fdesc_vnops.c

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/*
 * Copyright (c) 1992, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software donated to Berkeley by
 * Jan-Simon Pendry.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)fdesc_vnops.c	8.9 (Berkeley) 1/21/94
 *
 * $Id: fdesc_vnops.c,v 1.12 1993/04/06 16:17:17 jsp Exp $
 */

/*
 * /dev/fd Filesystem
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/proc.h>
#include <sys/kernel.h>	/* boottime */
#include <sys/resourcevar.h>
#include <sys/filedesc.h>
#include <sys/vnode.h>
#include <sys/malloc.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/buf.h>
#include <sys/dirent.h>
#include <miscfs/fdesc/fdesc.h>

#define cttyvp(p) ((p)->p_flag & P_CONTROLT ? (p)->p_session->s_ttyvp : NULL)

#define FDL_WANT	0x01
#define FDL_LOCKED	0x02
static int fdcache_lock;

dev_t devctty;

#if (FD_STDIN != FD_STDOUT-1) || (FD_STDOUT != FD_STDERR-1)
FD_STDIN, FD_STDOUT, FD_STDERR must be a sequence n, n+1, n+2
#endif

#define	NFDCACHE 3
#define	FD_NHASH(ix) ((ix) & NFDCACHE)

/*
 * Cache head
 */
struct fdcache {
	struct fdescnode	*fc_forw;
	struct fdescnode	*fc_back;
};

static struct fdcache fdcache[NFDCACHE];

/*
 * Initialise cache headers
 */
fdesc_init()
{
	struct fdcache *fc;

	devctty = makedev(nchrdev, 0);

	for (fc = fdcache; fc < fdcache + NFDCACHE; fc++)
		fc->fc_forw = fc->fc_back = (struct fdescnode *) fc;
}

/*
 * Compute hash list for given target vnode
 */
static struct fdcache *
fdesc_hash(ix)
	int ix;
{

	return (&fdcache[FD_NHASH(ix)]);
}

int
fdesc_allocvp(ftype, ix, mp, vpp)
	fdntype ftype;
	int ix;
	struct mount *mp;
	struct vnode **vpp;
{
	struct fdcache *fc;
	struct fdescnode *fd;
	int error = 0;

loop:
	fc = fdesc_hash(ix);
	for (fd = fc->fc_forw; fd != (struct fdescnode *) fc; fd = fd->fd_forw) {
		if (fd->fd_ix == ix && fd->fd_vnode->v_mount == mp) {
			if (vget(fd->fd_vnode, 0))
				goto loop;
			*vpp = fd->fd_vnode;
			return (error);
		}
	}

	/*
	 * otherwise lock the array while we call getnewvnode
	 * since that can block.
	 */ 
	if (fdcache_lock & FDL_LOCKED) {
		fdcache_lock |= FDL_WANT;
		sleep((caddr_t) &fdcache_lock, PINOD);
		goto loop;
	}
	fdcache_lock |= FDL_LOCKED;

	error = getnewvnode(VT_FDESC, mp, fdesc_vnodeop_p, vpp);
	if (error)
		goto out;
	MALLOC(fd, void *, sizeof(struct fdescnode), M_TEMP, M_WAITOK);
	(*vpp)->v_data = fd;
	fd->fd_vnode = *vpp;
	fd->fd_type = ftype;
	fd->fd_fd = -1;
	fd->fd_link = 0;
	fd->fd_ix = ix;
	fc = fdesc_hash(ix);
	insque(fd, fc);

out:;
	fdcache_lock &= ~FDL_LOCKED;

	if (fdcache_lock & FDL_WANT) {
		fdcache_lock &= ~FDL_WANT;
		wakeup((caddr_t) &fdcache_lock);
	}

	return (error);
}

/*
 * vp is the current namei directory
 * ndp is the name to locate in that directory...
 */
int
fdesc_lookup(ap)
	struct vop_lookup_args /* {
		struct vnode * a_dvp;
		struct vnode ** a_vpp;
		struct componentname * a_cnp;
	} */ *ap;
{
	struct vnode **vpp = ap->a_vpp;
	struct vnode *dvp = ap->a_dvp;
	char *pname;
	struct proc *p;
	int nfiles;
	unsigned fd;
	int error;
	struct vnode *fvp;
	char *ln;

