[444] | 1 | /* |
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| 2 | * Copyright (c) 1990, 2007 The Regents of the University of California. |
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| 3 | * All rights reserved. |
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| 4 | * |
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| 5 | * Redistribution and use in source and binary forms are permitted |
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| 6 | * provided that the above copyright notice and this paragraph are |
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| 7 | * duplicated in all such forms and that any documentation, |
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| 8 | * advertising materials, and other materials related to such |
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| 9 | * distribution and use acknowledge that the software was developed |
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| 10 | * by the University of California, Berkeley. The name of the |
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| 11 | * University may not be used to endorse or promote products derived |
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| 12 | * from this software without specific prior written permission. |
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| 13 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR |
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| 14 | * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED |
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| 15 | * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. |
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| 16 | */ |
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| 17 | |
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| 18 | /* |
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| 19 | FUNCTION |
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| 20 | <<freopen>>---open a file using an existing file descriptor |
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| 21 | |
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| 22 | INDEX |
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| 23 | freopen |
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| 24 | INDEX |
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| 25 | _freopen_r |
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| 26 | |
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| 27 | SYNOPSIS |
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| 28 | #include <stdio.h> |
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| 29 | FILE *freopen(const char *restrict <[file]>, const char *restrict <[mode]>, |
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| 30 | FILE *restrict <[fp]>); |
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| 31 | FILE *_freopen_r(struct _reent *<[ptr]>, const char *restrict <[file]>, |
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| 32 | const char *restrict <[mode]>, FILE *restrict <[fp]>); |
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| 33 | |
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| 34 | DESCRIPTION |
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| 35 | Use this variant of <<fopen>> if you wish to specify a particular file |
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| 36 | descriptor <[fp]> (notably <<stdin>>, <<stdout>>, or <<stderr>>) for |
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| 37 | the file. |
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| 38 | |
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| 39 | If <[fp]> was associated with another file or stream, <<freopen>> |
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| 40 | closes that other file or stream (but ignores any errors while closing |
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| 41 | it). |
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| 42 | |
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| 43 | <[file]> and <[mode]> are used just as in <<fopen>>. |
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| 44 | |
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| 45 | If <[file]> is <<NULL>>, the underlying stream is modified rather than |
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| 46 | closed. The file cannot be given a more permissive access mode (for |
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| 47 | example, a <[mode]> of "w" will fail on a read-only file descriptor), |
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| 48 | but can change status such as append or binary mode. If modification |
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| 49 | is not possible, failure occurs. |
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| 50 | |
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| 51 | RETURNS |
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| 52 | If successful, the result is the same as the argument <[fp]>. If the |
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| 53 | file cannot be opened as specified, the result is <<NULL>>. |
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| 54 | |
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| 55 | PORTABILITY |
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| 56 | ANSI C requires <<freopen>>. |
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| 57 | |
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| 58 | Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>, |
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| 59 | <<lseek>>, <<open>>, <<read>>, <<sbrk>>, <<write>>. |
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| 60 | */ |
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| 61 | |
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| 62 | #include <_ansi.h> |
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| 63 | #include <reent.h> |
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| 64 | #include <time.h> |
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| 65 | #include <stdio.h> |
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| 66 | #include <string.h> |
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| 67 | #include <errno.h> |
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| 68 | #include <fcntl.h> |
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| 69 | #include <stdlib.h> |
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| 70 | #include <sys/lock.h> |
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| 71 | #include "local.h" |
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| 72 | |
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| 73 | /* |
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| 74 | * Re-direct an existing, open (probably) file to some other file. |
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| 75 | */ |
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| 76 | |
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| 77 | FILE * |
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| 78 | _freopen_r (struct _reent *ptr, |
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| 79 | const char *__restrict file, |
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| 80 | const char *__restrict mode, |
