[PATCH v2 01/20] rv/rvgen: introduce AutomataError exception class

[Wander Lairson Costa <wander@redhat.com>]

Replace the generic except Exception block with a custom AutomataError
class that inherits from Exception. This provides more precise exception
handling for automata parsing and validation errors while avoiding
overly broad exception catches that could mask programming errors like
SyntaxError or TypeError.

The AutomataError class is raised when DOT file processing fails due to
invalid format, I/O errors, or malformed automaton definitions. The
main entry point catches this specific exception and provides a
user-friendly error message to stderr before exiting.

Signed-off-by: Wander Lairson Costa <wander@redhat.com>
---
 tools/verification/rvgen/__main__.py        |  9 ++++++---
 tools/verification/rvgen/rvgen/automata.py  | 17 ++++++++++++-----
 tools/verification/rvgen/rvgen/dot2c.py     |  4 ++--
 tools/verification/rvgen/rvgen/generator.py |  7 ++-----
 4 files changed, 22 insertions(+), 15 deletions(-)

diff --git a/tools/verification/rvgen/__main__.py b/tools/verification/rvgen/__main__.py
index fa6fc1f4de2f7..3bd438f8476ed 100644
--- a/tools/verification/rvgen/__main__.py
+++ b/tools/verification/rvgen/__main__.py
@@ -8,11 +8,15 @@
 # For further information, see:
 #   Documentation/trace/rv/da_monitor_synthesis.rst
 
+from sys import stderr
+
+
 if __name__ == '__main__':
     from rvgen.dot2k import dot2k
     from rvgen.generator import Monitor
     from rvgen.container import Container
     from rvgen.ltl2k import ltl2k
+    from rvgen.automata import AutomataError
     import argparse
     import sys
 
@@ -51,9 +55,8 @@ if __name__ == '__main__':
                 sys.exit(1)
         else:
             monitor = Container(vars(params))
-    except Exception as e:
-        print('Error: '+ str(e))
-        print("Sorry : :-(")
+    except AutomataError as e:
+        print(f"There was an error processing {params.spec}: {e}", file=sys.stderr)
         sys.exit(1)
 
     print("Writing the monitor into the directory %s" % monitor.name)
diff --git a/tools/verification/rvgen/rvgen/automata.py b/tools/verification/rvgen/rvgen/automata.py
index 3f06aef8d4fdc..6ecd5ccd8f3d3 100644
--- a/tools/verification/rvgen/rvgen/automata.py
+++ b/tools/verification/rvgen/rvgen/automata.py
@@ -10,6 +10,13 @@
 
 import ntpath
 
+class AutomataError(Exception):
+    """Exception raised for errors in automata parsing and validation.
+
+    Raised when DOT file processing fails due to invalid format, I/O errors,
+    or malformed automaton definitions.
+    """
+
 class Automata:
     """Automata class: Reads a dot file and part it as an automata.
 
@@ -32,11 +39,11 @@ class Automata:
         basename = ntpath.basename(self.__dot_path)
         if not basename.endswith(".dot") and not basename.endswith(".gv"):
             print("not a dot file")
-            raise Exception("not a dot file: %s" % self.__dot_path)
+            raise AutomataError("not a dot file: %s" % self.__dot_path)
 
         model_name = ntpath.splitext(basename)[0]
         if model_name.__len__() == 0:
-            raise Exception("not a dot file: %s" % self.__dot_path)
+            raise AutomataError("not a dot file: %s" % self.__dot_path)
 
         return model_name
 
@@ -45,8 +52,8 @@ class Automata:
         dot_lines = []
         try:
             dot_file = open(self.__dot_path)
-        except:
-            raise Exception("Cannot open the file: %s" % self.__dot_path)
+        except OSError as exc:
+            raise AutomataError(f"Cannot open the file: {self.__dot_path}") from exc
 
         dot_lines = dot_file.read().splitlines()
         dot_file.close()
@@ -55,7 +62,7 @@ class Automata:
         line = dot_lines[cursor].split()
 
         if (line[0] != "digraph") and (line[1] != "state_automaton"):
-            raise Exception("Not a valid .dot format: %s" % self.__dot_path)
+            raise AutomataError("Not a valid .dot format: %s" % self.__dot_path)
         else:
             cursor += 1
         return dot_lines
diff --git a/tools/verification/rvgen/rvgen/dot2c.py b/tools/verification/rvgen/rvgen/dot2c.py
index 06a26bf15a7e9..74147ae2942f9 100644
--- a/tools/verification/rvgen/rvgen/dot2c.py
+++ b/tools/verification/rvgen/rvgen/dot2c.py
@@ -13,7 +13,7 @@
 # For further information, see:
 #   Documentation/trace/rv/deterministic_automata.rst
 
-from .automata import Automata
+from .automata import Automata, AutomataError
 
 class Dot2c(Automata):
     enum_suffix = ""
@@ -71,7 +71,7 @@ class Dot2c(Automata):
             min_type = "unsigned int"
 
         if self.states.__len__() > 1000000:
-            raise Exception("Too many states: %d" % self.states.__len__())
+            raise AutomataError("Too many states: %d" % self.states.__len__())
 
         return min_type
 
diff --git a/tools/verification/rvgen/rvgen/generator.py b/tools/verification/rvgen/rvgen/generator.py
index 3441385c11770..a7bee6b1ea70c 100644
--- a/tools/verification/rvgen/rvgen/generator.py
+++ b/tools/verification/rvgen/rvgen/generator.py
@@ -51,10 +51,7 @@ class RVGenerator:
         raise FileNotFoundError("Could not find the rv directory, do you have the kernel source installed?")
 
     def _read_file(self, path):
-        try:
-            fd = open(path, 'r')
-        except OSError:
-            raise Exception("Cannot open the file: %s" % path)
+        fd = open(path, 'r')
 
         content = fd.read()
 
@@ -65,7 +62,7 @@ class RVGenerator:
         try:
             path = os.path.join(self.abs_template_dir, file)
             return self._read_file(path)
-        except Exception:
+        except OSError:
             # Specific template file not found. Try the generic template file in the template/
             # directory, which is one level up
             path = os.path.join(self.abs_template_dir, "..", file)
-- 
2.52.0