usr/src/sys/kern/vfs_vnops.c

/*
 * Copyright (c) 1982, 1986, 1989 Regents of the University of California.
 * All rights reserved.
 *
 * 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.
 *
 *      @(#)vfs_vnops.c 7.33 (Berkeley) 6/27/91
 */

#include "param.h"
#include "systm.h"
#include "kernel.h"
#include "file.h"
#include "stat.h"
#include "buf.h"
#include "proc.h"
#include "mount.h"
#include "namei.h"
#include "vnode.h"
#include "ioctl.h"
#include "tty.h"

struct  fileops vnops =
        { vn_read, vn_write, vn_ioctl, vn_select, vn_closefile };

/*
 * Common code for vnode open operations.
 * Check permissions, and call the VOP_OPEN or VOP_CREATE routine.
 */
vn_open(ndp, p, fmode, cmode)
        register struct nameidata *ndp;
        struct proc *p;
        int fmode, cmode;
{
        register struct vnode *vp;
        register struct ucred *cred = p->p_ucred;
        struct vattr vat;
        struct vattr *vap = &vat;
        int error;

        if (fmode & O_CREAT) {
                ndp->ni_nameiop = CREATE | LOCKPARENT | LOCKLEAF;
                if ((fmode & O_EXCL) == 0)
                        ndp->ni_nameiop |= FOLLOW;
                if (error = namei(ndp, p))
                        return (error);
                if (ndp->ni_vp == NULL) {
                        VATTR_NULL(vap);
                        vap->va_type = VREG;
                        vap->va_mode = cmode;
                        if (error = VOP_CREATE(ndp, vap, p))
                                return (error);
                        fmode &= ~O_TRUNC;
                        vp = ndp->ni_vp;
                } else {
                        VOP_ABORTOP(ndp);
                        if (ndp->ni_dvp == ndp->ni_vp)
                                vrele(ndp->ni_dvp);
                        else
                                vput(ndp->ni_dvp);
                        ndp->ni_dvp = NULL;
                        vp = ndp->ni_vp;
                        if (fmode & O_EXCL) {
                                error = EEXIST;
                                goto bad;
                        }
                        fmode &= ~O_CREAT;
                }
        } else {
                ndp->ni_nameiop = LOOKUP | FOLLOW | LOCKLEAF;
                if (error = namei(ndp, p))
                        return (error);
                vp = ndp->ni_vp;
        }
        if (vp->v_type == VSOCK) {
                error = EOPNOTSUPP;
                goto bad;
        }
        if ((fmode & O_CREAT) == 0) {
                if (fmode & FREAD) {
                        if (error = VOP_ACCESS(vp, VREAD, cred, p))
                                goto bad;
                }
                if (fmode & (FWRITE | O_TRUNC)) {
                        if (vp->v_type == VDIR) {
                                error = EISDIR;
                                goto bad;
                        }
                        if ((error = vn_writechk(vp)) ||
                            (error = VOP_ACCESS(vp, VWRITE, cred, p)))
                                goto bad;
                }
        }
        if (fmode & O_TRUNC) {
                VATTR_NULL(vap);
                vap->va_size = 0;
                if (error = VOP_SETATTR(vp, vap, cred, p))
                        goto bad;
        }
        if (error = VOP_OPEN(vp, fmode, cred, p))
                goto bad;
        if (fmode & FWRITE)
                vp->v_writecount++;
        return (0);
bad:
        vput(vp);
        return (error);
}

/*
 * Check for write permissions on the specified vnode.
 * The read-only status of the file system is checked.
 * Also, prototype text segments cannot be written.
 */
vn_writechk(vp)
        register struct vnode *vp;
{

