post-process: substitute exits for exceptions (#299)

* post-process: substitute exits for exceptions

The post-processing logic is getting larger and makes sense to make it
more Pythonian. Switching calls to exit for python exceptions to support
this.

* nit

Author: DavidKorczynski

post-processing/exceptions.py

@@ -0,0 +1,30 @@
+# Copyright 2022 Fuzz Introspector Authors
+#
+# 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.
+"""Exceptions used throughout the package."""
+
+
+class FuzzIntrospectorError(Exception):
+    """Base error"""
+
+
+class CalltreeError(FuzzIntrospectorError):
+    """Error for when dealing with calltrees"""
+
+
+class AnalysisError(FuzzIntrospectorError):
+    """Error for analysis logic"""
+
+
+class DataLoaderError(FuzzIntrospectorError):
+    """Error for handling data loader issues"""

post-processing/fuzz_analysis.py

@@ -29,6 +29,8 @@
 import fuzz_data_loader
 from enum import Enum
 
+from exceptions import AnalysisError
+
 logger = logging.getLogger(name=__name__)
 logger.setLevel(logging.INFO)
 
@@ -142,7 +144,9 @@ def callstack_set_curr_node(n, name, c):
             if demangled_name != "LLVMFuzzerTestOneInput" and "TestOneInput" not in demangled_name:
                 logger.info("Unexpected first node in the calltree.")
                 logger.info(f"Found: {demangled_name}")
-                exit(1)
+                raise AnalysisError(
+                    "First node in calltree seems to be non-fuzzer function"
+                )
             coverage_data = profile.coverage.get_hit_details("LLVMFuzzerTestOneInput")
             if len(coverage_data) == 0:
                 logger.error("There is no coverage data (not even all negative).")
@@ -165,7 +169,9 @@ def callstack_set_curr_node(n, name, c):
             node.cov_parent = callstack_get_parent(node, callstack)
         else:
             logger.error("A node should either be the first or it must have a parent")
-            exit(1)
+            raise AnalysisError(
+                "A node should either be the first or it must have a parent"
+            )
         node.cov_hitcount = node_hitcount
 
         # Map hitcount to color of target.

post-processing/fuzz_cfg_load.py

@@ -20,6 +20,8 @@
     Optional
 )
 
+from exceptions import CalltreeError
+
 logger = logging.getLogger(name=__name__)
 
 
@@ -72,7 +74,8 @@ def extract_all_callsites_recursive(
 def extract_all_callsites(calltree: Optional[CalltreeCallsite]) -> List[CalltreeCallsite]:
     if calltree is None:
         logger.error("Trying to extract from a None calltree")
-        exit(1)
+        raise CalltreeError("Calltree is None")
+
     cs_list: List[CalltreeCallsite] = []
     extract_all_callsites_recursive(calltree, cs_list)
     return cs_list

post-processing/fuzz_data_loader.py

@@ -32,6 +32,8 @@
 import fuzz_cov_load
 import fuzz_utils
 
+from exceptions import DataLoaderError
+
 logger = logging.getLogger(name=__name__)
 logger.setLevel(logging.INFO)
 
@@ -652,7 +654,9 @@ def add_func_to_reached_and_clone(merged_profile_old: MergedProjectProfile,
 
     if merged_profile.all_functions[func_to_add.function_name].hitcount == 0:
         logger.info("Error. Hitcount did not get set for some reason. Exiting")
-        exit(1)
+        raise DataLoaderError(
+            "Hitcount did not get set for some reason"
+        )
 
     return merged_profile