| Author: | Michał Górny |
|---|---|
| License: | 2-clause BSD license |
gemato provides a reference implementation of the full-tree Manifest checks as specified in GLEP 74 [1]. Originally focused on verifying the integrity and authenticity of the Gentoo ebuild repository, the tool can be used as a generic checksumming tool for any directory trees.
The basic purpose of gemato is to verify a directory tree against
Manifest files. In order to do that, run the gemato verify tool
against the requested directory:
gemato verify /var/db/repos/gentoo
The tool will automatically locate the top-level Manifest (if any) and check the specified directory recursively. If a subdirectory of the Manifest tree is specified, only the specified leaf is checked.
Creating a new Manifest tree can be accomplished using the gemato
create command against the top directory of the new Manifest tree:
gemato create -p ebuild /var/db/repos/gentoo
Note that for the create command you always need to specify either
a profile (via -p) or at least a hash set (via -H).
The gemato update command is provided to update an existing Manifest
tree:
gemato update -p ebuild /var/db/repos/gentoo
Alike create, update also requires specifying a profile (-p)
or a hash set (-H). The command locates the appropriate top-level
Manifest and updates the specified directory recursively.
If a subdirectory of the Manifest tree is specified, the entries
for the specified leaf and respective Manifest files are updated.
gemato provides a few other commands that could help debugging its behavior. Those are:
gemato hash -H <hashes> [<path>...]- Print hashes of the specified files in Manifest-like format. Used to verify that the hash backend works correctly.
gemato openpgp-verify [-K <key>] [<path>...]- Check OpenPGP signatures embedded in the specified files. Detached signatures are not supported. Used to verify that the OpenPGP backend works correctly.
gemato is written in Python and compatible with implementations of Python 2.7 and Python 3.4+. However, the support for Python 2 is considered 'best effort' and has some known limitations. For example, non-ASCII paths on command-line do not work.
gemato is currently tested against CPython 2.7, CPython 3.4 through 3.7, PyPy and PyPy3.
gemato depends only on standard Python library modules and their backports. The exact runtime dependencies depend on the standard library version used. Those are:
- Python 3.6+
- none -- only standard modules are used
- Python 3.4, 3.5
- Python 2.7
the above, plus:
Additionally, gemato calls the GnuPG executable to work with OpenPGP signatures. Both GnuPG 1.4.21 and 2.2+ are tested.
| [1] | GLEP 74: Full-tree verification using Manifest files (https://www.gentoo.org/glep/glep-0074.html) |
| [2] | BLAKE2 hash function extension module (https://pypi.python.org/pypi/pyblake2) (https://github.com/dchest/pyblake2) |
| [3] | SHA-3 (Keccak) for Python 2.7 - 3.5 (https://pypi.python.org/pypi/pysha3) (https://github.com/tiran/pysha3) |
| [4] | Read and write bzip2-compressed files (https://pypi.python.org/pypi/bz2file) (https://github.com/nvawda/bz2file) |
| [5] | Strictly speaking, Python 2.7 has a bz2 module.
However, this old module version does not support working on open
files nor multiple streams inside a single file. For this reason,
the external module is unconditionally required. |
| [6] | Backport of Python 3.3's 'lzma' module for XZ/LZMA compressed files (https://pypi.python.org/pypi/backports.lzma) (https://github.com/peterjc/backports.lzma) |