Function sys_acct

freebsd/kern/kern_acct.c:205–317

* Accounting system call. Written based on the specification and previous * implementation done by Mark Tinguely. */

 * implementation done by Mark Tinguely.
 */
int
sys_acct(struct thread *td, struct acct_args *uap)
{
	struct nameidata nd;
	int error, flags, i, replacing;

	error = priv_check(td, PRIV_ACCT);
	if (error)
		return (error);

	/*
	 * If accounting is to be started to a file, open that file for
	 * appending and make sure it's a 'normal'.
	 */
	if (uap->path != NULL) {
		NDINIT(&nd, LOOKUP, NOFOLLOW | AUDITVNODE1,
		    UIO_USERSPACE, uap->path, td);
		flags = FWRITE | O_APPEND;
		error = vn_open(&nd, &flags, 0, NULL);
		if (error)
			return (error);
		NDFREE(&nd, NDF_ONLY_PNBUF);
#ifdef MAC
		error = mac_system_check_acct(td->td_ucred, nd.ni_vp);
		if (error) {
			VOP_UNLOCK(nd.ni_vp);
			vn_close(nd.ni_vp, flags, td->td_ucred, td);
			return (error);
		}
#endif
		VOP_UNLOCK(nd.ni_vp);
		if (nd.ni_vp->v_type != VREG) {
			vn_close(nd.ni_vp, flags, td->td_ucred, td);
			return (EACCES);
		}
#ifdef MAC
	} else {
		error = mac_system_check_acct(td->td_ucred, NULL);
		if (error)
			return (error);
#endif
	}

	/*
	 * Disallow concurrent access to the accounting vnode while we swap
	 * it out, in order to prevent access after close.
	 */
	sx_xlock(&acct_sx);

	/*
	 * Don't log spurious disable/enable messages if we are
	 * switching from one accounting file to another due to log
	 * rotation.
	 */
	replacing = (acct_vp != NULL && uap->path != NULL);

	/*
	 * If accounting was previously enabled, kill the old space-watcher,