Better document IterableObj.iter_items and improve some subclasses by EliahKagan · Pull Request #1780 · gitpython-developers/GitPython
added 5 commits
December 22, 2023 02:52Where the behavior is intended. In the case of an invalid hash (or IOError, which in Python 2 was a subclass of OSError but now is just another name for it), the behavior of just yielding no items may be unintuitive, since on most other errors an exception is raised. However, examining the code reveals this behavior is clearly intentional. Furthrmore, it may be reasonable for applications to rely on it, and it may be convenient in some situations. For backward compatibility, it probably can't be changed significantly. This adds tests that show both an error that does raise an error-representing exception -- a well-formed hash not present in the repository raising ValueError with a suitable message -- and an error that silently causes the iterator to yield zero items.
Returning an explicit value from a generator function causes that value to be bound to the `value` attribute of the StopIteration exception. This is available as the result of "yield from" when it is used as an expression; or by explicitly catching StopIteration, binding the StopIteration exception to a variable, and accessing the attribute. This feature of generators is rarely used. The `return iter([])` statement in Submodule.iter_items uses this feature, causing the resulting StopIteration exception object to have a `value` attribute that refers to a separate second iterator that also yields no values (gitpython-developers#1779). From context, this behavior is clearly not the goal; a bare return statement should be used here (which has the same effect except for the `value` attribute of the StopIteration exception). The code had used a bare return prior to 82b131c (gitpython-developers#1282), when `return` was changed to `return iter([])`. That was part of a change that added numerous type annotations. It looks like it was either a mistake, or possibly an attempt to work around an old bug in a static type checker. This commit extends the test_iter_items_from_invalid_hash test to assert that the `value` attribute of the StopIteration is its usual default value of None. This commit only extends the test; it does not fix the bug.
This fixes the minor bug where a separate empty iterator was bound to the StopIteration exception raised as a result of returning from the generator function (gitpython-developers#1779). This change does not cause what exceptions are raised from GitPython code in any situations, nor how many items any iterators yield.
- Fill in the missing part of the explanation of why to favor iter_items over list_items in IterableObj and Iterable (gitpython-developers#1775). - Move the explanation of how subclasses must treat arguments from the list_items methods to the iter_items methods, because the iter_items methdos are the ones that are abstract and must be overridden by a well-behaved subclass, and also because, since the iter_items methods are preferred for use, they should be the place where less duplicated shared documentation resides. - Subtantially reword the existing documentation for clarity, especially regarding the signifance of extra args and kwargs. - Put the iter_items method before (i.e. above) the list_items method (in each of the IterableObj and Iterable classes), because that method is the one that should be used more often, and because it is also now the one with the more detailed docstring. - Remove and old comment on a return type that said exactly the exact same thing as the annotation. - In Iterable, note deprecation more consistently (and thus in more places). - Rewrite the IterableClassWatcher class docstring to explain exactly what that metaclass achieves.
EliahKagan
changed the title
Better document IterableObj.iter_items an slightly improve some subclasses
Better document IterableObj.iter_items and improve some subclasses
This was referenced
Dec 22, 2023EliahKagan added a commit to EliahKagan/GitPython that referenced this pull request
Dec 23, 2023This shortens the git.util.Iterable docstrings, removing most of the text duplicated from git.util.IterableObj docstrings and instead referring the reader to the specific corresponding methods in IterableObj. A comment about return types that appeared in both places but really only documented IterableObj is likewise removed from Iterable. This also reorders the classes, placing IterableObj before Iterable and its associated metaclass. This makes it easier to find, and may help remind users that IterableObj is the class they should use. These changes build on those in dfee31f (gitpython-developers#1780).
EliahKagan added a commit to EliahKagan/GitPython that referenced this pull request
Dec 24, 2023Three wrong references in docstrings to list_items methods had accidentally remained: one that was meant to be removed altogether, and two that were meant to be references to iter_items. This completes those changes, correcting the errors from dfee31f (gitpython-developers#1780) and 2b768c7 (gitpython-developers#1785) so the docstrings make sense and references to further information are to places with that information.
