Introduce a new class `SpdxLicenseExpressionCreator`, responsible for
converting license texts extracted from packages, into an SPDX-compliant
license expressions. If the `license_expression` Python package is
available on the system, it is used to determine the license text
extracted from a package is a valid SPDX license expression. If it is,
it's returned as is back to the caller. If it is not, or of the package
is not available on the system, the license text is wrapped in a
`ExtractedLicensingInfo` instance.
The `SpdxLicenseExpressionCreator` object keeps track of all generated
`ExtractedLicensingInfo` instances and de-duplicates them based on the
license text. This means that if two packages use the same
SPDX-non-compliant license text, they will be wrapped by an
`ExtractedLicensingInfo` instance with the same `LicenseRef-` ID.
The reason for fallback when `license_expression` package is not
available is that it is not available on RHEL and CentOS Stream. This
implementation allows us to ship the functionality in RHEL and
optionally enabling it by installing `license_expression` from a 3rd
party repository. In any case, the generated SBOM document will always
contain valid SPDX license expressions.
Extend unit tests to cover the newly added functionality.
Signed-off-by: Tomáš Hozza <thozza@redhat.com>
FIXUP: sbom/spdx: use compliant license expressions
Signed-off-by: Tomáš Hozza <thozza@redhat.com>
