Nagios Support Forum

On 10/25/2010 12:00 PM, Andreas Ericsson wrote:
> On 10/25/2010 11:00 AM, Ton Voon wrote:
>> I had an idea to try a different technique (include the
>> source, but override some specific functions), but I couldn't redefine
>> functions in C without the compiler complaining.
> There's no sane way to do that. The un-sane way is to sed out the funct=
ions
> you want to replace and then source the sed'ed source-file.

Well, if you want only *mild* insanity, look no further than at the
preprocessor.



> $ cat main.c
> main()
> {
> speak();
> }


> $ cat normal.c
> #include
>=20
> #ifndef DEBUGGABLE
> #define DEBUGGABLE(x) x
> #endif
>=20
> void DEBUGGABLE(speak) ()
> {
> printf("Business as usual\n");
> }


> $ cat debug.c
> #define DEBUGGABLE(x) debugged_ ## x
>=20
> #include "normal.c"
>=20
> void speak()
> {
> printf("This is the debug version\n");
> debugged_speak();
> }


> $ gcc -c -o normal.o normal.c
> $ gcc -o main main.c normal.o
> $ ./main
> Business as usual


> $ gcc -c -o debug.o debug.c
> $ gcc -o main main.c debug.o
> $ ./main
> This is the debug version
> Business as usual


> $ nm normal.o
> U puts
> 00000000 T speak

> $ nm debug.o
> 00000000 T debugged_speak
> U puts
> 00000014 T speak


Kind regards,
J. Bern
--=20
Jochen Bern, Systemingenieur --- LINworks GmbH
Postfach 100121, 64201 Darmstadt | Robert-Koch-Str. 9, 64331 Weiterstadt
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7
Tel. +49 6151 9067-231, Zentr. -0, Fax -299 - Amtsg. Darmstadt HRB 85202
Unternehmenssitz Weiterstadt, Gesch=E4ftsf=FChrer Metin Dogan, Oliver Mic=
hel





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