struct svc_service has a .vs_xdrsize field that is filled in by
servers for each of their RPC programs. This field is supposed to
contain the size of the largest procedure argument in the RPC
program. This value is also sometimes used to size network
transport buffers.
Currently, server implementations must manually calculate and
hard-code this value, which is error-prone and requires updates
when procedure arguments change.
Update xdrgen to determine which procedure argument structure is
largest, and emit a macro with a well-known name that contains
the size of that structure. Server code then uses this macro when
initializing the .vs_xdrsize field.
For NLM version 4, xdrgen now emits:
#define NLM4_MAX_ARGS_SZ (NLM4_nlm4_lockargs_sz)
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
"xdrgen definitions" was not providing a definition of a symbolic
constant for the RPC program number being defined.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
The program templates for decoder/argument.j2 and encoder/result.j2
unconditionally add 'struct' prefix to all types. This is incorrect
when an RPC protocol specification lists a typedef'd basic type or
an enum as a procedure argument or result (e.g., NFSv2's fhandle or
stat), resulting in compiler errors when building generated C code.
Fixes: 4b132aacb0 ("tools: Add xdrgen")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Refactor: Translating an on-the-wire value to a local host errno is
architecturally a job for the proc function, not the XDR decoder.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Obviously, "nfs_ok" is defined only for NFS protocols. Other XDR
protocols won't know "nfs_ok" from Adam.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This tracepoint was a "note to self" and is not operational. It is
added only to client-side code, which so far we haven't needed. It
will cause immediate breakage once we start generating client code,
though, so remove it now.
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>
