When an XDR counted array has a maximum element count, xdrgen adds
a bounds check to the encoder or decoder for that type. But in cases
where the .x provides no maximum element count, such as
struct notify4 {
/* composed from notify_type4 or notify_deviceid_type4 */
bitmap4 notify_mask;
notifylist4 notify_vals;
};
struct CB_NOTIFY4args {
stateid4 cna_stateid;
nfs_fh4 cna_fh;
notify4 cna_changes<>;
};
xdrgen is supposed to omit that bounds check. Some of the Jinja2
templates handle that correctly, but a few are incorrect and leave
the bounds check in place with a maximum of zero, which causes
encoding/decoding of that type to fail unconditionally.
Reported-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Introduce logic in the code generators to emit maxsize (XDR
width) definitions. In C, these are pre-processor macros.
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>
xdr_stream_encode_u32() returns XDR_UNIT on success.
xdr_stream_decode_u32() returns zero or -EMSGSIZE, but never
XDR_UNIT.
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>
