| File: | src/lib/libcurses/tinfo/setbuf.c |
| Warning: | line 120, column 11 Although the value stored to 'buf_ptr' is used in the enclosing expression, the value is never actually read from 'buf_ptr' |
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| 1 | /* $OpenBSD: setbuf.c,v 1.5 2010/01/12 23:22:06 nicm Exp $ */ |
| 2 | |
| 3 | /**************************************************************************** |
| 4 | * Copyright (c) 1998-2003,2007 Free Software Foundation, Inc. * |
| 5 | * * |
| 6 | * Permission is hereby granted, free of charge, to any person obtaining a * |
| 7 | * copy of this software and associated documentation files (the * |
| 8 | * "Software"), to deal in the Software without restriction, including * |
| 9 | * without limitation the rights to use, copy, modify, merge, publish, * |
| 10 | * distribute, distribute with modifications, sublicense, and/or sell * |
| 11 | * copies of the Software, and to permit persons to whom the Software is * |
| 12 | * furnished to do so, subject to the following conditions: * |
| 13 | * * |
| 14 | * The above copyright notice and this permission notice shall be included * |
| 15 | * in all copies or substantial portions of the Software. * |
| 16 | * * |
| 17 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * |
| 18 | * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * |
| 19 | * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * |
| 20 | * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, * |
| 21 | * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR * |
| 22 | * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR * |
| 23 | * THE USE OR OTHER DEALINGS IN THE SOFTWARE. * |
| 24 | * * |
| 25 | * Except as contained in this notice, the name(s) of the above copyright * |
| 26 | * holders shall not be used in advertising or otherwise to promote the * |
| 27 | * sale, use or other dealings in this Software without prior written * |
| 28 | * authorization. * |
| 29 | ****************************************************************************/ |
| 30 | |
| 31 | /**************************************************************************** |
| 32 | * Author: Zeyd M. Ben-Halim <zmbenhal@netcom.com> 1992,1995 * |
| 33 | * and: Eric S. Raymond <esr@snark.thyrsus.com> * |
| 34 | ****************************************************************************/ |
| 35 | |
| 36 | /* |
| 37 | ** setbuf.c |
| 38 | ** |
| 39 | ** Support for set_term(), reset_shell_mode(), reset_prog_mode(). |
| 40 | ** |
| 41 | */ |
| 42 | |
| 43 | #include <curses.priv.h> |
| 44 | |
| 45 | MODULE_ID("$Id: setbuf.c,v 1.5 2010/01/12 23:22:06 nicm Exp $") |
| 46 | |
| 47 | /* |
| 48 | * If the output file descriptor is connected to a tty (the typical case) it |
| 49 | * will probably be line-buffered. Keith Bostic pointed out that we don't want |
| 50 | * this; it hoses people running over networks by forcing out a bunch of small |
| 51 | * packets instead of one big one, so screen updates on ptys look jerky. |
| 52 | * Restore block buffering to prevent this minor lossage. |
| 53 | * |
| 54 | * The buffer size is a compromise. Ideally we'd like a buffer that can hold |
| 55 | * the maximum possible update size (the whole screen plus cup commands to |
| 56 | * change lines as it's painted). On a 66-line xterm this can become |
| 57 | * excessive. So we min it with the amount of data we think we can get through |
| 58 | * two Ethernet packets (maximum packet size - 100 for TCP/IP overhead). |
| 59 | * |
| 60 | * Why two ethernet packets? It used to be one, on the theory that said |
| 61 | * packets define the maximum size of atomic update. But that's less than the |
| 62 | * 2000 chars on a 25 x 80 screen, and we don't want local updates to flicker |
