The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_descrip.c

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    1 /*
    2  * Copyright (c) 1982, 1986, 1989, 1991, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  * (c) UNIX System Laboratories, Inc.
    5  * All or some portions of this file are derived from material licensed
    6  * to the University of California by American Telephone and Telegraph
    7  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
    8  * the permission of UNIX System Laboratories, Inc.
    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  * 4. 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  *      @(#)kern_descrip.c      8.6 (Berkeley) 4/19/94
   35  */
   36 
   37 #include <sys/cdefs.h>
   38 __FBSDID("$FreeBSD: releng/5.3/sys/kern/kern_descrip.c 136738 2004-10-21 09:30:48Z rwatson $");
   39 
   40 #include "opt_compat.h"
   41 
   42 #include <sys/param.h>
   43 #include <sys/limits.h>
   44 #include <sys/systm.h>
   45 #include <sys/syscallsubr.h>
   46 #include <sys/sysproto.h>
   47 #include <sys/conf.h>
   48 #include <sys/filedesc.h>
   49 #include <sys/lock.h>
   50 #include <sys/jail.h>
   51 #include <sys/kernel.h>
   52 #include <sys/limits.h>
   53 #include <sys/malloc.h>
   54 #include <sys/mutex.h>
   55 #include <sys/sysctl.h>
   56 #include <sys/vnode.h>
   57 #include <sys/mount.h>
   58 #include <sys/proc.h>
   59 #include <sys/namei.h>
   60 #include <sys/file.h>
   61 #include <sys/stat.h>
   62 #include <sys/filio.h>
   63 #include <sys/fcntl.h>
   64 #include <sys/unistd.h>
   65 #include <sys/resourcevar.h>
   66 #include <sys/event.h>
   67 #include <sys/sx.h>
   68 #include <sys/socketvar.h>
   69 #include <sys/signalvar.h>
   70 
   71 #include <vm/vm.h>
   72 #include <vm/vm_extern.h>
   73 #include <vm/uma.h>
   74 
   75 static MALLOC_DEFINE(M_FILEDESC, "file desc", "Open file descriptor table");
   76 static MALLOC_DEFINE(M_FILEDESC_TO_LEADER, "file desc to leader",
   77                      "file desc to leader structures");
   78 static MALLOC_DEFINE(M_SIGIO, "sigio", "sigio structures");
   79 
   80 static uma_zone_t file_zone;
   81 
   82 static   d_open_t  fdopen;
   83 #define NUMFDESC 64
   84 
   85 #define CDEV_MAJOR 22
   86 static struct cdevsw fildesc_cdevsw = {
   87         .d_version =    D_VERSION,
   88         .d_flags =      D_NEEDGIANT,
   89         .d_open =       fdopen,
   90         .d_name =       "FD",
   91         .d_maj =        CDEV_MAJOR,
   92 };
   93 
   94 /* How to treat 'new' parameter when allocating a fd for do_dup(). */
   95 enum dup_type { DUP_VARIABLE, DUP_FIXED };
   96 
   97 static int do_dup(struct thread *td, enum dup_type type, int old, int new,
   98     register_t *retval);
   99 static int      fd_first_free(struct filedesc *, int, int);
  100 static int      fd_last_used(struct filedesc *, int, int);
  101 static void     fdgrowtable(struct filedesc *, int);
  102 
  103 /*
  104  * Descriptor management.
  105  */
  106 struct filelist filehead;       /* head of list of open files */
  107 int nfiles;                     /* actual number of open files */
  108 struct sx filelist_lock;        /* sx to protect filelist */
  109 struct mtx sigio_lock;          /* mtx to protect pointers to sigio */
  110 
  111 /*
  112  * Find the first zero bit in the given bitmap, starting at low and not
  113  * exceeding size - 1.
  114  */
  115 static int
  116 fd_first_free(struct filedesc *fdp, int low, int size)
  117 {
  118         NDSLOTTYPE *map = fdp->fd_map;
  119         NDSLOTTYPE mask;
  120         int off, maxoff;
  121 
  122         if (low >= size)
  123                 return (low);
  124 
  125         off = NDSLOT(low);
  126         if (low % NDENTRIES) {
  127                 mask = ~(~(NDSLOTTYPE)0 >> (NDENTRIES - (low % NDENTRIES)));
  128                 if ((mask &= ~map[off]) != 0UL)
  129                         return (off * NDENTRIES + ffsl(mask) - 1);
  130                 ++off;
  131         }
  132         for (maxoff = NDSLOTS(size); off < maxoff; ++off)
  133                 if (map[off] != ~0UL)
  134                         return (off * NDENTRIES + ffsl(~map[off]) - 1);
  135         return (size);
  136 }
  137 
  138 /*
  139  * Find the highest non-zero bit in the given bitmap, starting at low and
  140  * not exceeding size - 1.
