replace vn_access with vn_writechk;

[unix-history] / 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 are permitted
* provided that the above copyright notice and this paragraph are
* duplicated in all such forms and that any documentation,
* advertising materials, and other materials related to such
* distribution and use acknowledge that the software was developed
* by the University of California, Berkeley.  The name of the
* University may not be used to endorse or promote products derived
* from this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
*      @(#)vfs_vnops.c 7.8 (Berkeley) %G%
*/

#include "param.h"
#include "systm.h"
#include "user.h"
#include "kernel.h"
#include "file.h"
#include "stat.h"
#include "buf.h"
#include "proc.h"
#include "uio.h"
#include "socket.h"
#include "socketvar.h"
#include "mount.h"
#include "vnode.h"
#include "../ufs/inode.h"
#include "../ufs/fs.h"
#include "../ufs/quota.h"
#include "ioctl.h"
#include "tty.h"

int     vn_read(), vn_write(), vn_ioctl(), vn_select(), vn_close();
struct  fileops vnops =
       { vn_read, vn_write, vn_ioctl, vn_select, vn_close };

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

       if (fmode & FCREAT) {
               ndp->ni_nameiop = CREATE | LOCKPARENT | LOCKLEAF;
               if ((fmode & FEXCL) == 0)
                       ndp->ni_nameiop |= FOLLOW;
               if (error = namei(ndp))
                       return (error);
               if (ndp->ni_vp == NULL) {
                       vattr_null(vap);
                       vap->va_type = VREG;
                       vap->va_mode = cmode;
                       if (error = VOP_CREATE(ndp, vap))
                               return (error);
                       fmode &= ~FTRUNC;
                       vp = ndp->ni_vp;
               } else {
                       vp = ndp->ni_vp;
                       ndp->ni_vp = 0;
                       VOP_ABORTOP(ndp);
                       ndp->ni_vp = vp;
                       if (fmode & FEXCL) {
                               error = EEXIST;
                               goto bad;
                       }
                       fmode &= ~FCREAT;
               }
       } else {
               ndp->ni_nameiop = LOOKUP | FOLLOW | LOCKLEAF;
               if (error = namei(ndp))
                       return (error);
               vp = ndp->ni_vp;
       }
       if (vp->v_type == VSOCK) {
               error = EOPNOTSUPP;
               goto bad;
       }
       if ((fmode & FCREAT) == 0) {
               if (fmode & FREAD) {
                       if (error = VOP_ACCESS(vp, VREAD, ndp->ni_cred))
                               goto bad;
               }
               if (fmode & (FWRITE|FTRUNC)) {
                       if (vp->v_type == VDIR) {
                               error = EISDIR;
                               goto bad;
                       }
                       if ((error = vn_writechk(vp)) ||
                           (error = VOP_ACCESS(vp, VWRITE, ndp->ni_cred)))
                               goto bad;
               }
       }
       if (fmode & FTRUNC) {
               vattr_null(vap);
               vap->va_size = 0;
               if (error = VOP_SETATTR(vp, vap, ndp->ni_cred))
                       goto bad;
       }
       VOP_UNLOCK(vp);
       if (setjmp(&u.u_qsave)) {
               if (error == 0)
                       error = EINTR;
               return (error);
       }
       error = VOP_OPEN(vp, fmode, ndp->ni_cred);
       if (error)
               vrele(vp);
       return (error);

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->m_flag & M_RDONLY) && vp->v_type != VCHR &&
           vp->v_type != VBLK && vp->v_type != VSOCK)
               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)
               xrele(vp);
       if (vp->v_flag & VTEXT)
               return (ETXTBSY);
       return (0);
}

/*
* Vnode version of rdwri() for calls on file systems.
*/
vn_rdwr(rw, vp, base, len, offset, segflg, ioflg, cred, aresid)
       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 uio auio;
       struct iovec aiov;
       int error;

