--- /dev/null
+/****************************************************************************
+ * Copyright (c) 1998 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 1.5 1999/02/27 20:00:15 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).
+ */
+void _nc_set_buffer(FILE *ofp, bool buffered)
+{
+ /* optional optimization hack -- do before any output to ofp */
+#if HAVE_SETVBUF || HAVE_SETBUFFER
+ unsigned buf_len;
+ char *buf_ptr;
+
+ if (getenv("NCURSES_NO_SETBUF") != 0)
+ return;
+
+ fflush(ofp);
+ if ((SP->_buffered = 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
+
+#endif /* HAVE_SETVBUF || HAVE_SETBUFFER */
+}
projects / ncurses.git / blobdiff