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Replace the suboptimal fuzz_tree harness with a better alternative
As discussed in the initial fuzzing integration PR[^1], `fuzz_tree.py`'s implementation was not ideal in terms of coverage and its reading/writing to hard-coded paths inside `/tmp` was problematic as (among other concerns), it causes intermittent crashes on ClusterFuzz[^2] when multiple workers execute the test at the same time on the same machine. The changes here replace `fuzz_tree.py` completely with a completely new `fuzz_repo.py` fuzz target which: - Uses `tempfile.TemporaryDirectory()` to safely manage tmpdir creation and tear down, including during multi-worker execution runs. - Retains the same feature coverage as `fuzz_tree.py`, but it also adds considerably more from much smaller data inputs and with less memory consumed (and it doesn't even have a seed corpus or target specific dictionary yet.) - Can likely be improved further in the future by exercising additional features of `Repo` to the harness. Because `fuzz_tree.py` was removed and `fuzz_repo.py` was not derived from it, the Apache License call outs in the docs were also updated as they only apply to the singe `fuzz_config.py` file now. [^1]: #1901 (comment) [^2]: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=68355
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‎README.md

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@@ -240,8 +240,8 @@ Please have a look at the [contributions file][contributing].
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[3-Clause BSD License](https://opensource.org/license/bsd-3-clause/), also known as the New BSD License. See the [LICENSE file][license].
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Two files exclusively used for fuzz testing are subject to [a separate license, detailed here](./fuzzing/README.md#license).
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These files are not included in the wheel or sdist packages published by the maintainers of GitPython.
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One file exclusively used for fuzz testing is subject to [a separate license, detailed here](./fuzzing/README.md#license).
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This file is not included in the wheel or sdist packages published by the maintainers of GitPython.
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[contributing]: https://github.com/gitpython-developers/GitPython/blob/main/CONTRIBUTING.md
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[license]: https://github.com/gitpython-developers/GitPython/blob/main/LICENSE

‎fuzzing/README.md

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@@ -225,14 +225,14 @@ to [the official OSS-Fuzz documentation][oss-fuzz-docs].
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## LICENSE
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All files located within the `fuzzing/` directory are subject to [the same license](../LICENSE)
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as [the other files in this repository](../README.md#license) with two exceptions:
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Two files located in this directory, [`fuzz_config.py`](./fuzz-targets/fuzz_config.py)
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and [`fuzz_tree.py`](./fuzz-targets/fuzz_tree.py), have been migrated here from the OSS-Fuzz project repository where
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they were originally created. As such, these two files retain their original license and copyright notice (Apache
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License, Version 2.0 and Copyright 2023 Google LLC respectively.) Each file includes a notice in their respective header
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comments stating that they have been modified. [LICENSE-APACHE](./LICENSE-APACHE) contains the original license used by
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the OSS-Fuzz project repository at the time they were migrated.
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as [the other files in this repository](../README.md#license) with one exception:
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[`fuzz_config.py`](./fuzz-targets/fuzz_config.py) was migrated to this repository from the OSS-Fuzz project's repository
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where it was originally created. As such, [`fuzz_config.py`](./fuzz-targets/fuzz_config.py) retains its original license
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and copyright notice (Apache License, Version 2.0 and Copyright 2023 Google LLC respectively) as in a header
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comment, followed by a notice stating that it has have been modified contributors to GitPython.
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[LICENSE-APACHE](./LICENSE-APACHE) contains the original license used by the OSS-Fuzz project repository at the time the
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file was migrated.
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[oss-fuzz-repo]: https://github.com/google/oss-fuzz
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‎fuzzing/dictionaries/fuzz_tree.dict

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‎fuzzing/fuzz-targets/fuzz_repo.py

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import atheris
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import io
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import sys
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import os
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import tempfile
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if getattr(sys, "frozen", False) and hasattr(sys, "_MEIPASS"):
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path_to_bundled_git_binary = os.path.abspath(os.path.join(os.path.dirname(__file__), "git"))
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os.environ["GIT_PYTHON_GIT_EXECUTABLE"] = path_to_bundled_git_binary
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with atheris.instrument_imports():
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import git
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def TestOneInput(data):
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fdp = atheris.FuzzedDataProvider(data)
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with tempfile.TemporaryDirectory() as temp_dir:
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repo = git.Repo.init(path=temp_dir)
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# Generate a minimal set of files based on fuzz data to minimize I/O operations.
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file_paths = [os.path.join(temp_dir, f"File{i}") for i in range(min(3, fdp.ConsumeIntInRange(1, 3)))]
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for file_path in file_paths:
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with open(file_path, "wb") as f:
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# The chosen upperbound for count of bytes we consume by writing to these
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# files is somewhat arbitrary and may be worth experimenting with if the
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# fuzzer coverage plateaus.
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f.write(fdp.ConsumeBytes(fdp.ConsumeIntInRange(1, 512)))
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repo.index.add(file_paths)
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repo.index.commit(fdp.ConsumeUnicodeNoSurrogates(fdp.ConsumeIntInRange(1, 80)))
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fuzz_tree = git.Tree(repo, git.Tree.NULL_BIN_SHA, 0, "")
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try:
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fuzz_tree._deserialize(io.BytesIO(data))
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except IndexError:
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return -1
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def main():
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atheris.Setup(sys.argv, TestOneInput)
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atheris.Fuzz()
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if __name__ == "__main__":
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main()

‎fuzzing/fuzz-targets/fuzz_tree.py

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