Commit 9abb3549 authored by Chuck Lever's avatar Chuck Lever
Browse files

xdrgen: Improve parse error reporting 



The current verbose Lark exception output makes it difficult to
quickly identify and fix syntax errors in XDR specifications. Users
must wade through hundreds of lines of cascading errors to find the
root cause.

Replace this with concise, compiler-style error messages showing
file, line, column, the unexpected token, and the source line with
a caret pointing to the error location.

Before:
  Unexpected token Token('__ANON_1', '+1') at line 14, column 35.
  Expected one of:
          * SEMICOLON
  Previous tokens: [Token('__ANON_0', 'LM_MAXSTRLEN')]
  [hundreds more cascading errors...]

After:
  file.x:14:35: parse error
  Unexpected number '+1'

      const LM_MAXNAMELEN = LM_MAXSTRLEN+1;
                                        ^

The error handler now raises XdrParseError on the first error,
preventing cascading messages that obscure the root cause.

Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent eb1f3b55

tools/net/sunrpc/xdrgen/subcmds/declarations.py

+8 −8
Original line number Diff line number Diff line
@@ -8,7 +8,6 @@ import logging 


from argparse import Namespace

from lark import logger

from lark.exceptions import UnexpectedInput



from generators.constant import XdrConstantGenerator

from generators.enum import XdrEnumGenerator
@@ -24,6 +23,7 @@ from xdr_ast import transform_parse_tree, _RpcProgram, Specification 
from xdr_ast import _XdrConstant, _XdrEnum, _XdrPointer

from xdr_ast import _XdrTypedef, _XdrStruct, _XdrUnion

from xdr_parse import xdr_parser, set_xdr_annotate

from xdr_parse import make_error_handler, XdrParseError



logger.setLevel(logging.INFO)
@@ -50,19 +50,19 @@ def emit_header_declarations( 
        gen.emit_declaration(definition.value)





def handle_parse_error(e: UnexpectedInput) -> bool:

    """Simple parse error reporting, no recovery attempted"""

    print(e)

    return True





def subcmd(args: Namespace) -> int:

    """Generate definitions and declarations"""



    set_xdr_annotate(args.annotate)

    parser = xdr_parser()

    with open(args.filename, encoding="utf-8") as f:

        parse_tree = parser.parse(f.read(), on_error=handle_parse_error)

        source = f.read()

        try:

            parse_tree = parser.parse(

                source, on_error=make_error_handler(source, args.filename)

            )

        except XdrParseError:

            return 1

        ast = transform_parse_tree(parse_tree)



        gen = XdrHeaderTopGenerator(args.language, args.peer)

tools/net/sunrpc/xdrgen/subcmds/definitions.py

+8 −8
Original line number Diff line number Diff line
@@ -8,7 +8,6 @@ import logging 


from argparse import Namespace

from lark import logger

from lark.exceptions import UnexpectedInput



from generators.constant import XdrConstantGenerator

from generators.enum import XdrEnumGenerator
@@ -24,6 +23,7 @@ from xdr_ast import transform_parse_tree, Specification 
from xdr_ast import _RpcProgram, _XdrConstant, _XdrEnum, _XdrPointer

from xdr_ast import _XdrTypedef, _XdrStruct, _XdrUnion

from xdr_parse import xdr_parser, set_xdr_annotate

from xdr_parse import make_error_handler, XdrParseError



logger.setLevel(logging.INFO)
@@ -69,19 +69,19 @@ def emit_header_maxsize(root: Specification, language: str, peer: str) -> None: 
        gen.emit_maxsize(definition.value)





def handle_parse_error(e: UnexpectedInput) -> bool:

    """Simple parse error reporting, no recovery attempted"""

    print(e)

    return True





def subcmd(args: Namespace) -> int:

    """Generate definitions"""



    set_xdr_annotate(args.annotate)

    parser = xdr_parser()

    with open(args.filename, encoding="utf-8") as f:

        parse_tree = parser.parse(f.read(), on_error=handle_parse_error)

        source = f.read()

        try:

            parse_tree = parser.parse(

                source, on_error=make_error_handler(source, args.filename)

            )

        except XdrParseError:

            return 1

        ast = transform_parse_tree(parse_tree)



        gen = XdrHeaderTopGenerator(args.language, args.peer)

tools/net/sunrpc/xdrgen/subcmds/lint.py

+8 −9
Original line number Diff line number Diff line
@@ -8,26 +8,25 @@ import logging 


from argparse import Namespace

from lark import logger

from lark.exceptions import UnexpectedInput



from xdr_parse import xdr_parser

from xdr_parse import xdr_parser, make_error_handler, XdrParseError

from xdr_ast import transform_parse_tree



logger.setLevel(logging.DEBUG)





def handle_parse_error(e: UnexpectedInput) -> bool:

    """Simple parse error reporting, no recovery attempted"""

    print(e)

    return True





def subcmd(args: Namespace) -> int:

    """Lexical and syntax check of an XDR specification"""



    parser = xdr_parser()

    with open(args.filename, encoding="utf-8") as f:

        parse_tree = parser.parse(f.read(), on_error=handle_parse_error)

        source = f.read()

        try:

            parse_tree = parser.parse(

                source, on_error=make_error_handler(source, args.filename)

