On Thu, 2013-10-03 at 14:42 -0400, Frozen Puck wrote:
>
>
> I have the most basic, simple starter sub-agent which simply outputs a
> hard-coded string (for now), which works fine when compiled as a C
> module:
> # net-snmp-config --compile-subagent Ctest sinIDENT.c
>
> (compiles cleanly)
> # ./Ctest
> # snmpget -v 1 -c public localhost sinIDENT.0
> # SIN-TOP-LEVEL-0::sinIDENT.0 = STRING: ZQXA
> (all's well)
> (kill Ctest)
>
>
> HOWEVER, if I rename that same module to sinIDENT.cpp and compile:
> # net-snmp-config --compile-subagent CppTest --cflags -lstdc++
> sinIDENT.cpp
> (compiles cleanly)
> # ./CppTest
> # snmpget -v 1 -c public localhost sinIDENT.0
> Error in packet
> Reason: (noSuchName) There is no such variable name in this MIB.
> Failed object: NAVCAN-CNS-SIN-TOP-LEVEL-0::sinIDENT.0
>
>
> My first thought was that there was fname mangling going on so I made
> sure that the header prevents that:
>
>
> #ifndef SINIDENT_H
> #define SINIDENT_H*/
> #ifdef __cplusplus
> extern "C" {
> #endif
> /* function declarations */
> void init_sinIDENT(void);
> Netsnmp_Node_Handler handle_sinIDENT;
> #ifdef __cplusplus
> }
> #endif
> #endif /* SINIDENT_H */
>
>
> And double checked the names:
> # nm Ctest | grep sin
> 08049770 T handle_sinIDENT
> 080497c0 T init_sinIDENT
> #
> # nm CppTest |grep sin (showing mangled non-C-calling-convention)
> 08049b80 t _GLOBAL__I_init_sinIDENT
> 0804b080 r _ZZ13init_sinIDENTE5C.161
> 0804b060 r _ZZ13init_sinIDENTE8__func__
> 08049c60 T handle_sinIDENT
> 08049bb0 T init_sinIDENT
>
>
> I have NO IDEA why the C++ version returns a failure. Please Help, I
> don't want to be restricted to 20 year old C!
>
The problem is that the generator expects to work with C code.
If you run the generator for both cases with the --norm flag that makes
it leave the temporary file it generates you will see that the actual
difference is that the C version calls init_sinIDENT (and includes the
sinIDENT.h header).
If you try the version that calls the init routine I expect it to work,
does it?
One could imagine an additional flag to --compile-subagent that lists
init_/shutdown_ routines it should look for in addition to the
automatically generated... but I am unsure about that being enough.
/MF
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