FreeBSD/Linux Kernel Cross Reference
sys/fs/ptyfs/ptyfs_subr.c

     /*      $NetBSD: ptyfs_subr.c,v 1.7 2006/05/14 21:31:52 elad Exp $      */
     
     /*
      * Copyright (c) 1993
      *      The Regents of the University of California.  All rights reserved.
      *
      * This code is derived from software contributed 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. 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.
     *
     *      @(#)ptyfs_subr.c        8.6 (Berkeley) 5/14/95
     */
    
    /*
     * Copyright (c) 1994 Christopher G. Demetriou.  All rights reserved.
     * Copyright (c) 1993 Jan-Simon Pendry
     *
     * This code is derived from software contributed 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.
     *
     *      @(#)procfs_subr.c       8.6 (Berkeley) 5/14/95
     */
    
    #include <sys/cdefs.h>
    __KERNEL_RCSID(0, "$NetBSD: ptyfs_subr.c,v 1.7 2006/05/14 21:31:52 elad Exp $");
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/time.h>
    #include <sys/kernel.h>
    #include <sys/vnode.h>
    #include <sys/malloc.h>
    #include <sys/stat.h>
    #include <sys/file.h>
    #include <sys/namei.h>
    #include <sys/filedesc.h>
    #include <sys/select.h>
    #include <sys/tty.h>
    #include <sys/pty.h>
    #include <sys/kauth.h>
    
    #include <fs/ptyfs/ptyfs.h>
    #include <miscfs/specfs/specdev.h>
    
    static struct lock ptyfs_hashlock;
    
    static LIST_HEAD(ptyfs_hashhead, ptyfsnode) *ptyfs_used_tbl, *ptyfs_free_tbl;
    static u_long ptyfs_used_mask, ptyfs_free_mask; /* size of hash table - 1 */
   static struct simplelock ptyfs_used_slock, ptyfs_free_slock;
   
   static void ptyfs_getinfo(struct ptyfsnode *, struct lwp *);
   
   static void ptyfs_hashins(struct ptyfsnode *);
   static void ptyfs_hashrem(struct ptyfsnode *);
   
   static struct vnode *ptyfs_used_get(ptyfstype, int, struct mount *);
   static struct ptyfsnode *ptyfs_free_get(ptyfstype, int, struct lwp *);
   
   static void ptyfs_rehash(struct simplelock *, struct ptyfs_hashhead **,
       u_long *);
   
   #define PTYHASH(type, pty, mask) (PTYFS_FILENO(type, pty) % (mask + 1))
   
   
   static void
   ptyfs_getinfo(struct ptyfsnode *ptyfs, struct lwp *l)
   {
           extern struct ptm_pty *ptyfs_save_ptm, ptm_ptyfspty;
   
           if (ptyfs->ptyfs_type == PTYFSroot) {
                   ptyfs->ptyfs_mode = S_IRUSR|S_IXUSR|S_IRGRP|S_IXGRP|
                       S_IROTH|S_IXOTH;
                   goto out;
           } else
                   ptyfs->ptyfs_mode = S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|
                       S_IROTH|S_IWOTH;
   
           if (ptyfs_save_ptm != NULL && ptyfs_save_ptm != &ptm_ptyfspty) {
                   int error;
                   struct nameidata nd;
                   char ttyname[64];
                   kauth_cred_t cred;
                   struct vattr va;
                   /*
                    * We support traditional ptys, so we copy the info
                    * from the inode
                    */
                   if ((error = (*ptyfs_save_ptm->makename)(
                           ptyfs_save_ptm, l, ttyname, sizeof(ttyname),
                           ptyfs->ptyfs_pty, ptyfs->ptyfs_type == PTYFSpts ? 't'
                           : 'p')) != 0)
                                   goto out;
                   NDINIT(&nd, LOOKUP, NOFOLLOW|LOCKLEAF, UIO_SYSSPACE, ttyname,
                        l);
                   if ((error = namei(&nd)) != 0)
                           goto out;
                   cred = kauth_cred_alloc();
                   error = VOP_GETATTR(nd.ni_vp, &va, cred, l);
                   kauth_cred_free(cred);
                   VOP_UNLOCK(nd.ni_vp, 0);
                   vrele(nd.ni_vp);
                   if (error)
                           goto out;
                   ptyfs->ptyfs_uid = va.va_uid;
                   ptyfs->ptyfs_gid = va.va_gid;
                   ptyfs->ptyfs_mode = va.va_mode;
                   ptyfs->ptyfs_flags = va.va_flags;
                   ptyfs->ptyfs_birthtime = va.va_birthtime;
                   ptyfs->ptyfs_ctime = va.va_ctime;
                   ptyfs->ptyfs_mtime = va.va_mtime;
                   ptyfs->ptyfs_atime = va.va_atime;
                   return;
           }
   out:
           ptyfs->ptyfs_uid = ptyfs->ptyfs_gid = 0;
           ptyfs->ptyfs_flags |= PTYFS_CHANGE;
           PTYFS_ITIMES(ptyfs, NULL, NULL, NULL);
           ptyfs->ptyfs_birthtime = ptyfs->ptyfs_mtime =
               ptyfs->ptyfs_atime = ptyfs->ptyfs_ctime;
           ptyfs->ptyfs_flags = 0;
   }
   