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

	p = ap->a_cnp->cn_proc;
	nfiles = p->p_fd->fd_nfiles;

	switch (VTOFDESC(dvp)->fd_type) {
	default:
	case Flink:
	case Fdesc:
	case Fctty:
		error = ENOTDIR;
		goto bad;

	case Froot:
		if (ap->a_cnp->cn_namelen == 2 && bcmp(pname, "fd", 2) == 0) {
			error = fdesc_allocvp(Fdevfd, FD_DEVFD, dvp->v_mount, &fvp);
			if (error)
				goto bad;
			*vpp = fvp;
			fvp->v_type = VDIR;
			VOP_LOCK(fvp);
			return (0);
		}

		if (ap->a_cnp->cn_namelen == 3 && bcmp(pname, "tty", 3) == 0) {
			struct vnode *ttyvp = cttyvp(p);
			if (ttyvp == NULL) {
				error = ENXIO;
				goto bad;
			}
			error = fdesc_allocvp(Fctty, FD_CTTY, dvp->v_mount, &fvp);
			if (error)
				goto bad;
			*vpp = fvp;
			fvp->v_type = VFIFO;
			VOP_LOCK(fvp);
			return (0);
		}

		ln = 0;
		switch (ap->a_cnp->cn_namelen) {
		case 5:
			if (bcmp(pname, "stdin", 5) == 0) {
				ln = "fd/0";
				fd = FD_STDIN;
			}
			break;
		case 6:
			if (bcmp(pname, "stdout", 6) == 0) {
				ln = "fd/1";
				fd = FD_STDOUT;
			} else
			if (bcmp(pname, "stderr", 6) == 0) {
				ln = "fd/2";
				fd = FD_STDERR;
			}
			break;
		}

		if (ln) {
			error = fdesc_allocvp(Flink, fd, dvp->v_mount, &fvp);
			if (error)
				goto bad;
			VTOFDESC(fvp)->fd_link = ln;
			*vpp = fvp;
			fvp->v_type = VLNK;
			VOP_LOCK(fvp);
			return (0);
		} else {
			error = ENOENT;
			goto bad;
		}

		/* FALL THROUGH */

	case Fdevfd:
		if (ap->a_cnp->cn_namelen == 2 && bcmp(pname, "..", 2) == 0) {
			error = fdesc_root(dvp->v_mount, vpp);
			return (error);
		}

		fd = 0;
		while (*pname >= '0' && *pname <= '9') {
			fd = 10 * fd + *pname++ - '0';
			if (fd >= nfiles)
				break;
		}

		if (*pname != '\0') {
			error = ENOENT;
			goto bad;
		}

		if (fd >= nfiles || p->p_fd->fd_ofiles[fd] == NULL) {
			error = EBADF;
			goto bad;
		}

		error = fdesc_allocvp(Fdesc, FD_DESC+fd, dvp->v_mount, &fvp);
		if (error)
			goto bad;
		VTOFDESC(fvp)->fd_fd = fd;
		*vpp = fvp;
		return (0);
	}

bad:;
	*vpp = NULL;
	return (error);
}

int
fdesc_open(ap)
	struct vop_open_args /* {
		struct vnode *a_vp;
		int  a_mode;
		struct ucred *a_cred;
		struct proc *a_p;
	} */ *ap;
{
	struct vnode *vp = ap->a_vp;
	int error = 0;

	switch (VTOFDESC(vp)->fd_type) {
	case Fdesc:
		/*
		 * XXX Kludge: set p->p_dupfd to contain the value of the
		 * the file descriptor being sought for duplication. The error 
		 * return ensures that the vnode for this device will be
		 * released by vn_open. Open will detect this special error and
		 * take the actions in dupfdopen.  Other callers of vn_open or
		 * VOP_OPEN will simply report the error.
		 */
		ap->a_p->p_dupfd = VTOFDESC(vp)->fd_fd;	/* XXX */
		error = ENODEV;
		break;

	case Fctty:
		error = cttyopen(devctty, ap->a_mode, 0, ap->a_p);
		break;
	}

	return (error);
}

static int
fdesc_attr(fd, vap, cred, p)
	int fd;
	struct vattr *vap;
	struct ucred *cred;
	struct proc *p;
{
	struct filedesc *fdp = p->p_fd;
	struct file *fp;
	struct stat stb;
	int error;

