procfs_vnops.c

来自「早期freebsd实现」· C语言 代码 · 共 815 行 · 第 1/2 页

	case Pfpregs:
	case Pctl:
	case Pstatus:
	case Pnote:
	case Pnotepg:
		vap->va_nlink = 1;
		vap->va_uid = procp->p_ucred->cr_uid;
		vap->va_gid = procp->p_ucred->cr_gid;
		break;

	default:
		panic("procfs_getattr");
	}

	return (error);
}

procfs_setattr(ap)
	struct vop_setattr_args *ap;
{
	/*
	 * just fake out attribute setting
	 * it's not good to generate an error
	 * return, otherwise things like creat()
	 * will fail when they try to set the
	 * file length to 0.  worse, this means
	 * that echo $note > /proc/$pid/note will fail.
	 */

	return (0);
}

/*
 * implement access checking.
 *
 * something very similar to this code is duplicated
 * throughout the 4bsd kernel and should be moved
 * into kern/vfs_subr.c sometime.
 *
 * actually, the check for super-user is slightly
 * broken since it will allow read access to write-only
 * objects.  this doesn't cause any particular trouble
 * but does mean that the i/o entry points need to check
 * that the operation really does make sense.
 */
procfs_access(ap)
	struct vop_access_args *ap;
{
	struct vattr *vap;
	struct vattr vattr;
	int error;

	/*
	 * If you're the super-user,
	 * you always get access.
	 */
	if (ap->a_cred->cr_uid == (uid_t) 0)
		return (0);
	vap = &vattr;
	if (error = VOP_GETATTR(ap->a_vp, vap, ap->a_cred, ap->a_p))
		return (error);

	/*
	 * Access check is based on only one of owner, group, public.
	 * If not owner, then check group. If not a member of the
	 * group, then check public access.
	 */
	if (ap->a_cred->cr_uid != vap->va_uid) {
		gid_t *gp;
		int i;

		(ap->a_mode) >>= 3;
		gp = ap->a_cred->cr_groups;
		for (i = 0; i < ap->a_cred->cr_ngroups; i++, gp++)
			if (vap->va_gid == *gp)
				goto found;
		ap->a_mode >>= 3;
found:
		;
	}

	if ((vap->va_mode & ap->a_mode) == ap->a_mode)
		return (0);

	return (EACCES);
}

/*
 * lookup.  this is incredibly complicated in the
 * general case, however for most pseudo-filesystems
 * very little needs to be done.
 *
 * unless you want to get a migraine, just make sure your
 * filesystem doesn't do any locking of its own.  otherwise
 * read and inwardly digest ufs_lookup().
 */
procfs_lookup(ap)
	struct vop_lookup_args *ap;
{
	struct componentname *cnp = ap->a_cnp;
	struct vnode **vpp = ap->a_vpp;
	struct vnode *dvp = ap->a_dvp;
	char *pname = cnp->cn_nameptr;
	int error = 0;
	pid_t pid;
	struct vnode *nvp;
	struct pfsnode *pfs;
	struct proc *procp;
	pfstype pfs_type;
	int i;

	if (cnp->cn_namelen == 1 && *pname == '.') {
		*vpp = dvp;
		VREF(dvp);
		/*VOP_LOCK(dvp);*/
		return (0);
	}

	*vpp = NULL;

	pfs = VTOPFS(dvp);
	switch (pfs->pfs_type) {
	case Proot:
		if (cnp->cn_flags & ISDOTDOT)
			return (EIO);

		if (CNEQ(cnp, "curproc", 7))
			pid = cnp->cn_proc->p_pid;
		else
			pid = atopid(pname, cnp->cn_namelen);
		if (pid == NO_PID)
			return (ENOENT);

		procp = PFIND(pid);
		if (procp == 0)
			return (ENOENT);

		error = procfs_allocvp(dvp->v_mount, &nvp, pid, Pproc);
		if (error)
			return (error);

		nvp->v_type = VDIR;
		pfs = VTOPFS(nvp);

