static int
ZlibTransformClose(
    ClientData instanceData,
    Tcl_Interp *interp)
{
    ZlibChannelData *cd = instanceData;
    int e, written, result = TCL_OK;

    /*
     * Delete the support timer.
     */

    ZlibTransformEventTimerKill(cd);

    /*
     * Flush any data waiting to be compressed.
     */

    if (cd->mode == TCL_ZLIB_STREAM_DEFLATE) {
	cd->outStream.avail_in = 0;
	do {
	    cd->outStream.next_out = (Bytef *) cd->outBuffer;
	    cd->outStream.avail_out = (unsigned) cd->outAllocated;
	    e = deflate(&cd->outStream, Z_FINISH);
	    written = cd->outAllocated - cd->outStream.avail_out;

	    /*
	     * Can't be sure that deflate() won't declare the buffer to be
	     * full (with Z_BUF_ERROR) so handle that case.
	     */

	    if (e == Z_BUF_ERROR) {
		e = Z_OK;
		written = cd->outAllocated;
	    }
	    if (e != Z_OK && e != Z_STREAM_END) {
		/* TODO: is this the right way to do errors on close? */
		if (!TclInThreadExit()) {
		    ConvertError(interp, e, cd->outStream.adler);
		}
		result = TCL_ERROR;
		break;
	    }

	    if (written && Tcl_WriteRaw(cd->parent, cd->outBuffer, written) < 0) {

		/* TODO: is this the right way to do errors on close?
		 * Note: when close is called from FinalizeIOSubsystem then
		 * interp may be NULL */
		if (!TclInThreadExit() && interp) {
		    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
			    "error while finalizing file: %s",
			    Tcl_PosixError(interp)));
		}
		result = TCL_ERROR;
		break;

	    }
	} while (e != Z_STREAM_END);
	(void) deflateEnd(&cd->outStream);
    } else {
	(void) inflateEnd(&cd->inStream);
    }

    do {
	cd->outStream.next_out = (Bytef *) cd->outBuffer;
	cd->outStream.avail_out = cd->outAllocated;

	e = deflate(&cd->outStream, Z_NO_FLUSH);
	produced = cd->outAllocated - cd->outStream.avail_out;

	if ((e == Z_OK && produced > 0) || e == Z_BUF_ERROR) {
	    /*
	     * deflate() indicates that it is out of space by returning
	     * Z_BUF_ERROR; in that case, we must write the whole buffer out
	     * and retry to compress what is left.
	     */

	    if (e == Z_BUF_ERROR) {
		produced = cd->outAllocated;
		e = Z_OK;
	    }
	    if (Tcl_WriteRaw(cd->parent, cd->outBuffer, produced) < 0) {
		*errorCodePtr = Tcl_GetErrno();
		return -1;
	    }
	}
    } while (e == Z_OK && produced > 0 && cd->outStream.avail_in > 0);

		Tcl_DStringAppendElement(dsPtr,
			Tcl_GetString(cd->compDictObj));
	    } else {
		Tcl_DStringAppendElement(dsPtr, "");
	    }
	} else {
	    if (cd->compDictObj) {
		int len;
		const char *str = Tcl_GetStringFromObj(cd->compDictObj, &len);

		Tcl_DStringAppend(dsPtr, str, len);
	    }
	    return TCL_OK;
	}
    }

    /*
     * The "header" option, which is only valid on inflating gzip channels,

	$stream put {*}$opts $line
    }
    set data [$stream get]
    list [string length $data] [string length [zlib decompress $data]]
} -cleanup {
    $stream close
} -result {12026 18000}
test zlib-12.2 {Patrick Dunnigan's issue} -constraints zlib -setup {
    set filesrc [makeFile {} test.input]
    set filedst [makeFile {} test.output]
    set f [open $filesrc "wb"]
    for {set i 0} {$i < 10000} {incr i} {
	puts -nonewline $f "x"
    }
    close $f
} -body {
    set fin [open $filesrc "rb"]
    set fout [open $filedst "wb"]
    set header [dict create filename "test.input" time 0]
    try {
	fcopy $fin [zlib push gzip $fout -header $header]
    } finally {
	close $fin
	close $fout
    }
    file size $filedst
} -cleanup {
    removeFile $filesrc
    removeFile $filedst
} -result 4152

::tcltest::cleanupTests
return

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# mode: tcl
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