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 | } |