The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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    1 /*      $NetBSD: ptyfs_subr.c,v 1.16 2008/05/05 17:11:16 ad Exp $       */
    2 
    3 /*
    4  * Copyright (c) 1993
    5  *      The Regents of the University of California.  All rights reserved.
    6  *
    7  * This code is derived from software contributed to Berkeley by
    8  * Jan-Simon Pendry.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 3. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  *      @(#)ptyfs_subr.c        8.6 (Berkeley) 5/14/95
   35  */
   36 
   37 /*
   38  * Copyright (c) 1994 Christopher G. Demetriou.  All rights reserved.
   39  * Copyright (c) 1993 Jan-Simon Pendry
   40  *
   41  * This code is derived from software contributed to Berkeley by
   42  * Jan-Simon Pendry.
   43  *
   44  * Redistribution and use in source and binary forms, with or without
   45  * modification, are permitted provided that the following conditions
   46  * are met:
   47  * 1. Redistributions of source code must retain the above copyright
   48  *    notice, this list of conditions and the following disclaimer.
   49  * 2. Redistributions in binary form must reproduce the above copyright
   50  *    notice, this list of conditions and the following disclaimer in the
   51  *    documentation and/or other materials provided with the distribution.
   52  * 3. All advertising materials mentioning features or use of this software
   53  *    must display the following acknowledgement:
   54  *      This product includes software developed by the University of
   55  *      California, Berkeley and its contributors.
   56  * 4. Neither the name of the University nor the names of its contributors
   57  *    may be used to endorse or promote products derived from this software
   58  *    without specific prior written permission.
   59  *
   60  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   61  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   62  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   63  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   64  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   65  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   66  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   67  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   68  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   69  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   70  * SUCH DAMAGE.
   71  *
   72  *      @(#)procfs_subr.c       8.6 (Berkeley) 5/14/95
   73  */
   74 
   75 #include <sys/cdefs.h>
   76 __KERNEL_RCSID(0, "$NetBSD: ptyfs_subr.c,v 1.16 2008/05/05 17:11:16 ad Exp $");
   77 
   78 #include <sys/param.h>
   79 #include <sys/systm.h>
   80 #include <sys/time.h>
   81 #include <sys/kernel.h>
   82 #include <sys/vnode.h>
   83 #include <sys/stat.h>
   84 #include <sys/malloc.h>
   85 #include <sys/file.h>
   86 #include <sys/namei.h>
   87 #include <sys/filedesc.h>
   88 #include <sys/select.h>
   89 #include <sys/tty.h>
   90 #include <sys/pty.h>
   91 #include <sys/kauth.h>
   92 #include <sys/lwp.h>
   93 
   94 #include <fs/ptyfs/ptyfs.h>
   95 #include <miscfs/specfs/specdev.h>
   96 
   97 static kmutex_t ptyfs_hashlock;
   98 
   99 static LIST_HEAD(ptyfs_hashhead, ptyfsnode) *ptyfs_used_tbl, *ptyfs_free_tbl;
  100 static u_long ptyfs_used_mask, ptyfs_free_mask; /* size of hash table - 1 */
  101 static kmutex_t ptyfs_used_slock, ptyfs_free_slock;
  102 
  103 static void ptyfs_getinfo(struct ptyfsnode *, struct lwp *);
  104 
  105 static void ptyfs_hashins(struct ptyfsnode *);
  106 static void ptyfs_hashrem(struct ptyfsnode *);
  107 
  108 static struct vnode *ptyfs_used_get(ptyfstype, int, struct mount *, int);
  109 static struct ptyfsnode *ptyfs_free_get(ptyfstype, int, struct lwp *);
  110 
