error: too many arguments to function 'gpm_xdr_set[proc].arg_fn'; expected 0, have 2

[jas4711]

Hi! We got some build errors of this package in recent Debian:

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1114140

This used to work, so something must have changed, but it seems the prototype is a bit weird, quoting /usr/include/tirpc/rpc/xdr.h:

#ifdef _KERNEL
typedef bool_t (*xdrproc_t)(XDR *, void *, u_int);
#else
/*
 * XXX can't actually prototype it, because some take three args!!!
 */
typedef bool_t (*xdrproc_t)(XDR *, ...);
#endif

Any ideas?

Thanks,
Simon

[simo5]

This has already been fixed in #112

[jas4711]

Thanks for the pointer! With that patch applied, I still get build errors - but maybe this is an krb5 rpc.h bug now?

../src/client/gpm_common.c: In function 'gpm_make_call':
../src/client/gpm_common.c:731:12: error: assignment to 'int (*)(XDR *, void *)' from incompatible pointer type 'xdrproc_t' {aka 'int (*)(void)'} [-Wincompatible-pointer-types]
  731 |     arg_fn = gpm_xdr_set[proc].arg_fn;
      |            ^
In file included from /usr/include/mit-krb5/gssrpc/rpc.h:46,
                 from ../rpcgen/gp_xdr.h:6,
                 from ../rpcgen/gp_rpc.h:9,
                 from ../src/client/gssapi_gpm.h:14,
                 from ../src/client/gpm_common.c:3:
/usr/include/mit-krb5/gssrpc/xdr.h:105:18: note: 'xdrproc_t' declared here
  105 | typedef bool_t (*xdrproc_t)();
      |                  ^~~~~~~~~

[simo5]

Sounds like it yes.
Fedora has this big patch that fixed a bounch of issues with declarations in MIT krb5:
https://src.fedoraproject.org/rpms/krb5/blob/rawhide/f/0016-Eliminate-old-style-function-declarations.patch

Among them this snippet fixes the issue you see above:

diff --git a/src/include/gssrpc/xdr.h b/src/include/gssrpc/xdr.h
index da9e173782..4e5c29bdc2 100644
--- a/src/include/gssrpc/xdr.h
+++ b/src/include/gssrpc/xdr.h
@@ -102,7 +102,6 @@ enum xdr_op {
  *
  * XXX can't actually prototype it, because some take three args!!!
  */
-typedef        bool_t (*xdrproc_t)();
 
 /*
  * The XDR handle.
@@ -143,6 +142,8 @@ typedef struct XDR {
        int             x_handy;        /* extra private word */
 } XDR;
 
+typedef        bool_t (*xdrproc_t)(XDR *, void *);
+
 /*
  * Operations defined on a XDR handle
  *

[simo5]

I think a proper patch for this function would rather use bool_t (*xdrproc_t)(XDR *, ...); like I did in gss-proxy itself. However it seems to work this way as well so far.