1 /* $NetBSD: refill.c,v 1.16 2012/03/27 15:05:42 christos Exp $ */
2
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 #include <sys/cdefs.h>
36 #if defined(LIBC_SCCS) && !defined(lint)
37 #if 0
38 static char sccsid[] = "@(#)refill.c 8.1 (Berkeley) 6/4/93";
39 #else
40 __RCSID("$NetBSD: refill.c,v 1.16 2012/03/27 15:05:42 christos Exp $");
41 #endif
42 #endif /* LIBC_SCCS and not lint */
43
44 #include <assert.h>
45 #include <errno.h>
46 #include <stdio.h>
47 #include <stdlib.h>
48 #include "reentrant.h"
49 #include "local.h"
50
51 #ifdef _REENTRANT
52 extern rwlock_t __sfp_lock;
53 #endif
54
55 static int
lflush(FILE * fp)56 lflush(FILE *fp)
57 {
58
59 _DIAGASSERT(fp != NULL);
60
61 if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
62 return __sflush(fp);
63 return 0;
64 }
65
66 /*
67 * Refill a stdio buffer.
68 * Return EOF on eof or error, 0 otherwise.
69 */
70 int
__srefill(FILE * fp)71 __srefill(FILE *fp)
72 {
73
74 _DIAGASSERT(fp != NULL);
75
76 /* make sure stdio is set up */
77 if (!__sdidinit)
78 __sinit();
79
80 fp->_r = 0; /* largely a convenience for callers */
81
82 /* SysV does not make this test; take it out for compatibility */
83 if (fp->_flags & __SEOF)
84 return EOF;
85
86 /* if not already reading, have to be reading and writing */
87 if ((fp->_flags & __SRD) == 0) {
88 if ((fp->_flags & __SRW) == 0) {
89 errno = EBADF;
90 fp->_flags |= __SERR;
91 return EOF;
92 }
93 /* switch to reading */
94 if (fp->_flags & __SWR) {
95 if (__sflush(fp))
96 return EOF;
97 fp->_flags &= ~__SWR;
98 fp->_w = 0;
99 fp->_lbfsize = 0;
100 }
101 fp->_flags |= __SRD;
102 } else {
103 /*
104 * We were reading. If there is an ungetc buffer,
105 * we must have been reading from that. Drop it,
106 * restoring the previous buffer (if any). If there
107 * is anything in that buffer, return.
108 */
109 if (HASUB(fp)) {
110 FREEUB(fp);
111 if ((fp->_r = fp->_ur) != 0) {
112 fp->_p = fp->_up;
113 return 0;
114 }
115 }
116 }
117
118 if (fp->_bf._base == NULL)
119 __smakebuf(fp);
120
121 /*
122 * Before reading from a line buffered or unbuffered file,
123 * flush all line buffered output files, per the ANSI C
124 * standard.
125 */
126 if (fp->_flags & (__SLBF|__SNBF)) {
127 rwlock_rdlock(&__sfp_lock);
128 (void) _fwalk(lflush);
129 rwlock_unlock(&__sfp_lock);
130 }
131 fp->_p = fp->_bf._base;
132 fp->_r = (int)(*fp->_read)(fp->_cookie, (char *)fp->_p,
133 (size_t)fp->_bf._size);
134 fp->_flags &= ~__SMOD; /* buffer contents are again pristine */
135 if (fp->_r <= 0) {
136 if (fp->_r == 0)
137 fp->_flags |= __SEOF;
138 else {
139 fp->_r = 0;
140 fp->_flags |= __SERR;
141 }
142 return EOF;
143 }
144 return 0;
145 }
146