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

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

On Thu, Feb 05, 2026 at 07:50:57AM +0100, Gabriele Monaco wrote:
> 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?

Good point. I am still learning the code base, I missed it. I will add
AutomataError to the of *ba.py files.

> 
> 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)