        /*
         * Disallow write attempts on read-only file systems;
         * unless the file is a socket or a block or character
         * device resident on the file system.
         */
        if (vp->v_mount->mnt_flag & MNT_RDONLY) {
                switch (vp->v_type) {
                case VREG: case VDIR: case VLNK:
                        return (EROFS);
                }
        }
        /*
         * If there's shared text associated with
         * the vnode, try to free it up once.  If
         * we fail, we can't allow writing.
         */
        if ((vp->v_flag & VTEXT) && !vnode_pager_uncache(vp))
                return (ETXTBSY);
        return (0);
}

/*
 * Vnode close call
 */
vn_close(vp, flags, cred, p)
        register struct vnode *vp;
        int flags;
        struct ucred *cred;
        struct proc *p;
{
        int error;

        if (flags & FWRITE)
                vp->v_writecount--;
        error = VOP_CLOSE(vp, flags, cred, p);
        vrele(vp);
        return (error);
}

/*
 * Package up an I/O request on a vnode into a uio and do it.
 */
vn_rdwr(rw, vp, base, len, offset, segflg, ioflg, cred, aresid, p)
        enum uio_rw rw;
        struct vnode *vp;
        caddr_t base;
        int len;
        off_t offset;
        enum uio_seg segflg;
        int ioflg;
        struct ucred *cred;
        int *aresid;
        struct proc *p;
{
        struct uio auio;
        struct iovec aiov;
        int error;

        if ((ioflg & IO_NODELOCKED) == 0)
                VOP_LOCK(vp);
        auio.uio_iov = &aiov;
        auio.uio_iovcnt = 1;
        aiov.iov_base = base;
        aiov.iov_len = len;
        auio.uio_resid = len;
        auio.uio_offset = offset;
        auio.uio_segflg = segflg;
        auio.uio_rw = rw;
        auio.uio_procp = p;
        if (rw == UIO_READ)
                error = VOP_READ(vp, &auio, ioflg, cred);
        else
                error = VOP_WRITE(vp, &auio, ioflg, cred);
        if (aresid)
                *aresid = auio.uio_resid;
        else
                if (auio.uio_resid && error == 0)
                        error = EIO;
        if ((ioflg & IO_NODELOCKED) == 0)
                VOP_UNLOCK(vp);
        return (error);
}

/*
 * File table vnode read routine.
 */
vn_read(fp, uio, cred)
        struct file *fp;
        struct uio *uio;
        struct ucred *cred;
{
        register struct vnode *vp = (struct vnode *)fp->f_data;
        int count, error;

        VOP_LOCK(vp);
        uio->uio_offset = fp->f_offset;
        count = uio->uio_resid;
        error = VOP_READ(vp, uio, (fp->f_flag & FNONBLOCK) ? IO_NDELAY : 0,
                cred);
        fp->f_offset += count - uio->uio_resid;
        VOP_UNLOCK(vp);
        return (error);
}

/*
 * File table vnode write routine.
 */
vn_write(fp, uio, cred)
        struct file *fp;
        struct uio *uio;
        struct ucred *cred;
{
        register struct vnode *vp = (struct vnode *)fp->f_data;
        int count, error, ioflag = 0;

        if (vp->v_type == VREG && (fp->f_flag & O_APPEND))
                ioflag |= IO_APPEND;
        if (fp->f_flag & FNONBLOCK)
                ioflag |= IO_NDELAY;
        VOP_LOCK(vp);
        uio->uio_offset = fp->f_offset;
        count = uio->uio_resid;
        error = VOP_WRITE(vp, uio, ioflag, cred);
        if (ioflag & IO_APPEND)
                fp->f_offset = uio->uio_offset;
        else
                fp->f_offset += count - uio->uio_resid;
        VOP_UNLOCK(vp);
        return (error);
}

