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Merged
Byron merged 6 commits into from
Apr 13, 2026
+88 −17
Merged

Harden commit trailer subprocess handling and align trailer I/O paths #2125

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bd58716
Use consistent interpret-trailers encoding
Copilot Apr 12, 2026
7cdf9c7
Normalize interpret-trailers subprocess IO
Copilot Apr 12, 2026
1e2a895
Handle mypy CI typing failure
Copilot Apr 12, 2026
34ec40d
Use commit encoding for trailer parsing
Copilot Apr 13, 2026
4aa8157
Refine trailer encoding review follow-up
Copilot Apr 13, 2026
633abdb
Fix trailer subprocess lifetime
Copilot Apr 13, 2026
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32 changes: 15 additions & 17 deletions git/objects/commit.py
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Original file line number Diff line number Diff line change
Expand Up @@ -450,14 +450,7 @@ def trailers_list(self) -> List[Tuple[str, str]]:
:return:
List containing key-value tuples of whitespace stripped trailer information.
"""
cmd = ["git", "interpret-trailers", "--parse"]
proc: Git.AutoInterrupt = self.repo.git.execute( # type: ignore[call-overload]
cmd,
as_process=True,
istream=PIPE,
)
trailer: str = proc.communicate(str(self.message).encode())[0].decode("utf8")
trailer = trailer.strip()
trailer = self._interpret_trailers(self.repo, self.message, ["--parse"]).strip()
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Copilot AI Apr 13, 2026

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trailers_list calls _interpret_trailers without passing/using the commit's actual encoding (self.encoding). Since commit messages can be configured via i18n.commitencoding, trailer parsing should encode/decode using that encoding to avoid mis-decoding or UnicodeDecodeError for non-UTF-8 commit messages. Consider passing self.encoding through to _interpret_trailers (or have the helper derive the encoding from the commit/repo config).

Suggested change
trailer = self._interpret_trailers(self.repo, self.message, ["--parse"]).strip()
proc = Popen(
[Git.GIT_PYTHON_GIT_EXECUTABLE, "interpret-trailers", "--parse"],
stdin=PIPE,
stdout=PIPE,
stderr=PIPE,
cwd=self.repo.working_tree_dir or self.repo.git_dir,
)
stdout, _stderr = proc.communicate(self.message.encode(self.encoding))
finalize_process(proc)
trailer = stdout.decode(self.encoding).strip()

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if not trailer:
return []
Expand All @@ -469,6 +462,19 @@ def trailers_list(self) -> List[Tuple[str, str]]:

return trailer_list

@classmethod
def _interpret_trailers(cls, repo: "Repo", message: Union[str, bytes], trailer_args: Sequence[str]) -> str:
cmd = [repo.git.GIT_PYTHON_GIT_EXECUTABLE, "interpret-trailers", *trailer_args]
proc: Git.AutoInterrupt = repo.git.execute( # type: ignore[call-overload]
cmd,
as_process=True,
istream=PIPE,
)
message_bytes = message if isinstance(message, bytes) else message.encode(cls.default_encoding, errors="strict")
stdout_bytes, _ = proc.communicate(message_bytes)
finalize_process(proc)
return stdout_bytes.decode(cls.default_encoding, errors="strict")
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Copilot AI Apr 13, 2026

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_interpret_trailers always encodes/decodes using cls.default_encoding (UTF-8) even when the repo/commit uses a different i18n.commitencoding. This can break trailer handling for commits whose bytes are not valid UTF-8 (e.g., ISO-8859-1), especially if callers pass bytes. Recommend adding an explicit encoding parameter (defaulting to the repo’s configured commit encoding) and using it consistently for both .encode() and .decode().

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@property
def trailers_dict(self) -> Dict[str, List[str]]:
"""Get the trailers of the message as a dictionary.
Expand Down Expand Up @@ -699,15 +705,7 @@ def create_from_tree(
trailer_args.append("--trailer")
trailer_args.append(f"{key}: {val}")

cmd = [repo.git.GIT_PYTHON_GIT_EXECUTABLE, "interpret-trailers"] + trailer_args
proc: Git.AutoInterrupt = repo.git.execute( # type: ignore[call-overload]
cmd,
as_process=True,
istream=PIPE,
)
stdout_bytes, _ = proc.communicate(str(message).encode())
finalize_process(proc)
message = stdout_bytes.decode("utf8")
message = cls._interpret_trailers(repo, str(message), trailer_args)
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create_from_tree has already computed conf_encoding from i18n.commitencoding, but trailer application calls _interpret_trailers without using it. To keep trailer I/O aligned with how the commit will be serialized, pass conf_encoding (or have _interpret_trailers derive it from the repo) when applying trailers.

Suggested change
message = cls._interpret_trailers(repo, str(message), trailer_args)
message = cls._interpret_trailers(
repo,
str(message),
trailer_args,
conf_encoding=conf_encoding,
)

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In create_from_tree(), trailers are applied via _interpret_trailers() without passing the repo-configured commit encoding (conf_encoding). This means interpret-trailers I/O is always UTF-8 even when the commit will be serialized using a different encoding, which is inconsistent with trailers_list() and can produce different on-disk bytes. Pass encoding=conf_encoding when calling _interpret_trailers here (and avoid double str() conversion if possible).

Suggested change
message = cls._interpret_trailers(repo, str(message), trailer_args)
if not isinstance(message, str):
message = str(message)
message = cls._interpret_trailers(repo, message, trailer_args, encoding=conf_encoding)

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Copilot AI Apr 13, 2026

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create_from_tree reads i18n.commitencoding into conf_encoding, but the trailer application path calls _interpret_trailers(...) without passing that encoding (so it always encodes/decodes as UTF-8). To keep trailer I/O aligned with the configured commit encoding (and avoid byte-length differences affecting wrapping/formatting), pass encoding=conf_encoding when calling _interpret_trailers here.

Suggested change
message = cls._interpret_trailers(repo, str(message), trailer_args)
message = cls._interpret_trailers(repo, str(message), trailer_args, encoding=conf_encoding)

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# END apply trailers

# CREATE NEW COMMIT
Expand Down
25 changes: 25 additions & 0 deletions test/test_commit.py
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Original file line number Diff line number Diff line change
Expand Up @@ -622,6 +622,31 @@ def test_create_from_tree_with_trailers_list(self, rw_dir):
"Issue": ["456"],
}

@with_rw_directory
def test_create_from_tree_with_non_utf8_trailers(self, rw_dir):
"""Test that trailer creation and parsing respect the configured commit encoding."""
rw_repo = Repo.init(osp.join(rw_dir, "test_trailers_non_utf8"))
with rw_repo.config_writer() as writer:
writer.set_value("i18n", "commitencoding", "ISO-8859-1")

path = osp.join(str(rw_repo.working_tree_dir), "hello.txt")
touch(path)
rw_repo.index.add([path])
tree = rw_repo.index.write_tree()

commit = Commit.create_from_tree(
rw_repo,
tree,
"Résumé",
head=True,
trailers={"Reviewed-by": "André <andre@example.com>"},
)

assert commit.encoding == "ISO-8859-1"
assert "Résumé" in commit.message
assert "Reviewed-by: André <andre@example.com>" in commit.message
assert commit.trailers_list == [("Reviewed-by", "André <andre@example.com>")]

@with_rw_directory
def test_index_commit_with_trailers(self, rw_dir):
"""Test that IndexFile.commit() supports adding trailers."""
Expand Down
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