/* * fseek.c - perform an fseek */ /* $Id$ */ #include #include #include #include "loc_incl.h" int fseek(FILE *stream, long int offset, int whence) { int adjust = 0; long pos; stream->_flags &= ~(_IOEOF | _IOERR); /* Clear both the end of file and error flags */ if (io_testflag(stream, _IOREADING)) { if (whence == SEEK_CUR && stream->_buf && !io_testflag(stream,_IONBF)) adjust = stream->_count; stream->_count = 0; } else if (io_testflag(stream,_IOWRITING)) { fflush(stream); } else /* neither reading nor writing. The buffer must be empty */ /* EMPTY */ ; pos = lseek(fileno(stream), offset - adjust, whence); if (io_testflag(stream, _IOREAD) && io_testflag(stream, _IOWRITE)) stream->_flags &= ~(_IOREADING | _IOWRITING); stream->_ptr = stream->_buf; return ((pos == -1) ? -1 : 0); }