  141  */
  142 static int
  143 fd_last_used(struct filedesc *fdp, int low, int size)
  144 {
  145         NDSLOTTYPE *map = fdp->fd_map;
  146         NDSLOTTYPE mask;
  147         int off, minoff;
  148 
  149         if (low >= size)
  150                 return (-1);
  151 
  152         off = NDSLOT(size);
  153         if (size % NDENTRIES) {
  154                 mask = ~(~(NDSLOTTYPE)0 << (size % NDENTRIES));
  155                 if ((mask &= map[off]) != 0)
  156                         return (off * NDENTRIES + flsl(mask) - 1);
  157                 --off;
  158         }
  159         for (minoff = NDSLOT(low); off >= minoff; --off)
  160                 if (map[off] != 0)
  161                         return (off * NDENTRIES + flsl(map[off]) - 1);
  162         return (size - 1);
  163 }
  164 
  165 static int
  166 fdisused(struct filedesc *fdp, int fd)
  167 {
  168         KASSERT(fd >= 0 && fd < fdp->fd_nfiles,
  169             ("file descriptor %d out of range (0, %d)", fd, fdp->fd_nfiles));
  170         return ((fdp->fd_map[NDSLOT(fd)] & NDBIT(fd)) != 0);
  171 }
  172 
  173 /*
  174  * Mark a file descriptor as used.
  175  */
  176 void
  177 fdused(struct filedesc *fdp, int fd)
  178 {
  179         FILEDESC_LOCK_ASSERT(fdp, MA_OWNED);
  180         KASSERT(!fdisused(fdp, fd),
  181             ("fd already used"));
  182         fdp->fd_map[NDSLOT(fd)] |= NDBIT(fd);
  183         if (fd > fdp->fd_lastfile)
  184                 fdp->fd_lastfile = fd;
  185         if (fd == fdp->fd_freefile)
  186                 fdp->fd_freefile = fd_first_free(fdp, fd, fdp->fd_nfiles);
  187 }
  188 
  189 /*
  190  * Mark a file descriptor as unused.
  191  */
  192 void
  193 fdunused(struct filedesc *fdp, int fd)
  194 {
  195         FILEDESC_LOCK_ASSERT(fdp, MA_OWNED);
  196         KASSERT(fdisused(fdp, fd),
  197             ("fd is already unused"));
  198         KASSERT(fdp->fd_ofiles[fd] == NULL,
  199             ("fd is still in use"));
  200         fdp->fd_map[NDSLOT(fd)] &= ~NDBIT(fd);
  201         if (fd < fdp->fd_freefile)
  202                 fdp->fd_freefile = fd;
  203         if (fd == fdp->fd_lastfile)
  204                 fdp->fd_lastfile = fd_last_used(fdp, 0, fd);
  205 }
  206 
  207 /*
  208  * System calls on descriptors.
  209  */
  210 #ifndef _SYS_SYSPROTO_H_
  211 struct getdtablesize_args {
  212         int     dummy;
  213 };
  214 #endif
  215 /*
  216  * MPSAFE
  217  */
  218 /* ARGSUSED */
  219 int
  220 getdtablesize(td, uap)
  221         struct thread *td;
  222         struct getdtablesize_args *uap;
  223 {
  224         struct proc *p = td->td_proc;
  225 
  226         PROC_LOCK(p);
  227         td->td_retval[0] =
  228             min((int)lim_cur(p, RLIMIT_NOFILE), maxfilesperproc);
  229         PROC_UNLOCK(p);
  230         return (0);
  231 }
  232 
  233 /*
  234  * Duplicate a file descriptor to a particular value.
  235  *
  236  * note: keep in mind that a potential race condition exists when closing
  237  * descriptors from a shared descriptor table (via rfork).
