refill.c revision 1dc9e472e19acfe6dc7f41e429236e7eef7ceda1 
1/*	$OpenBSD: refill.c,v 1.8 2005/08/08 08:05:36 espie 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
43	if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
44		return (__sflush(fp));
45	return (0);
46}
47
48/*
49 * Refill a stdio buffer.
50 * Return EOF on eof or error, 0 otherwise.
51 */
52int
53__srefill(FILE *fp)
54{
55
56	/* make sure stdio is set up */
57	if (!__sdidinit)
58		__sinit();
59
60	fp->_r = 0;		/* largely a convenience for callers */
61
62	/* SysV does not make this test; take it out for compatibility */
63	if (fp->_flags & __SEOF)
64		return (EOF);
65
66	/* if not already reading, have to be reading and writing */
67	if ((fp->_flags & __SRD) == 0) {
68		if ((fp->_flags & __SRW) == 0) {
69			errno = EBADF;
70			fp->_flags |= __SERR;
71			return (EOF);
72		}
73		/* switch to reading */
74		if (fp->_flags & __SWR) {
75			if (__sflush(fp))
76				return (EOF);
77			fp->_flags &= ~__SWR;
78			fp->_w = 0;
79			fp->_lbfsize = 0;
80		}
81		fp->_flags |= __SRD;
82	} else {
83		/*
84		 * We were reading.  If there is an ungetc buffer,
85		 * we must have been reading from that.  Drop it,
86		 * restoring the previous buffer (if any).  If there
87		 * is anything in that buffer, return.
88		 */
89		if (HASUB(fp)) {
90			FREEUB(fp);
91			if ((fp->_r = fp->_ur) != 0) {
92				fp->_p = fp->_up;
93				return (0);
94			}
95		}
96	}
97
98	if (fp->_bf._base == NULL)
99		__smakebuf(fp);
100
101	/*
102	 * Before reading from a line buffered or unbuffered file,
103	 * flush all line buffered output files, per the ANSI C
104	 * standard.
105	 */
106	if (fp->_flags & (__SLBF|__SNBF))
107		(void) _fwalk(lflush);
108	fp->_p = fp->_bf._base;
109	fp->_r = (*fp->_read)(fp->_cookie, (char *)fp->_p, fp->_bf._size);
110	fp->_flags &= ~__SMOD;	/* buffer contents are again pristine */
111	if (fp->_r <= 0) {
112		if (fp->_r == 0)
113			fp->_flags |= __SEOF;
114		else {
115			fp->_r = 0;
116			fp->_flags |= __SERR;
117		}
118		return (EOF);
119	}
120	return (0);
121}
122