/**************************************************************************** * Copyright (c) 1998-2000,2003 Free Software Foundation, Inc.              * *                                                                          * * Permission is hereby granted, free of charge, to any person obtaining a  * * copy of this software and associated documentation files (the            * * "Software"), to deal in the Software without restriction, including      * * without limitation the rights to use, copy, modify, merge, publish,      * * distribute, distribute with modifications, sublicense, and/or sell       * * copies of the Software, and to permit persons to whom the Software is    * * furnished to do so, subject to the following conditions:                 * *                                                                          * * The above copyright notice and this permission notice shall be included  * * in all copies or substantial portions of the Software.                   * *                                                                          * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS  * * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF               * * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.   * * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,   * * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR    * * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR    * * THE USE OR OTHER DEALINGS IN THE SOFTWARE.                               * *                                                                          * * Except as contained in this notice, the name(s) of the above copyright   * * holders shall not be used in advertising or otherwise to promote the     * * sale, use or other dealings in this Software without prior written       * * authorization.                                                           * ****************************************************************************//**************************************************************************** *  Author: Zeyd M. Ben-Halim <zmbenhal@netcom.com> 1992,1995               * *     and: Eric S. Raymond <esr@snark.thyrsus.com>                         * ****************************************************************************//***	setbuf.c****	Support for set_term(), reset_shell_mode(), reset_prog_mode().***/#include <curses.priv.h>MODULE_ID("$Id: setbuf.c,v 1.12 2003/11/15 23:55:34 tom Exp $")/* * If the output file descriptor is connected to a tty (the typical case) it * will probably be line-buffered.  Keith Bostic pointed out that we don't want * this; it hoses people running over networks by forcing out a bunch of small * packets instead of one big one, so screen updates on ptys look jerky. * Restore block buffering to prevent this minor lossage. * * The buffer size is a compromise.  Ideally we'd like a buffer that can hold * the maximum possible update size (the whole screen plus cup commands to * change lines as it's painted).  On a 66-line xterm this can become * excessive.  So we min it with the amount of data we think we can get through * two Ethernet packets (maximum packet size - 100 for TCP/IP overhead). * * Why two ethernet packets?  It used to be one, on the theory that said * packets define the maximum size of atomic update.  But that's less than the * 2000 chars on a 25 x 80 screen, and we don't want local updates to flicker * either.  Two packet lengths will handle up to a 35 x 80 screen. * * The magic '6' is the estimated length of the end-of-line cup sequence to go * to the next line.  It's generous.  We used to mess with the buffering in * init_mvcur() after cost computation, but that lost the sequences emitted by * init_acs() in setupscreen(). * * "The setvbuf function may be used only after the stream pointed to by stream * has been associated with an open file and before any other operation is * performed on the stream." (ISO 7.9.5.6.) * * Grrrr... * * On a lighter note, many implementations do in fact allow an application to * reset the buffering after it has been written to.  We try to do this because * otherwise we leave stdout in buffered mode after endwin() is called.  (This * also happens with SVr4 curses). * * There are pros/cons: * * con: *	There is no guarantee that we can reestablish buffering once we've *	dropped it. * *	We _may_ lose data if the implementation does not coordinate this with *	fflush. * * pro: *	An implementation is more likely to refuse to change the buffering than *	to do it in one of the ways mentioned above. * *	The alternative is to have the application try to change buffering *	itself, which is certainly no improvement. * * Just in case it does not work well on a particular system, the calls to * change buffering are all via the macro NC_BUFFERED.  Some implementations * do indeed get confused by changing setbuf on/off, and will overrun the * buffer.  So we disable this by default (there may yet be a workaround). */NCURSES_EXPORT(void)_nc_set_buffer(FILE *ofp, bool buffered){    /* optional optimization hack -- do before any output to ofp */#if HAVE_SETVBUF || HAVE_SETBUFFER    if (SP->_buffered != (int)buffered) {	unsigned buf_len;	char *buf_ptr;	if (getenv("NCURSES_NO_SETBUF") != 0)	    return;	fflush(ofp);#ifdef __DJGPP__	setmode(ofp, O_BINARY);#endif	if (buffered != 0) {	    buf_len = min(LINES * (COLS + 6), 2800);	    if ((buf_ptr = SP->_setbuf) == 0) {		if ((buf_ptr = typeMalloc(char, buf_len)) == NULL)		      return;		SP->_setbuf = buf_ptr;		/* Don't try to free this! */	    }#if !USE_SETBUF_0	    else		return;#endif	} else {#if !USE_SETBUF_0	    return;#else	    buf_len = 0;	    buf_ptr = 0;#endif	}#if HAVE_SETVBUF#ifdef SETVBUF_REVERSED		/* pre-svr3? */	(void) setvbuf(ofp, buf_ptr, buf_len, buf_len ? _IOFBF : _IOLBF);#else	(void) setvbuf(ofp, buf_ptr, buf_len ? _IOFBF : _IOLBF, buf_len);#endif#elif HAVE_SETBUFFER	(void) setbuffer(ofp, buf_ptr, (int) buf_len);#endif	SP->_buffered = buffered;    }#endif /* HAVE_SETVBUF || HAVE_SETBUFFER */}