refill.c revision 92905 
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 92905 2002-03-21 22:49:10Z obrien $";
43#endif /* LIBC_SCCS and not lint */
44
45#include "namespace.h"
46#include <errno.h>
47#include <stdio.h>
48#include <stdlib.h>
49#include "un-namespace.h"
50
51#include "libc_private.h"
52#include "local.h"
53
54static int lflush(FILE *);
55
56static int
57lflush(FILE *fp)
58{
59	int	ret = 0;
60
61	if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR)) {
62		FLOCKFILE(fp);
63		ret = __sflush(fp);
64		FUNLOCKFILE(fp);
65	}
66	return (ret);
67}
68
69/*
70 * Refill a stdio buffer.
71 * Return EOF on eof or error, 0 otherwise.
72 */
73int
74__srefill(FILE *fp)
75{
76
77	/* make sure stdio is set up */
78	if (!__sdidinit)
79		__sinit();
80
81	fp->_r = 0;		/* largely a convenience for callers */
82
83	/* SysV does not make this test; take it out for compatibility */
84	if (fp->_flags & __SEOF)
85		return (EOF);
86
87	/* if not already reading, have to be reading and writing */
88	if ((fp->_flags & __SRD) == 0) {
89		if ((fp->_flags & __SRW) == 0) {
90			errno = EBADF;
91			fp->_flags |= __SERR;
92			return (EOF);
93		}
94		/* switch to reading */
95		if (fp->_flags & __SWR) {
96			if (__sflush(fp))
97				return (EOF);
98			fp->_flags &= ~__SWR;
99			fp->_w = 0;
100			fp->_lbfsize = 0;
101		}
102		fp->_flags |= __SRD;
103	} else {
104		/*
105		 * We were reading.  If there is an ungetc buffer,
106		 * we must have been reading from that.  Drop it,
107		 * restoring the previous buffer (if any).  If there
108		 * is anything in that buffer, return.
109		 */
110		if (HASUB(fp)) {
111			FREEUB(fp);
112			if ((fp->_r = fp->_ur) != 0) {
113				fp->_p = fp->_extra->_up;
114				return (0);
115			}
116		}
117	}
118
119	if (fp->_bf._base == NULL)
120		__smakebuf(fp);
121
122	/*
123	 * Before reading from a line buffered or unbuffered file,
124	 * flush all line buffered output files, per the ANSI C
125	 * standard.
126	 */
127	if (fp->_flags & (__SLBF|__SNBF)) {
128		/* Ignore this file in _fwalk to avoid potential deadlock. */
129		fp->_flags |= __SIGN;
130		(void) _fwalk(lflush);
131		fp->_flags &= ~__SIGN;
132
133		/* Now flush this file without locking it. */
134		if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
135			__sflush(fp);
136	}
137	fp->_p = fp->_bf._base;
138	fp->_r = _sread(fp, (char *)fp->_p, fp->_bf._size);
139	fp->_flags &= ~__SMOD;	/* buffer contents are again pristine */
140	if (fp->_r <= 0) {
141		if (fp->_r == 0)
142			fp->_flags |= __SEOF;
143		else {
144			fp->_r = 0;
145			fp->_flags |= __SERR;
146		}
147		return (EOF);
148	}
149	return (0);
150}
151