Statistics
| Branch: | Revision:

root / prex-0.9.0 / usr / lib / libc / stdio / makebuf.c @ 03e9c04a

History | View | Annotate | Download (2.9 KB)

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
}