1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 
  22 /*
  23  * Copyright (c) 1989, 2010, Oracle and/or its affiliates. All rights reserved.
  24  * Copyright (c) 2012, Joyent Inc. All rights reserved.
  25  */
  26 
  27 /*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T     */
  28 /*      All Rights Reserved */
  29 
  30 #include <sys/types.h>
  31 #include <sys/sysmacros.h>
  32 #include <sys/param.h>
  33 #include <sys/systm.h>
  34 #include <sys/errno.h>
  35 #include <sys/signal.h>
  36 #include <sys/cred.h>
  37 #include <sys/user.h>
  38 #include <sys/conf.h>
  39 #include <sys/vfs.h>
  40 #include <sys/vnode.h>
  41 #include <sys/pathname.h>
  42 #include <sys/file.h>
  43 #include <sys/proc.h>
  44 #include <sys/var.h>
  45 #include <sys/cpuvar.h>
  46 #include <sys/open.h>
  47 #include <sys/cmn_err.h>
  48 #include <sys/priocntl.h>
  49 #include <sys/procset.h>
  50 #include <sys/prsystm.h>
  51 #include <sys/debug.h>
  52 #include <sys/kmem.h>
  53 #include <sys/atomic.h>
  54 #include <sys/fcntl.h>
  55 #include <sys/poll.h>
  56 #include <sys/rctl.h>
  57 #include <sys/port_impl.h>
  58 #include <sys/dtrace.h>
  59 
  60 #include <c2/audit.h>
  61 #include <sys/nbmlock.h>
  62 
  63 #ifdef DEBUG
  64 
  65 static uint32_t afd_maxfd;      /* # of entries in maximum allocated array */
  66 static uint32_t afd_alloc;      /* count of kmem_alloc()s */
  67 static uint32_t afd_free;       /* count of kmem_free()s */
  68 static uint32_t afd_wait;       /* count of waits on non-zero ref count */
  69 #define MAXFD(x)        (afd_maxfd = ((afd_maxfd >= (x))? afd_maxfd : (x)))
  70 #define COUNT(x)        atomic_inc_32(&x)
  71 
  72 #else   /* DEBUG */
  73 
  74 #define MAXFD(x)
  75 #define COUNT(x)
  76 
  77 #endif  /* DEBUG */
  78 
  79 kmem_cache_t *file_cache;
  80 
  81 static void port_close_fd(portfd_t *);
  82 
  83 /*
  84  * File descriptor allocation.
  85  *
  86  * fd_find(fip, minfd) finds the first available descriptor >= minfd.
  87  * The most common case is open(2), in which minfd = 0, but we must also
  88  * support fcntl(fd, F_DUPFD, minfd).
  89  *
  90  * The algorithm is as follows: we keep all file descriptors in an infix
  91  * binary tree in which each node records the number of descriptors
  92  * allocated in its right subtree, including itself.  Starting at minfd,
  93  * we ascend the tree until we find a non-fully allocated right subtree.
  94  * We then descend that subtree in a binary search for the smallest fd.
  95  * Finally, we ascend the tree again to increment the allocation count
  96  * of every subtree containing the newly-allocated fd.  Freeing an fd
  97  * requires only the last step: we ascend the tree to decrement allocation
  98  * counts.  Each of these three steps (ascent to find non-full subtree,
  99  * descent to find lowest fd, ascent to update allocation counts) is
 100  * O(log n), thus the algorithm as a whole is O(log n).
 101  *
 102  * We don't implement the fd tree using the customary left/right/parent
 103  * pointers, but instead take advantage of the glorious mathematics of
 104  * full infix binary trees.  For reference, here's an illustration of the
 105  * logical structure of such a tree, rooted at 4 (binary 100), covering
 106  * the range 1-7 (binary 001-111).  Our canonical trees do not include
 107  * fd 0; we'll deal with that later.
 108  *
 109  *            100
 110  *           /   \
 111  *          /     \
 112  *        010     110
 113  *        / \     / \
 114  *      001 011 101 111
 115  *
 116  * We make the following observations, all of which are easily proven by
 117  * induction on the depth of the tree:
 118  *
 119  * (T1) The least-significant bit (LSB) of any node is equal to its level
 120  *      in the tree.  In our example, nodes 001, 011, 101 and 111 are at
 121  *      level 0; nodes 010 and 110 are at level 1; and node 100 is at level 2.
 122  *
 123  * (T2) The child size (CSIZE) of node N -- that is, the total number of
 124  *      right-branch descendants in a child of node N, including itself -- is
 125  *      given by clearing all but the least significant bit of N.  This
 126  *      follows immediately from (T1).  Applying this rule to our example, we
 127  *      see that CSIZE(100) = 100, CSIZE(x10) = 10, and CSIZE(xx1) = 1.
 128  *
 129  * (T3) The nearest left ancestor (LPARENT) of node N -- that is, the nearest
 130  *      ancestor containing node N in its right child -- is given by clearing
 131  *      the LSB of N.  For example, LPARENT(111) = 110 and LPARENT(110) = 100.
 132  *      Clearing the LSB of nodes 001, 010 or 100 yields zero, reflecting
 133  *      the fact that these are leftmost nodes.  Note that this algorithm
 134  *      automatically skips generations as necessary.  For example, the parent
 135  *      of node 101 is 110, which is a *right* ancestor (not what we want);
 136  *      but its grandparent is 100, which is a left ancestor. Clearing the LSB
 137  *      of 101 gets us to 100 directly, skipping right past the uninteresting
 138  *      generation (110).
 139  *
 140  *      Note that since LPARENT clears the LSB, whereas CSIZE clears all *but*
 141  *      the LSB, we can express LPARENT() nicely in terms of CSIZE():
 142  *
 143  *      LPARENT(N) = N - CSIZE(N)
 144  *
 145  * (T4) The nearest right ancestor (RPARENT) of node N is given by:
 146  *
 147  *      RPARENT(N) = N + CSIZE(N)
 148  *
 149  * (T5) For every interior node, the children differ from their parent by
 150  *      CSIZE(parent) / 2.  In our example, CSIZE(100) / 2 = 2 = 10 binary,
 151  *      and indeed, the children of 100 are 100 +/- 10 = 010 and 110.
 152  *
 153  * Next, we'll need a few two's-complement math tricks.  Suppose a number,
 154  * N, has the following form:
 155  *
 156  *              N = xxxx10...0
 157  *
 158  * That is, the binary representation of N consists of some string of bits,
 159  * then a 1, then all zeroes.  This amounts to nothing more than saying that
 160  * N has a least-significant bit, which is true for any N != 0.  If we look
 161  * at N and N - 1 together, we see that we can combine them in useful ways:
 162  *
 163  *                N = xxxx10...0
 164  *            N - 1 = xxxx01...1
 165  *      ------------------------
 166  *      N & (N - 1) = xxxx000000
 167  *      N | (N - 1) = xxxx111111
 168  *      N ^ (N - 1) =     111111
 169  *
 170  * In particular, this suggests several easy ways to clear all but the LSB,
 171  * which by (T2) is exactly what we need to determine CSIZE(N) = 10...0.
 172  * We'll opt for this formulation:
 173  *
 174  *      (C1) CSIZE(N) = (N - 1) ^ (N | (N - 1))
 175  *
 176  * Similarly, we have an easy way to determine LPARENT(N), which requires
 177  * that we clear the LSB of N:
 178  *
 179  *      (L1) LPARENT(N) = N & (N - 1)
 180  *
 181  * We note in the above relations that (N | (N - 1)) - N = CSIZE(N) - 1.
 182  * When combined with (T4), this yields an easy way to compute RPARENT(N):
 183  *
 184  *      (R1) RPARENT(N) = (N | (N - 1)) + 1
 185  *
 186  * Finally, to accommodate fd 0 we must adjust all of our results by +/-1 to
 187  * move the fd range from [1, 2^n) to [0, 2^n - 1).  This is straightforward,
 188  * so there's no need to belabor the algebra; the revised relations become:
 189  *
 190  *      (C1a) CSIZE(N) = N ^ (N | (N + 1))
 191  *
 192  *      (L1a) LPARENT(N) = (N & (N + 1)) - 1
 193  *
 194  *      (R1a) RPARENT(N) = N | (N + 1)
 195  *
 196  * This completes the mathematical framework.  We now have all the tools
 197  * we need to implement fd_find() and fd_reserve().
 198  *
 199  * fd_find(fip, minfd) finds the smallest available file descriptor >= minfd.
 200  * It does not actually allocate the descriptor; that's done by fd_reserve().
 201  * fd_find() proceeds in two steps:
 202  *
 203  * (1) Find the leftmost subtree that contains a descriptor >= minfd.
