[micapat]

Hi everyone,

For information, I'm under Linux.

1.) Static functions

I would like to call a standard function, like for example :

PHP Code:

int UTIL_ClientsInGame(void); // _Z18UTIL_ClientsInGamev 


Is it possible with only "GetMemSig()" (Seems to easy )?

PHP Code:

void *pAddr = NULL;
if (pGameConfig->GetMemSig("UTIL_ClientsInGame", &pAddr) && pAddr)
{
    int (*pftCall)(void) = (int (*)(void)) pAddr; // This cast is ugly.
    return pftCall();
}

return -1; 


2.) Virtual functions

I saw some examples like:

PHP Code:

void VFuncs::CommitSuicide(CBaseEntity *pThisPtr)
{
    void **this_ptr = *(void ***)&pThisPtr;
    void **vtable = *(void ***)pThisPtr;
    void *func = vtable[m_Off_CommitSuicide]; 
 
    union {CBaseEntity *(VfuncEmptyClass::*mfpnew)( void );
    #ifndef __linux__
            void *addr;    } u;     u.addr = func;
    #else // GCC's member function pointers all contain a this pointer adjustor. You'd probably set it to 0 
                struct {void *addr; intptr_t adjustor;} s; } u; u.s.addr = func; u.s.adjustor = 0;
    #endif
 
    (reinterpret_cast<VfuncEmptyClass*>(this_ptr)->*u.mfpnew)();
} 


Is "vtable" common to all the instances of "CBaseEntity"?
==> If I keep a copy of the union "u" in this example, can I used it later for any "CBaseEntity", or should I retrieve each time the "vtable"?

Thanks!

[donrevan]

1) Yes, the example you posted should work fine!

2) Yes and no, each CBaseEntity shares the same vtable instance BUT subclasses have their own.
CBaseEntity vtable instances are shared among other CBaseEntities
CBaseCombatCharacter vtable instances are shared among other CBaseCombatCharacters
CBaseCombatWeapon vtable instances are shared among other CBaseCombatWeapons
.. and so on

you should just do the lookup for every entity

[micapat]

Thank you very much !

Just for testing, I tried to call "CreateEntityByName()" (@_Z18CreateEntityByNamePKcib).
I have no error with "pGameConfig->GetMemSig()", but it crashes my server.

I'm calling this function in "SDK_OnLoad", is it the issue? When it's possible to create an entity?

PHP Code:

static CBaseEntity *(*gl_pftCreateEntityByName)(const char *, int, bool) = NULL;

void UTIL_Prepare(IGameConfig *pGameConfig)
{
    void *pAddr = NULL; 

    // Get CreateEntityByName(const char *, int, bool)
    if (pGameConfig->GetMemSig("CreateEntityByName", &pAddr) && pAddr) 
    {
        gl_pftCreateEntityByName = (CBaseEntity *(*)(const char *, int, bool)) pAddr;
    }
    else
    {
        smutils->LogError(myself, "Can't find the function 'CreateEntityByName' !");
    }
}

CBaseEntity *UTIL_CreateEntityByName(const char *szClassname)
{
    if (gl_pftCreateEntityByName)
    {
        return gl_pftCreateEntityByName(szClassname, -1, true);
    }

    return NULL;
} 


[WildCard65]

Game(Incase of a simpler way to call CreateEntityByName).

And I think the best time to call it is after map load.

[donrevan]

If you just want to test things out you can late load your extension when a map is already loaded via "sm exts load NAME". I'm not sure if it crashes when you call CreateEntityByName too early, could be the case.

If it still crashes attach gdb and look at the address returned by GetMemSig or set a breakpoint on UTIL_CreateEntityByName to see where the problem is. GDB is usefull :)

[Powerlord]

Originally Posted by micapat Is "vtable" common to all the instances of "CBaseEntity"? ==> If I keep a copy of the union "u" in this example, can I used it later for any "CBaseEntity", or should I retrieve each time the "vtable"? Thanks!

No, each child class of CBaseEntity will have additional entries.

Having said that, as a general rule, the parent's vtable entries are always first in the child's vtable, unless the child has multiple parents.

TL;DR
Technically no, but yes in practice.

[micapat]

Thank you everyone for these information!
Using some printf(), I confirmed that the issue is from "UTIL_CreateEntityByName()" --> I will call this function after the map is loaded!

-----------------------

I stopped for the moment these tests: I'm struggling with a configuration issue...

When I enable the #define "SMEXT_CONF_METAMOD", I got no issue with the compilation, but my extension becomes really big (> 800ko)!
On the server, the extension doesn't load: "undefined symbol: _Z6ConMsgPKcz"...

I used this tutorial to install everything.

-----------------------

Spoiler

ldd railgun.<..>.so:

linux-gate.so.1 => (0xb77da000)
libstdc++.so.6 => /usr/lib/i386-linux-gnu/libstdc++.so.6 (0xb76b4000)
libc.so.6 => /lib/i386-linux-gnu/libc.so.6 (0xb7506000)
libm.so.6 => /lib/i386-linux-gnu/libm.so.6 (0xb74bf000)
/lib/ld-linux.so.2 (0x800d8000)
libgcc_s.so.1 => /lib/i386-linux-gnu/libgcc_s.so.1 (0xb74a2000)[/CODE]

ldd sdktools.<..>.so:

linux-gate.so.1 => (0xb779f000)
libvstdlib.so => not found
libtier0.so => not found
libm.so.6 => /lib/i386-linux-gnu/libm.so.6 (0xb76df000)
libstdc++.so.6 => /usr/lib/i386-linux-gnu/libstdc++.so.6 (0xb75f7000)
libgcc_s.so.1 => /lib/i386-linux-gnu/libgcc_s.so.1 (0xb75da000)
libc.so.6 => /lib/i386-linux-gnu/libc.so.6 (0xb742c000)
/lib/ld-linux.so.2 (0x8000b000)

==> Why these two libraries aren't linked for my extension?

I can see with ambuild --show-steps:

Spoiler

task 6: c++ _home_micapat_Alliedmodders_sourcemod_public_ smsdk_ext.o extension.o player.o util.o libvstdlib.so libtier0.so -m32 -Wl,--exclude-libs,ALL -lm -static-libgcc -lstdc++
/home/micapat/Alliedmodders/hl2sdk-csgo/lib/linux/tier1_i486.a
/home/micapat/Alliedmodders/hl2sdk-csgo/lib/linux/mathlib_i486.a
/home/micapat/Alliedmodders/hl2sdk-csgo/lib/linux/interfaces_i486.a -shared -o railgun.ext.2.csgo.so
-> railgun.ext.2.csgo/railgun.ext.2.csgo.so

-----------------------

I use ambuild:

cd build
python ../configure.py --sdks=csgo
ambuild

Am I missing something (LD_LIBRARY_PATH... ?).

[asherkin]

Use Clang rather than GCC.

[micapat]

Perfect, with Clang it works now .
Thank you!