refill.c revision 21673 
1/*-
2 * Copyright (c) 1990, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Chris Torek.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 *    must display the following acknowledgement:
18 *	This product includes software developed by the University of
19 *	California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 *    may be used to endorse or promote products derived from this software
22 *    without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37#if defined(LIBC_SCCS) && !defined(lint)
38#if 0
39static char sccsid[] = "@(#)refill.c	8.1 (Berkeley) 6/4/93";
40#endif
41static const char rcsid[] =
42		"$FreeBSD: head/lib/libc/stdio/refill.c 21673 1997-01-14 07:20:47Z jkh $";
43#endif /* LIBC_SCCS and not lint */
44
45#include <errno.h>
46#include <stdio.h>
47#include <stdlib.h>
48#include "local.h"
49
50static int lflush __P((FILE *));
51
52static int
53lflush(fp)
54	FILE *fp;
55{
56
57	if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
58		return (__sflush(fp));
59	return (0);
60}
61
62/*
63 * Refill a stdio buffer.
64 * Return EOF on eof or error, 0 otherwise.
65 */
66int
67__srefill(fp)
68	register FILE *fp;
69{
70
71	/* make sure stdio is set up */
72	if (!__sdidinit)
73		__sinit();
74
75	fp->_r = 0;		/* largely a convenience for callers */
76
77	/* SysV does not make this test; take it out for compatibility */
78	if (fp->_flags & __SEOF)
79		return (EOF);
80
81	/* if not already reading, have to be reading and writing */
82	if ((fp->_flags & __SRD) == 0) {
83		if ((fp->_flags & __SRW) == 0) {
84			errno = EBADF;
85			return (EOF);
86		}
87		/* switch to reading */
88		if (fp->_flags & __SWR) {
89			if (__sflush(fp))
90				return (EOF);
91			fp->_flags &= ~__SWR;
92			fp->_w = 0;
93			fp->_lbfsize = 0;
94		}
95		fp->_flags |= __SRD;
96	} else {
97		/*
98		 * We were reading.  If there is an ungetc buffer,
99		 * we must have been reading from that.  Drop it,
100		 * restoring the previous buffer (if any).  If there
101		 * is anything in that buffer, return.
102		 */
103		if (HASUB(fp)) {
104			FREEUB(fp);
105			if ((fp->_r = fp->_ur) != 0) {
106				fp->_p = fp->_up;
107				return (0);
108			}
109		}
110	}
111
112	if (fp->_bf._base == NULL)
113		__smakebuf(fp);
114
115	/*
116	 * Before reading from a line buffered or unbuffered file,
117	 * flush all line buffered output files, per the ANSI C
118	 * standard.
119	 */
120	if (fp->_flags & (__SLBF|__SNBF))
121		(void) _fwalk(lflush);
122	fp->_p = fp->_bf._base;
123	fp->_r = (*fp->_read)(fp->_cookie, (char *)fp->_p, fp->_bf._size);
124	fp->_flags &= ~__SMOD;	/* buffer contents are again pristine */
125	if (fp->_r <= 0) {
126		if (fp->_r == 0)
127			fp->_flags |= __SEOF;
128		else {
129			fp->_r = 0;
130			fp->_flags |= __SERR;
131		}
132		return (EOF);
133	}
134	return (0);
135}
136