  111 static void ptyfs_rehash(kmutex_t *, struct ptyfs_hashhead **,
  112     u_long *);
  113 
  114 #define PTYHASH(type, pty, mask) (PTYFS_FILENO(type, pty) % (mask + 1))
  115 
  116 
  117 static void
  118 ptyfs_getinfo(struct ptyfsnode *ptyfs, struct lwp *l)
  119 {
  120         extern struct ptm_pty *ptyfs_save_ptm, ptm_ptyfspty;
  121 
  122         if (ptyfs->ptyfs_type == PTYFSroot) {
  123                 ptyfs->ptyfs_mode = S_IRUSR|S_IXUSR|S_IRGRP|S_IXGRP|
  124                     S_IROTH|S_IXOTH;
  125                 goto out;
  126         } else
  127                 ptyfs->ptyfs_mode = S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|
  128                     S_IROTH|S_IWOTH;
  129 
  130         if (ptyfs_save_ptm != NULL && ptyfs_save_ptm != &ptm_ptyfspty) {
  131                 int error;
  132                 struct nameidata nd;
  133                 char ttyname[64];
  134                 kauth_cred_t cred;
  135                 struct vattr va;
  136                 /*
  137                  * We support traditional ptys, so we copy the info
  138                  * from the inode
  139                  */
  140                 if ((error = (*ptyfs_save_ptm->makename)(
  141                         ptyfs_save_ptm, l, ttyname, sizeof(ttyname),
  142                         ptyfs->ptyfs_pty, ptyfs->ptyfs_type == PTYFSpts ? 't'
  143                         : 'p')) != 0)
  144                                 goto out;
  145                 NDINIT(&nd, LOOKUP, NOFOLLOW|LOCKLEAF, UIO_SYSSPACE, ttyname);
  146                 if ((error = namei(&nd)) != 0)
  147                         goto out;
  148                 cred = kauth_cred_alloc();
  149                 error = VOP_GETATTR(nd.ni_vp, &va, cred);
  150                 kauth_cred_free(cred);
  151                 VOP_UNLOCK(nd.ni_vp, 0);
  152                 vrele(nd.ni_vp);
  153                 if (error)
  154                         goto out;
  155                 ptyfs->ptyfs_uid = va.va_uid;
  156                 ptyfs->ptyfs_gid = va.va_gid;
  157                 ptyfs->ptyfs_mode = va.va_mode;
  158                 ptyfs->ptyfs_flags = va.va_flags;
  159                 ptyfs->ptyfs_birthtime = va.va_birthtime;
  160                 ptyfs->ptyfs_ctime = va.va_ctime;
  161                 ptyfs->ptyfs_mtime = va.va_mtime;
  162                 ptyfs->ptyfs_atime = va.va_atime;
  163                 return;
  164         }
  165 out:
  166         ptyfs->ptyfs_uid = ptyfs->ptyfs_gid = 0;
  167         ptyfs->ptyfs_flags |= PTYFS_CHANGE;
  168         PTYFS_ITIMES(ptyfs, NULL, NULL, NULL);
  169         ptyfs->ptyfs_birthtime = ptyfs->ptyfs_mtime =
  170             ptyfs->ptyfs_atime = ptyfs->ptyfs_ctime;
  171         ptyfs->ptyfs_flags = 0;
  172 }
  173 
  174 
  175 /*
  176  * allocate a ptyfsnode/vnode pair.  the vnode is
  177  * referenced, and locked.
  178  *
  179  * the pid, ptyfs_type, and mount point uniquely
  180  * identify a ptyfsnode.  the mount point is needed
  181  * because someone might mount this filesystem
  182  * twice.
  183  *
  184  * all ptyfsnodes are maintained on a singly-linked
  185  * list.  new nodes are only allocated when they cannot
  186  * be found on this list.  entries on the list are
  187  * removed when the vfs reclaim entry is called.
  188  *
  189  * a single lock is kept for the entire list.  this is
  190  * needed because the getnewvnode() function can block
  191  * waiting for a vnode to become free, in which case there
  192  * may be more than one ptyess trying to get the same
  193  * vnode.  this lock is only taken if we are going to
  194  * call getnewvnode, since the kernel itself is single-threaded.
  195  *
  196  * if an entry is found on the list, then call vget() to
  197  * take a reference.  this is done because there may be
  198  * zero references to it and so it needs to removed from
  199  * the vnode free list.