 204  *     We start at the right subtree rooted at minfd.  If this subtree is
 205  *     not full -- if fip->fi_list[minfd].uf_alloc != CSIZE(minfd) -- then
 206  *     step 1 is done.  Otherwise, we know that all fds in this subtree
 207  *     are taken, so we ascend to RPARENT(minfd) using (R1a).  We repeat
 208  *     this process until we either find a candidate subtree or exceed
 209  *     fip->fi_nfiles.  We use (C1a) to compute CSIZE().
 210  *
 211  * (2) Find the smallest fd in the subtree discovered by step 1.
 212  *     Starting at the root of this subtree, we descend to find the
 213  *     smallest available fd.  Since the left children have the smaller
 214  *     fds, we will descend rightward only when the left child is full.
 215  *
 216  *     We begin by comparing the number of allocated fds in the root
 217  *     to the number of allocated fds in its right child; if they differ
 218  *     by exactly CSIZE(child), we know the left subtree is full, so we
 219  *     descend right; that is, the right child becomes the search root.
 220  *     Otherwise we leave the root alone and start following the right
 221  *     child's left children.  As fortune would have it, this is very
 222  *     simple computationally: by (T5), the right child of fd is just
 223  *     fd + size, where size = CSIZE(fd) / 2.  Applying (T5) again,
 224  *     we find that the right child's left child is fd + size - (size / 2) =
 225  *     fd + (size / 2); *its* left child is fd + (size / 2) - (size / 4) =
 226  *     fd + (size / 4), and so on.  In general, fd's right child's
 227  *     leftmost nth descendant is fd + (size >> n).  Thus, to follow
 228  *     the right child's left descendants, we just halve the size in
 229  *     each iteration of the search.
 230  *
 231  *     When we descend leftward, we must keep track of the number of fds
 232  *     that were allocated in all the right subtrees we rejected, so we
 233  *     know how many of the root fd's allocations are in the remaining
 234  *     (as yet unexplored) leftmost part of its right subtree.  When we
 235  *     encounter a fully-allocated left child -- that is, when we find
 236  *     that fip->fi_list[fd].uf_alloc == ralloc + size -- we descend right
 237  *     (as described earlier), resetting ralloc to zero.
 238  *
 239  * fd_reserve(fip, fd, incr) either allocates or frees fd, depending
 240  * on whether incr is 1 or -1.  Starting at fd, fd_reserve() ascends
 241  * the leftmost ancestors (see (T3)) and updates the allocation counts.
 242  * At each step we use (L1a) to compute LPARENT(), the next left ancestor.
 243  *
 244  * flist_minsize() finds the minimal tree that still covers all
 245  * used fds; as long as the allocation count of a root node is zero, we
 246  * don't need that node or its right subtree.
 247  *
 248  * flist_nalloc() counts the number of allocated fds in the tree, by starting
 249  * at the top of the tree and summing the right-subtree allocation counts as
 250  * it descends leftwards.
 251  *
 252  * Note: we assume that flist_grow() will keep fip->fi_nfiles of the form
 253  * 2^n - 1.  This ensures that the fd trees are always full, which saves
 254  * quite a bit of boundary checking.
 255  */
 256 static int
 257 fd_find(uf_info_t *fip, int minfd)
 258 {
 259         int size, ralloc, fd;
 260 
 261         ASSERT(MUTEX_HELD(&fip->fi_lock));
 262         ASSERT((fip->fi_nfiles & (fip->fi_nfiles + 1)) == 0);
 263 
 264         for (fd = minfd; (uint_t)fd < fip->fi_nfiles; fd |= fd + 1) {
 265                 size = fd ^ (fd | (fd + 1));
 266                 if (fip->fi_list[fd].uf_alloc == size)
 267                         continue;
 268                 for (ralloc = 0, size >>= 1; size != 0; size >>= 1) {
 269                         ralloc += fip->fi_list[fd + size].uf_alloc;
 270                         if (fip->fi_list[fd].uf_alloc == ralloc + size) {
 271                                 fd += size;
 272                                 ralloc = 0;
 273                         }
 274                 }
 275                 return (fd);
 276         }
 277         return (-1);
 278 }
 279 
 280 static void
 281 fd_reserve(uf_info_t *fip, int fd, int incr)
 282 {
 283         int pfd;
 284         uf_entry_t *ufp = &fip->fi_list[fd];
 285 
 286         ASSERT((uint_t)fd < fip->fi_nfiles);
 287         ASSERT((ufp->uf_busy == 0 && incr == 1) ||
 288             (ufp->uf_busy == 1 && incr == -1));
 289         ASSERT(MUTEX_HELD(&ufp->uf_lock));
 290         ASSERT(MUTEX_HELD(&fip->fi_lock));
 291 
 292         for (pfd = fd; pfd >= 0; pfd = (pfd & (pfd + 1)) - 1)
 293                 fip->fi_list[pfd].uf_alloc += incr;
 294 
 295         ufp->uf_busy += incr;
 296 }
 297 
 298 static int
 299 flist_minsize(uf_info_t *fip)
 300 {
 301         int fd;
 302 
 303         /*
 304          * We'd like to ASSERT(MUTEX_HELD(&fip->fi_lock)), but we're called
 305          * by flist_fork(), which relies on other mechanisms for mutual
 306          * exclusion.
 307          */
 308         ASSERT((fip->fi_nfiles & (fip->fi_nfiles + 1)) == 0);
 309 
 310         for (fd = fip->fi_nfiles; fd != 0; fd >>= 1)
 311                 if (fip->fi_list[fd >> 1].uf_alloc != 0)
 312                         break;
 313 
 314         return (fd);
 315 }
 316 
 317 static int
 318 flist_nalloc(uf_info_t *fip)
 319 {
 320         int fd;
 321         int nalloc = 0;
 322 
 323         ASSERT(MUTEX_HELD(&fip->fi_lock));
 324         ASSERT((fip->fi_nfiles & (fip->fi_nfiles + 1)) == 0);
 325 
 326         for (fd = fip->fi_nfiles; fd != 0; fd >>= 1)
 327                 nalloc += fip->fi_list[fd >> 1].uf_alloc;
 328 
 329         return (nalloc);
 330 }
 331 
 332 /*
 333  * Increase size of the fi_list array to accommodate at least maxfd.
 334  * We keep the size of the form 2^n - 1 for benefit of fd_find().
 335  */
 336 static void
 337 flist_grow(int maxfd)
 338 {
 339         uf_info_t *fip = P_FINFO(curproc);
 340         int newcnt, oldcnt;
 341         uf_entry_t *src, *dst, *newlist, *oldlist, *newend, *oldend;
 342         uf_rlist_t *urp;
 343 
 344         for (newcnt = 1; newcnt <= maxfd; newcnt = (newcnt << 1) | 1)
 345                 continue;
 346 
 347         newlist = kmem_zalloc(newcnt * sizeof (uf_entry_t), KM_SLEEP);
 348 
 349         mutex_enter(&fip->fi_lock);
 350         oldcnt = fip->fi_nfiles;
 351         if (newcnt <= oldcnt) {
 352                 mutex_exit(&fip->fi_lock);
 353                 kmem_free(newlist, newcnt * sizeof (uf_entry_t));
 354                 return;
 355         }
 356         ASSERT((newcnt & (newcnt + 1)) == 0);
 357         oldlist = fip->fi_list;
 358         oldend = oldlist + oldcnt;
 359         newend = newlist + oldcnt;      /* no need to lock beyond old end */
 360 
 361         /*
 362          * fi_list and fi_nfiles cannot change while any uf_lock is held,
 363          * so we must grab all the old locks *and* the new locks up to oldcnt.
 364          * (Locks beyond the end of oldcnt aren't visible until we store
 365          * the new fi_nfiles, which is the last thing we do before dropping
 366          * all the locks, so there's no need to acquire these locks).
 367          * Holding the new locks is necessary because when fi_list changes
 368          * to point to the new list, fi_nfiles won't have been stored yet.
 369          * If we *didn't* hold the new locks, someone doing a UF_ENTER()
 370          * could see the new fi_list, grab the new uf_lock, and then see
 371          * fi_nfiles change while the lock is held -- in violation of
 372          * UF_ENTER() semantics.
 373          */
 374         for (src = oldlist; src < oldend; src++)
 375                 mutex_enter(&src->uf_lock);
 376 
 377         for (dst = newlist; dst < newend; dst++)
 378                 mutex_enter(&dst->uf_lock);
 379 
 380         for (src = oldlist, dst = newlist; src < oldend; src++, dst++) {
 381                 dst->uf_file = src->uf_file;
 382                 dst->uf_fpollinfo = src->uf_fpollinfo;
 383                 dst->uf_refcnt = src->uf_refcnt;
 384                 dst->uf_alloc = src->uf_alloc;
 385                 dst->uf_flag = src->uf_flag;
 386                 dst->uf_busy = src->uf_busy;
 387                 dst->uf_portfd = src->uf_portfd;
 388         }
 389 
 390         /*
 391          * As soon as we store the new flist, future locking operations
 392          * will use it.  Therefore, we must ensure that all the state
 393          * we've just established reaches global visibility before the
 394          * new flist does.
