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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