/*
 * File table vnode stat routine.
 */
vn_stat(vp, sb, p)
        struct vnode *vp;
        register struct stat *sb;
        struct proc *p;
{
        struct vattr vattr;
        register struct vattr *vap;
        int error;
        u_short mode;

        vap = &vattr;
        error = VOP_GETATTR(vp, vap, p->p_ucred, p);
        if (error)
                return (error);
        /*
         * Copy from vattr table
         */
        sb->st_dev = vap->va_fsid;
        sb->st_ino = vap->va_fileid;
        mode = vap->va_mode;
        switch (vp->v_type) {
        case VREG:
                mode |= S_IFREG;
                break;
        case VDIR:
                mode |= S_IFDIR;
                break;
        case VBLK:
                mode |= S_IFBLK;
                break;
        case VCHR:
                mode |= S_IFCHR;
                break;
        case VLNK:
                mode |= S_IFLNK;
                break;
        case VSOCK:
                mode |= S_IFSOCK;
                break;
        case VFIFO:
                mode |= S_IFIFO;
                break;
        default:
                return (EBADF);
        };
        sb->st_mode = mode;
        sb->st_nlink = vap->va_nlink;
        sb->st_uid = vap->va_uid;
        sb->st_gid = vap->va_gid;
        sb->st_rdev = vap->va_rdev;
        sb->st_size = vap->va_size;
        sb->st_atime = vap->va_atime.tv_sec;
        sb->st_spare1 = 0;
        sb->st_mtime = vap->va_mtime.tv_sec;
        sb->st_spare2 = 0;
        sb->st_ctime = vap->va_ctime.tv_sec;
        sb->st_spare3 = 0;
        sb->st_blksize = vap->va_blocksize;
        sb->st_flags = vap->va_flags;
        sb->st_gen = vap->va_gen;
        sb->st_blocks = vap->va_bytes / S_BLKSIZE;
        return (0);
}

/*
 * File table vnode ioctl routine.
 */
vn_ioctl(fp, com, data, p)
        struct file *fp;
        int com;
        caddr_t data;
        struct proc *p;
{
        register struct vnode *vp = ((struct vnode *)fp->f_data);
        struct vattr vattr;
        int error;

        switch (vp->v_type) {

        case VREG:
        case VDIR:
                if (com == FIONREAD) {
                        if (error = VOP_GETATTR(vp, &vattr, p->p_ucred, p))
                                return (error);
                        *(off_t *)data = vattr.va_size - fp->f_offset;
                        return (0);
                }
                if (com == FIONBIO || com == FIOASYNC)  /* XXX */
                        return (0);                     /* XXX */
                /* fall into ... */

        default:
                return (ENOTTY);

        case VFIFO:
        case VCHR:
        case VBLK:
                error = VOP_IOCTL(vp, com, data, fp->f_flag, p->p_ucred, p);
                if (error == 0 && com == TIOCSCTTY) {
                        p->p_session->s_ttyvp = vp;
                        VREF(vp);
                }
                return (error);
        }
}

/*
 * File table vnode select routine.
 */
vn_select(fp, which, p)
        struct file *fp;
        int which;
        struct proc *p;
{

        return (VOP_SELECT(((struct vnode *)fp->f_data), which, fp->f_flag,
                fp->f_cred, p));
}

/*
 * File table vnode close routine.
 */
vn_closefile(fp, p)
        struct file *fp;
        struct proc *p;
{

        return (vn_close(((struct vnode *)fp->f_data), fp->f_flag,
                fp->f_cred, p));
}

/*
 * vn_fhtovp() - convert a fh to a vnode ptr (optionally locked)
 *      - look up fsid in mount list (if not found ret error)
 *      - get vp by calling VFS_FHTOVP() macro
 *      - if lockflag lock it with VOP_LOCK()
 */
vn_fhtovp(fhp, lockflag, vpp)
        fhandle_t *fhp;
        int lockflag;
        struct vnode **vpp;
{
        register struct mount *mp;

        if ((mp = getvfs(&fhp->fh_fsid)) == NULL)
                return (ESTALE);
        if (VFS_FHTOVP(mp, &fhp->fh_fid, vpp))
                return (ESTALE);
        if (!lockflag)
                VOP_UNLOCK(*vpp);
        return (0);
}