   
   /*
    * allocate a ptyfsnode/vnode pair.  the vnode is
    * referenced, and locked.
    *
    * the pid, ptyfs_type, and mount point uniquely
    * identify a ptyfsnode.  the mount point is needed
    * because someone might mount this filesystem
    * twice.
    *
    * all ptyfsnodes are maintained on a singly-linked
    * list.  new nodes are only allocated when they cannot
    * be found on this list.  entries on the list are
    * removed when the vfs reclaim entry is called.
    *
    * a single lock is kept for the entire list.  this is
    * needed because the getnewvnode() function can block
    * waiting for a vnode to become free, in which case there
    * may be more than one ptyess trying to get the same
    * vnode.  this lock is only taken if we are going to
    * call getnewvnode, since the kernel itself is single-threaded.
    *
    * if an entry is found on the list, then call vget() to
    * take a reference.  this is done because there may be
    * zero references to it and so it needs to removed from
    * the vnode free list.
    */
   int
   ptyfs_allocvp(struct mount *mp, struct vnode **vpp, ptyfstype type, int pty,
       struct lwp *l)
   {
           struct ptyfsnode *ptyfs;
           struct vnode *vp, *nvp;
           int error;
   
           do {
                   if ((*vpp = ptyfs_used_get(type, pty, mp)) != NULL)
                           return 0;
           } while (lockmgr(&ptyfs_hashlock, LK_EXCLUSIVE|LK_SLEEPFAIL, 0));
   
           if ((error = getnewvnode(VT_PTYFS, mp, ptyfs_vnodeop_p, &vp)) != 0) {
                   *vpp = NULL;
                   lockmgr(&ptyfs_hashlock, LK_RELEASE, NULL);
                   return error;
           }
   
           vp->v_data = ptyfs = ptyfs_free_get(type, pty, l);
           ptyfs->ptyfs_vnode = vp;
   
           switch (type) {
           case PTYFSroot: /* /pts = dr-xr-xr-x */
                   vp->v_type = VDIR;
                   vp->v_flag = VROOT;
                   break;
   
           case PTYFSpts:  /* /pts/N = cxxxxxxxxx */
           case PTYFSptc:  /* controlling side = cxxxxxxxxx */
                   vp->v_type = VCHR;
                   if ((nvp = checkalias(vp, PTYFS_MAKEDEV(ptyfs), mp)) != NULL) {
                           /*
                            * Discard unneeded vnode, but save its inode.
                            */
                           nvp->v_data = vp->v_data;
                           vp->v_data = NULL;
                           /* XXX spec_vnodeops has no locking, do it explicitly */
                           VOP_UNLOCK(vp, 0);
                           vp->v_op = spec_vnodeop_p;
                           vp->v_flag &= ~VLOCKSWORK;
                           vrele(vp);
                           vgone(vp);
                           lockmgr(&nvp->v_lock, LK_EXCLUSIVE, &nvp->v_interlock);
                           /*
                            * Reinitialize aliased inode.
                            */
                           vp = nvp;
                           ptyfs->ptyfs_vnode = vp;
                   }
                   break;
           default:
                   panic("ptyfs_allocvp");
           }
   
           ptyfs_hashins(ptyfs);
           uvm_vnp_setsize(vp, 0);
           lockmgr(&ptyfs_hashlock, LK_RELEASE, NULL);
   
           *vpp = vp;
           return 0;
   }
   
   int
   ptyfs_freevp(struct vnode *vp)
   {
           struct ptyfsnode *ptyfs = VTOPTYFS(vp);
   
           ptyfs_hashrem(ptyfs);
           vp->v_data = NULL;
           return 0;
   }
   
   /*
    * Initialize ptyfsnode hash table.
    */
   void
   ptyfs_hashinit(void)
   {
           lockinit(&ptyfs_hashlock, PINOD, "ptyfs_hashlock", 0, 0);
           ptyfs_used_tbl = hashinit(desiredvnodes / 4, HASH_LIST, M_UFSMNT,
               M_WAITOK, &ptyfs_used_mask);
           ptyfs_free_tbl = hashinit(desiredvnodes / 4, HASH_LIST, M_UFSMNT,
               M_WAITOK, &ptyfs_free_mask);
           simple_lock_init(&ptyfs_used_slock);
           simple_lock_init(&ptyfs_free_slock);
   }
   
   void
   ptyfs_hashreinit(void)
   {
       ptyfs_rehash(&ptyfs_used_slock, &ptyfs_used_tbl, &ptyfs_used_mask);
       ptyfs_rehash(&ptyfs_free_slock, &ptyfs_free_tbl, &ptyfs_free_mask);
   }
   
