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. Neither the name of the University nor the names of its contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#if defined(LIBC_SCCS) && !defined(lint)
34static char sccsid[] = "@(#)refill.c	8.1 (Berkeley) 6/4/93";
35#endif /* LIBC_SCCS and not lint */
36#include <sys/cdefs.h>
37__FBSDID("$FreeBSD: stable/10/lib/libc/stdio/refill.c 321074 2017-07-17 14:09:34Z kib $");
38
39#include "namespace.h"
40#include <errno.h>
41#include <stdio.h>
42#include <stdlib.h>
43#include "un-namespace.h"
44
45#include "libc_private.h"
46#include "local.h"
47
48static int lflush(FILE *);
49
50static int
51lflush(FILE *fp)
52{
53	int	ret = 0;
54
55	if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR)) {
56		FLOCKFILE_CANCELSAFE(fp);
57		ret = __sflush(fp);
58		FUNLOCKFILE_CANCELSAFE();
59	}
60	return (ret);
61}
62
63/*
64 * Refill a stdio buffer.
65 * Return EOF on eof or error, 0 otherwise.
66 */
67int
68__srefill(FILE *fp)
69{
70
71	/* make sure stdio is set up */
72	if (!__sdidinit)
73		__sinit();
74
75	ORIENT(fp, -1);
76
77	fp->_r = 0;		/* largely a convenience for callers */
78
79	/* SysV does not make this test; take it out for compatibility */
80	if (fp->_flags & __SEOF)
81		return (EOF);
82
83	/* if not already reading, have to be reading and writing */
84	if ((fp->_flags & __SRD) == 0) {
85		if ((fp->_flags & __SRW) == 0) {
86			errno = EBADF;
87			fp->_flags |= __SERR;
88			return (EOF);
89		}
90		/* switch to reading */
91		if (fp->_flags & __SWR) {
92			if (__sflush(fp))
93				return (EOF);
94			fp->_flags &= ~__SWR;
95			fp->_w = 0;
96			fp->_lbfsize = 0;
97		}
98		fp->_flags |= __SRD;
99	} else {
100		/*
101		 * We were reading.  If there is an ungetc buffer,
102		 * we must have been reading from that.  Drop it,
103		 * restoring the previous buffer (if any).  If there
104		 * is anything in that buffer, return.
105		 */
106		if (HASUB(fp)) {
107			FREEUB(fp);
108			if ((fp->_r = fp->_ur) != 0) {
109				fp->_p = fp->_up;
110				return (0);
111			}
112		}
113	}
114
115	if (fp->_bf._base == NULL)
116		__smakebuf(fp);
117
118	/*
119	 * Before reading from a line buffered or unbuffered file,
120	 * flush all line buffered output files, per the ANSI C
121	 * standard.
122	 */
123	if (fp->_flags & (__SLBF|__SNBF)) {
124		/* Ignore this file in _fwalk to avoid potential deadlock. */
125		fp->_flags |= __SIGN;
126		(void) _fwalk(lflush);
127		fp->_flags &= ~__SIGN;
128
129		/* Now flush this file without locking it. */
130		if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
131			__sflush(fp);
132	}
133	fp->_p = fp->_bf._base;
134	fp->_r = _sread(fp, (char *)fp->_p, fp->_bf._size);
135	fp->_flags &= ~__SMOD;	/* buffer contents are again pristine */
136	if (fp->_r <= 0) {
137		if (fp->_r == 0)
138			fp->_flags |= __SEOF;
139		else {
140			fp->_r = 0;
141			fp->_flags |= __SERR;
142		}
143		return (EOF);
144	}
145	return (0);
146}
147