  200  */
  201 int
  202 ptyfs_allocvp(struct mount *mp, struct vnode **vpp, ptyfstype type, int pty,
  203     struct lwp *l)
  204 {
  205         struct ptyfsnode *ptyfs;
  206         struct vnode *vp;
  207         int error;
  208 
  209  retry:
  210         if ((*vpp = ptyfs_used_get(type, pty, mp, LK_EXCLUSIVE)) != NULL)
  211                 return 0;
  212 
  213         if ((error = getnewvnode(VT_PTYFS, mp, ptyfs_vnodeop_p, &vp)) != 0) {
  214                 *vpp = NULL;
  215                 return error;
  216         }
  217 
  218         mutex_enter(&ptyfs_hashlock);
  219         if (ptyfs_used_get(type, pty, mp, 0) != NULL) {
  220                 mutex_exit(&ptyfs_hashlock);
  221                 ungetnewvnode(vp);
  222                 goto retry;
  223         }
  224 
  225         vp->v_data = ptyfs = ptyfs_free_get(type, pty, l);
  226         ptyfs->ptyfs_vnode = vp;
  227 
  228         switch (type) {
  229         case PTYFSroot: /* /pts = dr-xr-xr-x */
  230                 vp->v_type = VDIR;
  231                 vp->v_vflag = VV_ROOT;
  232                 break;
  233 
  234         case PTYFSpts:  /* /pts/N = cxxxxxxxxx */
  235         case PTYFSptc:  /* controlling side = cxxxxxxxxx */
  236                 vp->v_type = VCHR;
  237                 spec_node_init(vp, PTYFS_MAKEDEV(ptyfs));
  238                 break;
  239         default:
  240                 panic("ptyfs_allocvp");
  241         }
  242 
  243         ptyfs_hashins(ptyfs);
  244         uvm_vnp_setsize(vp, 0);
  245         mutex_exit(&ptyfs_hashlock);
  246 
  247         *vpp = vp;
  248         return 0;
  249 }
  250 
  251 int
  252 ptyfs_freevp(struct vnode *vp)
  253 {
  254         struct ptyfsnode *ptyfs = VTOPTYFS(vp);
  255 
  256         ptyfs_hashrem(ptyfs);
  257         vp->v_data = NULL;
  258         return 0;
  259 }
  260 
  261 /*
  262  * Initialize ptyfsnode hash table.
  263  */
  264 void
  265 ptyfs_hashinit(void)
  266 {
  267         ptyfs_used_tbl = hashinit(desiredvnodes / 4, HASH_LIST, true,
  268             &ptyfs_used_mask);
  269         ptyfs_free_tbl = hashinit(desiredvnodes / 4, HASH_LIST, true,
  270             &ptyfs_free_mask);
  271         mutex_init(&ptyfs_hashlock, MUTEX_DEFAULT, IPL_NONE);
  272         mutex_init(&ptyfs_used_slock, MUTEX_DEFAULT, IPL_NONE);
  273         mutex_init(&ptyfs_free_slock, MUTEX_DEFAULT, IPL_NONE);
  274 }
  275 
  276 void
  277 ptyfs_hashreinit(void)
  278 {
  279         ptyfs_rehash(&ptyfs_used_slock, &ptyfs_used_tbl, &ptyfs_used_mask);
  280         ptyfs_rehash(&ptyfs_free_slock, &ptyfs_free_tbl, &ptyfs_free_mask);
  281 }
  282 
  283 static void
  284 ptyfs_rehash(kmutex_t *hlock, struct ptyfs_hashhead **hhead,
  285     u_long *hmask)
  286 {
  287         struct ptyfsnode *pp;
  288         struct ptyfs_hashhead *oldhash, *hash;
  289         u_long i, oldmask, mask, val;
  290 
  291         hash = hashinit(desiredvnodes / 4, HASH_LIST, true, &mask);
  292 
  293         mutex_enter(hlock);
  294         oldhash = *hhead;
  295         oldmask = *hmask;
  296         *hhead = hash;
  297         *hmask = mask;
  298         for (i = 0; i <= oldmask; i++) {
  299                 while ((pp = LIST_FIRST(&oldhash[i])) != NULL) {
  300                         LIST_REMOVE(pp, ptyfs_hash);
  301                         val = PTYHASH(pp->ptyfs_type, pp->ptyfs_pty,
  302                             ptyfs_used_mask);
  303                         LIST_INSERT_HEAD(&hash[val], pp, ptyfs_hash);
  304                 }
  305         }
  306         mutex_exit(hlock);
  307         hashdone(oldhash, HASH_LIST, oldmask);
  308 }
  309 
  310 /*
  311  * Free ptyfsnode hash table.
  312  */
  313 void
  314 ptyfs_hashdone(void)
  315 {
  316 
  317         hashdone(ptyfs_used_tbl, HASH_LIST, ptyfs_used_mask);
  318         hashdone(ptyfs_free_tbl, HASH_LIST, ptyfs_free_mask);
  319 }
  320 
  321 /*
  322  * Get a ptyfsnode from the free table, or allocate one.
