bool ESDLcompiler::locateIncludedFile(StringBuffer& filepath, const char* prot, const char* srcDir, const char* fname, const char* ext)
{
    StringBuffer alternateExtFilename;
    alternateExtFilename.setf("%s%s%s", (prot && *prot) ? prot : "", srcDir, fname);

    const char* alt_ext;
    if (stricmp(ext, LEGACY_FILE_EXTENSION)==0)
        alt_ext = ESDL_FILE_EXTENSION;
    else
        alt_ext = LEGACY_FILE_EXTENSION;
    alternateExtFilename.append(alt_ext);

    OwnedIFile fileInSrcDir = createIFile(alternateExtFilename.str());
    if (fileInSrcDir->exists())
    {
        filepath.set(alternateExtFilename.str());
        return true;
    }

    ForEachItemIn(x, includeDirs)
    {
        const char* dir = includeDirs.item(x);
        if (dir && *dir)
        {
            StringBuffer pathInInclude(dir);
            pathInInclude.trim();
            if (pathInInclude.charAt(pathInInclude.length() - 1) != PATHSEPCHAR)
                pathInInclude.append(PATHSEPCHAR);
            pathInInclude.append(fname);
            VStringBuffer pathInIncludeFull("%s%s", pathInInclude.str(), ext);
            OwnedIFile fileInInclude = createIFile(pathInIncludeFull.str());
            if (fileInInclude->exists())
            {
                filepath.set(pathInIncludeFull.str());
                return true;
            }
            pathInIncludeFull.setf("%s%s", pathInInclude.str(), alt_ext);
            OwnedIFile altFileInInclude = createIFile(pathInIncludeFull.str());
            if (altFileInInclude->exists())
            {
                filepath.set(pathInIncludeFull.str());
                return true;
            }
        }
    }

    filepath.clear();
    return false;
}
    void prepareKey(IDistributedFile *index)
    {
        IDistributedFile *f = index;
        IDistributedSuperFile *super = f->querySuperFile();

        unsigned nparts = f->numParts(); // includes tlks if any, but unused in array
        performPartLookup.ensure(nparts);

        bool checkTLKConsistency = (nullptr != super) && !localKey && (0 != (TIRsorted & indexBaseHelper->getFlags()));
        if (nofilter)
        {
            while (nparts--) performPartLookup.append(true);
            if (!checkTLKConsistency) return;
        }
        else
        {
            while (nparts--) performPartLookup.append(false); // parts to perform lookup set later
        }

        Owned<IDistributedFileIterator> iter;
        if (super)
        {
            iter.setown(super->getSubFileIterator(true));
            verifyex(iter->first());
            f = &iter->query();
        }
        unsigned width = f->numParts();
        if (!localKey)
            --width;
        assertex(width);
        unsigned tlkCrc = 0;
        bool first = true;
        unsigned superSubIndex=0;
        bool fileCrc = false, rowCrc = false;
        for (;;)
        {
            Owned<IDistributedFilePart> part = f->getPart(width);
            if (checkTLKConsistency)
            {
                unsigned _tlkCrc;
                if (part->getCrc(_tlkCrc))
                    fileCrc = true;
                else if (part->queryAttributes().hasProp("@crc")) // NB: key "@crc" is not a crc on the file, but data within.
                {
                    _tlkCrc = part->queryAttributes().getPropInt("@crc");
                    rowCrc = true;
                }
                else if (part->queryAttributes().hasProp("@tlkCrc")) // backward compat.
                {
                    _tlkCrc = part->queryAttributes().getPropInt("@tlkCrc");
                    rowCrc = true;
                }
                else
                {
                    if (rowCrc || fileCrc)
                    {
                        checkTLKConsistency = false;
                        Owned<IException> e = MakeActivityWarning(&container, 0, "Cannot validate that tlks in superfile %s match, some crc attributes are missing", super->queryLogicalName());
                        queryJobChannel().fireException(e);
                    }
                }
                if (rowCrc && fileCrc)
                {
                    checkTLKConsistency = false;
                    Owned<IException> e = MakeActivityWarning(&container, 0, "Cannot validate that tlks in superfile %s match, due to mixed crc types.", super->queryLogicalName());
                    queryJobChannel().fireException(e);
                }
                if (checkTLKConsistency)
                {
                    if (first)
                    {
                        tlkCrc = _tlkCrc;
                        first = false;
                    }
                    else if (tlkCrc != _tlkCrc)
                        throw MakeActivityException(this, 0, "Sorted output on super files comprising of non coparitioned sub keys is not supported (TLK's do not match)");
                }
            }
            if (!nofilter)
            {
                Owned<IKeyIndex> keyIndex;
                unsigned copy;
                for (copy=0; copy<part->numCopies(); copy++)
                {
                    RemoteFilename rfn;
                    OwnedIFile ifile = createIFile(part->getFilename(rfn,copy));
                    if (ifile->exists())
                    {
                        StringBuffer remotePath;
                        rfn.getRemotePath(remotePath);
                        unsigned crc = 0;
                        part->getCrc(crc);
                        keyIndex.setown(createKeyIndex(remotePath.str(), crc, false, false));
                        break;
                    }
                }
                if (!keyIndex)
                    throw MakeThorException(TE_FileNotFound, "Top level key part does not exist, for key: %s", index->queryLogicalName());

                unsigned fixedSize = indexBaseHelper->queryDiskRecordSize()->querySerializedDiskMeta()->getFixedSize(); // used only if fixed
                Owned <IKeyManager> tlk = createLocalKeyManager(keyIndex, fixedSize, NULL);
                indexBaseHelper->createSegmentMonitors(tlk);
                tlk->finishSegmentMonitors();
                tlk->reset();
                while (tlk->lookup(false))
                {
                    if (tlk->queryFpos())
                        performPartLookup.replace(true, (aindex_t)(super?super->numSubFiles(true)*(tlk->queryFpos()-1)+superSubIndex:tlk->queryFpos()-1));
                }
            }
            if (!super||!iter->next())
                break;
            superSubIndex++;
            f = &iter->query();
            if (width != f->numParts()-1)
                throw MakeActivityException(this, 0, "Super key %s, with mixture of sub key width are not supported.", f->queryLogicalName());
        }
    }