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 | <<ftello64>>---return position in a stream or file |
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21 | |
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22 | INDEX |
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23 | ftello64 |
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24 | INDEX |
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25 | _ftello64_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 | _off64_t ftello64(FILE *<[fp]>); |
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30 | _off64_t _ftello64_r(struct _reent *<[ptr]>, FILE *<[fp]>); |
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31 | |
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32 | DESCRIPTION |
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33 | Objects of type <<FILE>> can have a ``position'' that records how much |
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34 | of the file your program has already read. Many of the <<stdio>> functions |
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35 | depend on this position, and many change it as a side effect. |
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36 | |
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37 | The result of <<ftello64>> is the current position for a large file |
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38 | identified by <[fp]>. If you record this result, you can later |
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39 | use it with <<fseeko64>> to return the file to this |
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40 | position. The difference between <<ftello>> and <<ftello64>> is that |
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41 | <<ftello>> returns <<off_t>> and <<ftello64>> is designed to work |
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42 | for large files (>2GB) and returns <<_off64_t>>. |
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43 | |
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44 | In the current implementation, <<ftello64>> simply uses a character |
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45 | count to represent the file position; this is the same number that |
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46 | would be recorded by <<fgetpos64>>. |
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47 | |
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48 | The function exists only if the __LARGE64_FILES flag is defined. |
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49 | An error occurs if the <[fp]> was not opened via <<fopen64>>. |
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50 | |
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51 | RETURNS |
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52 | <<ftello64>> returns the file position, if possible. If it cannot do |
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53 | this, it returns <<-1>>. Failure occurs on streams that do not support |
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54 | positioning or not opened via <<fopen64>>; the global <<errno>> indicates |
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55 | this condition with the value <<ESPIPE>>. |
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56 | |
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57 | PORTABILITY |
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58 | <<ftello64>> is a glibc extension. |
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59 | |
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60 | No supporting OS subroutines are required. |
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61 | */ |
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62 | |
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63 | #if defined(LIBC_SCCS) && !defined(lint) |
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64 | static char sccsid[] = "%W% (Berkeley) %G%"; |
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65 | #endif /* LIBC_SCCS and not lint */ |
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66 | |
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67 | /* |
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68 | * ftello64: return current offset. |
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69 | */ |
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70 | |
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71 | #include <stdio.h> |
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72 | #include <errno.h> |
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73 | |
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74 | #include "local.h" |
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75 | |
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76 | #ifdef __LARGE64_FILES |
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77 | |
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78 | _off64_t |
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79 | _ftello64_r (struct _reent *ptr, |
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80 | register FILE * fp) |
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81 | { |
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82 | _fpos64_t pos; |
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83 | |
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84 | /* Only do 64-bit tell on large file. */ |
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85 | if (!(fp->_flags & __SL64)) |
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86 | return (_off64_t) _ftello_r (ptr, fp); |
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87 | |
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88 | /* Ensure stdio is set up. */ |
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89 | |
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90 | CHECK_INIT (ptr, fp); |
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91 | |
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92 | _newlib_flockfile_start(fp); |
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93 | |
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94 | if (fp->_seek64 == NULL) |
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95 | { |
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96 | ptr->_errno = ESPIPE; |
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97 | _newlib_flockfile_exit(fp); |
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98 | return (_off64_t) -1; |
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99 | } |
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100 | |
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101 | /* Find offset of underlying I/O object, then adjust for buffered bytes. */ |
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102 | if (!(fp->_flags & __SRD) && (fp->_flags & __SWR) && |
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103 | fp->_p != NULL && fp->_p - fp->_bf._base > 0 && |
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104 | (fp->_flags & __SAPP)) |
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105 | { |
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106 | pos = fp->_seek64 (ptr, fp->_cookie, (_fpos64_t) 0, SEEK_END); |
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107 | if (pos == (_fpos64_t) -1) |
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108 | { |
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109 | _newlib_flockfile_exit (fp); |
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110 | return (_off64_t) -1; |
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111 | } |
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112 | } |
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113 | else if (fp->_flags & __SOFF) |
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114 | pos = fp->_offset; |
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115 | else |
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116 | { |
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117 | pos = fp->_seek64 (ptr, fp->_cookie, (_fpos64_t) 0, SEEK_CUR); |
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118 | if (pos == (_fpos64_t) -1) |
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119 | { |
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120 | _newlib_flockfile_exit(fp); |
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121 | return (_off64_t) pos; |
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122 | } |
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123 | } |
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124 | if (fp->_flags & __SRD) |
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125 | { |
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126 | /* |
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127 | * Reading. Any unread characters (including |
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128 | * those from ungetc) cause the position to be |
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129 | * smaller than that in the underlying object. |
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130 | */ |
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131 | pos -= fp->_r; |
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132 | if (HASUB (fp)) |
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133 | pos -= fp->_ur; |
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134 | } |
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135 | else if (fp->_flags & __SWR && fp->_p != NULL) |
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136 | { |
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137 | /* |
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138 | * Writing. Any buffered characters cause the |
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139 | * position to be greater than that in the |
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140 | * underlying object. |
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141 | */ |
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142 | pos += fp->_p - fp->_bf._base; |
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143 | } |
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144 | |
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145 | _newlib_flockfile_end(fp); |
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146 | return (_off64_t) pos; |
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147 | } |
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148 | |
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149 | #ifndef _REENT_ONLY |
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150 | |
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151 | _off64_t |
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152 | ftello64 (register FILE * fp) |
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153 | { |
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154 | return _ftello64_r (_REENT, fp); |
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155 | } |
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156 | |
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157 | #endif /* !_REENT_ONLY */ |
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158 | |
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159 | #endif /* __LARGE64_FILES */ |
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