1/*	$NetBSD: refill.c,v 1.15 2012/03/15 18:22:30 christos Exp $	*/
2
3/*-
4 * Copyright (c) 1990, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Chris Torek.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35#include <sys/cdefs.h>
36#if defined(LIBC_SCCS) && !defined(lint)
37#if 0
38static char sccsid[] = "@(#)refill.c	8.1 (Berkeley) 6/4/93";
39#else
40__RCSID("$NetBSD: refill.c,v 1.15 2012/03/15 18:22:30 christos Exp $");
41#endif
42#endif /* LIBC_SCCS and not lint */
43
44#include <assert.h>
45#include <errno.h>
46#include <stdio.h>
47#include <stdlib.h>
48#include "reentrant.h"
49#include "local.h"
50
51#ifdef _REENTRANT
52extern rwlock_t __sfp_lock;
53#endif
54
55static int
56lflush(FILE *fp)
57{
58
59	_DIAGASSERT(fp != NULL);
60
61	if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
62		return __sflush(fp);
63	return 0;
64}
65
66/*
67 * Refill a stdio buffer.
68 * Return EOF on eof or error, 0 otherwise.
69 */
70int
71__srefill(FILE *fp)
72{
73
74	_DIAGASSERT(fp != NULL);
75
76	/* make sure stdio is set up */
77	if (!__sdidinit)
78		__sinit();
79
80	fp->_r = 0;		/* largely a convenience for callers */
81
82	/* SysV does not make this test; take it out for compatibility */
83	if (fp->_flags & __SEOF)
84		return EOF;
85
86	/* if not already reading, have to be reading and writing */
87	if ((fp->_flags & __SRD) == 0) {
88		if ((fp->_flags & __SRW) == 0) {
89			errno = EBADF;
90			fp->_flags |= __SERR;
91			return EOF;
92		}
93		/* switch to reading */
94		if (fp->_flags & __SWR) {
95			if (__sflush(fp))
96				return EOF;
97			fp->_flags &= ~__SWR;
98			fp->_w = 0;
99			fp->_lbfsize = 0;
100		}
101		fp->_flags |= __SRD;
102	} else {
103		/*
104		 * We were reading.  If there is an ungetc buffer,
105		 * we must have been reading from that.  Drop it,
106		 * restoring the previous buffer (if any).  If there
107		 * is anything in that buffer, return.
108		 */
109		if (HASUB(fp)) {
110			FREEUB(fp);
111			if ((fp->_r = fp->_ur) != 0) {
112				fp->_p = fp->_up;
113				return 0;
114			}
115		}
116	}
117
118	if (fp->_bf._base == NULL)
119		__smakebuf(fp);
120
121	/*
122	 * Before reading from a line buffered or unbuffered file,
123	 * flush all line buffered output files, per the ANSI C
124	 * standard.
125	 */
126	if (fp->_flags & (__SLBF|__SNBF)) {
127		rwlock_rdlock(&__sfp_lock);
128		(void) _fwalk(lflush);
129		rwlock_unlock(&__sfp_lock);
130	}
131	fp->_p = fp->_bf._base;
132	fp->_r = (int)(*fp->_read)(fp->_cookie, (char *)fp->_p,
133	    (size_t)fp->_bf._size);
134	fp->_flags &= ~__SMOD;	/* buffer contents are again pristine */
135	if (fp->_r <= 0) {
136		if (fp->_r == 0)
137			fp->_flags |= __SEOF;
138		else {
139			fp->_r = 0;
140			fp->_flags |= __SERR;
141		}
142		return EOF;
143	}
144	return 0;
145}
146