 395          */
 396         membar_producer();
 397         fip->fi_list = newlist;
 398 
 399         /*
 400          * Routines like getf() make an optimistic check on the validity
 401          * of the supplied file descriptor: if it's less than the current
 402          * value of fi_nfiles -- examined without any locks -- then it's
 403          * safe to attempt a UF_ENTER() on that fd (which is a valid
 404          * assumption because fi_nfiles only increases).  Therefore, it
 405          * is critical that the new value of fi_nfiles not reach global
 406          * visibility until after the new fi_list: if it happened the
 407          * other way around, getf() could see the new fi_nfiles and attempt
 408          * a UF_ENTER() on the old fi_list, which would write beyond its
 409          * end if the fd exceeded the old fi_nfiles.
 410          */
 411         membar_producer();
 412         fip->fi_nfiles = newcnt;
 413 
 414         /*
 415          * The new state is consistent now, so we can drop all the locks.
 416          */
 417         for (dst = newlist; dst < newend; dst++)
 418                 mutex_exit(&dst->uf_lock);
 419 
 420         for (src = oldlist; src < oldend; src++) {
 421                 /*
 422                  * If any threads are blocked on the old cvs, wake them.
 423                  * This will force them to wake up, discover that fi_list
 424                  * has changed, and go back to sleep on the new cvs.
 425                  */
 426                 cv_broadcast(&src->uf_wanted_cv);
 427                 cv_broadcast(&src->uf_closing_cv);
 428                 mutex_exit(&src->uf_lock);
 429         }
 430 
 431         mutex_exit(&fip->fi_lock);
 432 
 433         /*
 434          * Retire the old flist.  We can't actually kmem_free() it now
 435          * because someone may still have a pointer to it.  Instead,
 436          * we link it onto a list of retired flists.  The new flist
 437          * is at least double the size of the previous flist, so the
 438          * total size of all retired flists will be less than the size
 439          * of the current one (to prove, consider the sum of a geometric
 440          * series in powers of 2).  exit() frees the retired flists.
 441          */
 442         urp = kmem_zalloc(sizeof (uf_rlist_t), KM_SLEEP);
 443         urp->ur_list = oldlist;
 444         urp->ur_nfiles = oldcnt;
 445 
 446         mutex_enter(&fip->fi_lock);
 447         urp->ur_next = fip->fi_rlist;
 448         fip->fi_rlist = urp;
 449         mutex_exit(&fip->fi_lock);
 450 }
 451 
 452 /*
 453  * Utility functions for keeping track of the active file descriptors.
 454  */
 455 void
 456 clear_stale_fd()                /* called from post_syscall() */
 457 {
 458         afd_t *afd = &curthread->t_activefd;
 459         int i;
 460 
 461         /* uninitialized is ok here, a_nfd is then zero */
 462         for (i = 0; i < afd->a_nfd; i++) {
 463                 /* assert that this should not be necessary */
 464                 ASSERT(afd->a_fd[i] == -1);
 465                 afd->a_fd[i] = -1;
 466         }
 467         afd->a_stale = 0;
 468 }
 469 
 470 void
 471 free_afd(afd_t *afd)            /* called below and from thread_free() */
 472 {
 473         int i;
 474 
 475         /* free the buffer if it was kmem_alloc()ed */
 476         if (afd->a_nfd > sizeof (afd->a_buf) / sizeof (afd->a_buf[0])) {
 477                 COUNT(afd_free);
 478                 kmem_free(afd->a_fd, afd->a_nfd * sizeof (afd->a_fd[0]));
 479         }
 480 
 481         /* (re)initialize the structure */
 482         afd->a_fd = &afd->a_buf[0];
 483         afd->a_nfd = sizeof (afd->a_buf) / sizeof (afd->a_buf[0]);
 484         afd->a_stale = 0;
 485         for (i = 0; i < afd->a_nfd; i++)
 486                 afd->a_fd[i] = -1;
 487 }
 488 
 489 static void
 490 set_active_fd(int fd)
 491 {
 492         afd_t *afd = &curthread->t_activefd;
 493         int i;
 494         int *old_fd;
 495         int old_nfd;
 496         int *new_fd;
 497         int new_nfd;
 498 
 499         if (afd->a_nfd == 0) {       /* first time initialization */
 500                 ASSERT(fd == -1);
 501                 mutex_enter(&afd->a_fdlock);
 502                 free_afd(afd);
 503                 mutex_exit(&afd->a_fdlock);
 504         }
 505 
 506         /* insert fd into vacant slot, if any */
 507         for (i = 0; i < afd->a_nfd; i++) {
 508                 if (afd->a_fd[i] == -1) {
 509                         afd->a_fd[i] = fd;
 510                         return;
 511                 }
 512         }
 513 
 514         /*
 515          * Reallocate the a_fd[] array to add one more slot.
 516          */
 517         ASSERT(fd == -1);
 518         old_nfd = afd->a_nfd;
 519         old_fd = afd->a_fd;
 520         new_nfd = old_nfd + 1;
 521         new_fd = kmem_alloc(new_nfd * sizeof (afd->a_fd[0]), KM_SLEEP);
 522         MAXFD(new_nfd);
 523         COUNT(afd_alloc);
 524 
 525         mutex_enter(&afd->a_fdlock);
 526         afd->a_fd = new_fd;
 527         afd->a_nfd = new_nfd;
 528         for (i = 0; i < old_nfd; i++)
 529                 afd->a_fd[i] = old_fd[i];
 530         afd->a_fd[i] = fd;
 531         mutex_exit(&afd->a_fdlock);
 532 
 533         if (old_nfd > sizeof (afd->a_buf) / sizeof (afd->a_buf[0])) {
 534                 COUNT(afd_free);
 535                 kmem_free(old_fd, old_nfd * sizeof (afd->a_fd[0]));
 536         }
 537 }
 538 
 539 void
 540 clear_active_fd(int fd)         /* called below and from aio.c */
 541 {
 542         afd_t *afd = &curthread->t_activefd;
 543         int i;
 544 
 545         for (i = 0; i < afd->a_nfd; i++) {
 546                 if (afd->a_fd[i] == fd) {
 547                         afd->a_fd[i] = -1;
 548                         break;
 549                 }
 550         }
 551         ASSERT(i < afd->a_nfd);           /* not found is not ok */
 552 }
 553 
 554 /*
 555  * Does this thread have this fd active?
 556  */
 557 static int
 558 is_active_fd(kthread_t *t, int fd)
 559 {
 560         afd_t *afd = &t->t_activefd;
 561         int i;
 562 
 563         ASSERT(t != curthread);
 564         mutex_enter(&afd->a_fdlock);
 565         /* uninitialized is ok here, a_nfd is then zero */
 566         for (i = 0; i < afd->a_nfd; i++) {
 567                 if (afd->a_fd[i] == fd) {
 568                         mutex_exit(&afd->a_fdlock);
 569                         return (1);
 570                 }
 571         }
 572         mutex_exit(&afd->a_fdlock);
 573         return (0);
 574 }
 575 
 576 /*
 577  * Convert a user supplied file descriptor into a pointer to a file
 578  * structure.  Only task is to check range of the descriptor (soft
 579  * resource limit was enforced at open time and shouldn't be checked
 580  * here).
 581  */
 582 file_t *
 583 getf(int fd)
 584 {
 585         uf_info_t *fip = P_FINFO(curproc);
 586         uf_entry_t *ufp;
 587         file_t *fp;
 588 
 589         if ((uint_t)fd >= fip->fi_nfiles)
 590                 return (NULL);
 591 
 592         /*
 593          * Reserve a slot in the active fd array now so we can call
 594          * set_active_fd(fd) for real below, while still inside UF_ENTER().
 595          */
 596         set_active_fd(-1);
 597 
 598         UF_ENTER(ufp, fip, fd);
 599 
 600         if ((fp = ufp->uf_file) == NULL) {
 601                 UF_EXIT(ufp);
 602 
 603                 if (fd == fip->fi_badfd && fip->fi_action > 0)
 604                         tsignal(curthread, fip->fi_action);
 605 
 606                 return (NULL);
 607         }
 608         ufp->uf_refcnt++;
 609 
 610         set_active_fd(fd);      /* record the active file descriptor */
 611 
 612         UF_EXIT(ufp);
 613 
 614         return (fp);
 615 }
 616 
 617 /*
 618  * Close whatever file currently occupies the file descriptor slot
 619  * and install the new file, usually NULL, in the file descriptor slot.
