1/*	$OpenBSD: refill.c,v 1.11 2009/11/09 00:18:27 kurt Exp $ */
2/*-
3 * Copyright (c) 1990, 1993
4 *	The Regents of the University of California.  All rights reserved.
5 *
6 * This code is derived from software contributed to Berkeley by
7 * Chris Torek.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 * 3. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#include <errno.h>
35#include <stdio.h>
36#include <stdlib.h>
37#include "local.h"
38
39static int
40lflush(FILE *fp)
41{
42	if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
43		return (__sflush_locked(fp));	/* ignored... */
44	return (0);
45}
46
47/*
48 * Refill a stdio buffer.
49 * Return EOF on eof or error, 0 otherwise.
50 */
51int
52__srefill(FILE *fp)
53{
54
55	/* make sure stdio is set up */
56	if (!__sdidinit)
57		__sinit();
58
59	fp->_r = 0;		/* largely a convenience for callers */
60
61	/* SysV does not make this test; take it out for compatibility */
62	if (fp->_flags & __SEOF)
63		return (EOF);
64
65	/* if not already reading, have to be reading and writing */
66	if ((fp->_flags & __SRD) == 0) {
67		if ((fp->_flags & __SRW) == 0) {
68			errno = EBADF;
69			fp->_flags |= __SERR;
70			return (EOF);
71		}
72		/* switch to reading */
73		if (fp->_flags & __SWR) {
74			if (__sflush(fp))
75				return (EOF);
76			fp->_flags &= ~__SWR;
77			fp->_w = 0;
78			fp->_lbfsize = 0;
79		}
80		fp->_flags |= __SRD;
81	} else {
82		/*
83		 * We were reading.  If there is an ungetc buffer,
84		 * we must have been reading from that.  Drop it,
85		 * restoring the previous buffer (if any).  If there
86		 * is anything in that buffer, return.
87		 */
88		if (HASUB(fp)) {
89			FREEUB(fp);
90			if ((fp->_r = fp->_ur) != 0) {
91				fp->_p = fp->_up;
92				return (0);
93			}
94		}
95	}
96
97	if (fp->_bf._base == NULL)
98		__smakebuf(fp);
99
100	/*
101	 * Before reading from a line buffered or unbuffered file,
102	 * flush all line buffered output files, per the ANSI C
103	 * standard.
104	 */
105	if (fp->_flags & (__SLBF|__SNBF)) {
106		/* Ignore this file in _fwalk to avoid potential deadlock. */
107		fp->_flags |= __SIGN;
108		(void) _fwalk(lflush);
109		fp->_flags &= ~__SIGN;
110
111		/* Now flush this file without locking it. */
112		if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
113			__sflush(fp);
114	}
115	fp->_p = fp->_bf._base;
116	fp->_r = (*fp->_read)(fp->_cookie, (char *)fp->_p, fp->_bf._size);
117	fp->_flags &= ~__SMOD;	/* buffer contents are again pristine */
118	if (fp->_r <= 0) {
119		if (fp->_r == 0)
120			fp->_flags |= __SEOF;
121		else {
122			fp->_r = 0;
123			fp->_flags |= __SERR;
124		}
125		return (EOF);
126	}
127	return (0);
128}
129