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
62 FILE *
fopen(const char * name,const char * type)63 fopen(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
81 static FILE *
_freopen_null(const char * type,FILE * iop)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
200 errret:
201 if (errno != EBADF)
202 (void) close(fd);
203
204 errret_noclose:
205 iop->_flag = 0; /* release iop */
206 return (NULL);
207 }
208
209 FILE *
freopen(const char * name,const char * type,FILE * iop)210 freopen(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