       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;
       if (rw == UIO_READ)
               error = VOP_READ(vp, &auio, &offset, ioflg, cred);
       else
               error = VOP_WRITE(vp, &auio, &offset, ioflg, cred);
       if (aresid)
               *aresid = auio.uio_resid;
       else
               if (auio.uio_resid && error == 0)
                       error = EIO;
       return (error);
}

vn_read(fp, uio, cred)
       struct file *fp;
       struct uio *uio;
       struct ucred *cred;
{

       return (VOP_READ((struct vnode *)fp->f_data, uio, &(fp->f_offset),
               (fp->f_flag & FNDELAY) ? IO_NDELAY : 0, cred));
}

vn_write(fp, uio, cred)
       struct file *fp;
       struct uio *uio;
       struct ucred *cred;
{
       register struct vnode *vp = (struct vnode *)fp->f_data;
       int ioflag = 0;

       if (vp->v_type == VREG && (fp->f_flag & FAPPEND))
               ioflag |= IO_APPEND;
       if (fp->f_flag & FNDELAY)
               ioflag |= IO_NDELAY;
       return (VOP_WRITE(vp, uio, &(fp->f_offset), ioflag, cred));
}

/*
* Get stat info for a vnode.
*/
vn_stat(vp, sb)
       struct vnode *vp;
       register struct stat *sb;
{
       struct vattr vattr;
       register struct vattr *vap;
       int error;
       u_short mode;

       vap = &vattr;
       error = VOP_GETATTR(vp, vap, u.u_cred);
       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 |= IFREG;
               break;
       case VDIR:
               mode |= IFDIR;
               break;
       case VBLK:
               mode |= IFBLK;
               break;
       case VCHR:
               mode |= IFCHR;
               break;
       case VLNK:
               mode |= IFLNK;
               break;
       case VSOCK:
               mode |= IFSOCK;
               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;
       /*
        * XXX THIS IS NOT CORRECT!!, but be sure to change ufs_getattr()
        * if you change it.
        */
       sb->st_blocks = vap->va_bytes;
       return (0);
}

/*
* Vnode ioctl call
*/
vn_ioctl(fp, com, data)
       struct file *fp;
       int com;
       caddr_t data;
{
       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, u.u_cred))
                               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 VCHR:
       case VBLK:
               u.u_r.r_val1 = 0;
               if (setjmp(&u.u_qsave)) {
                       if ((u.u_sigintr & sigmask(u.u_procp->p_cursig)) != 0)
                               return(EINTR);
                       u.u_eosys = RESTARTSYS;
                       return (0);
               }
               return (VOP_IOCTL(vp, com, data, fp->f_flag, u.u_cred));
       }
}

/*
* Vnode select call
*/
vn_select(fp, which)
       struct file *fp;
       int which;
{
       return(VOP_SELECT(((struct vnode *)fp->f_data), which, u.u_cred));
}

/*
* Vnode close call
*/
vn_close(fp)
       register struct file *fp;
{
       struct vnode *vp = ((struct vnode *)fp->f_data);
       int error;

       if (fp->f_flag & (FSHLOCK|FEXLOCK))
               vn_unlock(fp, FSHLOCK|FEXLOCK);
       /*
        * Must delete vnode reference from this file entry
        * before VOP_CLOSE, so that only other references
        * will prevent close.
        */
       fp->f_data = (caddr_t) 0;
       error = VOP_CLOSE(vp, fp->f_flag, u.u_cred);
       vrele(vp);
       return (error);
}

/*
* Place an advisory lock on a vnode.
* !! THIS IMPLIES THAT ALL STATEFUL FILE SERVERS WILL USE file table entries
*/
vn_lock(fp, cmd)
       register struct file *fp;
       int cmd;
{
       register int priority = PLOCK;
       register struct vnode *vp = (struct vnode *)fp->f_data;

