefile            |  2 +-
 tools/testing/selftests/kselftest/prefix.pl | 24 ---------------------
 tools/testing/selftests/kselftest/prefix.py | 24 +++++++++++++++++++++
 tools/testing/selftests/kselftest/runner.sh |  4 ++--
 4 files changed, 27 insertions(+), 27 deletions(-)
 delete mode 100755 tools/testing/selftests/kselftest/prefix.pl
 create mode 100755 tools/testing/selftests/kselftest/prefix.py

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index bc4fdb6f5..85ed9af96 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -285,7 +285,7 @@ ifdef INSTALL_PATH
 	mkdir -p $(INSTALL_PATH)/kselftest
 	install -m 744 kselftest/module.sh $(INSTALL_PATH)/kselftest/
 	install -m 744 kselftest/runner.sh $(INSTALL_PATH)/kselftest/
-	install -m 744 kselftest/prefix.pl $(INSTALL_PATH)/kselftest/
+	install -m 744 kselftest/prefix.py $(INSTALL_PATH)/kselftest/
 	install -m 744 kselftest/ktap_helpers.sh $(INSTALL_PATH)/kselftest/
 	install -m 744 kselftest/ksft.py $(INSTALL_PATH)/kselftest/
 	install -m 744 run_kselftest.sh $(INSTALL_PATH)/
diff --git a/tools/testing/selftests/kselftest/prefix.pl b/tools/testing/selftests/kselftest/prefix.pl
deleted file mode 100755
index 12a7f4ca2..000000000
--- a/tools/testing/selftests/kselftest/prefix.pl
+++ /dev/null
@@ -1,24 +0,0 @@
-#!/usr/bin/env perl
-# SPDX-License-Identifier: GPL-2.0
-# Prefix all lines with "# ", unbuffered. Command being piped in may need
-# to have unbuffering forced with "stdbuf -i0 -o0 -e0 $cmd".
-use strict;
-use IO::Handle;
-
-binmode STDIN;
-binmode STDOUT;
-
-STDOUT->autoflush(1);
-
-my $needed = 1;
-while (1) {
-	my $char;
-	my $bytes = sysread(STDIN, $char, 1);
-	exit 0 if ($bytes == 0);
-	if ($needed) {
-		print "# ";
-		$needed = 0;
-	}
-	print $char;
-	$needed = 1 if ($char eq "\n");
-}
diff --git a/tools/testing/selftests/kselftest/prefix.py b/tools/testing/selftests/kselftest/prefix.py
new file mode 100755
index 000000000..67c4fd0b6
--- /dev/null
+++ b/tools/testing/selftests/kselftest/prefix.py
@@ -0,0 +1,24 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+# Prefix all lines with "# ", unbuffered.
+
+import sys
+
+
+def main():
+    needed = True
+    while True:
+        char = sys.stdin.buffer.read(1)
+        if not char:
+            return 0
+        if needed:
+            sys.stdout.buffer.write(b"# ")
+            needed = False
+        sys.stdout.buffer.write(char)
+        sys.stdout.buffer.flush()
+        if char == b"\n":
+            needed = True
+
+
+if __name__ == "__main__":
+    sys.exit(main())
diff --git a/tools/testing/selftests/kselftest/runner.sh b/tools/testing/selftests/kselftest/runner.sh
index 311811dc5..1944c74f1 100644
--- a/tools/testing/selftests/kselftest/runner.sh
+++ b/tools/testing/selftests/kselftest/runner.sh
@@ -29,10 +29,10 @@ TR_CMD=$(command -v tr)
 # with sed instead of unbuffered output.
 tap_prefix()
 {
-	if [ ! -x /usr/bin/perl ]; then
+	if [ ! -x /usr/bin/python3 ]; then
 		sed -e 's/^/# /'
 	else
-		"$BASE_DIR"/kselftest/prefix.pl
+		"$BASE_DIR"/kselftest/prefix.py
 	fi
 }
 
-- 
2.43.0