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| 81 | register FILE *__restrict fp) |
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| 82 | { |
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| 83 | register int f; |
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| 84 | int flags, oflags, oflags2; |
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| 85 | int e = 0; |
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| 86 | |
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| 87 | CHECK_INIT (ptr, fp); |
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| 88 | |
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| 89 | /* We can't use the _newlib_flockfile_XXX macros here due to the |
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| 90 | interlocked locking with the sfp_lock. */ |
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| 91 | #ifdef _STDIO_WITH_THREAD_CANCELLATION_SUPPORT |
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| 92 | int __oldcancel; |
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| 93 | pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, &__oldcancel); |
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| 94 | #endif |
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| 95 | oflags2 = fp->_flags2; |
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| 96 | if (!(oflags2 & __SNLK)) |
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| 97 | _flockfile (fp); |
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| 98 | |
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| 99 | if ((flags = __sflags (ptr, mode, &oflags)) == 0) |
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| 100 | { |
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| 101 | if (!(oflags2 & __SNLK)) |
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| 102 | _funlockfile (fp); |
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| 103 | #ifdef _STDIO_WITH_THREAD_CANCELLATION_SUPPORT |
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| 104 | pthread_setcancelstate (__oldcancel, &__oldcancel); |
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| 105 | #endif |
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| 106 | _fclose_r (ptr, fp); |
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| 107 | return NULL; |
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| 108 | } |
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| 109 | |
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| 110 | /* |
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| 111 | * Remember whether the stream was open to begin with, and |
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| 112 | * which file descriptor (if any) was associated with it. |
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| 113 | * If it was attached to a descriptor, defer closing it, |
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| 114 | * so that, e.g., freopen("/dev/stdin", "r", stdin) works. |
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| 115 | * This is unnecessary if it was not a Unix file. |
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| 116 | */ |
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| 117 | |
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| 118 | if (fp->_flags == 0) |
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| 119 | fp->_flags = __SEOF; /* hold on to it */ |
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| 120 | else |
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| 121 | { |
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| 122 | if (fp->_flags & __SWR) |
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| 123 | _fflush_r (ptr, fp); |
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| 124 | /* |
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| 125 | * If close is NULL, closing is a no-op, hence pointless. |
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| 126 | * If file is NULL, the file should not be closed. |
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| 127 | */ |
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| 128 | if (fp->_close != NULL && file != NULL) |
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| 129 | fp->_close (ptr, fp->_cookie); |
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| 130 | } |
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| 131 | |
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| 132 | /* |
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| 133 | * Now get a new descriptor to refer to the new file, or reuse the |
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| 134 | * existing file descriptor if file is NULL. |
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| 135 | */ |
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| 136 | |
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| 137 | if (file != NULL) |
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| 138 | { |
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| 139 | f = _open_r (ptr, (char *) file, oflags, 0666); |
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| 140 | e = ptr->_errno; |
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| 141 | } |
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| 142 | else |
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| 143 | { |
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| 144 | #ifdef HAVE_FCNTL |
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| 145 | int oldflags; |
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| 146 | /* |
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| 147 | * Reuse the file descriptor, but only if the new access mode is |
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| 148 | * equal or less permissive than the old. F_SETFL correctly |
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| 149 | * ignores creation flags. |
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| 150 | */ |
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| 151 | f = fp->_file; |
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| 152 | if ((oldflags = _fcntl_r (ptr, f, F_GETFL, 0)) == -1 |
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| 153 | || ! ((oldflags & O_ACCMODE) == O_RDWR |
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| 154 | || ((oldflags ^ oflags) & O_ACCMODE) == 0) |
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| 155 | || _fcntl_r (ptr, f, F_SETFL, oflags) == -1) |
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| 156 | f = -1; |
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| 157 | #else |
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| 158 | /* We cannot modify without fcntl support. */ |
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| 159 | f = -1; |
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| 160 | #endif |
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| 161 | |
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| 162 | #ifdef __SCLE |
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| 163 | /* |
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| 164 | * F_SETFL doesn't change textmode. Don't mess with modes of ttys. |
