1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22/*
23 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
24 * Use is subject to license terms.
25 */
26
27/*	Copyright (c) 1988 AT&T	*/
28/*	  All Rights Reserved	*/
29
30#pragma weak __filbuf = _filbuf
31
32#include "lint.h"
33#include "file64.h"
34#include <stdio.h>
35#include <errno.h>
36#include <sys/types.h>
37#include <unistd.h>
38#include "stdiom.h"
39
40
41static int
42_xpg4_check(void)
43{
44	extern int	__xpg4;
45
46	return (__xpg4);
47}
48
49/* fill buffer, return first character or EOF */
50int
51_filbuf(FILE *iop)
52{
53	ssize_t res;
54	size_t nbyte;
55	Uchar *endbuf;
56#ifdef	_LP64
57	unsigned int	flag;
58#else
59	unsigned char	flag;
60#endif
61
62	if (!(iop->_flag & _IOREAD)) {	/* check, correct permissions */
63		if (iop->_flag & _IORW) {
64			iop->_flag |= _IOREAD;  /* change direction */
65						/* to read - fseek */
66		} else {
67			errno = EBADF;
68			return (EOF);
69		}
70	}
71
72	if (iop->_base == 0) {
73		/* Get the buffer and end of buffer */
74		if ((endbuf = _findbuf(iop)) == 0) {
75			return (EOF);
76		}
77	} else {
78		endbuf = _bufend(iop);
79	}
80
81	/*
82	 * Flush all line-buffered streams before we
83	 * read no-buffered or line-buffered input.
84	 */
85	if (iop->_flag & (_IONBF | _IOLBF))
86		_flushlbf();
87	/*
88	 * Changed the get family fns in Solaris 10 to comply with the
89	 * 1990 C Standard and standards based upon it.  If the
90	 * end-of-file indicator for the stream is set, or if the stream
91	 * is at end-of-file, the function will return EOF, and the file
92	 * position indicator for the stream will not be advanced.
93	 * Additional bytes appended to the file do not clear the EOF
94	 * indicator.
95	 */
96	if ((flag = iop->_flag) & _IOEOF) {
97		if (_xpg4_check()) {
98			/*
99			 * A previous read() has returned 0 (below),
100			 * therefore iop->_cnt was set to 0, and the EOF
101			 * indicator was set before returning EOF.  Reset
102			 * iop->_cnt to 0; it has likely been changed by
103			 * a function such as getc().
104			 */
105			iop->_cnt = 0;
106			return (EOF);
107		}
108	}
109
110	/*
111	 * Fill buffer or read 1 byte for unbuffered, handling any errors.
112	 */
113	iop->_ptr = iop->_base;
114	if (flag & _IONBF)
115		nbyte = 1;
116	else
117		nbyte = endbuf - iop->_base;
118	if ((res = _xread(iop, (char *)iop->_base, nbyte)) > 0) {
119		iop->_cnt = res - 1;
120		return (*iop->_ptr++);
121	}
122
123	iop->_cnt = 0;
124	if (res == 0)
125		iop->_flag |= _IOEOF;
126	else if (!cancel_active())
127		iop->_flag |= _IOERR;
128	return (EOF);
129}
130