[444] | 1 | /* |
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| 2 | * Copyright (c) 1990 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 | <<setvbuf>>---specify file or stream buffering |
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| 21 | |
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| 22 | INDEX |
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| 23 | setvbuf |
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| 24 | |
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| 25 | SYNOPSIS |
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| 26 | #include <stdio.h> |
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| 27 | int setvbuf(FILE *<[fp]>, char *<[buf]>, |
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| 28 | int <[mode]>, size_t <[size]>); |
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| 29 | |
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| 30 | DESCRIPTION |
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| 31 | Use <<setvbuf>> to specify what kind of buffering you want for the |
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| 32 | file or stream identified by <[fp]>, by using one of the following |
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| 33 | values (from <<stdio.h>>) as the <[mode]> argument: |
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| 34 | |
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| 35 | o+ |
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| 36 | o _IONBF |
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| 37 | Do not use a buffer: send output directly to the host system for the |
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| 38 | file or stream identified by <[fp]>. |
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| 39 | |
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| 40 | o _IOFBF |
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| 41 | Use full output buffering: output will be passed on to the host system |
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| 42 | only when the buffer is full, or when an input operation intervenes. |
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| 43 | |
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| 44 | o _IOLBF |
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| 45 | Use line buffering: pass on output to the host system at every |
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| 46 | newline, as well as when the buffer is full, or when an input |
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| 47 | operation intervenes. |
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| 48 | o- |
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| 49 | |
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| 50 | Use the <[size]> argument to specify how large a buffer you wish. You |
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| 51 | can supply the buffer itself, if you wish, by passing a pointer to a |
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| 52 | suitable area of memory as <[buf]>. Otherwise, you may pass <<NULL>> |
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| 53 | as the <[buf]> argument, and <<setvbuf>> will allocate the buffer. |
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| 54 | |
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| 55 | WARNINGS |
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| 56 | You may only use <<setvbuf>> before performing any file operation other |
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| 57 | than opening the file. |
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| 58 | |
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| 59 | If you supply a non-null <[buf]>, you must ensure that the associated |
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| 60 | storage continues to be available until you close the stream |
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| 61 | identified by <[fp]>. |
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| 62 | |
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| 63 | RETURNS |
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| 64 | A <<0>> result indicates success, <<EOF>> failure (invalid <[mode]> or |
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| 65 | <[size]> can cause failure). |
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| 66 | |
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| 67 | PORTABILITY |
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| 68 | Both ANSI C and the System V Interface Definition (Issue 2) require |
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| 69 | <<setvbuf>>. However, they differ on the meaning of a <<NULL>> buffer |
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| 70 | pointer: the SVID issue 2 specification says that a <<NULL>> buffer |
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| 71 | pointer requests unbuffered output. For maximum portability, avoid |
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| 72 | <<NULL>> buffer pointers. |
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| 73 | |
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| 74 | Both specifications describe the result on failure only as a |
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| 75 | nonzero value. |
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| 76 | |
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| 77 | Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>, |
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| 78 | <<lseek>>, <<read>>, <<sbrk>>, <<write>>. |
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| 79 | */ |
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| 80 | |
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| 81 | #include <_ansi.h> |
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| 82 | #include <stdio.h> |
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| 83 | #include <stdlib.h> |
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| 84 | #include "local.h" |
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| 85 | |
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| 86 | /* |
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| 87 | * Set one of the three kinds of buffering, optionally including a buffer. |
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| 88 | */ |
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| 89 | |
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| 90 | int |
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| 91 | setvbuf (register FILE * fp, |
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| 92 | char *buf, |
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| 93 | register int mode, |
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| 94 | register size_t size) |
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| 95 | { |
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| 96 | int ret = 0; |
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| 97 | struct _reent *reent = _REENT; |
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| 98 | size_t iosize; |
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| 99 | int ttyflag; |
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| 100 | |
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| 101 | CHECK_INIT (reent, fp); |
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| 102 | |
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| 103 | /* |
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| 104 | * Verify arguments. The `int' limit on `size' is due to this |
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| 105 | * particular implementation. Note, buf and size are ignored |
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| 106 | * when setting _IONBF. |
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| 107 | */ |
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| 108 | if (mode != _IONBF) |
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| 109 | if ((mode != _IOFBF && mode != _IOLBF) || (int)(_POINTER_INT) size < 0) |
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| 110 | return (EOF); |
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| 111 | |
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| 112 | |
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| 113 | /* |
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| 114 | * Write current buffer, if any; drop read count, if any. |
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| 115 | * Make sure putc() will not think fp is line buffered. |
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| 116 | * Free old buffer if it was from malloc(). Clear line and |
