GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libcurses/tinfo/setbuf.c Lines: 0 14 0.0 %
Date: 2017-11-13 Branches: 0 12 0.0 %

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/* $OpenBSD: setbuf.c,v 1.5 2010/01/12 23:22:06 nicm Exp $ */
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/****************************************************************************
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 * Copyright (c) 1998-2003,2007 Free Software Foundation, Inc.              *
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 *                                                                          *
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 * Permission is hereby granted, free of charge, to any person obtaining a  *
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 * copy of this software and associated documentation files (the            *
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 * "Software"), to deal in the Software without restriction, including      *
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 * without limitation the rights to use, copy, modify, merge, publish,      *
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 * distribute, distribute with modifications, sublicense, and/or sell       *
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 * copies of the Software, and to permit persons to whom the Software is    *
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 * furnished to do so, subject to the following conditions:                 *
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 *                                                                          *
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 * The above copyright notice and this permission notice shall be included  *
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 * in all copies or substantial portions of the Software.                   *
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 *                                                                          *
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 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS  *
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 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF               *
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 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.   *
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 * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,   *
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 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR    *
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 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR    *
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 * THE USE OR OTHER DEALINGS IN THE SOFTWARE.                               *
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 *                                                                          *
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 * Except as contained in this notice, the name(s) of the above copyright   *
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 * holders shall not be used in advertising or otherwise to promote the     *
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 * sale, use or other dealings in this Software without prior written       *
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 * authorization.                                                           *
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 ****************************************************************************/
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/****************************************************************************
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 *  Author: Zeyd M. Ben-Halim <zmbenhal@netcom.com> 1992,1995               *
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 *     and: Eric S. Raymond <esr@snark.thyrsus.com>                         *
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 ****************************************************************************/
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/*
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**	setbuf.c
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**
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**	Support for set_term(), reset_shell_mode(), reset_prog_mode().
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**
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*/
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#include <curses.priv.h>
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MODULE_ID("$Id: setbuf.c,v 1.5 2010/01/12 23:22:06 nicm Exp $")
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/*
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 * If the output file descriptor is connected to a tty (the typical case) it
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 * will probably be line-buffered.  Keith Bostic pointed out that we don't want
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 * this; it hoses people running over networks by forcing out a bunch of small
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 * packets instead of one big one, so screen updates on ptys look jerky.
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 * Restore block buffering to prevent this minor lossage.
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 *
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 * The buffer size is a compromise.  Ideally we'd like a buffer that can hold
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 * the maximum possible update size (the whole screen plus cup commands to
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 * change lines as it's painted).  On a 66-line xterm this can become
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 * excessive.  So we min it with the amount of data we think we can get through
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 * two Ethernet packets (maximum packet size - 100 for TCP/IP overhead).
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 *
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 * Why two ethernet packets?  It used to be one, on the theory that said
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 * packets define the maximum size of atomic update.  But that's less than the
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 * 2000 chars on a 25 x 80 screen, and we don't want local updates to flicker
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 * either.  Two packet lengths will handle up to a 35 x 80 screen.
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 *
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 * The magic '6' is the estimated length of the end-of-line cup sequence to go
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 * to the next line.  It's generous.  We used to mess with the buffering in
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 * init_mvcur() after cost computation, but that lost the sequences emitted by
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 * init_acs() in setupscreen().
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 *
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 * "The setvbuf function may be used only after the stream pointed to by stream
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 * has been associated with an open file and before any other operation is
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 * performed on the stream." (ISO 7.9.5.6.)
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 *
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 * Grrrr...
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 *
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 * On a lighter note, many implementations do in fact allow an application to
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 * reset the buffering after it has been written to.  We try to do this because
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 * otherwise we leave stdout in buffered mode after endwin() is called.  (This
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 * also happens with SVr4 curses).
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 *
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 * There are pros/cons:
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 *
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 * con:
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 *	There is no guarantee that we can reestablish buffering once we've
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 *	dropped it.
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 *
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 *	We _may_ lose data if the implementation does not coordinate this with
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 *	fflush.
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 *
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 * pro:
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 *	An implementation is more likely to refuse to change the buffering than
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 *	to do it in one of the ways mentioned above.
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 *
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 *	The alternative is to have the application try to change buffering
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 *	itself, which is certainly no improvement.
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 *
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 * Just in case it does not work well on a particular system, the calls to
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 * change buffering are all via the macro NC_BUFFERED.  Some implementations
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 * do indeed get confused by changing setbuf on/off, and will overrun the
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 * buffer.  So we disable this by default (there may yet be a workaround).
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 */
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NCURSES_EXPORT(void)
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_nc_set_buffer(FILE *ofp, bool buffered)
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{
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    /* optional optimization hack -- do before any output to ofp */
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#if HAVE_SETVBUF || HAVE_SETBUFFER
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    if (SP->_buffered != buffered) {
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	unsigned buf_len;
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	char *buf_ptr;
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	if (getenv("NCURSES_NO_SETBUF") != 0)
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	    return;
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	fflush(ofp);
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#ifdef __DJGPP__
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	setmode(ofp, O_BINARY);
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#endif
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	if (buffered != 0) {
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	    buf_len = min(LINES * (COLS + 6), 2800);
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	    if ((buf_ptr = SP->_setbuf) == 0) {
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		if ((buf_ptr = typeMalloc(char, buf_len)) == NULL)
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		      return;
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		SP->_setbuf = buf_ptr;
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		/* Don't try to free this! */
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	    }
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#if !USE_SETBUF_0
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	    else
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		return;
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#endif
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	} else {
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#if !USE_SETBUF_0
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	    return;
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#else
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	    buf_len = 0;
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	    buf_ptr = 0;
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#endif
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	}
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#if HAVE_SETVBUF
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#ifdef SETVBUF_REVERSED		/* pre-svr3? */
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	(void) setvbuf(ofp, buf_ptr, buf_len, buf_len ? _IOFBF : _IOLBF);
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#else
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	(void) setvbuf(ofp, buf_ptr, buf_len ? _IOFBF : _IOLBF, buf_len);
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#endif
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#elif HAVE_SETBUFFER
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	(void) setbuffer(ofp, buf_ptr, (int) buf_len);
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#endif
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	SP->_buffered = buffered;
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    }
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#endif /* HAVE_SETVBUF || HAVE_SETBUFFER */
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}