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Apr 6, 2024[](https://renovatebot.com) This PR contains the following updates: | Package | Change | Age | Adoption | Passing | Confidence | |---|---|---|---|---|---| | [GitPython](https://togithub.com/gitpython-developers/GitPython) | `==3.1.40` -> `==3.1.41` | [](https://docs.renovatebot.com/merge-confidence/) | [](https://docs.renovatebot.com/merge-confidence/) | [](https://docs.renovatebot.com/merge-confidence/) | [](https://docs.renovatebot.com/merge-confidence/) | --- > [!WARNING] > Some dependencies could not be looked up. Check the Dependency Dashboard for more information. ### GitHub Vulnerability Alerts #### [CVE-2024-22190](https://togithub.com/gitpython-developers/GitPython/security/advisories/GHSA-2mqj-m65w-jghx) ### Summary This issue exists because of an incomplete fix for CVE-2023-40590. On Windows, GitPython uses an untrusted search path if it uses a shell to run `git`, as well as when it runs `bash.exe` to interpret hooks. If either of those features are used on Windows, a malicious `git.exe` or `bash.exe` may be run from an untrusted repository. ### Details Although GitPython often avoids executing programs found in an untrusted search path since 3.1.33, two situations remain where this still occurs. Either can allow arbitrary code execution under some circumstances. #### When a shell is used GitPython can be told to run `git` commands through a shell rather than as direct subprocesses, by passing `shell=True` to any method that accepts it, or by both setting `Git.USE_SHELL = True` and not passing `shell=False`. Then the Windows `cmd.exe` shell process performs the path search, and GitPython does not prevent that shell from finding and running `git` in the current directory. When GitPython runs `git` directly rather than through a shell, the GitPython process performs the path search, and currently omits the current directory by setting `NoDefaultCurrentDirectoryInExePath` in its own environment during the `Popen` call. Although the `cmd.exe` shell will honor this environment variable when present, GitPython does not currently pass it into the shell subprocess's environment. Furthermore, because GitPython sets the subprocess CWD to the root of a repository's working tree, using a shell will run a malicious `git.exe` in an untrusted repository even if GitPython itself is run from a trusted location. This also applies if `Git.execute` is called directly with `shell=True` (or after `Git.USE_SHELL = True`) to run any command. #### When hook scripts are run On Windows, GitPython uses `bash.exe` to run hooks that appear to be scripts. However, unlike when running `git`, no steps are taken to avoid finding and running `bash.exe` in the current directory. This allows the author of an untrusted fork or branch to cause a malicious `bash.exe` to be run in some otherwise safe workflows. An example of such a scenario is if the user installs a trusted hook while on a trusted branch, then switches to an untrusted feature branch (possibly from a fork) to review proposed changes. If the untrusted feature branch contains a malicious `bash.exe` and the user's current working directory is the working tree, and the user performs an action that runs the hook, then although the hook itself is uncorrupted, it runs with the malicious `bash.exe`. Note that, while `bash.exe` is a shell, this is a separate scenario from when `git` is run using the unrelated Windows `cmd.exe` shell. ### PoC On Windows, create a `git.exe` file in a repository. Then create a `Repo` object, and call any method through it (directly or indirectly) that supports the `shell` keyword argument with `shell=True`: ```powershell mkdir testrepo git init testrepo cp ... testrepo git.exe # Replace "..." with any executable of choice. python -c "import git; print(git.Repo('testrepo').git.version(shell=True))" ``` The `git.exe` executable in the repository directory will be run. Or use no `Repo` object, but do it from the location with the `git.exe`: ```powershell cd testrepo python -c "import git; print(git.Git().version(shell=True))" ``` The `git.exe` executable in the current directory will be run. For the scenario with hooks, install a hook in a repository, create a `bash.exe` file in the current directory, and perform an operation that causes GitPython to attempt to run the hook: ```powershell mkdir testrepo cd testrepo git init mv .git/hooks/pre-commit.sample .git/hooks/pre-commit cp ... bash.exe # Replace "..." with any executable of choice. echo "Some text" >file.txt git add file.txt python -c "import git; git.Repo().index.commit('Some message')" ``` The `bash.exe` executable in the current directory will be run. ### Impact The greatest impact is probably in applications that set `Git.USE_SHELL = True` for historical reasons. (Undesired console windows had, in the past, been created in some kinds of applications, when it was not used.) Such an application may be vulnerable to arbitrary code execution from a malicious repository, even with no other exacerbating conditions. This is to say that, if a shell is used to run `git`, the full effect of CVE-2023-40590 is still present. Furthermore, as noted above, running the application itself from a trusted directory is not a sufficient mitigation. An application