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| 117 | * non buffer flags, and clear malloc flag. |
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| 118 | */ |
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| 119 | _newlib_flockfile_start (fp); |
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| 120 | _fflush_r (reent, fp); |
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| 121 | if (HASUB(fp)) |
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| 122 | FREEUB(reent, fp); |
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| 123 | fp->_r = fp->_lbfsize = 0; |
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| 124 | if (fp->_flags & __SMBF) |
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| 125 | _free_r (reent, (void *) fp->_bf._base); |
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| 126 | fp->_flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT | __SEOF); |
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| 127 | |
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| 128 | if (mode == _IONBF) |
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| 129 | goto nbf; |
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| 130 | |
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| 131 | /* |
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| 132 | * Find optimal I/O size for seek optimization. This also returns |
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| 133 | * a `tty flag' to suggest that we check isatty(fd), but we do not |
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| 134 | * care since our caller told us how to buffer. |
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| 135 | */ |
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| 136 | fp->_flags |= __swhatbuf_r (reent, fp, &iosize, &ttyflag); |
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| 137 | if (size == 0) |
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| 138 | { |
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| 139 | buf = NULL; |
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| 140 | size = iosize; |
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| 141 | } |
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| 142 | |
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| 143 | /* Allocate buffer if needed. */ |
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| 144 | if (buf == NULL) |
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| 145 | { |
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| 146 | if ((buf = malloc (size)) == NULL) |
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| 147 | { |
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| 148 | /* |
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| 149 | * Unable to honor user's request. We will return |
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| 150 | * failure, but try again with file system size. |
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| 151 | */ |
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| 152 | ret = EOF; |
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| 153 | if (size != iosize) |
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| 154 | { |
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| 155 | size = iosize; |
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| 156 | buf = malloc (size); |
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| 157 | } |
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| 158 | } |
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| 159 | if (buf == NULL) |
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| 160 | { |
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| 161 | /* No luck; switch to unbuffered I/O. */ |
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| 162 | nbf: |
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| 163 | fp->_flags |= __SNBF; |
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| 164 | fp->_w = 0; |
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| 165 | fp->_bf._base = fp->_p = fp->_nbuf; |
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| 166 | fp->_bf._size = 1; |
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| 167 | _newlib_flockfile_exit (fp); |
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| 168 | return (ret); |
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| 169 | } |
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| 170 | fp->_flags |= __SMBF; |
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| 171 | } |
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| 172 | |
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| 173 | /* |
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| 174 | * We're committed to buffering from here, so make sure we've |
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| 175 | * registered to flush buffers on exit. |
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| 176 | */ |
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| 177 | if (!reent->__sdidinit) |
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| 178 | __sinit(reent); |
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| 179 | |
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| 180 | #ifdef _FSEEK_OPTIMIZATION |
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| 181 | /* |
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| 182 | * Kill any seek optimization if the buffer is not the |
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| 183 | * right size. |
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| 184 | * |
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| 185 | * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)? |
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| 186 | */ |
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| 187 | if (size != iosize) |
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| 188 | fp->_flags |= __SNPT; |
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| 189 | #endif |
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| 190 | |
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| 191 | /* |
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| 192 | * Fix up the FILE fields, and set __cleanup for output flush on |
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| 193 | * exit (since we are buffered in some way). |
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| 194 | */ |
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| 195 | if (mode == _IOLBF) |
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| 196 | fp->_flags |= __SLBF; |
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| 197 | fp->_bf._base = fp->_p = (unsigned char *) buf; |
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| 198 | fp->_bf._size = size; |
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| 199 | /* fp->_lbfsize is still 0 */ |
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| 200 | if (fp->_flags & __SWR) |
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| 201 | { |
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| 202 | /* |
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| 203 | * Begin or continue writing: see __swsetup(). Note |
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| 204 | * that __SNBF is impossible (it was handled earlier). |
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| 205 | */ |
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| 206 | if (fp->_flags & __SLBF) |
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| 207 | { |
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| 208 | fp->_w = 0; |
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| 209 | fp->_lbfsize = -fp->_bf._size; |
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| 210 | } |
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| 211 | else |
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| 212 | fp->_w = size; |
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| 213 | } |
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| 214 | else |
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| 215 | { |
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| 216 | /* begin/continue reading, or stay in intermediate state */ |
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| 217 | fp->_w = 0; |
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| 218 | } |
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| 219 | |
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| 220 | _newlib_flockfile_end (fp); |
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| 221 | return 0; |
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| 222 | } |
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