1 /*
2 * Copyright (c) 1990 The Regents of the University of California.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms are permitted
6 * provided that the above copyright notice and this paragraph are
7 * duplicated in all such forms and that any documentation,
8 * and/or other materials related to such
9 * distribution and use acknowledge that the software was developed
10 * by the University of California, Berkeley. The name of the
11 * University may not be used to endorse or promote products derived
12 * from this software without specific prior written permission.
13 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
14 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
15 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
16 */
17
18 /*
19 FUNCTION
20 <<freopen64>>---open a large file using an existing file descriptor
21
22 INDEX
23 freopen64
24 INDEX
25 _freopen64_r
26
27 SYNOPSIS
28 #include <stdio.h>
29 FILE *freopen64(const char *<[file]>, const char *<[mode]>,
30 FILE *<[fp]>);
31 FILE *_freopen64_r(struct _reent *<[ptr]>, const char *<[file]>,
32 const char *<[mode]>, FILE *<[fp]>);
33
34 DESCRIPTION
35 Use this variant of <<fopen64>> if you wish to specify a particular file
36 descriptor <[fp]> (notably <<stdin>>, <<stdout>>, or <<stderr>>) for
37 the file.
38
39 If <[fp]> was associated with another file or stream, <<freopen64>>
40 closes that other file or stream (but ignores any errors while closing
41 it).
42
43 <[file]> and <[mode]> are used just as in <<fopen>>.
44
45 If <[file]> is <<NULL>>, the underlying stream is modified rather than
46 closed. The file cannot be given a more permissive access mode (for
47 example, a <[mode]> of "w" will fail on a read-only file descriptor),
48 but can change status such as append or binary mode. If modification
49 is not possible, failure occurs.
50
51 RETURNS
52 If successful, the result is the same as the argument <[fp]>. If the
53 file cannot be opened as specified, the result is <<NULL>>.
54
55 PORTABILITY
56 <<freopen>> is a glibc extension.
57
58 Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
59 <<lseek64>>, <<open64>>, <<read>>, <<sbrk>>, <<write>>.
60 */
61
62 #define _DEFAULT_SOURCE
63 #include <time.h>
64 #include <stdio.h>
65 #include <string.h>
66 #include <errno.h>
67 #include <fcntl.h>
68 #include <stdlib.h>
69 #include <sys/lock.h>
70 #include "../stdio/local.h"
71
72 /*
73 * Re-direct an existing, open (probably) file to some other file.
74 */
75
76 #ifdef __LARGE64_FILES
77
78 FILE *
freopen64(const char * file,const char * mode,register FILE * fp)79 freopen64 (
80 const char *file,
81 const char *mode,
82 register FILE *fp)
83 {
84 register int f;
85 int flags, oflags, oflags2;
86 int e = 0;
87
88
89 CHECK_INIT (ptr, fp);
90
91 /* We can't use the _newlib_flockfile_XXX macros here due to the
92 interlocked locking with the sfp_lock. */
93 #ifdef _STDIO_WITH_THREAD_CANCELLATION_SUPPORT
94 int __oldcancel;
95 pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, &__oldcancel);
96 #endif
97 oflags2 = fp->_flags2;
98 if (!(oflags2 & __SNLK))
99 _flockfile (fp);
100
101 if ((flags = __sflags (mode, &oflags)) == 0)
102 {
103 if (!(oflags2 & __SNLK))
104 _funlockfile (fp);
105 #ifdef _STDIO_WITH_THREAD_CANCELLATION_SUPPORT
106 pthread_setcancelstate (__oldcancel, &__oldcancel);
107 #endif
108 fclose (fp);
109 return NULL;
110 }
111
112 /*
113 * Remember whether the stream was open to begin with, and
114 * which file descriptor (if any) was associated with it.
115 * If it was attached to a descriptor, defer closing it,
116 * so that, e.g., freopen("/dev/stdin", "r", stdin) works.
117 * This is unnecessary if it was not a Unix file.
118 */
119
120 if (fp->_flags == 0)
121 fp->_flags = __SEOF; /* hold on to it */
122 else
123 {
124 if (fp->_flags & __SWR)
125 fflush (fp);
126 /*
127 * If close is NULL, closing is a no-op, hence pointless.
