linux-kernel - [PATCH v2] kunit: tool: continue past invalid utf-8 output

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Date:   Wed, 20 Oct 2021 16:21:21 -0700
From:   Daniel Latypov <dlatypov@...gle.com>
To:     brendanhiggins@...gle.com, davidgow@...gle.com
Cc:     linux-kernel@...r.kernel.org, kunit-dev@...glegroups.com,
        linux-kselftest@...r.kernel.org, skhan@...uxfoundation.org,
        Daniel Latypov <dlatypov@...gle.com>
Subject: [PATCH v2] kunit: tool: continue past invalid utf-8 output

kunit.py currently crashes and fails to parse kernel output if it's not
fully valid utf-8.

This can come from memory corruption or or just inadvertently printing
out binary data as strings.

E.g. adding this line into a kunit test
  pr_info("\x80")
will cause this exception
  UnicodeDecodeError: 'utf-8' codec can't decode byte 0x80 in position 1961: invalid start byte

We can tell Python how to handle errors, see
https://docs.python.org/3/library/codecs.html#error-handlers

Unfortunately, it doesn't seem like there's a way to specify this in
just one location, so we need to repeat ourselves quite a bit.

Specify `errors='backslashreplace'` so we instead:
* print out the offending byte as '\x80'
* try and continue parsing the output.
  * as long as the TAP lines themselves are valid, we're fine.

Signed-off-by: Daniel Latypov <dlatypov@...gle.com>
Reviewed-by: Brendan Higgins <brendanhiggins@...gle.com>
---
v1 -> v2: add comment to silence erroneous pytype error
---
 tools/testing/kunit/kunit.py        | 3 ++-
 tools/testing/kunit/kunit_kernel.py | 4 ++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/tools/testing/kunit/kunit.py b/tools/testing/kunit/kunit.py
index e1dd3180f0d1..68e6f461c758 100755
--- a/tools/testing/kunit/kunit.py
+++ b/tools/testing/kunit/kunit.py
@@ -477,9 +477,10 @@ def main(argv, linux=None):
 			sys.exit(1)
 	elif cli_args.subcommand == 'parse':
 		if cli_args.file == None:
+			sys.stdin.reconfigure(errors='backslashreplace')  # pytype: disable=attribute-error
 			kunit_output = sys.stdin
 		else:
-			with open(cli_args.file, 'r') as f:
+			with open(cli_args.file, 'r', errors='backslashreplace') as f:
 				kunit_output = f.read().splitlines()
 		request = KunitParseRequest(cli_args.raw_output,
 					    None,
diff --git a/tools/testing/kunit/kunit_kernel.py b/tools/testing/kunit/kunit_kernel.py
index faa6320e900e..f08c6c36a947 100644
--- a/tools/testing/kunit/kunit_kernel.py
+++ b/tools/testing/kunit/kunit_kernel.py
@@ -135,7 +135,7 @@ class LinuxSourceTreeOperationsQemu(LinuxSourceTreeOperations):
 					   stdin=subprocess.PIPE,
 					   stdout=subprocess.PIPE,
 					   stderr=subprocess.STDOUT,
-					   text=True, shell=True)
+					   text=True, shell=True, errors='backslashreplace')
 
 class LinuxSourceTreeOperationsUml(LinuxSourceTreeOperations):
 	"""An abstraction over command line operations performed on a source tree."""
@@ -172,7 +172,7 @@ class LinuxSourceTreeOperationsUml(LinuxSourceTreeOperations):
 					   stdin=subprocess.PIPE,
 					   stdout=subprocess.PIPE,
 					   stderr=subprocess.STDOUT,
-					   text=True)
+					   text=True, errors='backslashreplace')
 
 def get_kconfig_path(build_dir) -> str:
 	return get_file_path(build_dir, KCONFIG_PATH)

base-commit: 63b136c634a2bdffd78795bc33ac2d488152ffe8
-- 
2.33.0.1079.g6e70778dc9-goog