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

[Gabriele Monaco <gmonaco@redhat.com>]

On Wed, 2026-02-04 at 11:42 -0300, Wander Lairson Costa wrote:
> 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>

Looks very good, thanks.
Now I wonder though why is LTL not included in the change. ltl2ba.py raises a
few ValueError that should probably be treated just like these AutomataError.
You could either create a new exception class or share the same for all model
errors (DA and LTL).

What do you think?

Thanks,
Gabriele

> ---
>  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)