seekdir.c

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· C语言 代码 · 共 33 行

/* Copyright (c) 1982 Regents of the University of California */

static char sccsid[] = "@(#)seekdir.c 4.6 9/12/82";

#include <sys/param.h>
#include <dir.h>

/*
 * seek to an entry in a directory.
 * Only values returned by ``telldir'' should be passed to seekdir.
 */
void
seekdir(dirp, loc)
	register DIR *dirp;
	long loc;
{
	long curloc, base, offset;
	struct direct *dp;

	curloc = telldir(dirp);
	if (loc == curloc)
		return;
	base = loc & ~(DIRBLKSIZ - 1);
	offset = loc & (DIRBLKSIZ - 1);
	lseek(dirp->dd_fd, base, 0);
	dirp->dd_loc = 0;
	while (dirp->dd_loc < offset) {
		dp = readdir(dirp);
		if (dp == NULL)
			return;
	}
}