that does not direct GitPython to use a shell to run `git` subprocesses thus avoids most of the risk. However, there is no such straightforward way to prevent GitPython from running `bash.exe` to interpret hooks. So while the conditions needed for that to be exploited are more involved, it may be harder to mitigate decisively prior to patching. ### Possible solutions A straightforward approach would be to address each bug directly: - When a shell is used, pass `NoDefaultCurrentDirectoryInExePath` into the subprocess environment, because in that scenario the subprocess is the `cmd.exe` shell that itself performs the path search. - Set `NoDefaultCurrentDirectoryInExePath` in the GitPython process environment during the `Popen` call made to run hooks with a `bash.exe` subprocess. These need only be done on Windows. --- ### Release Notes <details> <summary>gitpython-developers/GitPython (GitPython)</summary> ### [`v3.1.41`](https://togithub.com/gitpython-developers/GitPython/releases/tag/3.1.41): - fix Windows security issue [Compare Source](https://togithub.com/gitpython-developers/GitPython/compare/3.1.40...3.1.41) The details about the Windows security issue [can be found in this advisory](https://togithub.com/gitpython-developers/GitPython/security/advisories/GHSA-2mqj-m65w-jghx). Special thanks go to [@​EliahKagan](https://togithub.com/EliahKagan) who reported the issue and fixed it in a single stroke, while being responsible for an incredible amount of improvements that he contributed over the last couple of months ❤️. #### What's Changed - Add `__all__` in git.exc by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1719](https://togithub.com/gitpython-developers/GitPython/pull/1719) - Set submodule update cadence to weekly by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1721](https://togithub.com/gitpython-developers/GitPython/pull/1721) - Never modify sys.path by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1720](https://togithub.com/gitpython-developers/GitPython/pull/1720) - Bump git/ext/gitdb from `8ec2390` to `ec58b7e` by [@​dependabot](https://togithub.com/dependabot) in [https://github.com/gitpython-developers/GitPython/pull/1722](https://togithub.com/gitpython-developers/GitPython/pull/1722) - Revise comments, docstrings, some messages, and a bit of code by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1725](https://togithub.com/gitpython-developers/GitPython/pull/1725) - Use zero-argument super() by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1726](https://togithub.com/gitpython-developers/GitPython/pull/1726) - Remove obsolete note in \_iter_packed_refs by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1727](https://togithub.com/gitpython-developers/GitPython/pull/1727) - Reorganize test_util and make xfail marks precise by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1729](https://togithub.com/gitpython-developers/GitPython/pull/1729) - Clarify license and make module top comments more consistent by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1730](https://togithub.com/gitpython-developers/GitPython/pull/1730) - Deprecate compat.is\_<platform>, rewriting all uses by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1732](https://togithub.com/gitpython-developers/GitPython/pull/1732) - Revise and restore some module docstrings by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1735](https://togithub.com/gitpython-developers/GitPython/pull/1735) - Make the rmtree callback Windows-only by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1739](https://togithub.com/gitpython-developers/GitPython/pull/1739) - List all non-passing tests in test summaries by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1740](https://togithub.com/gitpython-developers/GitPython/pull/1740) - Document some minor subtleties in test_util.py by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1749](https://togithub.com/gitpython-developers/GitPython/pull/1749) - Always read metadata files as UTF-8 in setup.py by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1748](https://togithub.com/gitpython-developers/GitPython/pull/1748) - Test native Windows on CI by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1745](https://togithub.com/gitpython-developers/GitPython/pull/1745) - Test macOS on CI by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1752](https://togithub.com/gitpython-developers/GitPython/pull/1752) - Let close_fds be True on all platforms by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1753](https://togithub.com/gitpython-developers/GitPython/pull/1753) - Fix IndexFile.from_tree on Windows by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1751](https://togithub.com/gitpython-developers/GitPython/pull/1751) - Remove unused TASKKILL fallback in AutoInterrupt by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1754](https://togithub.com/gitpython-developers/GitPython/pull/1754) - Don't return with operand when conceptually void by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1755](https://togithub.com/gitpython-developers/GitPython/pull/1755) - Group .gitignore entries by purpose by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1758](https://togithub.com/gitpython-developers/GitPython/pull/1758) - Adding dubious ownership