core: harden analysis against projects without fuzzers

src/fuzz_introspector/datatypes/project_profile.py

@@ -183,10 +183,17 @@ def get_function_summaries(self) -> Tuple[int, int, int, float, float]:
         reached_func_count = self._get_total_reached_function_count()
         unreached_func_count = self._get_total_unreached_function_count()
         total_functions = reached_func_count + unreached_func_count
-        reached_percentage = (float(reached_func_count) /
-                              float(total_functions)) * 100
-        unreached_percentage = (float(unreached_func_count) /
-                                float(total_functions)) * 100
+        try:
+            reached_percentage = (float(reached_func_count) /
+                                  float(total_functions)) * 100
+        except ZeroDivisionError:
+            reached_percentage = 0.0
+
+        try:
+            unreached_percentage = (float(unreached_func_count) /
+                                    float(total_functions)) * 100
+        except ZeroDivisionError:
+            unreached_percentage = 0.0
         return (total_functions, reached_func_count, unreached_func_count,
                 reached_percentage, unreached_percentage)
 
@@ -273,8 +280,11 @@ def reached_func_percentage(self):
         reached_func_count = self._get_total_reached_function_count()
         unreached_func_count = self._get_total_unreached_function_count()
         total_functions = reached_func_count + unreached_func_count
-        reached_percentage = (float(reached_func_count) /
-                              float(total_functions)) * 100
+        try:
+            reached_percentage = (float(reached_func_count) /
+                                  float(total_functions)) * 100
+        except ZeroDivisionError:
+            reached_percentage = 0.0
         return reached_percentage
 
     def get_profiles_coverage_files(self) -> List[str]:
@@ -377,7 +387,11 @@ def write_stats_to_summary_file(self) -> None:
          unreached_func_percentage) = self.get_function_summaries()
 
         covered_funcs = self.get_all_runtime_covered_functions()
-        cov_percentage = round(len(covered_funcs) / total_functions, 2) * 100.0
+        try:
+            cov_percentage = round(len(covered_funcs) / total_functions,
+                                   2) * 100.0
+        except ZeroDivisionError:
+            cov_percentage = 0.0
 
         json_report.add_project_key_value_to_report(
             "stats", {
@@ -411,6 +425,10 @@ def _set_basefolder(self) -> None:
                 continue
             all_strs.append(os.path.dirname(f.function_source_file))
 
+        if len(all_strs) == 0:
+            self.basefolder = ""
+            return
+
         self.basefolder = utils.longest_common_prefix(all_strs) + "/"
 
     def _get_total_unreached_function_count(self) -> int:

src/fuzz_introspector/html_helpers.py

@@ -325,7 +325,11 @@ def create_percentage_graph(title: str, numerator: int,
     """Creates a percentage tag within a <div> tag. This is used to show
     "how much X is of Y" for a {numerator, denominator} pair.
     """
-    percentage = round(float(numerator) / float(denominator), 2) * 100.0
+    try:
+        percentage = round(float(numerator) / float(denominator), 2) * 100.0
+    except ZeroDivisionError:
+        percentage = 0.0
+
     subtitle = f"{numerator} / {denominator}"
     return f"""<div style="flex:1; margin-right: 20px"class="report-box mt-0">
             <div style="font-weight: 600; text-align: center;">

src/fuzz_introspector/html_report.py

@@ -205,8 +205,11 @@ def create_boxed_top_summary_info(
                 title="No coverage data was found",
                 description=html_constants.WARNING_NO_COVERAGE))
     # Add coverage conclusion
-    coverage_percentage = float(
-        len(covered_funcs) / float(proj_profile.total_functions) * 100.0)
+    try:
+        coverage_percentage = float(
+            len(covered_funcs) / float(proj_profile.total_functions) * 100.0)
+    except ZeroDivisionError:
+        coverage_percentage = 0.0
     if coverage_percentage > 50.0:
         sentence = f"""Fuzzers reach {"%.5s%%"%(str(coverage_percentage))} code coverage."""
         conclusions.append(