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Add fseeko function

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This commit is contained in:
Erik van der Kouwe 2010-08-16 17:06:08 +00:00
parent 66b8f17a29
commit a3e4dcafe0
3 changed files with 23 additions and 5 deletions
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1
include/stdio.h
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@ -117,6 +117,7 @@ _PROTOTYPE( size_t fwrite,
(const void *_ptr, size_t _size, size_t _nmemb, FILE *_stream) );
_PROTOTYPE( int fgetpos, (FILE *_stream, fpos_t *_pos) );
_PROTOTYPE( int fseek, (FILE *_stream, long _offset, int _whence) );
_PROTOTYPE( int fseeko, (FILE *_stream, off_t _offset, int _whence) );
_PROTOTYPE( int fsetpos, (FILE *_stream, fpos_t *_pos) );
_PROTOTYPE( long ftell, (FILE *_stream) );
_PROTOTYPE( void rewind, (FILE *_stream) );

8
lib/libc/stdio/fseek.c
View file

@ -3,6 +3,7 @@
*/
/* $Header$ */
#include <assert.h>
#include <stdio.h>
#if (SEEK_CUR != 1) || (SEEK_END != 2) || (SEEK_SET != 0)
@ -17,6 +18,13 @@ off_t _lseek(int fildes, off_t offset, int whence);
int
fseek(FILE *stream, long int offset, int whence)
{
assert(sizeof(offset) == sizeof(off_t));
return fseeko(stream, (off_t) offset, whence);
}
int
fseeko(FILE *stream, off_t offset, int whence)
{
int adjust = 0;
long pos;

19
man/man3/fseek.3
View file

@ -3,20 +3,23 @@
.TH FSEEK 3 "February 24, 1986"
.AT 3
.SH NAME
fseek, ftell, rewind \- reposition a stream
fseek, fseeko, ftell, rewind \- reposition a stream
.SH SYNOPSIS
.nf
.ft B
#include <stdio.h>
int fseek(FILE *\fIstream\fP, long \fIoffset\fP, int \fIptrname\fP)
int fseeko(FILE *\fIstream\fP, off_t \fIoffset\fP, int \fIptrname\fP)
long ftell(FILE *\fIstream\fP)
void rewind(FILE *\fIstream\fP)
.ft R
.fi
.SH DESCRIPTION
.B Fseek
sets the position of the next input or output
and
.B fseeko
set the position of the next input or output
operation on the
.IR stream .
The new position is at the signed distance
@ -28,7 +31,9 @@ according as
has the value 0, 1, or 2.
.PP
.B Fseek
undoes any effects of
and
.B fseeko
undo any effects of
.BR ungetc (3).
.PP
.B Ftell
@ -40,7 +45,9 @@ on some other systems it is a magic cookie,
and the only foolproof way to obtain an
.I offset
for
.BR fseek .
.BR fseek
and
.BR fseeko .
.PP
.BR Rewind "(\fIstream\fR)"
is equivalent to
@ -50,4 +57,6 @@ is equivalent to
.BR fopen (3).
.SH DIAGNOSTICS
.B Fseek
returns \-1 for improper seeks, otherwise zero.
and
.B fseeko
return \-1 for improper seeks, otherwise zero.