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 #if defined(LIBC_SCCS) && !defined(lint)
34 static char sccsid[] = "@(#)makebuf.c 8.1 (Berkeley) 6/4/93";
35 #endif /* LIBC_SCCS and not lint */
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD$");
38
39 #include "namespace.h"
40 #include <sys/types.h>
41 #include <sys/stat.h>
42 #include <unistd.h>
43 #include <stdio.h>
44 #include <stdlib.h>
45 #include "un-namespace.h"
46
47 #include "libc_private.h"
48 #include "local.h"
49
50 /*
51 * Allocate a file buffer, or switch to unbuffered I/O.
52 * Per the ANSI C standard, ALL tty devices default to line buffered.
53 *
54 * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek
55 * optimisation) right after the _fstat() that finds the buffer size.
56 */
57 void
__smakebuf(FILE * fp)58 __smakebuf(FILE *fp)
59 {
60 void *p;
61 int flags;
62 size_t size;
63 int couldbetty;
64
65 if (fp->_flags & __SNBF) {
66 fp->_bf._base = fp->_p = fp->_nbuf;
67 fp->_bf._size = 1;
68 return;
69 }
70 flags = __swhatbuf(fp, &size, &couldbetty);
71 if ((p = malloc(size)) == NULL) {
72 fp->_flags |= __SNBF;
73 fp->_bf._base = fp->_p = fp->_nbuf;
74 fp->_bf._size = 1;
75 return;
76 }
77 __cleanup = _cleanup;
78 flags |= __SMBF;
79 fp->_bf._base = fp->_p = p;
80 fp->_bf._size = size;
81 if (couldbetty && isatty(fp->_file))
82 flags |= __SLBF;
83 fp->_flags |= flags;
84 }
85
86 /*
87 * Internal routine to determine `proper' buffering for a file.
88 */
89 int
__swhatbuf(FILE * fp,size_t * bufsize,int * couldbetty)90 __swhatbuf(FILE *fp, size_t *bufsize, int *couldbetty)
91 {
92 struct stat st;
93
94 if (fp->_file < 0 || _fstat(fp->_file, &st) < 0) {
95 *couldbetty = 0;
96 *bufsize = BUFSIZ;
97 return (__SNPT);
98 }
99
100 /* could be a tty iff it is a character device */
101 *couldbetty = (st.st_mode & S_IFMT) == S_IFCHR;
102 if (st.st_blksize <= 0) {
103 *bufsize = BUFSIZ;
104 return (__SNPT);
105 }
106
107 /*
108 * Optimise fseek() only if it is a regular file. (The test for
109 * __sseek is mainly paranoia.) It is safe to set _blksize
110 * unconditionally; it will only be used if __SOPT is also set.
111 */
112 *bufsize = st.st_blksize;
113 fp->_blksize = st.st_blksize;
114 return ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek ?
115 __SOPT : __SNPT);
116 }
117