| 63 | * either. Two packet lengths will handle up to a 35 x 80 screen. |
| 64 | * |
| 65 | * The magic '6' is the estimated length of the end-of-line cup sequence to go |
| 66 | * to the next line. It's generous. We used to mess with the buffering in |
| 67 | * init_mvcur() after cost computation, but that lost the sequences emitted by |
| 68 | * init_acs() in setupscreen(). |
| 69 | * |
| 70 | * "The setvbuf function may be used only after the stream pointed to by stream |
| 71 | * has been associated with an open file and before any other operation is |
| 72 | * performed on the stream." (ISO 7.9.5.6.) |
| 73 | * |
| 74 | * Grrrr... |
| 75 | * |
| 76 | * On a lighter note, many implementations do in fact allow an application to |
| 77 | * reset the buffering after it has been written to. We try to do this because |
| 78 | * otherwise we leave stdout in buffered mode after endwin() is called. (This |
| 79 | * also happens with SVr4 curses). |
| 80 | * |
| 81 | * There are pros/cons: |
| 82 | * |
| 83 | * con: |
| 84 | * There is no guarantee that we can reestablish buffering once we've |
| 85 | * dropped it. |
| 86 | * |
| 87 | * We _may_ lose data if the implementation does not coordinate this with |
| 88 | * fflush. |
| 89 | * |
| 90 | * pro: |
| 91 | * An implementation is more likely to refuse to change the buffering than |
| 92 | * to do it in one of the ways mentioned above. |
| 93 | * |
| 94 | * The alternative is to have the application try to change buffering |
| 95 | * itself, which is certainly no improvement. |
| 96 | * |
| 97 | * Just in case it does not work well on a particular system, the calls to |
| 98 | * change buffering are all via the macro NC_BUFFERED. Some implementations |
| 99 | * do indeed get confused by changing setbuf on/off, and will overrun the |
| 100 | * buffer. So we disable this by default (there may yet be a workaround). |
| 101 | */ |
| 102 | NCURSES_EXPORT(void)void |
| 103 | _nc_set_buffer(FILE *ofp, bool_Bool buffered) |
| 104 | { |
| 105 | /* optional optimization hack -- do before any output to ofp */ |
| 106 | #if HAVE_SETVBUF1 || HAVE_SETBUFFER1 |
| 107 | if (SP->_buffered != buffered) { |
| 108 | unsigned buf_len; |
| 109 | char *buf_ptr; |
| 110 | |
| 111 | if (getenv("NCURSES_NO_SETBUF") != 0) |
| 112 | return; |
| 113 | |
| 114 | fflush(ofp); |
| 115 | #ifdef __DJGPP__ |
| 116 | setmode(ofp, O_BINARY0); |
| 117 | #endif |
| 118 | if (buffered != 0) { |
| 119 | buf_len = min(LINES * (COLS + 6), 2800)((LINES * (COLS + 6)) > (2800) ? (2800) : (LINES * (COLS + 6))); |
| 120 | if ((buf_ptr = SP->_setbuf) == 0) { |
Although the value stored to 'buf_ptr' is used in the enclosing expression, the value is never actually read from 'buf_ptr' | |
| 121 | if ((buf_ptr = typeMalloc(char, buf_len)(char *)malloc((buf_len)*sizeof(char))) == NULL((void*)0)) |
| 122 | return; |
| 123 | SP->_setbuf = buf_ptr; |
| 124 | /* Don't try to free this! */ |
| 125 | } |
| 126 | #if !USE_SETBUF_00 |
| 127 | else |
| 128 | return; |
| 129 | #endif |
| 130 | } else { |
| 131 | #if !USE_SETBUF_00 |
| 132 | return; |
| 133 | #else |
| 134 | buf_len = 0; |
| 135 | buf_ptr = 0; |
| 136 | #endif |
| 137 | } |
| 138 | |
| 139 | #if HAVE_SETVBUF1 |
| 140 | #ifdef SETVBUF_REVERSED /* pre-svr3? */ |
| 141 | (void) setvbuf(ofp, buf_ptr, buf_len, buf_len ? _IOFBF0 : _IOLBF1); |
| 142 | #else |
| 143 | (void) setvbuf(ofp, buf_ptr, buf_len ? _IOFBF0 : _IOLBF1, buf_len); |
| 144 | #endif |
| 145 | #elif HAVE_SETBUFFER1 |
| 146 | (void) setbuffer(ofp, buf_ptr, (int) buf_len); |
| 147 | #endif |
| 148 | |
| 149 | SP->_buffered = buffered; |
| 150 | } |
| 151 | #endif /* HAVE_SETVBUF || HAVE_SETBUFFER */ |
| 152 | } |