linux/tools/net/sunrpc/xdrgen/generators/union.py
Chuck Lever 4b132aacb0 tools: Add xdrgen
Add a Python-based tool for translating XDR specifications into XDR
encoder and decoder functions written in the Linux kernel's C coding
style. The generator attempts to match the usual C coding style of
the Linux kernel's SunRPC consumers.

This approach is similar to the netlink code generator in
tools/net/ynl .

The maintainability benefits of machine-generated XDR code include:

- Stronger type checking
- Reduces the number of bugs introduced by human error
- Makes the XDR code easier to audit and analyze
- Enables rapid prototyping of new RPC-based protocols
- Hardens the layering between protocol logic and marshaling
- Makes it easier to add observability on demand
- Unit tests might be built for both the tool and (automatically)
  for the generated code

In addition, converting the XDR layer to use memory-safe languages
such as Rust will be easier if much of the code can be converted
automatically.

Tested-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2024-09-20 19:31:39 -04:00

244 lines
8.0 KiB
Python

#!/usr/bin/env python3
# ex: set filetype=python:
"""Generate code to handle XDR unions"""
from jinja2 import Environment
from generators import SourceGenerator
from generators import create_jinja2_environment, get_jinja2_template
from xdr_ast import _XdrBasic, _XdrUnion, _XdrVoid
from xdr_ast import _XdrDeclaration, _XdrCaseSpec, public_apis
def emit_union_declaration(environment: Environment, node: _XdrUnion) -> None:
"""Emit one declaration pair for an XDR union type"""
if node.name in public_apis:
template = get_jinja2_template(environment, "declaration", "close")
print(template.render(name=node.name))
def emit_union_switch_spec_definition(
environment: Environment, node: _XdrDeclaration
) -> None:
"""Emit a definition for an XDR union's discriminant"""
assert isinstance(node, _XdrBasic)
template = get_jinja2_template(environment, "definition", "switch_spec")
print(
template.render(
name=node.name,
type=node.spec.type_name,
classifier=node.spec.c_classifier,
)
)
def emit_union_case_spec_definition(
environment: Environment, node: _XdrDeclaration
) -> None:
"""Emit a definition for an XDR union's case arm"""
if isinstance(node.arm, _XdrVoid):
return
assert isinstance(node.arm, _XdrBasic)
template = get_jinja2_template(environment, "definition", "case_spec")
print(
template.render(
name=node.arm.name,
type=node.arm.spec.type_name,
classifier=node.arm.spec.c_classifier,
)
)
def emit_union_definition(environment: Environment, node: _XdrUnion) -> None:
"""Emit one XDR union definition"""
template = get_jinja2_template(environment, "definition", "open")
print(template.render(name=node.name))
emit_union_switch_spec_definition(environment, node.discriminant)
for case in node.cases:
emit_union_case_spec_definition(environment, case)
if node.default is not None:
emit_union_case_spec_definition(environment, node.default)
template = get_jinja2_template(environment, "definition", "close")
print(template.render(name=node.name))
def emit_union_switch_spec_decoder(
environment: Environment, node: _XdrDeclaration
) -> None:
"""Emit a decoder for an XDR union's discriminant"""
assert isinstance(node, _XdrBasic)
template = get_jinja2_template(environment, "decoder", "switch_spec")
print(template.render(name=node.name, type=node.spec.type_name))
def emit_union_case_spec_decoder(environment: Environment, node: _XdrCaseSpec) -> None:
"""Emit decoder functions for an XDR union's case arm"""
if isinstance(node.arm, _XdrVoid):
return
template = get_jinja2_template(environment, "decoder", "case_spec")
for case in node.values:
print(template.render(case=case))
assert isinstance(node.arm, _XdrBasic)
template = get_jinja2_template(environment, "decoder", node.arm.template)
print(
template.render(
name=node.arm.name,
type=node.arm.spec.type_name,
classifier=node.arm.spec.c_classifier,
)
)
template = get_jinja2_template(environment, "decoder", "break")
print(template.render())
def emit_union_default_spec_decoder(environment: Environment, node: _XdrUnion) -> None:
"""Emit a decoder function for an XDR union's default arm"""
default_case = node.default
