1 /*
2 * Copyright (c) 1990, 2007 The Regents of the University of California.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms are permitted
6 * provided that the above copyright notice and this paragraph are
7 * duplicated in all such forms and that any documentation,
8 * and/or other materials related to such
9 * distribution and use acknowledge that the software was developed
10 * by the University of California, Berkeley. The name of the
11 * University may not be used to endorse or promote products derived
12 * from this software without specific prior written permission.
13 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
14 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
15 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
16 */
17 /* No user fns here. Pesch 15apr92. */
18
19 #define _DEFAULT_SOURCE
20 #include <_ansi.h>
21 #include <stdio.h>
22 #include <stdlib.h>
23 #include <sys/stat.h>
24 #include <sys/types.h>
25 #include <sys/unistd.h>
26 #include "local.h"
27
28 #define _DEFAULT_ASPRINTF_BUFSIZE 64
29
30 /*
31 * Allocate a file buffer, or switch to unbuffered I/O.
32 * Per the ANSI C standard, ALL tty devices default to line buffered.
33 *
34 * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek
35 * optimization) right after the _fstat() that finds the buffer size.
36 */
37
38 void
_smakebuf(register FILE * fp)39 _smakebuf (
40 register FILE *fp)
41 {
42 register void *p;
43 int flags;
44 size_t size;
45 int couldbetty;
46
47 if (fp->_flags & __SNBF)
48 {
49 fp->_bf._base = fp->_p = fp->_nbuf;
50 fp->_bf._size = 1;
51 return;
52 }
53 flags = _swhatbuf ( fp, &size, &couldbetty);
54 if ((p = malloc (size)) == NULL)
55 {
56 if (!(fp->_flags & __SSTR))
57 {
58 fp->_flags = (fp->_flags & ~__SLBF) | __SNBF;
59 fp->_bf._base = fp->_p = fp->_nbuf;
60 fp->_bf._size = 1;
61 }
62 }
63 else
64 {
65 fp->_flags |= __SMBF;
66 fp->_bf._base = fp->_p = (unsigned char *) p;
67 fp->_bf._size = size;
68 if (couldbetty && isatty (fp->_file))
69 fp->_flags = (fp->_flags & ~__SNBF) | __SLBF;
70 fp->_flags |= flags;
71 }
72 }
73
74 /*
75 * Internal routine to determine `proper' buffering for a file.
76 */
77 int
_swhatbuf(FILE * fp,size_t * bufsize,int * couldbetty)78 _swhatbuf (
79 FILE *fp,
80 size_t *bufsize,
81 int *couldbetty)
82 {
83 #ifdef _FSEEK_OPTIMIZATION
84 const int snpt = __SNPT;
85 #else
86 const int snpt = 0;
87 #endif
88
89 #ifdef __USE_INTERNAL_STAT64
90 struct stat64 st;
91
92 if (fp->_file < 0 || fstat64 (fp->_file, &st) < 0)
93 #else
94 struct stat st;
95
96 if (fp->_file < 0 || fstat (fp->_file, &st) < 0)
97 #endif
98 {
99 *couldbetty = 0;
100 /* Check if we are be called by asprintf family for initial buffer. */
101 if (fp->_flags & __SMBF)
102 *bufsize = _DEFAULT_ASPRINTF_BUFSIZE;
103 else
104 *bufsize = BUFSIZ;
105 return (0);
106 }
107
108 /* could be a tty iff it is a character device */
109 *couldbetty = S_ISCHR(st.st_mode);
110 #ifdef HAVE_BLKSIZE
111 if (st.st_blksize > 0)
112 {
113 /*
114 * Optimise fseek() only if it is a regular file. (The test for
115 * __sseek is mainly paranoia.) It is safe to set _blksize
116 * unconditionally; it will only be used if __SOPT is also set.
117 */
118 *bufsize = st.st_blksize;
119 fp->_blksize = st.st_blksize;
120 return ((st.st_mode & S_IFMT) == S_IFREG ? __SOPT : snpt);
121 }
122 #endif
123 *bufsize = BUFSIZ;
124 return (snpt);
125 }
126