	if (fd >= fdp->fd_nfiles || (fp = fdp->fd_ofiles[fd]) == NULL)
		return (EBADF);

	switch (fp->f_type) {
	case DTYPE_VNODE:
		error = VOP_GETATTR((struct vnode *) fp->f_data, vap, cred, p);
		if (error == 0 && vap->va_type == VDIR) {
			/*
			 * don't allow directories to show up because
			 * that causes loops in the namespace.
			 */
			vap->va_type = VFIFO;
		}
		break;

	case DTYPE_SOCKET:
		error = soo_stat((struct socket *)fp->f_data, &stb);
		if (error == 0) {
			vattr_null(vap);
			vap->va_type = VSOCK;
			vap->va_mode = stb.st_mode;
			vap->va_nlink = stb.st_nlink;
			vap->va_uid = stb.st_uid;
			vap->va_gid = stb.st_gid;
			vap->va_fsid = stb.st_dev;
			vap->va_fileid = stb.st_ino;
			vap->va_size = stb.st_size;
			vap->va_blocksize = stb.st_blksize;
			vap->va_atime = stb.st_atimespec;
			vap->va_mtime = stb.st_mtimespec;
			vap->va_ctime = stb.st_ctimespec;
			vap->va_gen = stb.st_gen;
			vap->va_flags = stb.st_flags;
			vap->va_rdev = stb.st_rdev;
			vap->va_bytes = stb.st_blocks * stb.st_blksize;
		}
		break;

	default:
		panic("fdesc attr");
		break;
	}

	return (error);
}

int
fdesc_getattr(ap)
	struct vop_getattr_args /* {
		struct vnode *a_vp;
		struct vattr *a_vap;
		struct ucred *a_cred;
		struct proc *a_p;
	} */ *ap;
{
	struct vnode *vp = ap->a_vp;
	struct vattr *vap = ap->a_vap;
	unsigned fd;
	int error = 0;

	switch (VTOFDESC(vp)->fd_type) {
	case Froot:
	case Fdevfd:
	case Flink:
	case Fctty:
		bzero((caddr_t) vap, sizeof(*vap));
		vattr_null(vap);
		vap->va_fileid = VTOFDESC(vp)->fd_ix;

		switch (VTOFDESC(vp)->fd_type) {
		case Flink:
			vap->va_mode = S_IRUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH;
			vap->va_type = VLNK;
			vap->va_nlink = 1;
			vap->va_size = strlen(VTOFDESC(vp)->fd_link);
			break;

		case Fctty:
			vap->va_mode = S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH;
			vap->va_type = VFIFO;
			vap->va_nlink = 1;
			vap->va_size = 0;
			break;

		default:
			vap->va_mode = S_IRUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH;
			vap->va_type = VDIR;
			vap->va_nlink = 2;
			vap->va_size = DEV_BSIZE;
			break;
		}
		vap->va_uid = 0;
		vap->va_gid = 0;
		vap->va_fsid = vp->v_mount->mnt_stat.f_fsid.val[0];
		vap->va_blocksize = DEV_BSIZE;
		vap->va_atime.ts_sec = boottime.tv_sec;
		vap->va_atime.ts_nsec = 0;
		vap->va_mtime = vap->va_atime;
		vap->va_ctime = vap->va_mtime;
		vap->va_gen = 0;
		vap->va_flags = 0;
		vap->va_rdev = 0;
		vap->va_bytes = 0;
		break;

	case Fdesc:
		fd = VTOFDESC(vp)->fd_fd;
		error = fdesc_attr(fd, vap, ap->a_cred, ap->a_p);
		break;

	default:
		panic("fdesc_getattr");
		break;	
	}

	if (error == 0)
		vp->v_type = vap->va_type;

	return (error);
}

int
fdesc_setattr(ap)
	struct vop_setattr_args /* {
		struct vnode *a_vp;
		struct vattr *a_vap;
		struct ucred *a_cred;
		struct proc *a_p;
	} */ *ap;
{
	struct filedesc *fdp = ap->a_p->p_fd;
	struct file *fp;
	unsigned fd;
	int error;