# Avoid a gcc warning about a default case with boolean discriminant
if default_case is None and node.discriminant.spec.type_name == "bool":
return
template = get_jinja2_template(environment, "decoder", "default_spec")
print(template.render())
if default_case is None or isinstance(default_case.arm, _XdrVoid):
template = get_jinja2_template(environment, "decoder", "break")
print(template.render())
return
assert isinstance(default_case.arm, _XdrBasic)
template = get_jinja2_template(environment, "decoder", default_case.arm.template)
print(
template.render(
name=default_case.arm.name,
type=default_case.arm.spec.type_name,
classifier=default_case.arm.spec.c_classifier,
)
)
def emit_union_decoder(environment: Environment, node: _XdrUnion) -> None:
"""Emit one XDR union decoder"""
template = get_jinja2_template(environment, "decoder", "open")
print(template.render(name=node.name))
emit_union_switch_spec_decoder(environment, node.discriminant)
for case in node.cases:
emit_union_case_spec_decoder(environment, case)
emit_union_default_spec_decoder(environment, node)
template = get_jinja2_template(environment, "decoder", "close")
print(template.render())
def emit_union_switch_spec_encoder(
environment: Environment, node: _XdrDeclaration
) -> None:
"""Emit an encoder for an XDR union's discriminant"""
assert isinstance(node, _XdrBasic)
template = get_jinja2_template(environment, "encoder", "switch_spec")
print(template.render(name=node.name, type=node.spec.type_name))
def emit_union_case_spec_encoder(environment: Environment, node: _XdrCaseSpec) -> None:
"""Emit encoder functions for an XDR union's case arm"""
if isinstance(node.arm, _XdrVoid):
return
template = get_jinja2_template(environment, "encoder", "case_spec")
for case in node.values:
print(template.render(case=case))
assert isinstance(node.arm, _XdrBasic)
template = get_jinja2_template(environment, "encoder", node.arm.template)
print(
template.render(
name=node.arm.name,
type=node.arm.spec.type_name,
)
)
template = get_jinja2_template(environment, "encoder", "break")
print(template.render())
def emit_union_default_spec_encoder(environment: Environment, node: _XdrUnion) -> None:
"""Emit an encoder function for an XDR union's default arm"""
default_case = node.default
# Avoid a gcc warning about a default case with boolean discriminant
if default_case is None and node.discriminant.spec.type_name == "bool":
return
template = get_jinja2_template(environment, "encoder", "default_spec")
print(template.render())
if default_case is None or isinstance(default_case.arm, _XdrVoid):
template = get_jinja2_template(environment, "encoder", "break")
print(template.render())
return
assert isinstance(default_case.arm, _XdrBasic)
template = get_jinja2_template(environment, "encoder", default_case.arm.template)
print(
template.render(
name=default_case.arm.name,
type=default_case.arm.spec.type_name,
)
)
def emit_union_encoder(environment, node: _XdrUnion) -> None:
"""Emit one XDR union encoder"""
template = get_jinja2_template(environment, "encoder", "open")
print(template.render(name=node.name))
emit_union_switch_spec_encoder(environment, node.discriminant)
for case in node.cases:
emit_union_case_spec_encoder(environment, case)
emit_union_default_spec_encoder(environment, node)
template = get_jinja2_template(environment, "encoder", "close")
print(template.render())
class XdrUnionGenerator(SourceGenerator):
"""Generate source code for XDR unions"""
def __init__(self, language: str, peer: str):
"""Initialize an instance of this class"""
self.environment = create_jinja2_environment(language, "union")
self.peer = peer
def emit_declaration(self, node: _XdrUnion) -> None:
"""Emit one declaration pair for an XDR union"""
emit_union_declaration(self.environment, node)
def emit_definition(self, node: _XdrUnion) -> None:
"""Emit one definition for an XDR union"""
emit_union_definition(self.environment, node)
def emit_decoder(self, node: _XdrUnion) -> None:
"""Emit one decoder function for an XDR union"""
emit_union_decoder(self.environment, node)
def emit_encoder(self, node: _XdrUnion) -> None:
"""Emit one encoder function for an XDR union"""
emit_union_encoder(self.environment, node)