Better error handling for DEP5 parse errors

Before, the Debian Copyright object was created lazily. When it is first
needed, it is created. The Projects that were passed to other processes
did not yet have Copyright objects (because they weren't yet needed, and
can't be pickled). However, this sometimes resulted in every process
separately trying to parse the DEP5 file, and failing.

Now, the DEP5 file is parsed immediately instead of being lazily
created. We circumvent the pickling problem by unsetting the attribute
and re-parsing the file in the process. This is a bit stupid, but it
shouldn't result in errors if the DEP5 file is not changed in the
meantime.

Signed-off-by: Carmen Bianca BAKKER <carmenbianca@fsfe.org>

src/reuse/_util.py

@@ -242,15 +242,19 @@ def _parse_dep5(path: StrPath) -> Copyright:
         _LOGGER.debug(_("no '{}' file, or could not read it").format(path))
         raise
     except UnicodeError:
-        _LOGGER.exception(_("'{}' could not be parsed as utf-8").format(path))
+        _LOGGER.error(_("'{}' could not be parsed as utf-8").format(path))
         raise
-    # FIXME: I don't really expect the ValueError as a parsing error here. Let's
-    # make an upstream fix.
-    except (DebianError, ValueError):
-        _LOGGER.exception(
+    # TODO: Remove ValueError once
+    # <https://salsa.debian.org/python-debian-team/python-debian/-/merge_requests/123>
+    # is closed
+    except (DebianError, ValueError) as error:
+        _LOGGER.error(
             _(
-                "'{}' has syntax errors and could not be parsed as dep5 file"
-            ).format(path)
+                "'{path}' has syntax errors and could not be parsed as dep5"
+                " file. We received the following error message:\n"
+                "\n"
+                "{message}"
+            ).format(path=path, message=str(error))
         )
         raise
 

src/reuse/project.py

@@ -117,8 +117,11 @@ def from_directory(
             dep5_copyright: Optional[Copyright] = _parse_dep5(
                 root / ".reuse/dep5"
             )
-        except (OSError, DebianError, UnicodeError, ValueError):
+        except OSError:
             dep5_copyright = None
+        except (DebianError, UnicodeError, ValueError):
+            dep5_copyright = None
+            _LOGGER.warning(_("Proceeding as if no DEP5 file existed."))
 
         meson_build_path = root / "meson.build"
         uses_meson = meson_build_path.is_file()

src/reuse/report.py

@@ -2,11 +2,13 @@
 # SPDX-FileCopyrightText: 2022 Florian Snow <florian@familysnow.net>
 # SPDX-FileCopyrightText: 2022 Pietro Albini <pietro.albini@ferrous-systems.com>
 # SPDX-FileCopyrightText: 2023 Carmen Bianca BAKKER <carmenbianca@fsfe.org>
+# SPDX-FileCopyrightText: 2023 Coop IT Easy SC <https://coopiteasy.be>
 #
 # SPDX-License-Identifier: GPL-3.0-or-later
 
 """Module that contains reports about files and projects for linting."""
 
+import contextlib
 import datetime
 import logging
 import multiprocessing as mp
@@ -20,7 +22,7 @@
 from uuid import uuid4
 
 from . import __REUSE_version__, __version__
-from ._util import _LICENSING, StrPath, _checksum
+from ._util import _LICENSING, StrPath, _checksum, _parse_dep5
 from .project import Project, ReuseInfo
 
 _LOGGER = logging.getLogger(__name__)
@@ -34,11 +36,34 @@ class _MultiprocessingContainer:
     def __init__(
         self, project: Project, do_checksum: bool, add_license_concluded: bool
     ):
-        self.project = project
+        # TODO: We create a copy of the project in the following song-and-dance
+        # because the debian Copyright object cannot be pickled.
+        new_project = Project(
+            project.root,
+            vcs_strategy=project.vcs_strategy.__class__,
+            license_map=project.license_map,
+            licenses=project.licenses.copy(),
+            # Unset dep5_copyright
+            dep5_copyright=None,
+            include_submodules=project.include_submodules,
+            include_meson_subprojects=project.include_meson_subprojects,
+        )
+        new_project.licenses_without_extension = (
+            project.licenses_without_extension
+        )
+
+        self.project = new_project
+        # Remember that a dep5_copyright was (or was not) set prior.
+        self.has_dep5 = bool(project.dep5_copyright)
         self.do_checksum = do_checksum
         self.add_license_concluded = add_license_concluded
 
     def __call__(self, file_: StrPath) -> "_MultiprocessingResult":
+        if self.has_dep5:
+            with contextlib.suppress(Exception):
+                self.project.dep5_copyright = _parse_dep5(
+                    self.project.root / ".reuse/dep5"
+                )
         # pylint: disable=broad-except
         try:
             return _MultiprocessingResult(

tests/test_project.py

@@ -398,4 +398,28 @@ def test_relative_from_root_no_shared_base_path(empty_directory):
     ) == Path("src/hello.py")
 
 
+def test_duplicate_field_dep5(empty_directory, caplog):
+    """When a duplicate field is in a dep5 file, correctly handle errors."""
+    dep5_text = cleandoc(
+        """
+        Format: https://example.com/format/1.0
+        Upstream-Name: Some project
+        Upstream-Contact: Jane Doe
+        Source: https://example.com/
+
+        Files: foo.py
+        Copyright: 2017 Jane Doe
+        Copyright: 2017 John Doe
+        License: GPL-3.0-or-later
+        """
+    )
+    (empty_directory / ".reuse").mkdir()
+    (empty_directory / ".reuse/dep5").write_text(dep5_text)
+
+    project = Project.from_directory(empty_directory)
+    assert project.dep5_copyright is None
+    assert "syntax errors" in caplog.text
+    assert 'Duplicate field "Copyright"' in caplog.text
+
+
 # REUSE-IgnoreEnd