Question

I’m using IDebugSymbols::GetNameByOffset and I’m finding that I get the same symbol name for different functions that overload the same name.

E.g. The code I’m looking up the symbols for might be as follows:

void SomeFunction(int) {..} void SomeFunction(float) {..} 

At runtime, when I have an address of an instruction from each of these functions I’d like to use GetNameByOffset and tell the two apart somehow. I’ve experimented with calling SetSymbolOptions toggling the SYMOPT_UNDNAME and SYMOPT_NO_CPP flags as documented here, but this didn’t work.

Does anyone know how to tell these to symbols apart in the debugger engine universe?

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Edit: Please see me comment on the accepted answer for a minor amendment to the proposed solution.

Answer 1

Quote from dbgeng.h:

     // A symbol name may not be unique, particularly     // when overloaded functions exist which all     // have the same name.  If GetOffsetByName     // finds multiple matches for the name it     // can return any one of them.  In that     // case it will return S_FALSE to indicate     // that ambiguity was arbitrarily resolved.     // A caller can then use SearchSymbols to     // find all of the matches if it wishes to     // perform different disambiguation.     STDMETHOD(GetOffsetByName)(         THIS_         __in PCSTR Symbol,         __out PULONG64 Offset         ) PURE; 

So, I would get the name with IDebugSymbols::GetNameByOffset() (it comes back like ‘module!name’ I believe), make sure it is an overload (if you’re not sure) using IDebugSymbols::GetOffsetByName() (which is supposed to return S_FALSE for multiple overloads), and look up all possibilities with this name using StartSymbolMatch()/EndSymbolMatch(). Not a one liner though (and not really helpful for that matter…)

Another option would be to go with

 HRESULT   IDebugSymbols3::GetFunctionEntryByOffset(     IN ULONG64  Offset,     IN ULONG  Flags,     OUT OPTIONAL PVOID  Buffer,     IN ULONG  BufferSize,     OUT OPTIONAL PULONG  BufferNeeded     ); // It can be used to retrieve FPO data on a particular function: FPO_DATA fpo; HRESULT hres=m_Symbols3->GetFunctionEntryByOffset(         addr,   // Offset         0,      // Flags         &fpo,       // Buffer         sizeof(fpo),    // BufferSize         0       // BufferNeeded         )); 

and then use fpo.cdwParams for basic parameter size discrimination (cdwParams=size of parameters)