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/*
31 * University Copyright- Copyright (c) 1982, 1986, 1988
32 * The Regents of the University of California
33 * All Rights Reserved
34 *
35 * University Acknowledgment- Portions of this document are derived from
36 * software developed by the University of California, Berkeley, and its
37 * contributors.
38 */
39
40/*
41 * Copyright 2020 Robert Mustacchi
42 */
43
44#include "lint.h"
45#include "file64.h"
46#include <sys/types.h>
47#include <stdio.h>
48#include <mtlib.h>
49#include <fcntl.h>
50#include <unistd.h>
51#include <limits.h>
52#include <thread.h>
53#include <synch.h>
54#include <stdlib.h>
55#include <errno.h>
56#include "stdiom.h"
57#include "xpg6.h"
58
59/* Final argument to _endopen depends on build environment */
60#define	LARGE_OPEN		(_FILE_OFFSET_BITS == 64)
61
62FILE *
63fopen(const char *name, const char *type) /* open name, return new stream */
64{
65	FILE *iop;
66	FILE  *rc;
67
68	iop = _findiop();
69	/*
70	 * Note that iop is not locked here, since no other thread could
71	 * possibly call _endopen with the same iop at this point.
72	 */
73	rc = _endopen(name, type, iop, LARGE_OPEN);
74
75	if (rc == NULL && iop != NULL)
76		iop->_flag = 0; /* release iop */
77
78	return (rc);
79}
80
81static FILE *
82_freopen_null(const char *type, FILE *iop)
83{
84	char	plus, mode;
85	int	oflag, nflag, fd, accmode;
86	mbstate_t	*mb;
87
88	if (iop == NULL || iop->_flag == 0) {
89		errno = EBADF;
90		return (NULL);
91	}
92
93	/*
94	 * If this is not a file-based stream (as in we have no file
95	 * descriptor), then we need to close this, but still actually return an
96	 * error.
97	 */
98	if (_get_fd(iop) == -1) {
99		(void) close_fd(iop);
100		errno = EBADF;
101		return (NULL);
102	}
103
104	if (!(iop->_flag & _IONBF) && (iop->_flag & (_IOWRT | _IOREAD | _IORW)))
105		(void) _fflush_u(iop);
106
107	if (iop->_flag & _IOMYBUF) {
108		free((char *)iop->_base - PUSHBACK);
109	}
110	iop->_base = NULL;
111	iop->_ptr = NULL;
112	/*
113	 * Clear stream orientation, clear stream encoding rule, and set
114	 * stream's mbstate_t object to describe an initial conversion state.
115	 */
116	mb = _getmbstate(iop);
117	if (mb != NULL)
118		(void) memset(mb, 0, sizeof (mbstate_t));
119	iop->_cnt = 0;
120	_setorientation(iop, _NO_MODE);
121
122	fd = FILENO(iop);
123	mode = type[0];
124	if (mode != 'r' && mode != 'w' && mode != 'a') {
125		errno = EINVAL;
126		goto errret;
127	}
128
129	if ((oflag = fcntl(fd, F_GETFL)) == -1)
130		goto errret;
131
132	if ((plus = type[1]) == 'b')
133		plus = type[2];
134
135	/*
136	 * Because the filename has not been specified, the underlying file
137	 * will not be closed and reopened.  The access modes of an open
138	 * file descriptor can't be changed via fcntl().  When '+' is
139	 * specified, the old access mode needs to be O_RDWR.  When 'r' is
140	 * specified, the old access mode needs to be O_RDONLY or O_RDWR.
141	 * When 'a' or 'w' is specified, the old access mode needs to be
142	 * O_WRONLY or O_RDWR.  Otherwise, fail with EBADF, indicating that
143	 * the underlying file descriptor was not opened with a mode that
144	 * would allow the stream to do successful I/O with the requested mode.
145	 */
146
147	accmode = oflag & O_ACCMODE;
148	if ((accmode == O_RDONLY && (mode != 'r' || plus == '+')) ||
149	    (accmode == O_WRONLY && (mode == 'r' || plus == '+'))) {
150		(void) close(fd);
151		errno = EBADF;
152		goto errret_noclose;
153	}
154
155#ifdef	_LP64
156	iop->_flag &= ~_DEF_FLAG_MASK;	/* clear lower 8-bits */
157	if (mode == 'r') {
158		iop->_flag |= _IOREAD;
159		nflag = oflag & ~O_APPEND;
160	} else if (mode == 'w') {
161		iop->_flag |= _IOWRT;
162		nflag = oflag & ~O_APPEND;
163	} else {
164		iop->_flag |= _IOWRT;
165		nflag = oflag | O_APPEND;
166	}
167	if (plus == '+') {
168		iop->_flag = (iop->_flag & ~(_IOREAD | _IOWRT)) | _IORW;
169	}
170#else
171	if (mode == 'r') {
172		iop->_flag = _IOREAD;
173		nflag = oflag & ~O_APPEND;
174	} else if (mode == 'w') {
175		iop->_flag = _IOWRT;
176		nflag = oflag & ~O_APPEND;
177	} else {
178		iop->_flag = _IOWRT;
179		nflag = oflag | O_APPEND;
180	}
181	if (plus == '+') {
182		iop->_flag = _IORW;
183	}
184#endif
185	/*
186	 * Change mode of underlying fd as much as possible without closing
187	 * and reopening it.  Ignore truncate failures, eg. with stdout.
188	 */
189	if (mode == 'w')
190		(void) ftruncate64(fd, (off64_t)0);
191
192	if (fcntl(fd, F_SETFL, nflag) == -1)
193		goto errret;
194
195	/* ignore seek failures, eg. with pipes */
196	(void) lseek64(fd, (off64_t)0, SEEK_SET);
197
198	return (iop);
199
200errret:
201	if (errno != EBADF)
202		(void) close(fd);
203
204errret_noclose:
205	iop->_flag = 0;		/* release iop */
206	return (NULL);
207}
208
209FILE *
210freopen(const char *name, const char *type, FILE *iop)
211{
212	FILE *rc;
213	rmutex_t *lk;
214
215	if (name == NULL && __xpg6 & _C99SUSv3_freopen_NULL_filename) {
216		/*
217		 * XPG6:  If name is a null pointer, freopen will attempt to
218		 * change the mode of the stream to that specified by type.
219		 */
220		FLOCKFILE(lk, iop);
221		rc = _freopen_null(type, iop);
222		FUNLOCKFILE(lk);
223		return (rc);
224	}
225	/*
226	 * there may be concurrent calls to reopen the same stream - need
227	 * to make freopen() atomic
228	 */
229	FLOCKFILE(lk, iop);
230	/*
231	 * new function to do everything that fclose() does, except
232	 * to release the iop - this cannot yet be released since
233	 * _endopen() is yet to be called on this iop
234	 */
235
236	(void) close_fd(iop);
237
238	rc = _endopen(name, type, iop, LARGE_OPEN);
239
240	if (rc == NULL)
241		iop->_flag = 0; /* release iop */
242
243	FUNLOCKFILE(lk);
244	return (rc);
245}
246