       if ((cmd & LOCK_EX) == 0)
               priority += 4;
       if (setjmp(&u.u_qsave)) {
               if ((u.u_sigintr & sigmask(u.u_procp->p_cursig)) != 0)
                       return(EINTR);
               u.u_eosys = RESTARTSYS;
               return (0);
       }
       /*
        * If there's a exclusive lock currently applied
        * to the file, then we've gotta wait for the
        * lock with everyone else.
        */
again:
       while (vp->v_flag & VEXLOCK) {
               /*
                * If we're holding an exclusive
                * lock, then release it.
                */
               if (fp->f_flag & FEXLOCK) {
                       vn_unlock(fp, FEXLOCK);
                       continue;
               }
               if (cmd & LOCK_NB)
                       return (EWOULDBLOCK);
               vp->v_flag |= VLWAIT;
               sleep((caddr_t)&vp->v_exlockc, priority);
       }
       if ((cmd & LOCK_EX) && (vp->v_flag & VSHLOCK)) {
               /*
                * Must wait for any shared locks to finish
                * before we try to apply a exclusive lock.
                *
                * If we're holding a shared
                * lock, then release it.
                */
               if (fp->f_flag & FSHLOCK) {
                       vn_unlock(fp, FSHLOCK);
                       goto again;
               }
               if (cmd & LOCK_NB)
                       return (EWOULDBLOCK);
               vp->v_flag |= VLWAIT;
               sleep((caddr_t)&vp->v_shlockc, PLOCK);
               goto again;
       }
       if (fp->f_flag & FEXLOCK)
               panic("vn_lock");
       if (cmd & LOCK_EX) {
               cmd &= ~LOCK_SH;
               vp->v_exlockc++;
               vp->v_flag |= VEXLOCK;
               fp->f_flag |= FEXLOCK;
       }
       if ((cmd & LOCK_SH) && (fp->f_flag & FSHLOCK) == 0) {
               vp->v_shlockc++;
               vp->v_flag |= VSHLOCK;
               fp->f_flag |= FSHLOCK;
       }
       return (0);
}

/*
* Unlock a file.
*/
vn_unlock(fp, kind)
       register struct file *fp;
       int kind;
{
       register struct vnode *vp = (struct vnode *)fp->f_data;
       int flags;

       kind &= fp->f_flag;
       if (vp == NULL || kind == 0)
               return;
       flags = vp->v_flag;
       if (kind & FSHLOCK) {
               if ((flags & VSHLOCK) == 0)
                       panic("vn_unlock: SHLOCK");
               if (--vp->v_shlockc == 0) {
                       vp->v_flag &= ~VSHLOCK;
                       if (flags & VLWAIT)
                               wakeup((caddr_t)&vp->v_shlockc);
               }
               fp->f_flag &= ~FSHLOCK;
       }
       if (kind & FEXLOCK) {
               if ((flags & VEXLOCK) == 0)
                       panic("vn_unlock: EXLOCK");
               if (--vp->v_exlockc == 0) {
                       vp->v_flag &= ~(VEXLOCK|VLWAIT);
                       if (flags & VLWAIT)
                               wakeup((caddr_t)&vp->v_exlockc);
               }
               fp->f_flag &= ~FEXLOCK;
       }
}

/*
* 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;
       int error;

       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);
}

/*
* Revoke access the current tty by all processes.
* Used only by the super-user in init
* to give ``clean'' terminals at login.
*/
vhangup()
{

       if (u.u_error = suser(u.u_cred, &u.u_acflag))
               return;
       if (u.u_ttyp == NULL)
               return;
       forceclose(u.u_ttyd);
       if ((u.u_ttyp->t_state) & TS_ISOPEN)
               gsignal(u.u_ttyp->t_pgid, SIGHUP);
       u.u_ttyp->t_session = 0;
       u.u_ttyp->t_pgid = 0;
}

forceclose(dev)
       dev_t dev;
{
       register struct file *fp;
       register struct vnode *vp;

       for (fp = file; fp < fileNFILE; fp++) {
               if (fp->f_count == 0)
                       continue;
               if (fp->f_type != DTYPE_VNODE)
                       continue;
               vp = (struct vnode *)fp->f_data;
               if (vp == 0)
                       continue;
               if (vp->v_type != VCHR)
                       continue;
               if (vp->v_rdev != dev)
                       continue;
               fp->f_flag &= ~(FREAD|FWRITE);
       }
}

/*
* Vnode reference, just increment the count
*/
void vref(vp)
       struct vnode *vp;
{

       vp->v_count++;
}

/*
* Vnode release, just decrement the count and call VOP_INACTIVE()
*/
void vrele(vp)
       register struct vnode *vp;
{

       if (vp == NULL)
               return;
       vp->v_count--;
       if (vp->v_count < 0)
               printf("inode %d, bad ref count %d\n",
                       VTOI(vp)->i_number, vp->v_count);
       if (vp->v_count == 0)
               VOP_INACTIVE(vp);
}

/*
* vput(), just unlock and vrele()
*/
vput(vp)
       register struct vnode *vp;
{
       VOP_UNLOCK(vp);
       vrele(vp);
}

/*
* Noop
*/
vfs_noop()
{

       return (ENXIO);
}

/*
* Null op
*/
vfs_nullop()
{

       return (0);
}