  323  * Removes the node from the free table.
  324  */
  325 struct ptyfsnode *
  326 ptyfs_free_get(ptyfstype type, int pty, struct lwp *l)
  327 {
  328         struct ptyfs_hashhead *ppp;
  329         struct ptyfsnode *pp;
  330 
  331         mutex_enter(&ptyfs_free_slock);
  332         ppp = &ptyfs_free_tbl[PTYHASH(type, pty, ptyfs_free_mask)];
  333         LIST_FOREACH(pp, ppp, ptyfs_hash) {
  334                 if (pty == pp->ptyfs_pty && pp->ptyfs_type == type) {
  335                         LIST_REMOVE(pp, ptyfs_hash);
  336                         mutex_exit(&ptyfs_free_slock);
  337                         return pp;
  338                 }
  339         }
  340         mutex_exit(&ptyfs_free_slock);
  341 
  342         MALLOC(pp, void *, sizeof(struct ptyfsnode), M_TEMP, M_WAITOK);
  343         pp->ptyfs_pty = pty;
  344         pp->ptyfs_type = type;
  345         pp->ptyfs_fileno = PTYFS_FILENO(pty, type);
  346         ptyfs_getinfo(pp, l);
  347         return pp;
  348 }
  349 
  350 struct vnode *
  351 ptyfs_used_get(ptyfstype type, int pty, struct mount *mp, int flags)
  352 {
  353         struct ptyfs_hashhead *ppp;
  354         struct ptyfsnode *pp;
  355         struct vnode *vp;
  356 
  357 loop:
  358         mutex_enter(&ptyfs_used_slock);
  359         ppp = &ptyfs_used_tbl[PTYHASH(type, pty, ptyfs_used_mask)];
  360         LIST_FOREACH(pp, ppp, ptyfs_hash) {
  361                 vp = PTYFSTOV(pp);
  362                 if (pty == pp->ptyfs_pty && pp->ptyfs_type == type &&
  363                     vp->v_mount == mp) {
  364                         if (flags == 0) {
  365                                 mutex_exit(&ptyfs_used_slock);
  366                         } else {
  367                                 mutex_enter(&vp->v_interlock);
  368                                 mutex_exit(&ptyfs_used_slock);
  369                                 if (vget(vp, flags | LK_INTERLOCK))
  370                                         goto loop;
  371                         }
  372                         return vp;
  373                 }
  374         }
  375         mutex_exit(&ptyfs_used_slock);
  376         return NULL;
  377 }
  378 
  379 /*
  380  * Insert the ptyfsnode into the used table and lock it.
  381  */
  382 static void
  383 ptyfs_hashins(struct ptyfsnode *pp)
  384 {
  385         struct ptyfs_hashhead *ppp;
  386 
  387         /* lock the ptyfsnode, then put it on the appropriate hash list */
  388         vlockmgr(&pp->ptyfs_vnode->v_lock, LK_EXCLUSIVE);
  389 
  390         mutex_enter(&ptyfs_used_slock);
  391         ppp = &ptyfs_used_tbl[PTYHASH(pp->ptyfs_type, pp->ptyfs_pty,
  392             ptyfs_used_mask)];
  393         LIST_INSERT_HEAD(ppp, pp, ptyfs_hash);
  394         mutex_exit(&ptyfs_used_slock);
  395 }
  396 
  397 /*
  398  * Remove the ptyfsnode from the used table, and add it to the free table
  399  */
  400 static void
  401 ptyfs_hashrem(struct ptyfsnode *pp)
  402 {
  403         struct ptyfs_hashhead *ppp;
  404 
  405         mutex_enter(&ptyfs_used_slock);
  406         LIST_REMOVE(pp, ptyfs_hash);
  407         mutex_exit(&ptyfs_used_slock);
  408 
  409         mutex_enter(&ptyfs_free_slock);
  410         ppp = &ptyfs_free_tbl[PTYHASH(pp->ptyfs_type, pp->ptyfs_pty,
  411             ptyfs_free_mask)];
  412         LIST_INSERT_HEAD(ppp, pp, ptyfs_hash);
  413         mutex_exit(&ptyfs_free_slock);
  414 }

Cache object: 8f6e0239689b12b46814c8aa0ff2efe8


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