From b3ea98c60629124ab8b96dad012b7c45b944cdd9 Mon Sep 17 00:00:00 2001 From: Gilles Peskine Date: Wed, 21 Sep 2022 22:00:06 +0200 Subject: [PATCH] Replace the output file atomically When writing the new .data file, first write the new content, then replace the target. This way, there isn't a temporary state in which the file is partially written. This temporary state can be misleading if the build is interrupted. It's annoying if you're watching changes to the output and the changes appear as emptying the file following by the new version appearing. Now interrupted builds don't leave a file that appears to be up to date but isn't, and when watching the output, there's a single transition to the new version. Signed-off-by: Gilles Peskine --- scripts/mbedtls_dev/test_case.py | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/scripts/mbedtls_dev/test_case.py b/scripts/mbedtls_dev/test_case.py index 43ddf203b6..8f08703678 100644 --- a/scripts/mbedtls_dev/test_case.py +++ b/scripts/mbedtls_dev/test_case.py @@ -92,9 +92,11 @@ def write_data_file(filename: str, """ if caller is None: caller = os.path.basename(sys.argv[0]) - with open(filename, 'w') as out: + tempfile = filename + '.new' + with open(tempfile, 'w') as out: out.write('# Automatically generated by {}. Do not edit!\n' .format(caller)) for tc in test_cases: tc.write(out) out.write('\n# End of automatically generated file.\n') + os.replace(tempfile, filename)