Migrated fuzzing harnesses and build script to fuzzing dir

src/icalendar/fuzzing/build.sh

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+#!/bin/bash -eu
+# Copyright 2023 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+################################################################################
+
+cd "$SRC"/icalendar
+pip3 install .
+
+# Build fuzzers in $OUT
+for fuzzer in $(find $SRC -name 'src/icalendar/fuzzing/*_fuzzer.py');do
+  compile_python_fuzzer "$fuzzer" 
+done
+zip -q $OUT/ical_fuzzer_seed_corpus.zip $SRC/corpus/*

src/icalendar/fuzzing/enhanced_fdp.py

@@ -0,0 +1,111 @@
+# Copyright 2021 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+################################################################################
+"""
+Defines the EnhancedFuzzedDataProvider
+"""
+from contextlib import contextmanager
+from enum import Enum
+from io import BytesIO, StringIO
+from tempfile import NamedTemporaryFile
+from typing import Optional, Union
+
+from atheris import FuzzedDataProvider
+
+
+class EnhancedFuzzedDataProvider(FuzzedDataProvider):
+    """
+    Extends the functionality of FuzzedDataProvider
+    """
+
+    def _consume_random_count(self) -> int:
+        """
+        :return: A count of bytes that is strictly in range 0<=n<=remaining_bytes
+        """
+        return self.ConsumeIntInRange(0, self.remaining_bytes())
+
+    def _consume_file_data(self, all_data: bool, as_bytes: bool) -> Union[bytes, str]:
+        """
+        Consumes data for a file
+        :param all_data: Whether to consume all remaining bytes from the buffer
+        :param as_bytes: Consumed output is bytes if true, otherwise a string
+        :return: The consumed output
+        """
+        if all_data:
+            file_data = self.ConsumeRemainingBytes() if as_bytes else self.ConsumeRemainingString()
+        else:
+            file_data = self.ConsumeRandomBytes() if as_bytes else self.ConsumeRandomString()
+
+        return file_data
+
+    def ConsumeRandomBytes(self) -> bytes:
+        """
+        Consume a 'random' count of the remaining bytes
+        :return: 0<=n<=remaining_bytes bytes
+        """
+        return self.ConsumeBytes(self._consume_random_count())
+
+    def ConsumeRemainingBytes(self) -> bytes:
+        """
+        :return: The remaining buffer
+        """
+        return self.ConsumeBytes(self.remaining_bytes())
+
+    def ConsumeRandomString(self) -> str:
+        """
+        Consume a 'random' length string, excluding surrogates
+        :return: The string
+        """
+        return self.ConsumeUnicodeNoSurrogates(self._consume_random_count())
+
+    def ConsumeRemainingString(self) -> str:
+        """
+        :return: The remaining buffer, as a string without surrogates
+        """
+        return self.ConsumeUnicodeNoSurrogates(self.remaining_bytes())
+
+    def PickValueInEnum(self, enum):
+        return self.PickValueInList([e.value for e in enum])
+
+    @contextmanager
+    def ConsumeMemoryFile(self, all_data: bool, as_bytes: bool) -> Union[BytesIO, StringIO]:
+        """
+        Consumes a file-like object, that resides entirely in memory
+        :param all_data: Whether to populate the file with all remaining data or not
+        :param as_bytes: Whether the file should hold bytes or strings
+        :return: The in-memory file
+        """
+        file_data = self._consume_file_data(all_data, as_bytes)
+        file = BytesIO(file_data) if as_bytes else StringIO(file_data)
+        yield file
+        file.close()
+
+    @contextmanager
+    def ConsumeTemporaryFile(self, all_data: bool, as_bytes: bool, suffix: Optional[str] = None) -> str:
+        """
+        Consumes a temporary file, handling its deletion
+        :param all_data: Whether to populate the file with all remaining data or not
+        :param as_bytes: Whether the file should hold bytes or strings
+        :param suffix: A suffix to use for the generated file, e.g. 'txt'
+        :return: The path to the temporary file
+        """
+        file_data = self._consume_file_data(all_data, as_bytes)
+        mode = 'w+b' if as_bytes else 'w+'
+        tfile = NamedTemporaryFile(mode=mode, suffix=suffix)
+        tfile.write(file_data)
+        tfile.seek(0)
+        tfile.flush()
+        yield tfile.name
+        tfile.close()

src/icalendar/fuzzing/ical_fuzzer.py

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+#!/usr/bin/python3
+# Copyright 2023 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+################################################################################
+import atheris
+import sys
+
+with atheris.instrument_imports(include=['icalendar']):
+    from icalendar import Calendar
+
+from enhanced_fdp import EnhancedFuzzedDataProvider
+
+
+def TestOneInput(data):
+    fdp = EnhancedFuzzedDataProvider(data)
+    try:
+        Calendar.from_ical(fdp.ConsumeRemainingString())
+        for event in Calendar.walk('VEVENT'):
+            event.to_ical().decode('utf-8')
+    except ValueError as e:
+        if "component" in str(e) or "parse" in str(e) or "Expected datetime" in str(e):
+            return -1
+        raise e
+    except IndexError:
+        return -1
+
+
+def main():
+    atheris.Setup(sys.argv, TestOneInput)
+    atheris.Fuzz()
+
+
+if __name__ == "__main__":
+    main()