 620  * The close must complete before we release the file descriptor slot.
 621  * If newfp != NULL we only return an error if we can't allocate the
 622  * slot so the caller knows that it needs to free the filep;
 623  * in the other cases we return the error number from closef().
 624  */
 625 int
 626 closeandsetf(int fd, file_t *newfp)
 627 {
 628         proc_t *p = curproc;
 629         uf_info_t *fip = P_FINFO(p);
 630         uf_entry_t *ufp;
 631         file_t *fp;
 632         fpollinfo_t *fpip;
 633         portfd_t *pfd;
 634         int error;
 635 
 636         if ((uint_t)fd >= fip->fi_nfiles) {
 637                 if (newfp == NULL)
 638                         return (EBADF);
 639                 flist_grow(fd);
 640         }
 641 
 642         if (newfp != NULL) {
 643                 /*
 644                  * If ufp is reserved but has no file pointer, it's in the
 645                  * transition between ufalloc() and setf().  We must wait
 646                  * for this transition to complete before assigning the
 647                  * new non-NULL file pointer.
 648                  */
 649                 mutex_enter(&fip->fi_lock);
 650                 if (fd == fip->fi_badfd) {
 651                         mutex_exit(&fip->fi_lock);
 652                         if (fip->fi_action > 0)
 653                                 tsignal(curthread, fip->fi_action);
 654                         return (EBADF);
 655                 }
 656                 UF_ENTER(ufp, fip, fd);
 657                 while (ufp->uf_busy && ufp->uf_file == NULL) {
 658                         mutex_exit(&fip->fi_lock);
 659                         cv_wait_stop(&ufp->uf_wanted_cv, &ufp->uf_lock, 250);
 660                         UF_EXIT(ufp);
 661                         mutex_enter(&fip->fi_lock);
 662                         UF_ENTER(ufp, fip, fd);
 663                 }
 664                 if ((fp = ufp->uf_file) == NULL) {
 665                         ASSERT(ufp->uf_fpollinfo == NULL);
 666                         ASSERT(ufp->uf_flag == 0);
 667                         fd_reserve(fip, fd, 1);
 668                         ufp->uf_file = newfp;
 669                         UF_EXIT(ufp);
 670                         mutex_exit(&fip->fi_lock);
 671                         return (0);
 672                 }
 673                 mutex_exit(&fip->fi_lock);
 674         } else {
 675                 UF_ENTER(ufp, fip, fd);
 676                 if ((fp = ufp->uf_file) == NULL) {
 677                         UF_EXIT(ufp);
 678                         return (EBADF);
 679                 }
 680         }
 681 
 682         ASSERT(ufp->uf_busy);
 683         ufp->uf_file = NULL;
 684         ufp->uf_flag = 0;
 685 
 686         /*
 687          * If the file descriptor reference count is non-zero, then
 688          * some other lwp in the process is performing system call
 689          * activity on the file.  To avoid blocking here for a long
 690          * time (the other lwp might be in a long term sleep in its
 691          * system call), we scan all other lwps in the process to
 692          * find the ones with this fd as one of their active fds,
 693          * set their a_stale flag, and set them running if they
 694          * are in an interruptible sleep so they will emerge from
 695          * their system calls immediately.  post_syscall() will
 696          * test the a_stale flag and set errno to EBADF.
 697          */
 698         ASSERT(ufp->uf_refcnt == 0 || p->p_lwpcnt > 1);
 699         if (ufp->uf_refcnt > 0) {
 700                 kthread_t *t;
 701 
 702                 /*
 703                  * We call sprlock_proc(p) to ensure that the thread
 704                  * list will not change while we are scanning it.
 705                  * To do this, we must drop ufp->uf_lock and then
 706                  * reacquire it (so we are not holding both p->p_lock
 707                  * and ufp->uf_lock at the same time).  ufp->uf_lock
 708                  * must be held for is_active_fd() to be correct
 709                  * (set_active_fd() is called while holding ufp->uf_lock).
 710                  *
 711                  * This is a convoluted dance, but it is better than
 712                  * the old brute-force method of stopping every thread
 713                  * in the process by calling holdlwps(SHOLDFORK1).
 714                  */
 715 
 716                 UF_EXIT(ufp);
 717                 COUNT(afd_wait);
 718 
 719                 mutex_enter(&p->p_lock);
 720                 sprlock_proc(p);
 721                 mutex_exit(&p->p_lock);
 722 
 723                 UF_ENTER(ufp, fip, fd);
 724                 ASSERT(ufp->uf_file == NULL);
 725 
 726                 if (ufp->uf_refcnt > 0) {
 727                         for (t = curthread->t_forw;
 728                             t != curthread;
 729                             t = t->t_forw) {
 730                                 if (is_active_fd(t, fd)) {
 731                                         thread_lock(t);
 732                                         t->t_activefd.a_stale = 1;
 733                                         t->t_post_sys = 1;
 734                                         if (ISWAKEABLE(t))
 735                                                 setrun_locked(t);
 736                                         thread_unlock(t);
 737                                 }
 738                         }
 739                 }
 740 
 741                 UF_EXIT(ufp);
 742 
 743                 mutex_enter(&p->p_lock);
 744                 sprunlock(p);
 745 
 746                 UF_ENTER(ufp, fip, fd);
 747                 ASSERT(ufp->uf_file == NULL);
 748         }
 749 
 750         /*
 751          * Wait for other lwps to stop using this file descriptor.
 752          */
 753         while (ufp->uf_refcnt > 0) {
 754                 cv_wait_stop(&ufp->uf_closing_cv, &ufp->uf_lock, 250);
 755                 /*
 756                  * cv_wait_stop() drops ufp->uf_lock, so the file list
 757                  * can change.  Drop the lock on our (possibly) stale
 758                  * ufp and let UF_ENTER() find and lock the current ufp.
 759                  */
 760                 UF_EXIT(ufp);
 761                 UF_ENTER(ufp, fip, fd);
 762         }
 763 
 764 #ifdef DEBUG
 765         /*
 766          * catch a watchfd on device's pollhead list but not on fpollinfo list
 767          */
 768         if (ufp->uf_fpollinfo != NULL)
 769                 checkwfdlist(fp->f_vnode, ufp->uf_fpollinfo);
 770 #endif  /* DEBUG */
 771 
 772         /*
 773          * We may need to cleanup some cached poll states in t_pollstate
 774          * before the fd can be reused. It is important that we don't
 775          * access a stale thread structure. We will do the cleanup in two
 776          * phases to avoid deadlock and holding uf_lock for too long.
 777          * In phase 1, hold the uf_lock and call pollblockexit() to set
 778          * state in t_pollstate struct so that a thread does not exit on
 779          * us. In phase 2, we drop the uf_lock and call pollcacheclean().
 780          */
 781         pfd = ufp->uf_portfd;
 782         ufp->uf_portfd = NULL;
 783         fpip = ufp->uf_fpollinfo;
 784         ufp->uf_fpollinfo = NULL;
 785         if (fpip != NULL)
 786                 pollblockexit(fpip);
 787         UF_EXIT(ufp);
 788         if (fpip != NULL)
 789                 pollcacheclean(fpip, fd);
 790         if (pfd)
 791                 port_close_fd(pfd);
 792 
 793         /*
 794          * Keep the file descriptor entry reserved across the closef().
 795          */
 796         error = closef(fp);
 797 
 798         setf(fd, newfp);
 799 
 800         /* Only return closef() error when closing is all we do */
 801         return (newfp == NULL ? error : 0);
 802 }
 803 
 804 /*
 805  * Decrement uf_refcnt; wakeup anyone waiting to close the file.
 806  */
 807 void
 808 releasef(int fd)
 809 {
 810         uf_info_t *fip = P_FINFO(curproc);
 811         uf_entry_t *ufp;
 812 
 813         UF_ENTER(ufp, fip, fd);
 814         ASSERT(ufp->uf_refcnt > 0);
 815         clear_active_fd(fd);    /* clear the active file descriptor */
 816         if (--ufp->uf_refcnt == 0)
 817                 cv_broadcast(&ufp->uf_closing_cv);
 818         UF_EXIT(ufp);
 819 }
 820 
 821 /*
 822  * Identical to releasef() but can be called from another process.
 823  */
 824 void
 825 areleasef(int fd, uf_info_t *fip)
 826 {
 827         uf_entry_t *ufp;
 828 
 829         UF_ENTER(ufp, fip, fd);
 830         ASSERT(ufp->uf_refcnt > 0);
 831         if (--ufp->uf_refcnt == 0)
 832                 cv_broadcast(&ufp->uf_closing_cv);
 833         UF_EXIT(ufp);
 834 }
 835 
 836 /*
 837  * Duplicate all file descriptors across a fork.
