Tcl_DString nameBuf, ds;
    const TCHAR *nativeName;
    TCHAR nativeFullPath[MAX_PATH];
    static const char extensions[][5] = {"", ".com", ".exe", ".bat", ".cmd"};

    /*
     * Look for the program as an external program. First try the name as it
     * is, then try adding .com, .exe, and .bat, in that order, to the name,
     * is, then try adding .com, .exe, .bat and .cmd, in that order, to the name,
     * looking for an executable.
     *
     * Using the raw SearchPath() function doesn't do quite what is necessary.
     * If the name of the executable already contains a '.' character, it will
     * not try appending the specified extension when searching (in other
     * words, SearchPath will not find the program "a.b.exe" if the arguments
     * specified "a.b" and ".exe"). So, first look for the file as it is

    if (applType == APPL_NONE) {
	TclWinConvertError(GetLastError());
	Tcl_SetObjResult(interp, Tcl_ObjPrintf("couldn't execute \"%s\": %s",
		originalName, Tcl_PosixError(interp)));
	return APPL_NONE;
    }

    if ((applType == APPL_DOS) || (applType == APPL_WIN3X)) {
    if (applType == APPL_WIN3X) {
	/*
	 * Replace long path name of executable with short path name for
	 * 16-bit applications. Otherwise the application may not be able to
	 * correctly parse its own command line to separate off the
	 * application name from the arguments.
	 */

 *	None.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

static const char *
BuildCmdLineBypassBS(
    const char *current,
    const char **bspos
) {
    /* mark first backslash possition */
    if (!*bspos) {
	*bspos = current;
    }
    do {
	current++;
    } while (*current == '\\');
    return current;
}

static void
QuoteCmdLineBackslash(
    Tcl_DString *dsPtr,
    const char *start,
    const char *current,
    const char *bspos
) {
    if (!bspos) {
	if (current > start) { /* part before current (special) */
	    Tcl_DStringAppend(dsPtr, start, (int) (current - start));
	}
    } else {
    	if (bspos > start) { /* part before first backslash */
	    Tcl_DStringAppend(dsPtr, start, (int) (bspos - start));
	}
	while (bspos++ < current) { /* each backslash twice */
	    TclDStringAppendLiteral(dsPtr, "\\\\");
	}
    }
}

static const char *
QuoteCmdLinePart(
    Tcl_DString *dsPtr,
    const char *start,
    const char *special,
    const char *specMetaChars,
    const char **bspos
) {
    if (!*bspos) {
	/* rest before special (before quote) */
	QuoteCmdLineBackslash(dsPtr, start, special, NULL);
	start = special;
    } else {
	/* rest before first backslash and backslashes into new quoted block */
	QuoteCmdLineBackslash(dsPtr, start, *bspos, NULL);
	start = *bspos;
    }
    /* 
     * escape all special chars enclosed in quotes like `"..."`, note that here we 
     * don't must escape `\` (with `\`), because it's outside of the main quotes,
     * so `\` remains `\`, but important - not at end of part, because results as 
     * before the quote,  so `%\%\` should be escaped as `"%\%"\\`).
     */
    TclDStringAppendLiteral(dsPtr, "\""); /* opening escape quote-char */
    do {
    	*bspos = NULL;
	special++;
	if (*special == '\\') {
	    /* bypass backslashes (and mark first backslash possition)*/
	    special = BuildCmdLineBypassBS(special, bspos);
	    if (*special == '\0') break;
	}
    } while (*special && strchr(specMetaChars, *special));
    if (!*bspos) {
	/* unescaped rest before quote */
	QuoteCmdLineBackslash(dsPtr, start, special, NULL);
    } else {
	/* unescaped rest before first backslash (rather belongs to the main block) */
	QuoteCmdLineBackslash(dsPtr, start, *bspos, NULL);
    }
    TclDStringAppendLiteral(dsPtr, "\""); /* closing escape quote-char */
    return special;
}

static void
BuildCommandLine(
    const char *executable,	/* Full path of executable (including
				 * extension). Replacement for argv[0]. */
    int argc,			/* Number of arguments. */
    const char **argv,		/* Argument strings in UTF. */
    Tcl_DString *linePtr)	/* Initialized Tcl_DString that receives the
				 * command line (TCHAR). */
{
    const char *arg, *start, *special;
    int quote, i;
    const char *arg, *start, *special, *bspos;
    int quote = 0, i;
    Tcl_DString ds;

    /* characters to enclose in quotes if unpaired quote flag set */
    const static char *specMetaChars = "&|^<>!()%";
    /* characters to enclose in quotes in any case (regardless unpaired-flag) */
    const static char *specMetaChars2 = "%";

    /* Quote flags:
     *   CL_ESCAPE   - escape argument;
     *   CL_QUOTE    - enclose in quotes;
     *   CL_UNPAIRED - previous arguments chain contains unpaired quote-char;
     */
    enum {CL_ESCAPE = 1, CL_QUOTE = 2, CL_UNPAIRED = 4};

    Tcl_DStringInit(&ds);

    /*
     * Prime the path. Add a space separator if we were primed with something.
     */

