Re: [PATCH] Sepolgen: improve parser error recovery

[Joshua Brindle <method@manicmethod.com>]

Karl MacMillan wrote:
> Sepolgen has long not recovered from parsing errors, leading to
> a blacklist of none bad modules in the source. I finally tracked
> down the problem (lexer state) and this patch fixes the problem
> by causing the lexer to be rebuilt on error.
> ---

So do the modules that were blacklisted still fail to parse and this 
just handles it by reinitializing the lexer and parser?

>   sepolgen/src/sepolgen/refparser.py |   28 ++++++++++++----------------
>   1 files changed, 12 insertions(+), 16 deletions(-)
>
> diff --git a/sepolgen/src/sepolgen/refparser.py
> b/sepolgen/src/sepolgen/refparser.py
> index 23beb39..5c5093c 100644
> --- a/sepolgen/src/sepolgen/refparser.py
> +++ b/sepolgen/src/sepolgen/refparser.py
> @@ -279,7 +279,7 @@ parse_file = ""
>   #     refpolicy.SupportMacros and should always be present during parsing
>   #     though it may not contain any macros.
>   spt = None
> -success=True
> +success = True
>
>   # utilities
>   def collect(stmts, parent, val=None):
> @@ -921,9 +921,7 @@ def p_optional_semi(p):
>   #
>
>   def p_error(tok):
> -    global error
> -    global parse_file
> -    global success
> +    global error, parse_file, success, parser
>       error = "%s: Syntax error on line %d %s [type=%s]" % (parse_file,
> tok.lineno, tok.value, tok.type)
>       print error
>       success = False
> @@ -939,6 +937,7 @@ parser = None
>   lexer = None
>   def create_globals(module, support, debug):
>       global parser, lexer, m, spt
> +
>       if not parser:
>           lexer = lex.lex()
>           parser = yacc.yacc(method="LALR", debug=debug, write_tables=0)
> @@ -955,17 +954,20 @@ def create_globals(module, support, debug):
>
>   def parse(text, module=None, support=None, debug=False):
>       create_globals(module, support, debug)
> -    lexer.lexdata = []
> -    lexer.lexpos = 0
> -    lexer.lineno = 1
> +    global error, parser, lexer, success
> +
> +    success = True
>
>       try:
> -        parser.parse(text, debug=debug)
> +        parser.parse(text, debug=debug, lexer=lexer)
>       except Exception, e:
> -        global error
> +        parser = None
> +        lexer = None
>           error = "internal parser error: %s" % str(e) + "\n" +
> traceback.format_exc()
>
> -    if error is not None:
> +    if not success:
> +        # force the parser and lexer to be rebuilt - we have some
> problems otherwise
> +        parser = None
>           msg = 'could not parse text: "%s"' % error
>           raise ValueError(msg)
>       return m
> @@ -973,15 +975,9 @@ def parse(text, module=None, support=None, debug=False):
>   def list_headers(root):
>       modules = []
>       support_macros = None
> -    blacklist = ["init.if", "inetd.if", "uml.if", "thunderbird.if"]
>
>       for dirpath, dirnames, filenames in os.walk(root):
>           for name in filenames:
> -            # FIXME: these make the parser barf in various
> unrecoverable ways, so we must skip
> -            # them.
> -            if name in blacklist:
> -                continue
> -
>               modname = os.path.splitext(name)
>               filename = os.path.join(dirpath, name)
>
> --
> 1.6.6
>
> --
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