Not yet complete.
The tool doesn't do any math yet. Thus, even though the maximum XDR
width of a union is the width of the union enumerator plus the width
of its largest arm, we're using the sum of all the elements of the
union for the moment.
This means that buffer size requirements are overestimated, and that
the generated maxsize macro cannot yet be used for determining data
element alignment in the XDR buffer.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
The XDR width of a pointer type is the sum of the widths of each of
the struct's fields, except for the last field. The width of the
implicit boolean "value follows" field is added as well.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
The byte size of a variable-length opaque is conveyed in an unsigned
integer. If there is a specified maximum size, that is included in
the type's widths list.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
The XDR width for a fixed-length opaque is the byte size of the
opaque rounded up to the next XDR_UNIT, divided by XDR_UNIT.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
RFC 4506 says that an XDR enum is represented as a signed integer
on the wire; thus its width is 1 XDR_UNIT.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
The generic parts of the RPC layer need to know the widths (in
XDR_UNIT increments) of the XDR data types defined for each
protocol.
As a first step, add dictionaries to keep track of the symbolic and
actual maximum XDR width of XDR types.
This makes it straightforward to look up the width of a type by its
name. The built-in dictionaries are pre-loaded with the widths of
the built-in XDR types as defined in RFC 4506.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
In order to compute the numeric on-the-wire width of XDR types,
xdrgen needs to keep track of the numeric value of constants that
are defined in the input specification so it can perform
calculations with those values.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Clean up: Add a __post_init__ function to the data classes that
need to update the "structs" and "pass_by_reference" sets.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
I misread RFC 4506. The built-in data type is called simply
"string", as there is no fixed-length variety.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Clean up: Make both arms of the type_specifier AST transformer
match. No behavior change is expected.
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>