   static void
   ptyfs_rehash(struct simplelock *hlock, struct ptyfs_hashhead **hhead,
       u_long *hmask)
   {
           struct ptyfsnode *pp;
           struct ptyfs_hashhead *oldhash, *hash;
           u_long i, oldmask, mask, val;
   
           hash = hashinit(desiredvnodes / 4, HASH_LIST, M_UFSMNT, M_WAITOK,
               &mask);
   
           simple_lock(hlock);
           oldhash = *hhead;
           oldmask = *hmask;
           *hhead = hash;
           *hmask = mask;
           for (i = 0; i <= oldmask; i++) {
                   while ((pp = LIST_FIRST(&oldhash[i])) != NULL) {
                           LIST_REMOVE(pp, ptyfs_hash);
                           val = PTYHASH(pp->ptyfs_type, pp->ptyfs_pty,
                               ptyfs_used_mask);
                           LIST_INSERT_HEAD(&hash[val], pp, ptyfs_hash);
                   }
           }
           simple_unlock(hlock);
           hashdone(oldhash, M_UFSMNT);
   }
   
   /*
    * Free ptyfsnode hash table.
    */
   void
   ptyfs_hashdone(void)
   {
           hashdone(ptyfs_used_tbl, M_UFSMNT);
           hashdone(ptyfs_free_tbl, M_UFSMNT);
   }
   
   /*
    * Get a ptyfsnode from the free table, or allocate one.
    * Removes the node from the free table.
    */
   struct ptyfsnode *
   ptyfs_free_get(ptyfstype type, int pty, struct lwp *l)
   {
           struct ptyfs_hashhead *ppp;
           struct ptyfsnode *pp;
   
           simple_lock(&ptyfs_free_slock);
           ppp = &ptyfs_free_tbl[PTYHASH(type, pty, ptyfs_free_mask)];
           LIST_FOREACH(pp, ppp, ptyfs_hash) {
                   if (pty == pp->ptyfs_pty && pp->ptyfs_type == type) {
                           LIST_REMOVE(pp, ptyfs_hash);
                           simple_unlock(&ptyfs_free_slock);
                           return pp;
                   }
           }
           simple_unlock(&ptyfs_free_slock);
   
           MALLOC(pp, void *, sizeof(struct ptyfsnode), M_TEMP, M_WAITOK);
           pp->ptyfs_pty = pty;
           pp->ptyfs_type = type;
           pp->ptyfs_fileno = PTYFS_FILENO(pty, type);
           ptyfs_getinfo(pp, l);
           return pp;
   }
   
   struct vnode *
   ptyfs_used_get(ptyfstype type, int pty, struct mount *mp)
   {
           struct ptyfs_hashhead *ppp;
           struct ptyfsnode *pp;
           struct vnode *vp;
   
   loop:
           simple_lock(&ptyfs_used_slock);
           ppp = &ptyfs_used_tbl[PTYHASH(type, pty, ptyfs_used_mask)];
           LIST_FOREACH(pp, ppp, ptyfs_hash) {
                   vp = PTYFSTOV(pp);
                   if (pty == pp->ptyfs_pty && pp->ptyfs_type == type &&
                       vp->v_mount == mp) {
                           simple_lock(&vp->v_interlock);
                           simple_unlock(&ptyfs_used_slock);
                           if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK))
                                   goto loop;
                           return vp;
                   }
           }
           simple_unlock(&ptyfs_used_slock);
           return NULL;
   }
   
   /*
    * Insert the ptyfsnode into the used table and lock it.
    */
   static void
   ptyfs_hashins(struct ptyfsnode *pp)
   {
           struct ptyfs_hashhead *ppp;
   
           /* lock the ptyfsnode, then put it on the appropriate hash list */
           lockmgr(&pp->ptyfs_vnode->v_lock, LK_EXCLUSIVE, NULL);
   
           simple_lock(&ptyfs_used_slock);
           ppp = &ptyfs_used_tbl[PTYHASH(pp->ptyfs_type, pp->ptyfs_pty,
               ptyfs_used_mask)];
           LIST_INSERT_HEAD(ppp, pp, ptyfs_hash);
           simple_unlock(&ptyfs_used_slock);
   }
   
   /*
    * Remove the ptyfsnode from the used table, and add it to the free table
    */
   static void
   ptyfs_hashrem(struct ptyfsnode *pp)
   {
           struct ptyfs_hashhead *ppp;
   
           simple_lock(&ptyfs_used_slock);
           LIST_REMOVE(pp, ptyfs_hash);
           simple_unlock(&ptyfs_used_slock);
   
           simple_lock(&ptyfs_free_slock);
           ppp = &ptyfs_free_tbl[PTYHASH(pp->ptyfs_type, pp->ptyfs_pty,
               ptyfs_free_mask)];
           LIST_INSERT_HEAD(ppp, pp, ptyfs_hash);
           simple_unlock(&ptyfs_free_slock);
   }

Cache object: d055a76b00d90951fc7b9245a28baed4