fseeko64
—set file position for large file ¶Synopsis
#include <stdio.h> int fseeko64(FILE *fp, _off64_t offset, int whence); int _fseeko64_r (struct _reent *ptr, FILE *fp, _off64_t offset, int whence);
Description
Objects of type FILE
can have a “position” that records how much
of the file your program has already read. Many of the stdio
functions
depend on this position, and many change it as a side effect.
You can use fseeko64
to set the position for the file identified by
fp that was opened via fopen64
. The value of offset determines
the new position, in one of three ways selected by the value of whence
(defined as macros in ‘stdio.h
’):
SEEK_SET
—offset is the absolute file position (an offset
from the beginning of the file) desired. offset must be positive.
SEEK_CUR
—offset is relative to the current file position.
offset can meaningfully be either positive or negative.
SEEK_END
—offset is relative to the current end of file.
offset can meaningfully be either positive (to increase the size
of the file) or negative.
See ftello64
to determine the current file position.
Returns
fseeko64
returns 0
when successful. On failure, the
result is EOF
. The reason for failure is indicated in errno
:
either ESPIPE
(the stream identified by fp doesn’t support
repositioning or wasn’t opened via fopen64
) or EINVAL
(invalid file position).
Portability
fseeko64
is a glibc extension.
Supporting OS subroutines required: close
, fstat64
, isatty
,
lseek64
, read
, sbrk
, write
.