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fix: always quote control chars #52

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Merged
merged 1 commit into from
Sep 25, 2025
Merged

fix: always quote control chars #52

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18 changes: 9 additions & 9 deletions src/logfmter/formatter.py
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,12 @@
"threadName",
)

QUOTE_CHARS = str.maketrans(
"", "", " =" + "".join(chr(c) for c in list(range(0x20)) + [0x7F])
)
REPLACEMENTS = {chr(c): f"\\u{c:04x}" for c in list(range(0x20)) + [0x7F]}
REPLACEMENTS.update({"\n": "\\n", "\t": "\\t", "\r": "\\r"})


class _DefaultFormatter(logging.Formatter):
def format(self, record):
Expand All @@ -59,13 +65,7 @@ def format_string(cls, value: str) -> str:
Process the provided string with any necessary quoting and/or escaping.
"""
needs_dquote_escaping = '"' in value
needs_newline_escaping = "\n" in value
needs_quoting = (
" " in value
or "=" in value
or needs_dquote_escaping
or needs_newline_escaping
)
needs_quoting = needs_dquote_escaping or value.translate(QUOTE_CHARS) != value
needs_backslash_escaping = "\\" in value and needs_quoting

if needs_backslash_escaping:
Expand All @@ -74,8 +74,8 @@ def format_string(cls, value: str) -> str:
if needs_dquote_escaping:
value = value.replace('"', '\\"')

if needs_newline_escaping:
value = value.replace("\n", "\\n")
for char, replacement in REPLACEMENTS.items():
value = value.replace(char, replacement)

if needs_quoting:
value = '"{}"'.format(value)
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13 changes: 12 additions & 1 deletion tests/test_formatter.py
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Original file line number Diff line number Diff line change
Expand Up @@ -16,13 +16,24 @@
("=", '"="'),
# All double quotes must be escaped.
('"', '"\\""'),
# Null bytes must be escaped and quoted
("\x00", r'"\u0000"'),
# All whitespace chars must be escaped and quoted
("\n", '"\\n"'),
("\r", '"\\r"'),
("\t", '"\\t"'),
# All other control chars must be escaped and quoted
("\x07", r'"\u0007"'),
(
"".join(chr(c) for c in range(0x20) if chr(c) not in "\t\n\r"),
r'"\u0000\u0001\u0002\u0003\u0004\u0005\u0006\u0007\u0008\u000b\u000c\u000e\u000f\u0010\u0011\u0012\u0013\u0014\u0015\u0016\u0017\u0018\u0019\u001a\u001b\u001c\u001d\u001e\u001f"',
),
# If the string requires escaping and quoting, then both
# operations should be performed.
(' "', '" \\""'),
# If the string is empty, then it should be left empty.
("", ""),
# If the string contains a newline, then it should be escaped.
("\n", '"\\n"'),
("\n\n", '"\\n\\n"'),
# If the string contains a backslash and needs to be quoted, then
# the backslashes need to be escaped.
Expand Down