1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1990, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Chris Torek.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 #if defined(LIBC_SCCS) && !defined(lint)
36 static char sccsid[] = "@(#)makebuf.c 8.1 (Berkeley) 6/4/93";
37 #endif /* LIBC_SCCS and not lint */
38 #include "namespace.h"
39 #include <sys/types.h>
40 #include <sys/stat.h>
41 #include <unistd.h>
42 #include <stdio.h>
43 #include <stdlib.h>
44 #include "un-namespace.h"
45
46 #include "libc_private.h"
47 #include "local.h"
48
49 /*
50 * Allocate a file buffer, or switch to unbuffered I/O.
51 * Per the ANSI C standard, ALL tty devices default to line buffered.
52 *
53 * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek
54 * optimisation) right after the _fstat() that finds the buffer size.
55 */
56 void
__smakebuf(FILE * fp)57 __smakebuf(FILE *fp)
58 {
59 void *p;
60 int flags;
61 size_t size;
62 int couldbetty;
63
64 if (fp->_flags & __SNBF) {
65 fp->_bf._base = fp->_p = fp->_nbuf;
66 fp->_bf._size = 1;
67 return;
68 }
69 flags = __swhatbuf(fp, &size, &couldbetty);
70 if ((p = malloc(size)) == NULL) {
71 fp->_flags |= __SNBF;
72 fp->_bf._base = fp->_p = fp->_nbuf;
73 fp->_bf._size = 1;
74 return;
75 }
76 __cleanup = _cleanup;
77 flags |= __SMBF;
78 fp->_bf._base = fp->_p = p;
79 fp->_bf._size = size;
80 if (couldbetty && isatty(fp->_file))
81 flags |= __SLBF;
82 fp->_flags |= flags;
83 }
84
85 /*
86 * Internal routine to determine `proper' buffering for a file.
87 */
88 int
__swhatbuf(FILE * fp,size_t * bufsize,int * couldbetty)89 __swhatbuf(FILE *fp, size_t *bufsize, int *couldbetty)
90 {
91 struct stat st;
92
93 if (fp->_file < 0 || _fstat(fp->_file, &st) < 0) {
94 *couldbetty = 0;
95 *bufsize = BUFSIZ;
96 return (__SNPT);
97 }
98
99 /* could be a tty iff it is a character device */
100 *couldbetty = (st.st_mode & S_IFMT) == S_IFCHR;
101 if (st.st_blksize <= 0) {
102 *bufsize = BUFSIZ;
103 return (__SNPT);
104 }
105
106 /*
107 * Optimise fseek() only if it is a regular file. (The test for
108 * __sseek is mainly paranoia.) It is safe to set _blksize
109 * unconditionally; it will only be used if __SOPT is also set.
110 */
111 *bufsize = st.st_blksize;
112 fp->_blksize = st.st_blksize;
113 return ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek ?
114 __SOPT : __SNPT);
115 }
116