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
43 if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
44 return (__sflush(fp));
45 return (0);
46 }
47
48 /*
49 * Refill a stdio buffer.
50 * Return EOF on eof or error, 0 otherwise.
51 */
52 int
__srefill(FILE * fp)53 __srefill(FILE *fp)
54 {
55
56 /* make sure stdio is set up */
57 if (!__sdidinit)
58 __sinit();
59
60 fp->_r = 0; /* largely a convenience for callers */
61
62 /* SysV does not make this test; take it out for compatibility */
63 if (fp->_flags & __SEOF)
64 return (EOF);
65
66 /* if not already reading, have to be reading and writing */
67 if ((fp->_flags & __SRD) == 0) {
68 if ((fp->_flags & __SRW) == 0) {
69 errno = EBADF;
70 fp->_flags |= __SERR;
71 return (EOF);
72 }
73 /* switch to reading */
74 if (fp->_flags & __SWR) {
75 if (__sflush(fp))
76 return (EOF);
77 fp->_flags &= ~__SWR;
78 fp->_w = 0;
79 fp->_lbfsize = 0;
80 }
81 fp->_flags |= __SRD;
82 } else {
83 /*
84 * We were reading. If there is an ungetc buffer,
85 * we must have been reading from that. Drop it,
86 * restoring the previous buffer (if any). If there
87 * is anything in that buffer, return.
88 */
89 if (HASUB(fp)) {
90 FREEUB(fp);
91 if ((fp->_r = fp->_ur) != 0) {
92 fp->_p = fp->_up;
93 return (0);
94 }
95 }
96 }
97
98 if (fp->_bf._base == NULL)
99 __smakebuf(fp);
100
101 /*
102 * Before reading from a line buffered or unbuffered file,
103 * flush all line buffered output files, per the ANSI C
104 * standard.
105 */
106 if (fp->_flags & (__SLBF|__SNBF))
107 (void) _fwalk(lflush);
108 fp->_p = fp->_bf._base;
109 fp->_r = (*fp->_read)(fp->_cookie, (char *)fp->_p, fp->_bf._size);
110 fp->_flags &= ~__SMOD; /* buffer contents are again pristine */
111 if (fp->_r <= 0) {
112 if (fp->_r == 0)
113 fp->_flags |= __SEOF;
114 else {
115 fp->_r = 0;
116 fp->_flags |= __SERR;
117 }
118 return (EOF);
119 }
120 return (0);
121 }
122