FSEEK(3)                  OpenBSD Programmer's Manual                 FSEEK(3)

NAME
     fgetpos, fseek, fseeko, fsetpos, ftell, ftello, rewind - reposition a
     stream

SYNOPSIS
     #include <stdio.h>

     int
     fgetpos(FILE *stream, fpos_t *pos);

     int
     fseek(FILE *stream, long offset, int whence);

     int
     fseeko(FILE *stream, off_t offset, int whence);

     int
     fsetpos(FILE *stream, const fpos_t *pos);

     long
     ftell(FILE *stream);

     off_t
     ftello(FILE *stream);

     void
     rewind(FILE *stream);

DESCRIPTION
     The fseek() function sets the file position indicator for the stream
     pointed to by stream.  The new position, measured in bytes, is obtained
     by adding offset bytes to the position specified by whence.  If whence is
     set to SEEK_SET, SEEK_CUR, or SEEK_END, the offset is relative to the
     start of the file, the current position indicator, or end-of-file, re-
     spectively.  A successful call to the fseek() function clears the end-of-
     file indicator for the stream and undoes any effects of the ungetc(3)
     function on the same stream.

     The fseeko() function is identical to fseek() except that it takes an
     off_t as its offset.

     The ftell() function obtains the current value of the file position indi-
     cator for the stream pointed to by stream.

     The ftello() function is identical to ftell() except that its return val-
     ue is of type off_t.

     The rewind() function sets the file position indicator for the stream
     pointed to by stream to the beginning of the file.  It is equivalent to:

           (void)fseek(stream, 0L, SEEK_SET)

     except that the error indicator for the stream is also cleared (see
     clearerr(3)).

     The fgetpos() and fsetpos() functions are alternate interfaces equivalent
     to ftell() and fseek() (with whence set to SEEK_SET), setting and storing
     the current value of the file offset into or from the object referenced
     by pos.  On some (non-UNIX) systems an ``fpos_t'' object may be a complex
     object and these routines may be the only way to portably reposition a
     text stream.

RETURN VALUES
     The rewind() function returns no value.  Upon successful completion,
     fgetpos(), fseek(), fseeko(), fsetpos() return 0 and ftell() and ftello()
     return the current offset.  Otherwise, fseek() and fseeko() return -1 and
     the others return a non-zero value and the global variable errno is set
     to indicate the error.

ERRORS
     [EBADF]       The stream specified is not a seekable stream.

     [EINVAL]      The whence argument to fseek() was not SEEK_SET, SEEK_END,
                   or SEEK_CUR.

     The functions fgetpos(), fseek(), fseeko(), fsetpos(), ftell(), and
     ftello() may also fail and set errno for any of the errors specified for
     the routines fflush(3), fstat(2), lseek(2), and malloc(3).

SEE ALSO
     lseek(2)

STANDARDS
     The fgetpos(), fsetpos(), fseek(), ftell(), and rewind() functions con-
     form to ANSI X3.159-1989 (``ANSI C'') and X/Open Portability Guide Issue
     4 (``XPG4'').

     The fseeko() and ftello() functions conform to X/Open Portability Guide
     Issue 4 (``XPG4'').

OpenBSD 4.0                    February 21, 2000                             2
