wsetup.c

来自「基于4个mips核的noc设计」· C语言 代码 · 共 76 行

/*
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#include <stdio.h>
#include <unistd.h>
#include "local.h"

/*
 * Various output routines call wsetup to be sure it is safe to write,
 * because either _flags does not include __SWR, or _buf is NULL.
 * _wsetup returns 0 if OK to write, nonzero otherwise.
 */
int
__swsetup(fp)
	register FILE *fp;
{

	/* make sure stdio is set up */
	if (!__sdidinit)
		__sinit();

	/*
	 * If we are not writing, we had better be reading and writing.
	 */
	if ((fp->_flags & __SWR) == 0) {
		if ((fp->_flags & __SRW) == 0)
			return (EOF);
		if (fp->_flags & __SRD) {
			/* clobber any ungetc data */
			if (HASUB(fp))
				FREEUB(fp);
			fp->_flags &= ~(__SRD|__SEOF);
			fp->_r = 0;
			fp->_p = fp->_bf._base;
		}
		/*
		 * If appending and switching to write,
		 * adjust the seek accordingly.
		 */
		if ((fp->_flags & __SAPM) != 0)
			fp->_offset = lseek(fp->_file, (off_t)0, SEEK_END);
		fp->_flags |= __SWR;
	}

	/*
	 * Make a buffer if necessary, then set _w.
	 */
	if (fp->_bf._base == NULL)
		__smakebuf(fp);
	if (fp->_flags & __SLBF) {
		/*
		 * It is line buffered, so make _lbfsize be -_bufsize
		 * for the putc() macro.  We will change _lbfsize back
		 * to 0 whenever we turn off __SWR.
		 */
		fp->_w = 0;
		fp->_lbfsize = -fp->_bf._size;
	} else
		fp->_w = fp->_flags & __SNBF ? 0 : fp->_bf._size;
	return (0);
}