 838  */
 839 void
 840 flist_fork(uf_info_t *pfip, uf_info_t *cfip)
 841 {
 842         int fd, nfiles;
 843         uf_entry_t *pufp, *cufp;
 844 
 845         mutex_init(&cfip->fi_lock, NULL, MUTEX_DEFAULT, NULL);
 846         cfip->fi_rlist = NULL;
 847 
 848         /*
 849          * We don't need to hold fi_lock because all other lwp's in the
 850          * parent have been held.
 851          */
 852         cfip->fi_nfiles = nfiles = flist_minsize(pfip);
 853 
 854         cfip->fi_list = kmem_zalloc(nfiles * sizeof (uf_entry_t), KM_SLEEP);
 855 
 856         for (fd = 0, pufp = pfip->fi_list, cufp = cfip->fi_list; fd < nfiles;
 857             fd++, pufp++, cufp++) {
 858                 cufp->uf_file = pufp->uf_file;
 859                 cufp->uf_alloc = pufp->uf_alloc;
 860                 cufp->uf_flag = pufp->uf_flag;
 861                 cufp->uf_busy = pufp->uf_busy;
 862                 if (pufp->uf_file == NULL) {
 863                         ASSERT(pufp->uf_flag == 0);
 864                         if (pufp->uf_busy) {
 865                                 /*
 866                                  * Grab locks to appease ASSERTs in fd_reserve
 867                                  */
 868                                 mutex_enter(&cfip->fi_lock);
 869                                 mutex_enter(&cufp->uf_lock);
 870                                 fd_reserve(cfip, fd, -1);
 871                                 mutex_exit(&cufp->uf_lock);
 872                                 mutex_exit(&cfip->fi_lock);
 873                         }
 874                 }
 875         }
 876 }
 877 
 878 /*
 879  * Close all open file descriptors for the current process.
 880  * This is only called from exit(), which is single-threaded,
 881  * so we don't need any locking.
 882  */
 883 void
 884 closeall(uf_info_t *fip)
 885 {
 886         int fd;
 887         file_t *fp;
 888         uf_entry_t *ufp;
 889 
 890         ufp = fip->fi_list;
 891         for (fd = 0; fd < fip->fi_nfiles; fd++, ufp++) {
 892                 if ((fp = ufp->uf_file) != NULL) {
 893                         ufp->uf_file = NULL;
 894                         if (ufp->uf_portfd != NULL) {
 895                                 portfd_t *pfd;
 896                                 /* remove event port association */
 897                                 pfd = ufp->uf_portfd;
 898                                 ufp->uf_portfd = NULL;
 899                                 port_close_fd(pfd);
 900                         }
 901                         ASSERT(ufp->uf_fpollinfo == NULL);
 902                         (void) closef(fp);
 903                 }
 904         }
 905 
 906         kmem_free(fip->fi_list, fip->fi_nfiles * sizeof (uf_entry_t));
 907         fip->fi_list = NULL;
 908         fip->fi_nfiles = 0;
 909         while (fip->fi_rlist != NULL) {
 910                 uf_rlist_t *urp = fip->fi_rlist;
 911                 fip->fi_rlist = urp->ur_next;
 912                 kmem_free(urp->ur_list, urp->ur_nfiles * sizeof (uf_entry_t));
 913                 kmem_free(urp, sizeof (uf_rlist_t));
 914         }
 915 }
 916 
 917 /*
 918  * Internal form of close.  Decrement reference count on file
 919  * structure.  Decrement reference count on the vnode following
 920  * removal of the referencing file structure.
 921  */
 922 int
 923 closef(file_t *fp)
 924 {
 925         vnode_t *vp;
 926         int error;
 927         int count;
 928         int flag;
 929         offset_t offset;
 930 
 931         /*
 932          * audit close of file (may be exit)
 933          */
 934         if (AU_AUDITING())
 935                 audit_closef(fp);
 936         ASSERT(MUTEX_NOT_HELD(&P_FINFO(curproc)->fi_lock));
 937 
 938         mutex_enter(&fp->f_tlock);
 939 
 940         ASSERT(fp->f_count > 0);
 941 
 942         count = fp->f_count--;
 943         flag = fp->f_flag;
 944         offset = fp->f_offset;
 945 
 946         vp = fp->f_vnode;
 947 
 948         error = VOP_CLOSE(vp, flag, count, offset, fp->f_cred, NULL);
 949 
 950         if (count > 1) {
 951                 mutex_exit(&fp->f_tlock);
 952                 return (error);
 953         }
 954         ASSERT(fp->f_count == 0);
 955         mutex_exit(&fp->f_tlock);
 956 
 957         /*
 958          * If DTrace has getf() subroutines active, it will set dtrace_closef
 959          * to point to code that implements a barrier with respect to probe
 960          * context.  This must be called before the file_t is freed (and the
 961          * vnode that it refers to is released) -- but it must be after the
 962          * file_t has been removed from the uf_entry_t.  That is, there must
 963          * be no way for a racing getf() in probe context to yield the fp that
 964          * we're operating upon.
 965          */
 966         if (dtrace_closef != NULL)
 967                 (*dtrace_closef)();
 968 
 969         VN_RELE(vp);
 970         /*
 971          * deallocate resources to audit_data
 972          */
 973         if (audit_active)
 974                 audit_unfalloc(fp);
 975         crfree(fp->f_cred);
 976         kmem_cache_free(file_cache, fp);
 977         return (error);
 978 }
 979 
 980 /*
 981  * This is a combination of ufalloc() and setf().
 982  */
 983 int
 984 ufalloc_file(int start, file_t *fp)
 985 {
 986         proc_t *p = curproc;
 987         uf_info_t *fip = P_FINFO(p);
 988         int filelimit;
 989         uf_entry_t *ufp;
 990         int nfiles;
 991         int fd;
 992 
 993         /*
 994          * Assertion is to convince the correctness of the following
 995          * assignment for filelimit after casting to int.
 996          */
 997         ASSERT(p->p_fno_ctl <= INT_MAX);
 998         filelimit = (int)p->p_fno_ctl;
 999 
1000         for (;;) {
1001                 mutex_enter(&fip->fi_lock);
1002                 fd = fd_find(fip, start);
1003                 if (fd >= 0 && fd == fip->fi_badfd) {
1004                         start = fd + 1;
1005                         mutex_exit(&fip->fi_lock);
1006                         continue;
1007                 }
1008                 if ((uint_t)fd < filelimit)
1009                         break;
1010                 if (fd >= filelimit) {
1011                         mutex_exit(&fip->fi_lock);
1012                         mutex_enter(&p->p_lock);
1013                         (void) rctl_action(rctlproc_legacy[RLIMIT_NOFILE],
1014                             p->p_rctls, p, RCA_SAFE);
1015                         mutex_exit(&p->p_lock);
1016                         return (-1);
1017                 }
1018                 /* fd_find() returned -1 */
1019                 nfiles = fip->fi_nfiles;
1020                 mutex_exit(&fip->fi_lock);
1021                 flist_grow(MAX(start, nfiles));
1022         }
1023 
1024         UF_ENTER(ufp, fip, fd);
1025         fd_reserve(fip, fd, 1);
1026         ASSERT(ufp->uf_file == NULL);
1027         ufp->uf_file = fp;
1028         UF_EXIT(ufp);
1029         mutex_exit(&fip->fi_lock);
1030         return (fd);
1031 }
1032 
1033 /*
1034  * Allocate a user file descriptor greater than or equal to "start".
1035  */
1036 int
1037 ufalloc(int start)
1038 {
1039         return (ufalloc_file(start, NULL));
1040 }
1041 
1042 /*
1043  * Check that a future allocation of count fds on proc p has a good
1044  * chance of succeeding.  If not, do rctl processing as if we'd failed
1045  * the allocation.
1046  *
1047  * Our caller must guarantee that p cannot disappear underneath us.
1048  */
1049 int
1050 ufcanalloc(proc_t *p, uint_t count)
1051 {
1052         uf_info_t *fip = P_FINFO(p);
1053         int filelimit;
1054         int current;
1055 
1056         if (count == 0)
1057                 return (1);
1058 
1059         ASSERT(p->p_fno_ctl <= INT_MAX);
1060         filelimit = (int)p->p_fno_ctl;
1061 
1062         mutex_enter(&fip->fi_lock);
1063         current = flist_nalloc(fip);            /* # of in-use descriptors */
1064         mutex_exit(&fip->fi_lock);
1065 
1066         /*
1067          * If count is a positive integer, the worst that can happen is
1068          * an overflow to a negative value, which is caught by the >= 0 check.
1069          */
1070         current += count;
1071         if (count <= INT_MAX && current >= 0 && current <= filelimit)
1072                 return (1);
1073 
1074         mutex_enter(&p->p_lock);
1075         (void) rctl_action(rctlproc_legacy[RLIMIT_NOFILE],
1076             p->p_rctls, p, RCA_SAFE);
1077         mutex_exit(&p->p_lock);
1078         return (0);
1079 }
1080 
1081 /*
1082  * Allocate a user file descriptor and a file structure.