handling by [@​marioaag](https://togithub.com/marioaag) in [https://github.com/gitpython-developers/GitPython/pull/1746](https://togithub.com/gitpython-developers/GitPython/pull/1746) - Avoid brittle assumptions about preexisting temporary files in tests by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1759](https://togithub.com/gitpython-developers/GitPython/pull/1759) - Overhaul noqa directives by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1760](https://togithub.com/gitpython-developers/GitPython/pull/1760) - Clarify some Git.execute kill_after_timeout limitations by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1761](https://togithub.com/gitpython-developers/GitPython/pull/1761) - Bump actions/setup-python from 4 to 5 by [@​dependabot](https://togithub.com/dependabot) in [https://github.com/gitpython-developers/GitPython/pull/1763](https://togithub.com/gitpython-developers/GitPython/pull/1763) - Don't install black on Cygwin by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1766](https://togithub.com/gitpython-developers/GitPython/pull/1766) - Extract all "import gc" to module level by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1765](https://togithub.com/gitpython-developers/GitPython/pull/1765) - Extract remaining local "import gc" to module level by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1768](https://togithub.com/gitpython-developers/GitPython/pull/1768) - Replace xfail with gc.collect in TestSubmodule.test_rename by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1767](https://togithub.com/gitpython-developers/GitPython/pull/1767) - Enable CodeQL by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1769](https://togithub.com/gitpython-developers/GitPython/pull/1769) - Replace some uses of the deprecated mktemp function by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1770](https://togithub.com/gitpython-developers/GitPython/pull/1770) - Bump github/codeql-action from 2 to 3 by [@​dependabot](https://togithub.com/dependabot) in [https://github.com/gitpython-developers/GitPython/pull/1773](https://togithub.com/gitpython-developers/GitPython/pull/1773) - Run some Windows environment variable tests only on Windows by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1774](https://togithub.com/gitpython-developers/GitPython/pull/1774) - Fix TemporaryFileSwap regression where file_path could not be Path by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1776](https://togithub.com/gitpython-developers/GitPython/pull/1776) - Improve hooks tests by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1777](https://togithub.com/gitpython-developers/GitPython/pull/1777) - Fix if items of Index is of type PathLike by [@​stegm](https://togithub.com/stegm) in [https://github.com/gitpython-developers/GitPython/pull/1778](https://togithub.com/gitpython-developers/GitPython/pull/1778) - Better document IterableObj.iter_items and improve some subclasses by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1780](https://togithub.com/gitpython-developers/GitPython/pull/1780) - Revert "Don't install black on Cygwin" by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1783](https://togithub.com/gitpython-developers/GitPython/pull/1783) - Add missing pip in $PATH on Cygwin CI by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1784](https://togithub.com/gitpython-developers/GitPython/pull/1784) - Shorten Iterable docstrings and put IterableObj first by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1785](https://togithub.com/gitpython-developers/GitPython/pull/1785) - Fix incompletely revised Iterable/IterableObj docstrings by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1786](https://togithub.com/gitpython-developers/GitPython/pull/1786) - Pre-deprecate setting Git.USE_SHELL by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1782](https://togithub.com/gitpython-developers/GitPython/pull/1782) - Deprecate Git.USE_SHELL by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1787](https://togithub.com/gitpython-developers/GitPython/pull/1787) - In handle_process_output don't forward finalizer result by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1788](https://togithub.com/gitpython-developers/GitPython/pull/1788) - Fix mypy warning "Missing return statement" by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1789](https://togithub.com/gitpython-developers/GitPython/pull/1789) - Fix two remaining Windows untrusted search path cases by [@​EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1792](https://togithub.com/gitpython-developers/GitPython/pull/1792) #### New Contributors - [@​marioaag](https://togithub.com/marioaag) made their first contribution in [https://github.com/gitpython-developers/GitPython/pull/1746](https://togithub.com/gitpython-developers/GitPython/pull/1746) - [@​stegm](https://togithub.com/stegm) made their first contribution in [https://github.com/gitpython-developers/GitPython/pull/1778](https://togithub.com/gitpython-developers/GitPython/pull/1778) **Full Changelog**: gitpython-developers/GitPython@3.1.40...3.1.41 </details> --- ### Configuration 📅 **Schedule**: Branch creation - "" (UTC), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Disabled by config. 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