1 /* $OpenBSD: refill.c,v 1.8 2005/08/08 08:05:36 espie Exp $ */
2 /*-
3 * Copyright (c) 1990, 1993
4 * The Regents of the University of California. All rights reserved.
5 *
6 * This code is derived from software contributed to Berkeley by
7 * Chris Torek.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34 #include <errno.h>
35 #include <stdio.h>
36 #include <stdlib.h>
37 #include "local.h"
38
39 static int
lflush(FILE * fp)40 lflush(FILE *fp)
41 {
42 if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
43 return (__sflush_locked(fp)); /* ignored... */
44 return (0);
45 }
46
47 /*
48 * Refill a stdio buffer.
49 * Return EOF on eof or error, 0 otherwise.
50 */
51 int
__srefill(FILE * fp)52 __srefill(FILE *fp)
53 {
54
55 /* make sure stdio is set up */
56 if (!__sdidinit)
57 __sinit();
58
59 fp->_r = 0; /* largely a convenience for callers */
60
61 /* SysV does not make this test; take it out for compatibility */
62 if (fp->_flags & __SEOF)
63 return (EOF);
64
65 /* if not already reading, have to be reading and writing */
66 if ((fp->_flags & __SRD) == 0) {
67 if ((fp->_flags & __SRW) == 0) {
68 errno = EBADF;
69 fp->_flags |= __SERR;
70 return (EOF);
71 }
72 /* switch to reading */
73 if (fp->_flags & __SWR) {
74 if (__sflush(fp))
75 return (EOF);
76 fp->_flags &= ~__SWR;
77 fp->_w = 0;
78 fp->_lbfsize = 0;
79 }
80 fp->_flags |= __SRD;
81 } else {
82 /*
83 * We were reading. If there is an ungetc buffer,
84 * we must have been reading from that. Drop it,
85 * restoring the previous buffer (if any). If there
86 * is anything in that buffer, return.
87 */
88 if (HASUB(fp)) {
89 FREEUB(fp);
90 if ((fp->_r = fp->_ur) != 0) {
91 fp->_p = fp->_up;
92 return (0);
93 }
94 }
95 }
96
97 if (fp->_bf._base == NULL)
98 __smakebuf(fp);
99
100 /*
101 * Before reading from a line buffered or unbuffered file,
102 * flush all line buffered output files, per the ANSI C
103 * standard.
104 */
105 if (fp->_flags & (__SLBF|__SNBF)) {
106 /* Ignore this file in _fwalk to avoid potential deadlock. */
107 fp->_flags |= __SIGN;
108 (void) _fwalk(lflush);
109 fp->_flags &= ~__SIGN;
110
111 /* Now flush this file without locking it. */
112 if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
113 __sflush(fp);
114 }
115 fp->_p = fp->_bf._base;
116 fp->_r = (*fp->_read)(fp->_cookie, (char *)fp->_p, fp->_bf._size);
117 fp->_flags &= ~__SMOD; /* buffer contents are again pristine */
118 if (fp->_r <= 0) {
119 if (fp->_r == 0)
120 fp->_flags |= __SEOF;
121 else {
122 fp->_r = 0;
123 fp->_flags |= __SERR;
124 }
125 return (EOF);
126 }
127 return (0);
128 }
129