1083  * Initialize the descriptor to point at the file structure.
1084  * If fdp is NULL, the user file descriptor will not be allocated.
1085  */
1086 int
1087 falloc(vnode_t *vp, int flag, file_t **fpp, int *fdp)
1088 {
1089         file_t *fp;
1090         int fd;
1091 
1092         if (fdp) {
1093                 if ((fd = ufalloc(0)) == -1)
1094                         return (EMFILE);
1095         }
1096         fp = kmem_cache_alloc(file_cache, KM_SLEEP);
1097         /*
1098          * Note: falloc returns the fp locked
1099          */
1100         mutex_enter(&fp->f_tlock);
1101         fp->f_count = 1;
1102         fp->f_flag = (ushort_t)flag;
1103         fp->f_flag2 = (flag & (FSEARCH|FEXEC)) >> 16;
1104         fp->f_vnode = vp;
1105         fp->f_offset = 0;
1106         fp->f_audit_data = 0;
1107         crhold(fp->f_cred = CRED());
1108         /*
1109          * allocate resources to audit_data
1110          */
1111         if (audit_active)
1112                 audit_falloc(fp);
1113         *fpp = fp;
1114         if (fdp)
1115                 *fdp = fd;
1116         return (0);
1117 }
1118 
1119 /*ARGSUSED*/
1120 static int
1121 file_cache_constructor(void *buf, void *cdrarg, int kmflags)
1122 {
1123         file_t *fp = buf;
1124 
1125         mutex_init(&fp->f_tlock, NULL, MUTEX_DEFAULT, NULL);
1126         return (0);
1127 }
1128 
1129 /*ARGSUSED*/
1130 static void
1131 file_cache_destructor(void *buf, void *cdrarg)
1132 {
1133         file_t *fp = buf;
1134 
1135         mutex_destroy(&fp->f_tlock);
1136 }
1137 
1138 void
1139 finit()
1140 {
1141         file_cache = kmem_cache_create("file_cache", sizeof (file_t), 0,
1142             file_cache_constructor, file_cache_destructor, NULL, NULL, NULL, 0);
1143 }
1144 
1145 void
1146 unfalloc(file_t *fp)
1147 {
1148         ASSERT(MUTEX_HELD(&fp->f_tlock));
1149         if (--fp->f_count <= 0) {
1150                 /*
1151                  * deallocate resources to audit_data
1152                  */
1153                 if (audit_active)
1154                         audit_unfalloc(fp);
1155                 crfree(fp->f_cred);
1156                 mutex_exit(&fp->f_tlock);
1157                 kmem_cache_free(file_cache, fp);
1158         } else
1159                 mutex_exit(&fp->f_tlock);
1160 }
1161 
1162 /*
1163  * Given a file descriptor, set the user's
1164  * file pointer to the given parameter.
1165  */
1166 void
1167 setf(int fd, file_t *fp)
1168 {
1169         uf_info_t *fip = P_FINFO(curproc);
1170         uf_entry_t *ufp;
1171 
1172         if (AU_AUDITING())
1173                 audit_setf(fp, fd);
1174 
1175         if (fp == NULL) {
1176                 mutex_enter(&fip->fi_lock);
1177                 UF_ENTER(ufp, fip, fd);
1178                 fd_reserve(fip, fd, -1);
1179                 mutex_exit(&fip->fi_lock);
1180         } else {
1181                 UF_ENTER(ufp, fip, fd);
1182                 ASSERT(ufp->uf_busy);
1183         }
1184         ASSERT(ufp->uf_fpollinfo == NULL);
1185         ASSERT(ufp->uf_flag == 0);
1186         ufp->uf_file = fp;
1187         cv_broadcast(&ufp->uf_wanted_cv);
1188         UF_EXIT(ufp);
1189 }
1190 
1191 /*
1192  * Given a file descriptor, return the file table flags, plus,
1193  * if this is a socket in asynchronous mode, the FASYNC flag.
1194  * getf() may or may not have been called before calling f_getfl().
1195  */
1196 int
1197 f_getfl(int fd, int *flagp)
1198 {
1199         uf_info_t *fip = P_FINFO(curproc);
1200         uf_entry_t *ufp;
1201         file_t *fp;
1202         int error;
1203 
1204         if ((uint_t)fd >= fip->fi_nfiles)
1205                 error = EBADF;
1206         else {
1207                 UF_ENTER(ufp, fip, fd);
1208                 if ((fp = ufp->uf_file) == NULL)
1209                         error = EBADF;
1210                 else {
1211                         vnode_t *vp = fp->f_vnode;
1212                         int flag = fp->f_flag | (fp->f_flag2 << 16);
1213 
1214                         /*
1215                          * BSD fcntl() FASYNC compatibility.
1216                          */
1217                         if (vp->v_type == VSOCK)
1218                                 flag |= sock_getfasync(vp);
1219                         *flagp = flag;
1220                         error = 0;
1221                 }
1222                 UF_EXIT(ufp);
1223         }
1224 
1225         return (error);
1226 }
1227 
1228 /*
1229  * Given a file descriptor, return the user's file flags.
1230  * Force the FD_CLOEXEC flag for writable self-open /proc files.
1231  * getf() may or may not have been called before calling f_getfd_error().
1232  */
1233 int
1234 f_getfd_error(int fd, int *flagp)
1235 {
1236         uf_info_t *fip = P_FINFO(curproc);
1237         uf_entry_t *ufp;
1238         file_t *fp;
1239         int flag;
1240         int error;
1241 
1242         if ((uint_t)fd >= fip->fi_nfiles)
1243                 error = EBADF;
1244         else {
1245                 UF_ENTER(ufp, fip, fd);
1246                 if ((fp = ufp->uf_file) == NULL)
1247                         error = EBADF;
1248                 else {
1249                         flag = ufp->uf_flag;
1250                         if ((fp->f_flag & FWRITE) && pr_isself(fp->f_vnode))
1251                                 flag |= FD_CLOEXEC;
1252                         *flagp = flag;
1253                         error = 0;
1254                 }
1255                 UF_EXIT(ufp);
1256         }
1257 
1258         return (error);
1259 }
1260 
1261 /*
1262  * getf() must have been called before calling f_getfd().
1263  */
1264 char
1265 f_getfd(int fd)
1266 {
1267         int flag = 0;
1268         (void) f_getfd_error(fd, &flag);
1269         return ((char)flag);
1270 }
1271 
1272 /*
1273  * Given a file descriptor and file flags, set the user's file flags.
1274  * At present, the only valid flag is FD_CLOEXEC.
1275  * getf() may or may not have been called before calling f_setfd_error().
1276  */
1277 int
1278 f_setfd_error(int fd, int flags)
1279 {
1280         uf_info_t *fip = P_FINFO(curproc);
1281         uf_entry_t *ufp;
1282         int error;
1283 
1284         if ((uint_t)fd >= fip->fi_nfiles)
1285                 error = EBADF;
1286         else {
1287                 UF_ENTER(ufp, fip, fd);
1288                 if (ufp->uf_file == NULL)
1289                         error = EBADF;
1290                 else {
1291                         ufp->uf_flag = flags & FD_CLOEXEC;
1292                         error = 0;
1293                 }
1294                 UF_EXIT(ufp);
1295         }
1296         return (error);
1297 }
1298 
1299 void
1300 f_setfd(int fd, char flags)
1301 {
1302         (void) f_setfd_error(fd, flags);
1303 }
1304 
1305 #define BADFD_MIN       3
1306 #define BADFD_MAX       255
1307 
1308 /*
1309  * Attempt to allocate a file descriptor which is bad and which
1310  * is "poison" to the application.  It cannot be closed (except
1311  * on exec), allocated for a different use, etc.