		*vpp = nvp;
		return (0);

	case Pproc:
		if (cnp->cn_flags & ISDOTDOT) {
			error = procfs_root(dvp->v_mount, vpp);
			return (error);
		}

		procp = PFIND(pfs->pfs_pid);
		if (procp == 0)
			return (ENOENT);

		for (i = 0; i < Nprocent; i++) {
			struct pfsnames *dp = &procent[i];

			if (cnp->cn_namelen == dp->d_namlen &&
			    bcmp(pname, dp->d_name, dp->d_namlen) == 0) {
			    	pfs_type = dp->d_pfstype;
				goto found;
			}
		}
		return (ENOENT);

	found:
		if (pfs_type == Pfile) {
			nvp = procfs_findtextvp(procp);
			if (nvp) {
				VREF(nvp);
				VOP_LOCK(nvp);
			} else {
				error = ENXIO;
			}
		} else {
			error = procfs_allocvp(dvp->v_mount, &nvp,
					pfs->pfs_pid, pfs_type);
			if (error)
				return (error);

			nvp->v_type = VREG;
			pfs = VTOPFS(nvp);
		}
		*vpp = nvp;
		return (error);

	default:
		return (ENOTDIR);
	}
}

/*
 * readdir returns directory entries from pfsnode (vp).
 *
 * the strategy here with procfs is to generate a single
 * directory entry at a time (struct pfsdent) and then
 * copy that out to userland using uiomove.  a more efficent
 * though more complex implementation, would try to minimize
 * the number of calls to uiomove().  for procfs, this is
 * hardly worth the added code complexity.
 *
 * this should just be done through read()
 */
procfs_readdir(ap)
	struct vop_readdir_args *ap;
{
	struct uio *uio = ap->a_uio;
	struct pfsdent d;
	struct pfsdent *dp = &d;
	struct pfsnode *pfs;
	int error;
	int count;
	int i;

	pfs = VTOPFS(ap->a_vp);

	if (uio->uio_resid < UIO_MX)
		return (EINVAL);
	if (uio->uio_offset & (UIO_MX-1))
		return (EINVAL);
	if (uio->uio_offset < 0)
		return (EINVAL);

	error = 0;
	count = 0;
	i = uio->uio_offset / UIO_MX;

	switch (pfs->pfs_type) {
	/*
	 * this is for the process-specific sub-directories.
	 * all that is needed to is copy out all the entries
	 * from the procent[] table (top of this file).
	 */
	case Pproc: {
		while (uio->uio_resid >= UIO_MX) {
			struct pfsnames *dt;

			if (i >= Nprocent)
				break;

			dt = &procent[i];
			
			dp->d_reclen = UIO_MX;
			dp->d_fileno = PROCFS_FILENO(pfs->pfs_pid, dt->d_pfstype);
			dp->d_type = DT_REG;
			dp->d_namlen = dt->d_namlen;
			bcopy(dt->d_name, dp->d_name, sizeof(dt->d_name)-1);
			error = uiomove((caddr_t) dp, UIO_MX, uio);
			if (error)
				break;
			count += UIO_MX;
			i++;
		}

	    	break;

	    }

	/*
	 * this is for the root of the procfs filesystem
	 * what is needed is a special entry for "curproc"
	 * followed by an entry for each process on allproc
#ifdef PROCFS_ZOMBIE
	 * and zombproc.
#endif
	 */

	case Proot: {
		int pcnt;
#ifdef PROCFS_ZOMBIE
		int doingzomb = 0;
#endif
		volatile struct proc *p;

		p = allproc;

#define PROCFS_XFILES	1	/* number of other entries, like "curproc" */
		pcnt = PROCFS_XFILES;

		while (p && uio->uio_resid >= UIO_MX) {
			bzero((char *) dp, UIO_MX);
			dp->d_type = DT_DIR;
			dp->d_reclen = UIO_MX;

			switch (i) {
			case 0:
				/* ship out entry for "curproc" */
				dp->d_fileno = PROCFS_FILENO(PID_MAX+1, Pproc);
				dp->d_namlen = sprintf(dp->d_name, "curproc");
				break;

			default:
				if (pcnt >= i) {
					dp->d_fileno = PROCFS_FILENO(p->p_pid, Pproc);
					dp->d_namlen = sprintf(dp->d_name, "%ld", (long) p->p_pid);
				}

				p = p->p_next;

