Annotation of prex-old/usr/lib/libc/stdio/makebuf.c, Revision 1.1.1.1
1.1 nbrk 1: /*-
2: * Copyright (c) 1990, 1993
3: * The Regents of the University of California. All rights reserved.
4: *
5: * This code is derived from software contributed to Berkeley by
6: * Chris Torek.
7: *
8: * Redistribution and use in source and binary forms, with or without
9: * modification, are permitted provided that the following conditions
10: * are met:
11: * 1. Redistributions of source code must retain the above copyright
12: * notice, this list of conditions and the following disclaimer.
13: * 2. Redistributions in binary form must reproduce the above copyright
14: * notice, this list of conditions and the following disclaimer in the
15: * documentation and/or other materials provided with the distribution.
16: * 3. Neither the name of the University nor the names of its contributors
17: * may be used to endorse or promote products derived from this software
18: * without specific prior written permission.
19: *
20: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30: * SUCH DAMAGE.
31: */
32:
33: #include <sys/types.h>
34: #include <sys/stat.h>
35: #include <unistd.h>
36: #include <stdio.h>
37: #include <stdlib.h>
38: #include "local.h"
39:
40: /*
41: * Internal routine to determine `proper' buffering for a file.
42: */
43: static int
44: __swhatbuf(FILE *fp, size_t *bufsize, int *couldbetty)
45: {
46: struct stat st;
47:
48: *bufsize = BUFSIZ;
49: *couldbetty = 0;
50: if (fp->_file < 0 || fstat(fp->_file, &st) < 0)
51: return 0;
52:
53: /* could be a tty iff it is a character device */
54: *couldbetty = S_ISCHR(st.st_mode);
55: return 0;
56: }
57:
58: /*
59: * Allocate a file buffer, or switch to unbuffered I/O.
60: * Per the ANSI C standard, ALL tty devices default to line buffered.
61: *
62: * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek
63: * optimisation) right after the fstat() that finds the buffer size.
64: */
65: void
66: __smakebuf(fp)
67: FILE *fp;
68: {
69: void *p;
70: int flags;
71: size_t size;
72: int couldbetty;
73:
74: if (fp->_flags & __SNBF) {
75: fp->_bf._base = fp->_p = fp->_nbuf;
76: fp->_bf._size = 1;
77: return;
78: }
79: flags = __swhatbuf(fp, &size, &couldbetty);
80: if ((p = malloc(size)) == NULL) {
81: fp->_flags |= __SNBF;
82: fp->_bf._base = fp->_p = fp->_nbuf;
83: fp->_bf._size = 1;
84: return;
85: }
86: __cleanup = _cleanup;
87: flags |= __SMBF;
88: fp->_bf._base = fp->_p = p;
89: fp->_bf._size = size;
90: if (couldbetty && isatty(fp->_file))
91: flags |= __SLBF;
92:
93: fp->_flags |= flags;
94: }
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