[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 | <<fseek>>, <<fseeko>>---set file position |
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| 21 | |
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| 22 | INDEX |
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| 23 | fseek |
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| 24 | INDEX |
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| 25 | fseeko |
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| 26 | INDEX |
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| 27 | _fseek_r |
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| 28 | INDEX |
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| 29 | _fseeko_r |
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| 30 | |
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| 31 | SYNOPSIS |
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| 32 | #include <stdio.h> |
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| 33 | int fseek(FILE *<[fp]>, long <[offset]>, int <[whence]>); |
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| 34 | int fseeko(FILE *<[fp]>, off_t <[offset]>, int <[whence]>); |
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| 35 | int _fseek_r(struct _reent *<[ptr]>, FILE *<[fp]>, |
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| 36 | long <[offset]>, int <[whence]>); |
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| 37 | int _fseeko_r(struct _reent *<[ptr]>, FILE *<[fp]>, |
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| 38 | off_t <[offset]>, int <[whence]>); |
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| 39 | |
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| 40 | DESCRIPTION |
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| 41 | Objects of type <<FILE>> can have a ``position'' that records how much |
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| 42 | of the file your program has already read. Many of the <<stdio>> functions |
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| 43 | depend on this position, and many change it as a side effect. |
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| 44 | |
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| 45 | You can use <<fseek>>/<<fseeko>> to set the position for the file identified by |
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| 46 | <[fp]>. The value of <[offset]> determines the new position, in one |
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| 47 | of three ways selected by the value of <[whence]> (defined as macros |
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| 48 | in `<<stdio.h>>'): |
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| 49 | |
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| 50 | <<SEEK_SET>>---<[offset]> is the absolute file position (an offset |
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| 51 | from the beginning of the file) desired. <[offset]> must be positive. |
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| 52 | |
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| 53 | <<SEEK_CUR>>---<[offset]> is relative to the current file position. |
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| 54 | <[offset]> can meaningfully be either positive or negative. |
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| 55 | |
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| 56 | <<SEEK_END>>---<[offset]> is relative to the current end of file. |
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| 57 | <[offset]> can meaningfully be either positive (to increase the size |
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| 58 | of the file) or negative. |
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| 59 | |
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| 60 | See <<ftell>>/<<ftello>> to determine the current file position. |
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| 61 | |
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| 62 | RETURNS |
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| 63 | <<fseek>>/<<fseeko>> return <<0>> when successful. On failure, the |
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| 64 | result is <<EOF>>. The reason for failure is indicated in <<errno>>: |
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| 65 | either <<ESPIPE>> (the stream identified by <[fp]> doesn't support |
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| 66 | repositioning) or <<EINVAL>> (invalid file position). |
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| 67 | |
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| 68 | PORTABILITY |
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| 69 | ANSI C requires <<fseek>>. |
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| 70 | |
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| 71 | <<fseeko>> is defined by the Single Unix specification. |
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| 72 | |
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| 73 | Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>, |
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| 74 | <<lseek>>, <<read>>, <<sbrk>>, <<write>>. |
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| 75 | */ |
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| 76 | |
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| 77 | #include <_ansi.h> |
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| 78 | #include <reent.h> |
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| 79 | #include <stdio.h> |
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| 80 | #include <errno.h> |
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| 81 | #include "local.h" |
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| 82 | |
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| 83 | int |
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| 84 | _fseek_r (struct _reent *ptr, |
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| 85 | register FILE *fp, |
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| 86 | long offset, |
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| 87 | int whence) |
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| 88 | { |
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| 89 | return _fseeko_r (ptr, fp, offset, whence); |
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| 90 | } |
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| 91 | |
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| 92 | #ifndef _REENT_ONLY |
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| 93 | |
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| 94 | int |
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| 95 | fseek (register FILE *fp, |
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| 96 | long offset, |
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| 97 | int whence) |
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| 98 | { |
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| 99 | return _fseek_r (_REENT, fp, offset, whence); |
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| 100 | } |
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| 101 | |
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| 102 | #endif /* !_REENT_ONLY */ |
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