XDR specification files can contain lines prefixed with '%' that
pass through unchanged to generated output. Traditional rpcgen
removes the '%' and emits the remainder verbatim, allowing direct
insertion of C includes, pragma directives, or other language-
specific content into the generated code.
Until now, xdrgen silently discarded these lines during parsing.
This prevented specifications from including necessary headers or
preprocessor directives that might be required for the generated
code to compile correctly.
The grammar now captures pass-through lines instead of ignoring
them. A new AST node type represents pass-through content, and
the AST transformer strips the leading '%' character. Definition
and source generators emit pass-through content in document order,
preserving the original placement within the specification.
This brings xdrgen closer to feature parity with traditional
rpcgen while maintaining the existing document-order processing
model.
Existing generated xdrgen source code has been regenerated.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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>