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| 165 | */ |
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| 166 | if (0 <= f && ! _isatty_r (ptr, f) |
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| 167 | && setmode (f, oflags & (O_BINARY | O_TEXT)) == -1) |
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| 168 | f = -1; |
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| 169 | #endif |
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| 170 | |
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| 171 | if (f < 0) |
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| 172 | { |
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| 173 | e = EBADF; |
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| 174 | if (fp->_close != NULL) |
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| 175 | fp->_close (ptr, fp->_cookie); |
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| 176 | } |
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| 177 | } |
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| 178 | |
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| 179 | /* |
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| 180 | * Finish closing fp. Even if the open succeeded above, |
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| 181 | * we cannot keep fp->_base: it may be the wrong size. |
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| 182 | * This loses the effect of any setbuffer calls, |
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| 183 | * but stdio has always done this before. |
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| 184 | */ |
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| 185 | |
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| 186 | if (fp->_flags & __SMBF) |
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| 187 | _free_r (ptr, (char *) fp->_bf._base); |
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| 188 | fp->_w = 0; |
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| 189 | fp->_r = 0; |
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| 190 | fp->_p = NULL; |
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| 191 | fp->_bf._base = NULL; |
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| 192 | fp->_bf._size = 0; |
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| 193 | fp->_lbfsize = 0; |
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| 194 | if (HASUB (fp)) |
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| 195 | FREEUB (ptr, fp); |
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| 196 | fp->_ub._size = 0; |
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| 197 | if (HASLB (fp)) |
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| 198 | FREELB (ptr, fp); |
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| 199 | fp->_lb._size = 0; |
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| 200 | fp->_flags &= ~__SORD; |
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| 201 | fp->_flags2 &= ~__SWID; |
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| 202 | memset (&fp->_mbstate, 0, sizeof (_mbstate_t)); |
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| 203 | |
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| 204 | if (f < 0) |
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| 205 | { /* did not get it after all */ |
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| 206 | __sfp_lock_acquire (); |
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| 207 | fp->_flags = 0; /* set it free */ |
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| 208 | ptr->_errno = e; /* restore in case _close clobbered */ |
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| 209 | if (!(oflags2 & __SNLK)) |
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| 210 | _funlockfile (fp); |
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| 211 | #ifndef __SINGLE_THREAD__ |
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| 212 | __lock_close_recursive (fp->_lock); |
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| 213 | #endif |
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| 214 | __sfp_lock_release (); |
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| 215 | #ifdef _STDIO_WITH_THREAD_CANCELLATION_SUPPORT |
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| 216 | pthread_setcancelstate (__oldcancel, &__oldcancel); |
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| 217 | #endif |
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| 218 | return NULL; |
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| 219 | } |
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| 220 | |
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| 221 | fp->_flags = flags; |
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| 222 | fp->_file = f; |
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| 223 | fp->_cookie = (void *) fp; |
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| 224 | fp->_read = __sread; |
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| 225 | fp->_write = __swrite; |
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| 226 | fp->_seek = __sseek; |
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| 227 | fp->_close = __sclose; |
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| 228 | |
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| 229 | #ifdef __SCLE |
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| 230 | if (__stextmode (fp->_file)) |
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| 231 | fp->_flags |= __SCLE; |
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| 232 | #endif |
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| 233 | |
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| 234 | if (!(oflags2 & __SNLK)) |
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| 235 | _funlockfile (fp); |
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| 236 | #ifdef _STDIO_WITH_THREAD_CANCELLATION_SUPPORT |
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| 237 | pthread_setcancelstate (__oldcancel, &__oldcancel); |
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| 238 | #endif |
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| 239 | return fp; |
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| 240 | } |
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| 241 | |
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| 242 | #ifndef _REENT_ONLY |
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| 243 | |
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| 244 | FILE * |
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| 245 | freopen (const char *__restrict file, |
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| 246 | const char *__restrict mode, |
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| 247 | register FILE *__restrict fp) |
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| 248 | { |
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| 249 | return _freopen_r (_REENT, file, mode, fp); |
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| 250 | } |
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| 251 | |
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| 252 | #endif /*!_REENT_ONLY */ |
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