128 * If file is NULL, the file should not be closed.
129 */
130 if (fp->_close != NULL && file != NULL)
131 fp->_close (fp->_cookie);
132 }
133
134 /*
135 * Now get a new descriptor to refer to the new file, or reuse the
136 * existing file descriptor if file is NULL.
137 */
138
139 if (file != NULL)
140 {
141 f = open64 ((char *) file, oflags, 0666);
142 e = _REENT_ERRNO(ptr);
143 }
144 else
145 {
146 #ifdef _HAVE_FCNTL
147 int oldflags;
148 /*
149 * Reuse the file descriptor, but only if the new access mode is
150 * equal or less permissive than the old. F_SETFL correctly
151 * ignores creation flags.
152 */
153 f = fp->_file;
154 if ((oldflags = fcntl (f, F_GETFL, 0)) == -1
155 || ! ((oldflags & O_ACCMODE) == O_RDWR
156 || ((oldflags ^ oflags) & O_ACCMODE) == 0)
157 || fcntl (f, F_SETFL, oflags) == -1)
158 f = -1;
159 #else
160 /* We cannot modify without fcntl support. */
161 f = -1;
162 #endif
163
164 #ifdef __SCLE
165 /*
166 * F_SETFL doesn't change textmode. Don't mess with modes of ttys.
167 */
168 if (0 <= f && ! isatty (f)
169 && setmode (f, oflags & (O_BINARY | O_TEXT)) == -1)
170 f = -1;
171 #endif
172
173 if (f < 0)
174 {
175 e = EBADF;
176 if (fp->_close != NULL)
177 fp->_close (fp->_cookie);
178 }
179 }
180
181 /*
182 * Finish closing fp. Even if the open succeeded above,
183 * we cannot keep fp->_base: it may be the wrong size.
184 * This loses the effect of any setbuffer calls,
185 * but stdio has always done this before.
186 */
187
188 if (fp->_flags & __SMBF)
189 free ((char *) fp->_bf._base);
190 fp->_w = 0;
191 fp->_r = 0;
192 fp->_p = NULL;
193 fp->_bf._base = NULL;
194 fp->_bf._size = 0;
195 fp->_lbfsize = 0;
196 if (HASUB (fp))
197 FREEUB (ptr, fp);
198 fp->_ub._size = 0;
199 if (HASLB (fp))
200 FREELB (ptr, fp);
201 fp->_lb._size = 0;
202 fp->_flags &= ~__SORD;
203 fp->_flags2 &= ~__SWID;
204 memset (&fp->_mbstate, 0, sizeof (_mbstate_t));
205
206 if (f < 0)
207 { /* did not get it after all */
208 __sfp_lock_acquire ();
209 fp->_flags = 0; /* set it free */
210 _REENT_ERRNO(ptr) = e; /* restore in case _close clobbered */
211 if (!(oflags2 & __SNLK))
212 _funlockfile (fp);
213 #ifndef __SINGLE_THREAD__
214 __lock_close_recursive (fp->_lock);
215 #endif
216 __sfp_lock_release ();
217 #if !defined (__SINGLE_THREAD__) && defined (_POSIX_THREADS)
218 pthread_setcancelstate (__oldcancel, &__oldcancel);
219 #endif
220 return NULL;
221 }
222
223 fp->_flags = flags;
224 fp->_file = f;
225 fp->_cookie = (void *) fp;
226 fp->_read = __sread;
227 fp->_write = __swrite64;
228 fp->_seek = __sseek;
229 fp->_seek64 = __sseek64;
230 fp->_close = __sclose;
231
232 #ifdef __SCLE
233 if (__stextmode(fp->_file))
234 fp->_flags |= __SCLE;
235 #endif
236
237 fp->_flags |= __SL64;
238
239 if (!(oflags2 & __SNLK))
240 _funlockfile (fp);
241 #if !defined (__SINGLE_THREAD__) && defined (_POSIX_THREADS)
242 pthread_setcancelstate (__oldcancel, &__oldcancel);
243 #endif
244 return fp;
245 }
246
247 #endif /* __LARGE64_FILES */
248
