kern_prot.c

来自「操作系统SunOS 4.1.3版本的源码」· C语言 代码 · 共 114 行

#ifndef lint
static        char sccsid[] = "@(#)kern_prot.c 1.1 92/07/30 Copyr 1983 Sun Micro";
#endif

/*
 * System calls related to processes and protection
 */

#include <machine/reg.h>

#include <sys/param.h>
#include "boot/systm.h"
#include <sys/user.h>
#include <sys/vfs.h>
#include "boot/vnode.h"
#include <sys/proc.h>
#include <sys/timeb.h>
#include <sys/times.h>
#include <sys/reboot.h>
#include <sys/buf.h>
#include <sys/acct.h>

#undef	u
extern struct user u;


/*
 * Routines to allocate and free credentials structures
 */

int cractive = 0;

struct credlist {
	union {
		struct ucred cru_cred;
		struct credlist *cru_next;
	} cl_U;
#define	cl_cred	cl_U.cru_cred
#define	cl_next	cl_U.cru_next
};

struct credlist *crfreelist = NULL;

/*
 * Allocate a zeroed cred structure and crhold it.
 */
struct ucred *
crget()
{
	register struct ucred *cr;

	if (crfreelist) {
		cr = &crfreelist->cl_cred;
		crfreelist = ((struct credlist *)cr)->cl_next;
	} else {
		cr = (struct ucred *)kmem_alloc((u_int)sizeof(*cr));
	}
	bzero((caddr_t)cr, sizeof(*cr));
	crhold(cr);
	cractive++;
	return(cr);
}

/*
 * Free a cred structure.
 * Throws away space when ref count gets to 0.
 */
void
crfree(cr)
	struct ucred *cr;
{
	int	s = spl6();

	if (--cr->cr_ref != 0) {
		(void) splx(s);
		return;
	}
	((struct credlist *)cr)->cl_next = crfreelist;
	crfreelist = (struct credlist *)cr;
	cractive--;
	(void) splx(s);
}

/*
 * Copy cred structure to a new one and free the old one.
 */
struct ucred *
crcopy(cr)
	struct ucred *cr;
{
	struct ucred *newcr;

	newcr = crget();
	*newcr = *cr;
	crfree(cr);
	newcr->cr_ref = 1;
	return(newcr);
}

/*
 * Dup cred struct to a new held one.
 */
struct ucred *
crdup(cr)
	struct ucred *cr;
{
	struct ucred *newcr;

	newcr = crget();
	*newcr = *cr;
	newcr->cr_ref = 1;
	return(newcr);
}