Getting symbol names from the DLL export table

gistfile1.cpp

    // If no symbol information is found because the .pdb is missing we try the alternative
    // of finding the nearest exported symbol from the DLL. Although it can be inaccurate it is
    // better than displaying nothing and usually our clients do not have our pdbs because they
    // send us minidumps.
    else if (MapAndLoad_ != 0 && UnMapAndLoad_ != 0 && ImageDirectoryEntryToData_ != 0 &&
        ImageRvaToVa_ != 0 && UnDecorateSymbolName_ != 0)
    {
        _LOADED_IMAGE loadedImage;
        if (MapAndLoad_(moduleInfo.ImageName, 0, &loadedImage, TRUE, TRUE))
        {
            ULONG size;
            _IMAGE_EXPORT_DIRECTORY* imageExportDirectory = (_IMAGE_EXPORT_DIRECTORY*)
                ImageDirectoryEntryToData_(loadedImage.MappedAddress, false, 
                IMAGE_DIRECTORY_ENTRY_EXPORT, &size);

            if (imageExportDirectory != 0)
            {
                // http://msdn.microsoft.com/en-us/magazine/ms809762.aspx
                DWORD* names = (DWORD*)ImageRvaToVa_(loadedImage.FileHeader, 
                    loadedImage.MappedAddress, imageExportDirectory->AddressOfNames, NULL);
                WORD* ordinals = (WORD*)ImageRvaToVa_(loadedImage.FileHeader, 
                    loadedImage.MappedAddress, imageExportDirectory->AddressOfNameOrdinals, NULL);
                DWORD* functions = (DWORD*)ImageRvaToVa_(loadedImage.FileHeader, 
                    loadedImage.MappedAddress, imageExportDirectory->AddressOfFunctions, NULL);

                NsUInt32 nearestAddress = 0xffffffff;
                NsChar* nearestName = 0;

                for (DWORD i = 0; i < imageExportDirectory->NumberOfNames; i++)
                {
                    DWORD64 ptr = functions[ordinals[i]];
                    DWORD64 rva = (NsByte*)(addr) - (NsByte*)(moduleInfo.BaseOfImage);
                    
                    if (rva >= ptr)
                    {
                        DWORD64 delta = rva - ptr;

                        if (delta < nearestAddress)
                        {
                            nearestAddress = NsSize(delta);
                            nearestName = (NsChar *)ImageRvaToVa_(loadedImage.FileHeader, 
                                loadedImage.MappedAddress, names[i], NULL);
                        }
                    }
                }
                
                if (nearestAddress != 0xffffffff)
                {
                    NsChar undecorated[512];
                    UnDecorateSymbolName_(nearestName, undecorated, 512, UNDNAME_NAME_ONLY);

                    NsChar lineInfoBuffer[512];
                    String::FormatBuffer(lineInfoBuffer, 512, "!%s + 0x%x bytes", undecorated,
                        nearestAddress);
                    String::Append(buffer, bufferSize, lineInfoBuffer);
                }
            }
            
            UnMapAndLoad_(&loadedImage);
        }