1312  */
1313 int
1314 f_badfd(int start, int *fdp, int action)
1315 {
1316         int fdr;
1317         int badfd;
1318         uf_info_t *fip = P_FINFO(curproc);
1319 
1320 #ifdef _LP64
1321         /* No restrictions on 64 bit _file */
1322         if (get_udatamodel() != DATAMODEL_ILP32)
1323                 return (EINVAL);
1324 #endif
1325 
1326         if (start > BADFD_MAX || start < BADFD_MIN)
1327                 return (EINVAL);
1328 
1329         if (action >= NSIG || action < 0)
1330                 return (EINVAL);
1331 
1332         mutex_enter(&fip->fi_lock);
1333         badfd = fip->fi_badfd;
1334         mutex_exit(&fip->fi_lock);
1335 
1336         if (badfd != -1)
1337                 return (EAGAIN);
1338 
1339         fdr = ufalloc(start);
1340 
1341         if (fdr > BADFD_MAX) {
1342                 setf(fdr, NULL);
1343                 return (EMFILE);
1344         }
1345         if (fdr < 0)
1346                 return (EMFILE);
1347 
1348         mutex_enter(&fip->fi_lock);
1349         if (fip->fi_badfd != -1) {
1350                 /* Lost race */
1351                 mutex_exit(&fip->fi_lock);
1352                 setf(fdr, NULL);
1353                 return (EAGAIN);
1354         }
1355         fip->fi_action = action;
1356         fip->fi_badfd = fdr;
1357         mutex_exit(&fip->fi_lock);
1358         setf(fdr, NULL);
1359 
1360         *fdp = fdr;
1361 
1362         return (0);
1363 }
1364 
1365 /*
1366  * Allocate a file descriptor and assign it to the vnode "*vpp",
1367  * performing the usual open protocol upon it and returning the
1368  * file descriptor allocated.  It is the responsibility of the
1369  * caller to dispose of "*vpp" if any error occurs.
1370  */
1371 int
1372 fassign(vnode_t **vpp, int mode, int *fdp)
1373 {
1374         file_t *fp;
1375         int error;
1376         int fd;
1377 
1378         if (error = falloc((vnode_t *)NULL, mode, &fp, &fd))
1379                 return (error);
1380         if (error = VOP_OPEN(vpp, mode, fp->f_cred, NULL)) {
1381                 setf(fd, NULL);
1382                 unfalloc(fp);
1383                 return (error);
1384         }
1385         fp->f_vnode = *vpp;
1386         mutex_exit(&fp->f_tlock);
1387         /*
1388          * Fill in the slot falloc reserved.
1389          */
1390         setf(fd, fp);
1391         *fdp = fd;
1392         return (0);
1393 }
1394 
1395 /*
1396  * When a process forks it must increment the f_count of all file pointers
1397  * since there is a new process pointing at them.  fcnt_add(fip, 1) does this.
1398  * Since we are called when there is only 1 active lwp we don't need to
1399  * hold fi_lock or any uf_lock.  If the fork fails, fork_fail() calls
1400  * fcnt_add(fip, -1) to restore the counts.
1401  */
1402 void
1403 fcnt_add(uf_info_t *fip, int incr)
1404 {
1405         int i;
1406         uf_entry_t *ufp;
1407         file_t *fp;
1408 
1409         ufp = fip->fi_list;
1410         for (i = 0; i < fip->fi_nfiles; i++, ufp++) {
1411                 if ((fp = ufp->uf_file) != NULL) {
1412                         mutex_enter(&fp->f_tlock);
1413                         ASSERT((incr == 1 && fp->f_count >= 1) ||
1414                             (incr == -1 && fp->f_count >= 2));
1415                         fp->f_count += incr;
1416                         mutex_exit(&fp->f_tlock);
1417                 }
1418         }
1419 }
1420 
1421 /*
1422  * This is called from exec to close all fd's that have the FD_CLOEXEC flag
1423  * set and also to close all self-open for write /proc file descriptors.
1424  */
1425 void
1426 close_exec(uf_info_t *fip)
1427 {
1428         int fd;
1429         file_t *fp;
1430         fpollinfo_t *fpip;
1431         uf_entry_t *ufp;
1432         portfd_t *pfd;
1433 
1434         ufp = fip->fi_list;
1435         for (fd = 0; fd < fip->fi_nfiles; fd++, ufp++) {
1436                 if ((fp = ufp->uf_file) != NULL &&
1437                     ((ufp->uf_flag & FD_CLOEXEC) ||
1438                     ((fp->f_flag & FWRITE) && pr_isself(fp->f_vnode)))) {
1439                         fpip = ufp->uf_fpollinfo;
1440                         mutex_enter(&fip->fi_lock);
1441                         mutex_enter(&ufp->uf_lock);
1442                         fd_reserve(fip, fd, -1);
1443                         mutex_exit(&fip->fi_lock);
1444                         ufp->uf_file = NULL;
1445                         ufp->uf_fpollinfo = NULL;
1446                         ufp->uf_flag = 0;
1447                         /*
1448                          * We may need to cleanup some cached poll states
1449                          * in t_pollstate before the fd can be reused. It
1450                          * is important that we don't access a stale thread
1451                          * structure. We will do the cleanup in two
1452                          * phases to avoid deadlock and holding uf_lock for
1453                          * too long. In phase 1, hold the uf_lock and call
1454                          * pollblockexit() to set state in t_pollstate struct
1455                          * so that a thread does not exit on us. In phase 2,
1456                          * we drop the uf_lock and call pollcacheclean().
1457                          */
1458                         pfd = ufp->uf_portfd;
1459                         ufp->uf_portfd = NULL;
1460                         if (fpip != NULL)
1461                                 pollblockexit(fpip);
1462                         mutex_exit(&ufp->uf_lock);
1463                         if (fpip != NULL)
1464                                 pollcacheclean(fpip, fd);
1465                         if (pfd)
1466                                 port_close_fd(pfd);
1467                         (void) closef(fp);
1468                 }
1469         }
1470 
1471         /* Reset bad fd */
1472         fip->fi_badfd = -1;
1473         fip->fi_action = -1;
1474 }
1475 
1476 /*
1477  * Utility function called by most of the *at() system call interfaces.
1478  *
1479  * Generate a starting vnode pointer for an (fd, path) pair where 'fd'
1480  * is an open file descriptor for a directory to be used as the starting
1481  * point for the lookup of the relative pathname 'path' (or, if path is
1482  * NULL, generate a vnode pointer for the direct target of the operation).
1483  *
1484  * If we successfully return a non-NULL startvp, it has been the target
1485  * of VN_HOLD() and the caller must call VN_RELE() on it.
1486  */
1487 int
1488 fgetstartvp(int fd, char *path, vnode_t **startvpp)
1489 {
1490         vnode_t         *startvp;
1491         file_t          *startfp;
1492         char            startchar;
1493 
1494         if (fd == AT_FDCWD && path == NULL)
1495                 return (EFAULT);
1496 
1497         if (fd == AT_FDCWD) {
1498                 /*
1499                  * Start from the current working directory.
1500                  */
1501                 startvp = NULL;
1502         } else {
1503                 if (path == NULL)
1504                         startchar = '\0';
1505                 else if (copyin(path, &startchar, sizeof (char)))
1506                         return (EFAULT);
1507 
1508                 if (startchar == '/') {
1509                         /*
1510                          * 'path' is an absolute pathname.
1511                          */
1512                         startvp = NULL;
1513                 } else {
1514                         /*
1515                          * 'path' is a relative pathname or we will
1516                          * be applying the operation to 'fd' itself.
1517                          */
1518                         if ((startfp = getf(fd)) == NULL)
1519                                 return (EBADF);
1520                         startvp = startfp->f_vnode;
1521                         VN_HOLD(startvp);
1522                         releasef(fd);
1523                 }
1524         }
1525         *startvpp = startvp;
1526         return (0);
1527 }
1528 
1529 /*
1530  * Called from fchownat() and fchmodat() to set ownership and mode.
1531  * The contents of *vap must be set before calling here.
1532  */
1533 int
1534 fsetattrat(int fd, char *path, int flags, struct vattr *vap)
1535 {
1536         vnode_t         *startvp;
1537         vnode_t         *vp;
1538         int             error;
1539 
1540         /*
1541          * Since we are never called to set the size of a file, we don't
1542          * need to check for non-blocking locks (via nbl_need_check(vp)).
1543          */
1544         ASSERT(!(vap->va_mask & AT_SIZE));
1545 
1546         if ((error = fgetstartvp(fd, path, &startvp)) != 0)
1547                 return (error);
1548         if (AU_AUDITING() && startvp != NULL)
1549                 audit_setfsat_path(1);
1550 
1551         /*
1552          * Do lookup for fchownat/fchmodat when path not NULL
1553          */
1554         if (path != NULL) {
1555                 if (error = lookupnameat(path, UIO_USERSPACE,
1556                     (flags == AT_SYMLINK_NOFOLLOW) ?
1557                     NO_FOLLOW : FOLLOW,
1558                     NULLVPP, &vp, startvp)) {
1559                         if (startvp != NULL)
1560                                 VN_RELE(startvp);
1561                         return (error);
1562                 }
1563         } else {
1564                 vp = startvp;
1565                 ASSERT(vp);
1566                 VN_HOLD(vp);
1567         }
1568 
1569         if (vn_is_readonly(vp)) {
1570                 error = EROFS;
1571         } else {
1572                 error = VOP_SETATTR(vp, vap, 0, CRED(), NULL);
1573         }
1574 
1575         if (startvp != NULL)
1576                 VN_RELE(startvp);
1577         VN_RELE(vp);
1578 
1579         return (error);
1580 }
1581 
1582 /*
1583  * Return true if the given vnode is referenced by any
1584  * entry in the current process's file descriptor table.
