1 /*
2 * Copyright (c) 1990 The Regents of the University of California.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms are permitted
6 * provided that the above copyright notice and this paragraph are
7 * duplicated in all such forms and that any documentation,
8 * and/or other materials related to such
9 * distribution and use acknowledge that the software was developed
10 * by the University of California, Berkeley. The name of the
11 * University may not be used to endorse or promote products derived
12 * from this software without specific prior written permission.
13 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
14 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
15 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
16 */
17
18 /*
19 FUNCTION
20 <<fseek>>, <<fseeko>>---set file position
21
22 INDEX
23 fseek
24 INDEX
25 fseeko
26 INDEX
27 _fseek_r
28 INDEX
29 _fseeko_r
30
31 SYNOPSIS
32 #include <stdio.h>
33 int fseek(FILE *<[fp]>, long <[offset]>, int <[whence]>);
34 int fseeko(FILE *<[fp]>, off_t <[offset]>, int <[whence]>);
35 int fseek( FILE *<[fp]>,
36 long <[offset]>, int <[whence]>);
37 int fseeko( FILE *<[fp]>,
38 off_t <[offset]>, int <[whence]>);
39
40 DESCRIPTION
41 Objects of type <<FILE>> can have a ``position'' that records how much
42 of the file your program has already read. Many of the <<stdio>> functions
43 depend on this position, and many change it as a side effect.
44
45 You can use <<fseek>>/<<fseeko>> to set the position for the file identified by
46 <[fp]>. The value of <[offset]> determines the new position, in one
47 of three ways selected by the value of <[whence]> (defined as macros
48 in `<<stdio.h>>'):
49
50 <<SEEK_SET>>---<[offset]> is the absolute file position (an offset
51 from the beginning of the file) desired. <[offset]> must be positive.
52
53 <<SEEK_CUR>>---<[offset]> is relative to the current file position.
54 <[offset]> can meaningfully be either positive or negative.
55
56 <<SEEK_END>>---<[offset]> is relative to the current end of file.
57 <[offset]> can meaningfully be either positive (to increase the size
58 of the file) or negative.
59
60 See <<ftell>>/<<ftello>> to determine the current file position.
61
62 RETURNS
63 <<fseek>>/<<fseeko>> return <<0>> when successful. On failure, the
64 result is <<EOF>>. The reason for failure is indicated in <<errno>>:
65 either <<ESPIPE>> (the stream identified by <[fp]> doesn't support
66 repositioning) or <<EINVAL>> (invalid file position).
67
68 PORTABILITY
69 ANSI C requires <<fseek>>.
70
71 <<fseeko>> is defined by the Single Unix specification.
72
73 Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
74 <<lseek>>, <<read>>, <<sbrk>>, <<write>>.
75 */
76
77 #define _DEFAULT_SOURCE
78 #include <_ansi.h>
79 #include <stdio.h>
80 #include <errno.h>
81 #include "local.h"
82
83 int
fseek(register FILE * fp,long offset,int whence)84 fseek (
85 register FILE *fp,
86 long offset,
87 int whence)
88 {
89 return fseeko ( fp, offset, whence);
90 }
91
