fseek(3)                                                       fseek(3)

  fseek()

  NAME

    fgetpos(), fseek(), fsetpos(), ftell(), rewind() - reposition a stream

  SYNOPSIS

    #include 

    int fseek (FILE *stream, long offset, int whence)
    long ftell (FILE *stream)
    void rewind (FILE *stream)
    int fgetpos (FILE *stream, fpos_t *pos)
    int fsetpos (FILE *stream, fpos_t *pos)

  DESCRIPTION

    The fseek(3) 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, respectively. A
    successful call to the fseek(3) function clears the end-of-file indicator
    for the stream and undoes any effects of the ungetc(3) function on the
    same stream.

    The ftell(3) function obtains the current value of the file position
    indicator for the stream pointed to by stream.

    The rewind(3) 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(3) and fsetpos(3) functions are alternate interfaces
    equivalent to ftell(3) and fseek(3) (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 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(3) function returns no value. Upon successful completion,
    fgetpos(3), fseek(3), fsetpos(3) return 0, and ftell(3) returns the
    current offset. Otherwise, -1 is returned 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(3) was not SEEK_SET, SEEK_END, or
        SEEK_CUR.

    The function fgetpos(3), fseek(3), fsetpos(3), and ftell(3) 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)

  USAGE NOTES

    All of these functions are thread safe.

    None of these functions are async-signal safe.