#ifdef PROCFS_ZOMBIE
				if (p == 0 && doingzomb == 0) {
					doingzomb = 1;
					p = zombproc;
				}
#endif

				if (pcnt++ < i)
					continue;

				break;
			}
			error = uiomove((caddr_t) dp, UIO_MX, uio);
			if (error)
				break;
			count += UIO_MX;
			i++;
		}

		break;

	    }

	default:
		error = ENOTDIR;
		break;
	}

	uio->uio_offset = i * UIO_MX;

	return (error);
}

/*
 * convert decimal ascii to pid_t
 */
static pid_t
atopid(b, len)
	const char *b;
	u_int len;
{
	pid_t p = 0;

	while (len--) {
		char c = *b++;
		if (c < '0' || c > '9')
			return (NO_PID);
		p = 10 * p + (c - '0');
		if (p > PID_MAX)
			return (NO_PID);
	}

	return (p);
}

/*
 * procfs vnode operations.
 */
int (**procfs_vnodeop_p)();
struct vnodeopv_entry_desc procfs_vnodeop_entries[] = {
	{ &vop_default_desc, vn_default_error },
	{ &vop_lookup_desc, procfs_lookup },		/* lookup */
	{ &vop_create_desc, procfs_create },		/* create */
	{ &vop_mknod_desc, procfs_mknod },		/* mknod */
	{ &vop_open_desc, procfs_open },		/* open */
	{ &vop_close_desc, procfs_close },		/* close */
	{ &vop_access_desc, procfs_access },		/* access */
	{ &vop_getattr_desc, procfs_getattr },		/* getattr */
	{ &vop_setattr_desc, procfs_setattr },		/* setattr */
	{ &vop_read_desc, procfs_read },		/* read */
	{ &vop_write_desc, procfs_write },		/* write */
	{ &vop_ioctl_desc, procfs_ioctl },		/* ioctl */
	{ &vop_select_desc, procfs_select },		/* select */
	{ &vop_mmap_desc, procfs_mmap },		/* mmap */
	{ &vop_fsync_desc, procfs_fsync },		/* fsync */
	{ &vop_seek_desc, procfs_seek },		/* seek */
	{ &vop_remove_desc, procfs_remove },		/* remove */
	{ &vop_link_desc, procfs_link },		/* link */
	{ &vop_rename_desc, procfs_rename },		/* rename */
	{ &vop_mkdir_desc, procfs_mkdir },		/* mkdir */
	{ &vop_rmdir_desc, procfs_rmdir },		/* rmdir */
	{ &vop_symlink_desc, procfs_symlink },		/* symlink */
	{ &vop_readdir_desc, procfs_readdir },		/* readdir */
	{ &vop_readlink_desc, procfs_readlink },	/* readlink */
	{ &vop_abortop_desc, procfs_abortop },		/* abortop */
	{ &vop_inactive_desc, procfs_inactive },	/* inactive */
	{ &vop_reclaim_desc, procfs_reclaim },		/* reclaim */
	{ &vop_lock_desc, procfs_lock },		/* lock */
	{ &vop_unlock_desc, procfs_unlock },		/* unlock */
	{ &vop_bmap_desc, procfs_bmap },		/* bmap */
	{ &vop_strategy_desc, procfs_strategy },	/* strategy */
	{ &vop_print_desc, procfs_print },		/* print */
	{ &vop_islocked_desc, procfs_islocked },	/* islocked */
	{ &vop_pathconf_desc, procfs_pathconf },	/* pathconf */
	{ &vop_advlock_desc, procfs_advlock },		/* advlock */
	{ &vop_blkatoff_desc, procfs_blkatoff },	/* blkatoff */
	{ &vop_valloc_desc, procfs_valloc },		/* valloc */
	{ &vop_vfree_desc, procfs_vfree },		/* vfree */
	{ &vop_truncate_desc, procfs_truncate },	/* truncate */
	{ &vop_update_desc, procfs_update },		/* update */
	{ (struct vnodeop_desc*)NULL, (int(*)())NULL }
};
struct vnodeopv_desc procfs_vnodeop_opv_desc =
	{ &procfs_vnodeop_p, procfs_vnodeop_entries };