refill.c revision 82818 
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 82818 2001-09-02 19:52:09Z ache $";
43#endif /* LIBC_SCCS and not lint */
44
45#include "namespace.h"
46#include <errno.h>
47#include <limits.h>
48#include <stdio.h>
49#include <stdlib.h>
50#include "un-namespace.h"
51
52#include "libc_private.h"
53#include "local.h"
54
55static int lflush __P((FILE *));
56
57static int
58lflush(FILE *fp)
59{
60	int	ret = 0;
61
62	if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR)) {
63		FLOCKFILE(fp);
64		ret = __sflush(fp);
65		FUNLOCKFILE(fp);
66	}
67	return (ret);
68}
69
70/*
71 * Refill a stdio buffer.
72 * Return EOF on eof or error, 0 otherwise.
73 */
74int
75__srefill(FILE *fp)
76{
77
78	/* make sure stdio is set up */
79	if (!__sdidinit)
80		__sinit();
81
82	fp->_r = 0;		/* largely a convenience for callers */
83
84	/* SysV does not make this test; take it out for compatibility */
85	if (fp->_flags & __SEOF)
86		return (EOF);
87
88	/* if not already reading, have to be reading and writing */
89	if ((fp->_flags & __SRD) == 0) {
90		if ((fp->_flags & __SRW) == 0) {
91			errno = EBADF;
92			fp->_flags |= __SERR;
93			return (EOF);
94		}
95		/* switch to reading */
96		if (fp->_flags & __SWR) {
97			if (__sflush(fp))
98				return (EOF);
99			fp->_flags &= ~__SWR;
100			fp->_w = 0;
101			fp->_lbfsize = 0;
102		}
103		fp->_flags |= __SRD;
104	} else {
105		/*
106		 * We were reading.  If there is an ungetc buffer,
107		 * we must have been reading from that.  Drop it,
108		 * restoring the previous buffer (if any).  If there
109		 * is anything in that buffer, return.
110		 */
111		if (HASUB(fp)) {
112			FREEUB(fp);
113			if ((fp->_r = fp->_ur) != 0) {
114				fp->_p = fp->_extra->_up;
115				return (0);
116			}
117		}
118	}
119
120	if (fp->_bf._base == NULL)
121		__smakebuf(fp);
122
123	/*
124	 * Before reading from a line buffered or unbuffered file,
125	 * flush all line buffered output files, per the ANSI C
126	 * standard.
127	 */
128	if (fp->_flags & (__SLBF|__SNBF)) {
129		/* Ignore this file in _fwalk to avoid potential deadlock. */
130		fp->_flags |= __SIGN;
131		(void) _fwalk(lflush);
132		fp->_flags &= ~__SIGN;
133
134		/* Now flush this file without locking it. */
135		if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
136			__sflush(fp);
137	}
138	fp->_p = fp->_bf._base;
139	fp->_r = (*fp->_read)(fp->_cookie, (char *)fp->_p, fp->_bf._size);
140	fp->_flags &= ~__SMOD;	/* buffer contents are again pristine */
141	if (fp->_r <= 0) {
142		if (fp->_r == 0)
143			fp->_flags |= __SEOF;
144		else {
145			fp->_r = 0;
146			fp->_flags |= __SERR;
147			fp->_flags &= ~__SOFF;
148		}
149		return (EOF);
150	} else if (fp->_flags & __SOFF) {
151		if (fp->_offset > OFF_MAX - fp->_r)
152			fp->_flags &= ~__SOFF;
153		else
154			fp->_offset += fp->_r;
155	}
156	return (0);
157}
158