    TclDStringAppendDString(&ds, linePtr);
    if (Tcl_DStringLength(linePtr) > 0) {
	TclDStringAppendLiteral(&ds, " ");
    }

    for (i = 0; i < argc; i++) {
	if (i == 0) {
	    arg = executable;
	} else {
	    arg = argv[i];
	    TclDStringAppendLiteral(&ds, " ");
	}

	quote = 0;
	quote &= ~(CL_ESCAPE|CL_QUOTE); /* reset escape flags */
	bspos = NULL;
	if (arg[0] == '\0') {
	    quote = 1;
	    quote = CL_QUOTE;
	} else {
	    int count;
	    Tcl_UniChar ch = 0;

	    for (start = arg; *start != '\0'; start += count) {
		count = TclUtfToUniChar(start, &ch);
		if (Tcl_UniCharIsSpace(ch)) {	/* INTL: ISO space. */
		    quote = 1;
		    break;
		}
	    }
	}
	if (quote) {
	    Tcl_UniChar ch;
	    for (start = arg;
		*start != '\0' &&
		    (quote & (CL_ESCAPE|CL_QUOTE)) != (CL_ESCAPE|CL_QUOTE);
		start += count
	    ) {
		count = Tcl_UtfToUniChar(start, &ch);
		if (count > 1) continue;
		if (Tcl_UniCharIsSpace(ch)) {
		    quote |= CL_QUOTE; /* quote only */
		    if (bspos) { /* if backslash found - escape & quote */
			quote |= CL_ESCAPE;
			break;
		    }
		    continue;
		}
		if (strchr(specMetaChars, *start)) {
		    quote |= (CL_ESCAPE|CL_QUOTE); /*escape & quote */
		    break;
		}
		if (*start == '"') {
		    quote |= CL_ESCAPE; /* escape only */
		    continue;
		}
		if (*start == '\\') {
		    bspos = start;
		    if (quote & CL_QUOTE) { /* if quote - escape & quote */
			quote |= CL_ESCAPE;
			break;
		    }
		    continue;
		}
	    }
	    bspos = NULL;
	}
	if (quote & CL_QUOTE) {
	    /* start of argument (main opening quote-char) */
	    TclDStringAppendLiteral(&ds, "\"");
	}
	start = arg;
	for (special = arg; ; ) {
	    if ((*special == '\\') && (special[1] == '\\' ||
		    special[1] == '"' || (quote && special[1] == '\0'))) {
		Tcl_DStringAppend(&ds, start, (int) (special - start));
		start = special;
		while (1) {
		    special++;
		    if (*special == '"' || (quote && *special == '\0')) {
			/*
			 * N backslashes followed a quote -> insert N * 2 + 1
			 * backslashes then a quote.
	if (!(quote & CL_ESCAPE)) {
			 */

			Tcl_DStringAppend(&ds, start,
				(int) (special - start));
	    /* nothing to escape */
	    Tcl_DStringAppend(&ds, arg, -1);
	} else {
	    start = arg;
	    for (special = arg; *special != '\0'; ) {
			break;
		    }
		    if (*special != '\\') {
		/* position of `\` is important before quote or at end (equal `\"` because quoted) */
		if (*special == '\\') {
			break;
		    }
		}
		Tcl_DStringAppend(&ds, start, (int) (special - start));
		start = special;
	    }
	    if (*special == '"') {
		Tcl_DStringAppend(&ds, start, (int) (special - start));
		TclDStringAppendLiteral(&ds, "\\\"");
		start = special + 1;
	    }
	    if (*special == '\0') {
		break;
	    }
	    special++;
	}
	Tcl_DStringAppend(&ds, start, (int) (special - start));
	if (quote) {
		    /* bypass backslashes (and mark first backslash possition)*/
		    special = BuildCmdLineBypassBS(special, &bspos);
		    if (*special == '\0') break;
		}
		/* ["] */
		if (*special == '"') {
		    quote ^= CL_UNPAIRED; /* invert unpaired flag - observe unpaired quotes */
		    /* add part before (and escape backslashes before quote) */
		    QuoteCmdLineBackslash(&ds, start, special, bspos);
		    bspos = NULL;
		    /* escape using backslash */
		    TclDStringAppendLiteral(&ds, "\\\"");
		    start = ++special;
		    continue;
		}
		/* unpaired (escaped) quote causes special handling on meta-chars */
		if ((quote & CL_UNPAIRED) && strchr(specMetaChars, *special)) {
		    special = QuoteCmdLinePart(&ds, start, special, specMetaChars, &bspos);
		    /* start to current or first backslash */
		    start = !bspos ? special : bspos;
		    continue;
		}
		/* special case for % - should be enclosed always (paired also) */
		if (strchr(specMetaChars2, *special)) {
		    special = QuoteCmdLinePart(&ds, start, special, specMetaChars2, &bspos);
		    /* start to current or first backslash */
		    start = !bspos ? special : bspos;
		    continue;
		}
		/* other not special (and not meta) character */
		bspos = NULL; /* reset last backslash possition (not interesting) */
		special++;
	    }
	    /* rest of argument (and escape backslashes before closing main quote) */
	    QuoteCmdLineBackslash(&ds, start, special, 
	    	(quote & CL_QUOTE) ? bspos : NULL);
	}
	if (quote & CL_QUOTE) {
	    /* end of argument (main closing quote-char) */
	    TclDStringAppendLiteral(&ds, "\"");
	}
    }
    Tcl_DStringFree(linePtr);
    Tcl_WinUtfToTChar(Tcl_DStringValue(&ds), Tcl_DStringLength(&ds), linePtr);
    Tcl_DStringFree(&ds);
}