103 lines
3.1 KiB
C
103 lines
3.1 KiB
C
/*
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* Copyright (c) 1990 The Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms are permitted
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* provided that the above copyright notice and this paragraph are
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* duplicated in all such forms and that any documentation,
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* and/or other materials related to such
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* distribution and use acknowledge that the software was developed
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* by the University of California, Berkeley. The name of the
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* University may not be used to endorse or promote products derived
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* from this software without specific prior written permission.
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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*/
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/*
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FUNCTION
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<<fseek>>, <<fseeko>>---set file position
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INDEX
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fseek
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INDEX
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fseeko
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INDEX
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_fseek_r
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INDEX
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_fseeko_r
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SYNOPSIS
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#include <stdio.h>
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int fseek(FILE *<[fp]>, long <[offset]>, int <[whence]>);
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int fseeko(FILE *<[fp]>, off_t <[offset]>, int <[whence]>);
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int _fseek_r(struct _reent *<[ptr]>, FILE *<[fp]>,
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long <[offset]>, int <[whence]>);
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int _fseeko_r(struct _reent *<[ptr]>, FILE *<[fp]>,
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off_t <[offset]>, int <[whence]>);
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DESCRIPTION
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Objects of type <<FILE>> can have a ``position'' that records how much
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of the file your program has already read. Many of the <<stdio>> functions
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depend on this position, and many change it as a side effect.
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You can use <<fseek>>/<<fseeko>> to set the position for the file identified by
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<[fp]>. The value of <[offset]> determines the new position, in one
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of three ways selected by the value of <[whence]> (defined as macros
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in `<<stdio.h>>'):
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<<SEEK_SET>>---<[offset]> is the absolute file position (an offset
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from the beginning of the file) desired. <[offset]> must be positive.
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<<SEEK_CUR>>---<[offset]> is relative to the current file position.
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<[offset]> can meaningfully be either positive or negative.
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<<SEEK_END>>---<[offset]> is relative to the current end of file.
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<[offset]> can meaningfully be either positive (to increase the size
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of the file) or negative.
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See <<ftell>>/<<ftello>> to determine the current file position.
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RETURNS
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<<fseek>>/<<fseeko>> return <<0>> when successful. On failure, the
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result is <<EOF>>. The reason for failure is indicated in <<errno>>:
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either <<ESPIPE>> (the stream identified by <[fp]> doesn't support
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repositioning) or <<EINVAL>> (invalid file position).
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PORTABILITY
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ANSI C requires <<fseek>>.
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<<fseeko>> is defined by the Single Unix specification.
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Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
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<<lseek>>, <<read>>, <<sbrk>>, <<write>>.
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*/
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#include <_ansi.h>
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#include <reent.h>
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#include <stdio.h>
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#include <errno.h>
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#include "local.h"
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int
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_fseek_r (struct _reent *ptr,
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register FILE *fp,
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long offset,
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int whence)
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{
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return _fseeko_r (ptr, fp, offset, whence);
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}
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#ifndef _REENT_ONLY
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int
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fseek (register FILE *fp,
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long offset,
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int whence)
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{
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return _fseek_r (_REENT, fp, offset, whence);
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}
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#endif /* !_REENT_ONLY */
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