1585  */
1586 int
1587 fisopen(vnode_t *vp)
1588 {
1589         int fd;
1590         file_t *fp;
1591         vnode_t *ovp;
1592         uf_info_t *fip = P_FINFO(curproc);
1593         uf_entry_t *ufp;
1594 
1595         mutex_enter(&fip->fi_lock);
1596         for (fd = 0; fd < fip->fi_nfiles; fd++) {
1597                 UF_ENTER(ufp, fip, fd);
1598                 if ((fp = ufp->uf_file) != NULL &&
1599                     (ovp = fp->f_vnode) != NULL && VN_CMP(vp, ovp)) {
1600                         UF_EXIT(ufp);
1601                         mutex_exit(&fip->fi_lock);
1602                         return (1);
1603                 }
1604                 UF_EXIT(ufp);
1605         }
1606         mutex_exit(&fip->fi_lock);
1607         return (0);
1608 }
1609 
1610 /*
1611  * Return zero if at least one file currently open (by curproc) shouldn't be
1612  * allowed to change zones.
1613  */
1614 int
1615 files_can_change_zones(void)
1616 {
1617         int fd;
1618         file_t *fp;
1619         uf_info_t *fip = P_FINFO(curproc);
1620         uf_entry_t *ufp;
1621 
1622         mutex_enter(&fip->fi_lock);
1623         for (fd = 0; fd < fip->fi_nfiles; fd++) {
1624                 UF_ENTER(ufp, fip, fd);
1625                 if ((fp = ufp->uf_file) != NULL &&
1626                     !vn_can_change_zones(fp->f_vnode)) {
1627                         UF_EXIT(ufp);
1628                         mutex_exit(&fip->fi_lock);
1629                         return (0);
1630                 }
1631                 UF_EXIT(ufp);
1632         }
1633         mutex_exit(&fip->fi_lock);
1634         return (1);
1635 }
1636 
1637 #ifdef DEBUG
1638 
1639 /*
1640  * The following functions are only used in ASSERT()s elsewhere.
1641  * They do not modify the state of the system.
1642  */
1643 
1644 /*
1645  * Return true (1) if the current thread is in the fpollinfo
1646  * list for this file descriptor, else false (0).
1647  */
1648 static int
1649 curthread_in_plist(uf_entry_t *ufp)
1650 {
1651         fpollinfo_t *fpip;
1652 
1653         ASSERT(MUTEX_HELD(&ufp->uf_lock));
1654         for (fpip = ufp->uf_fpollinfo; fpip; fpip = fpip->fp_next)
1655                 if (fpip->fp_thread == curthread)
1656                         return (1);
1657         return (0);
1658 }
1659 
1660 /*
1661  * Sanity check to make sure that after lwp_exit(),
1662  * curthread does not appear on any fd's fpollinfo list.
1663  */
1664 void
1665 checkfpollinfo(void)
1666 {
1667         int fd;
1668         uf_info_t *fip = P_FINFO(curproc);
1669         uf_entry_t *ufp;
1670 
1671         mutex_enter(&fip->fi_lock);
1672         for (fd = 0; fd < fip->fi_nfiles; fd++) {
1673                 UF_ENTER(ufp, fip, fd);
1674                 ASSERT(!curthread_in_plist(ufp));
1675                 UF_EXIT(ufp);
1676         }
1677         mutex_exit(&fip->fi_lock);
1678 }
1679 
1680 /*
1681  * Return true (1) if the current thread is in the fpollinfo
1682  * list for this file descriptor, else false (0).
1683  * This is the same as curthread_in_plist(),
1684  * but is called w/o holding uf_lock.
1685  */
1686 int
1687 infpollinfo(int fd)
1688 {
1689         uf_info_t *fip = P_FINFO(curproc);
1690         uf_entry_t *ufp;
1691         int rc;
1692 
1693         UF_ENTER(ufp, fip, fd);
1694         rc = curthread_in_plist(ufp);
1695         UF_EXIT(ufp);
1696         return (rc);
1697 }
1698 
1699 #endif  /* DEBUG */
1700 
1701 /*
1702  * Add the curthread to fpollinfo list, meaning this fd is currently in the
1703  * thread's poll cache. Each lwp polling this file descriptor should call
1704  * this routine once.
1705  */
1706 void
1707 addfpollinfo(int fd)
1708 {
1709         struct uf_entry *ufp;
1710         fpollinfo_t *fpip;
1711         uf_info_t *fip = P_FINFO(curproc);
1712 
1713         fpip = kmem_zalloc(sizeof (fpollinfo_t), KM_SLEEP);
1714         fpip->fp_thread = curthread;
1715         UF_ENTER(ufp, fip, fd);
1716         /*
1717          * Assert we are not already on the list, that is, that
1718          * this lwp did not call addfpollinfo twice for the same fd.
1719          */
1720         ASSERT(!curthread_in_plist(ufp));
1721         /*
1722          * addfpollinfo is always done inside the getf/releasef pair.
1723          */
1724         ASSERT(ufp->uf_refcnt >= 1);
1725         fpip->fp_next = ufp->uf_fpollinfo;
1726         ufp->uf_fpollinfo = fpip;
1727         UF_EXIT(ufp);
1728 }
1729 
1730 /*
1731  * Delete curthread from fpollinfo list if it is there.
1732  */
1733 void
1734 delfpollinfo(int fd)
1735 {
1736         struct uf_entry *ufp;
1737         struct fpollinfo *fpip;
1738         struct fpollinfo **fpipp;
1739         uf_info_t *fip = P_FINFO(curproc);
1740 
1741         UF_ENTER(ufp, fip, fd);
1742         for (fpipp = &ufp->uf_fpollinfo;
1743             (fpip = *fpipp) != NULL;
1744             fpipp = &fpip->fp_next) {
1745                 if (fpip->fp_thread == curthread) {
1746                         *fpipp = fpip->fp_next;
1747                         kmem_free(fpip, sizeof (fpollinfo_t));
1748                         break;
1749                 }
1750         }
1751         /*
1752          * Assert that we are not still on the list, that is, that
1753          * this lwp did not call addfpollinfo twice for the same fd.
1754          */
1755         ASSERT(!curthread_in_plist(ufp));
1756         UF_EXIT(ufp);
1757 }
1758 
1759 /*
1760  * fd is associated with a port. pfd is a pointer to the fd entry in the
1761  * cache of the port.
1762  */
1763 
1764 void
1765 addfd_port(int fd, portfd_t *pfd)
1766 {
1767         struct uf_entry *ufp;
1768         uf_info_t *fip = P_FINFO(curproc);
1769 
1770         UF_ENTER(ufp, fip, fd);
1771         /*
1772          * addfd_port is always done inside the getf/releasef pair.
1773          */
1774         ASSERT(ufp->uf_refcnt >= 1);
1775         if (ufp->uf_portfd == NULL) {
1776                 /* first entry */
1777                 ufp->uf_portfd = pfd;
1778                 pfd->pfd_next = NULL;
1779         } else {
1780                 pfd->pfd_next = ufp->uf_portfd;
1781                 ufp->uf_portfd = pfd;
1782                 pfd->pfd_next->pfd_prev = pfd;
1783         }
1784         UF_EXIT(ufp);
1785 }
1786 
1787 void
1788 delfd_port(int fd, portfd_t *pfd)
1789 {
1790         struct uf_entry *ufp;
1791         uf_info_t *fip = P_FINFO(curproc);
1792 
1793         UF_ENTER(ufp, fip, fd);
1794         /*
1795          * delfd_port is always done inside the getf/releasef pair.
1796          */
1797         ASSERT(ufp->uf_refcnt >= 1);
1798         if (ufp->uf_portfd == pfd) {
1799                 /* remove first entry */
1800                 ufp->uf_portfd = pfd->pfd_next;
1801         } else {
1802                 pfd->pfd_prev->pfd_next = pfd->pfd_next;
1803                 if (pfd->pfd_next != NULL)
1804                         pfd->pfd_next->pfd_prev = pfd->pfd_prev;
1805         }
1806         UF_EXIT(ufp);
1807 }
1808 
1809 static void
1810 port_close_fd(portfd_t *pfd)
1811 {
1812         portfd_t        *pfdn;
1813 
1814         /*
1815          * At this point, no other thread should access
1816          * the portfd_t list for this fd. The uf_file, uf_portfd
1817          * pointers in the uf_entry_t struct for this fd would
1818          * be set to NULL.
1819          */
1820         for (; pfd != NULL; pfd = pfdn) {
1821                 pfdn = pfd->pfd_next;
1822                 port_close_pfd(pfd);
1823         }
1824 }