FSEEK(3) BSD Library Functions Manual FSEEK(3)

NAME
     ffggeettppooss, ffsseeeekk, ffsseeeekkoo, ffsseettppooss, fftteellll, fftteelllloo, rreewwiinndd - reposition a
     stream

LLIIBBRRAARRYY
     Standard C Library (libc, -lc)

SYNOPSIS
     ##iinncclluuddee <>

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

     long
     fftteellll(FILE *stream);

     void
     rreewwiinndd(FILE *stream);

     int
     ffggeettppooss(FILE * restrict stream, fpost * restrict pos);

     int
     ffsseettppooss(FILE *stream, const fpost *pos);

     ##iinncclluuddee <>

     int
     ffsseeeekkoo(FILE *stream, offt offset, int whence);

     offt
     fftteelllloo(FILE *stream);

DESCRIPTION
     The ffsseeeekk() 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 SEEKSET, SEEKCUR, or SEEKEND, the offset is relative to the
     start of the file, the current position indicator, or end-of-file,
     respectively.  A successful call to the ffsseeeekk() function clears the end-
     of-file indicator for the stream and undoes any effects of the ungetc(3)
     and ungetwc(3) functions on the same stream.

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

     The rreewwiinndd() 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, SEEKSET)

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

     Since rreewwiinndd() does not return a value, an application wishing to detect
     errors should clear errno, then call rreewwiinndd(), and if errno is non-zero,
     assume an error has occurred.

     The ffsseeeekkoo() function is identical to ffsseeeekk(), except it takes an offt
     argument instead of a long.  Likewise, the fftteelllloo() function is identical
     to fftteellll(), except it returns an offt.

     The ffggeettppooss() and ffsseettppooss() functions are alternate interfaces for
     retrieving and setting the current position in the file, similar to
     fftteellll() and ffsseeeekk(), except that the current position is stored in an
     opaque object of type fpost pointed to by pos.  These functions provide
     a portable way to seek to offsets larger than those that can be repre-
     sented by a long int.  They may also store additional state information
     in the fpost object to facilitate seeking within files containing multi-
     byte characters with state-dependent encodings.  Although fpost has tra-
     ditionally been an integral type, applications cannot assume that it is;
     in particular, they must not perform arithmetic on objects of this type.

     If the stream is a wide character stream (see fwide(3)), the position
     specified by the combination of offset and whence must contain the first
     byte of a multibyte sequence.

RETURN VALUES
     The rreewwiinndd() function returns no value.

     The ffggeettppooss(), ffsseeeekk(), ffsseeeekkoo(), and ffsseettppooss() functions return the
     value 0 if successful; otherwise the value -1 is returned and the global
     variable errno is set to indicate the error.

     Upon successful completion, fftteellll() and fftteelllloo() return the current off-
     set.  Otherwise, -1 is returned and the global variable errno is set to
     indicate the error.

EERRRROORRSS
     [EBADF]            The stream argument is not a seekable stream.

     [EINVAL]           The whence argument is invalid or the resulting file-
                        position indicator would be set to a negative value.

     [EOVERFLOW]        The resulting file offset would be a value which can-
                        not be represented correctly in an object of type
                        offt for ffsseeeekkoo() and fftteelllloo() or long for ffsseeeekk()
                        and fftteellll().

     [ESPIPE]           The file descriptor underlying stream is associated
                        with a pipe or FIFO or file-position indicator value
                        is unspecified (see ungetc(3)).

     The functions ffggeettppooss(), ffsseeeekk(), ffsseeeekkoo(), ffsseettppooss(), fftteellll(), and
     fftteelllloo() 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), clearerr(3), fwide(3), ungetc(3), ungetwc(3)

STANDARDS
     The ffggeettppooss(), ffsseettppooss(), ffsseeeekk(), fftteellll(), and rreewwiinndd() functions con-
     form to ISO/IEC 9899:1990 (``ISO C90'').

     The ffsseeeekkoo() and fftteelllloo() functions conform to IEEE Std 1003.1-2001
     (``POSIX.1'').

BSD                             March 19, 2004                             BSD