            )

        except XdrParseError:

            return 1

        transform_parse_tree(parse_tree)



    return 0

tools/net/sunrpc/xdrgen/subcmds/source.py

+8 −8
Original line number Diff line number Diff line
@@ -8,7 +8,6 @@ import logging 


from argparse import Namespace

from lark import logger

from lark.exceptions import UnexpectedInput



from generators.source_top import XdrSourceTopGenerator

from generators.enum import XdrEnumGenerator
@@ -23,6 +22,7 @@ from xdr_ast import _XdrAst, _XdrEnum, _XdrPointer 
from xdr_ast import _XdrStruct, _XdrTypedef, _XdrUnion



from xdr_parse import xdr_parser, set_xdr_annotate

from xdr_parse import make_error_handler, XdrParseError



logger.setLevel(logging.INFO)
@@ -92,19 +92,19 @@ def generate_client_source(filename: str, root: Specification, language: str) -> 
    # cel: todo: client needs PROC macros





def handle_parse_error(e: UnexpectedInput) -> bool:

    """Simple parse error reporting, no recovery attempted"""

    print(e)

    return True





def subcmd(args: Namespace) -> int:

    """Generate encoder and decoder functions"""



    set_xdr_annotate(args.annotate)

    parser = xdr_parser()

    with open(args.filename, encoding="utf-8") as f:

        parse_tree = parser.parse(f.read(), on_error=handle_parse_error)

        source = f.read()

        try:

            parse_tree = parser.parse(

                source, on_error=make_error_handler(source, args.filename)

            )

        except XdrParseError:

            return 1

        ast = transform_parse_tree(parse_tree)

        match args.peer:

            case "server":

tools/net/sunrpc/xdrgen/xdr_parse.py

+86 −0
Original line number Diff line number Diff line
@@ -3,12 +3,40 @@ 


"""Common parsing code for xdrgen"""



import sys

from typing import Callable



from lark import Lark

from lark.exceptions import UnexpectedInput, UnexpectedToken





# Set to True to emit annotation comments in generated source

annotate = False



# Map internal Lark token names to human-readable names

TOKEN_NAMES = {

    "__ANON_0": "identifier",

    "__ANON_1": "number",

    "SEMICOLON": "';'",

    "LBRACE": "'{'",

    "RBRACE": "'}'",

    "LPAR": "'('",

    "RPAR": "')'",

    "LSQB": "'['",

    "RSQB": "']'",

    "LESSTHAN": "'<'",

    "MORETHAN": "'>'",

    "EQUAL": "'='",

    "COLON": "':'",

    "COMMA": "','",

    "STAR": "'*'",

    "$END": "end of file",

}





class XdrParseError(Exception):

    """Raised when XDR parsing fails"""





def set_xdr_annotate(set_it: bool) -> None:

    """Set 'annotate' if --annotate was specified on the command line"""
@@ -21,6 +49,64 @@ def get_xdr_annotate() -> bool: 
    return annotate





def make_error_handler(source: str, filename: str) -> Callable[[UnexpectedInput], bool]:

    """Create an error handler that reports the first parse error and aborts.



    Args:

        source: The XDR source text being parsed

        filename: The name of the file being parsed



    Returns:

        An error handler function for use with Lark's on_error parameter

    """

    lines = source.splitlines()



    def handle_parse_error(e: UnexpectedInput) -> bool:

        """Report a parse error with context and abort parsing"""

        line_num = e.line

        column = e.column

        line_text = lines[line_num - 1] if 0 < line_num <= len(lines) else ""



        # Build the error message

        msg_parts = [f"{filename}:{line_num}:{column}: parse error"]



        # Show what was found vs what was expected

        if isinstance(e, UnexpectedToken):

            token = e.token

            if token.type == "__ANON_0":

                found = f"identifier '{token.value}'"

            elif token.type == "__ANON_1":

                found = f"number '{token.value}'"

            else:

                found = f"'{token.value}'"

            msg_parts.append(f"Unexpected {found}")



            # Provide helpful expected tokens list

            expected = e.expected

            if expected:

                readable = [

                    TOKEN_NAMES.get(exp, exp.lower().replace("_", " "))

                    for exp in sorted(expected)

                ]

                if len(readable) == 1:

                    msg_parts.append(f"Expected {readable[0]}")

                elif len(readable) <= 4:

                    msg_parts.append(f"Expected one of: {', '.join(readable)}")

        else:

            msg_parts.append(str(e).split("\n")[0])



        # Show the offending line with a caret pointing to the error

        msg_parts.append("")

        msg_parts.append(f"    {line_text}")

        prefix = line_text[: column - 1].expandtabs()

        msg_parts.append(f"    {' ' * len(prefix)}^")



        sys.stderr.write("\n".join(msg_parts) + "\n")

        raise XdrParseError()



    return handle_parse_error





def xdr_parser() -> Lark:

    """Return a Lark parser instance configured with the XDR language grammar"""