  238  */
  239 #ifndef _SYS_SYSPROTO_H_
  240 struct dup2_args {
  241         u_int   from;
  242         u_int   to;
  243 };
  244 #endif
  245 /*
  246  * MPSAFE
  247  */
  248 /* ARGSUSED */
  249 int
  250 dup2(td, uap)
  251         struct thread *td;
  252         struct dup2_args *uap;
  253 {
  254 
  255         return (do_dup(td, DUP_FIXED, (int)uap->from, (int)uap->to,
  256                     td->td_retval));
  257 }
  258 
  259 /*
  260  * Duplicate a file descriptor.
  261  */
  262 #ifndef _SYS_SYSPROTO_H_
  263 struct dup_args {
  264         u_int   fd;
  265 };
  266 #endif
  267 /*
  268  * MPSAFE
  269  */
  270 /* ARGSUSED */
  271 int
  272 dup(td, uap)
  273         struct thread *td;
  274         struct dup_args *uap;
  275 {
  276 
  277         return (do_dup(td, DUP_VARIABLE, (int)uap->fd, 0, td->td_retval));
  278 }
  279 
  280 /*
  281  * The file control system call.
  282  */
  283 #ifndef _SYS_SYSPROTO_H_
  284 struct fcntl_args {
  285         int     fd;
  286         int     cmd;
  287         long    arg;
  288 };
  289 #endif
  290 /*
  291  * MPSAFE
  292  */
  293 /* ARGSUSED */
  294 int
  295 fcntl(td, uap)
  296         struct thread *td;
  297         struct fcntl_args *uap;
  298 {
  299         struct flock fl;
  300         intptr_t arg;
  301         int error;
  302 
  303         error = 0;
  304         switch (uap->cmd) {
  305         case F_GETLK:
  306         case F_SETLK:
  307         case F_SETLKW:
  308                 error = copyin((void *)(intptr_t)uap->arg, &fl, sizeof(fl));
  309                 arg = (intptr_t)&fl;
  310                 break;
  311         default:
  312                 arg = uap->arg;
  313                 break;
  314         }
  315         if (error)
  316                 return (error);
  317         error = kern_fcntl(td, uap->fd, uap->cmd, arg);
  318         if (error)
  319                 return (error);
  320         if (uap->cmd == F_GETLK)
  321                 error = copyout(&fl, (void *)(intptr_t)uap->arg, sizeof(fl));
  322         return (error);
  323 }
  324 
  325 int
  326 kern_fcntl(struct thread *td, int fd, int cmd, intptr_t arg)
  327 {
  328         struct filedesc *fdp;
  329         struct flock *flp;
  330         struct file *fp;
  331         struct proc *p;
  332         char *pop;
  333         struct vnode *vp;
  334         u_int newmin;
  335         int error, flg, tmp;
  336         int giant_locked;
  337 
  338         /*
  339          * XXXRW: Some fcntl() calls require Giant -- others don't.  Try to
  340          * avoid grabbing Giant for calls we know don't need it.
  341          */
  342         switch (cmd) {
  343         case F_DUPFD:
  344         case F_GETFD:
  345         case F_SETFD:
  346         case F_GETFL:
  347                 giant_locked = 0;
  348                 break;
  349 
  350         default:
  351                 giant_locked = 1;
  352                 mtx_lock(&Giant);
  353         }
  354 
  355         error = 0;
  356         flg = F_POSIX;
  357         p = td->td_proc;
  358         fdp = p->p_fd;
  359         FILEDESC_LOCK(fdp);
  360         if ((unsigned)fd >= fdp->fd_nfiles ||
  361             (fp = fdp->fd_ofiles[fd]) == NULL) {
  362                 FILEDESC_UNLOCK(fdp);
  363                 error = EBADF;
  364                 goto done2;
  365         }
  366         pop = &fdp->fd_ofileflags[fd];
  367 
  368         switch (cmd) {
  369         case F_DUPFD:
  370                 /* mtx_assert(&Giant, MA_NOTOWNED); */
  371                 FILEDESC_UNLOCK(fdp);
  372                 newmin = arg;
  373                 PROC_LOCK(p);
  374                 if (newmin >= lim_cur(p, RLIMIT_NOFILE) ||
  375                     newmin >= maxfilesperproc) {
  376                         PROC_UNLOCK(p);
  377                         error = EINVAL;
  378                         break;
  379                 }
  380                 PROC_UNLOCK(p);
  381                 error = do_dup(td, DUP_VARIABLE, fd, newmin, td->td_retval);
  382                 break;
  383 
  384         case F_GETFD:
  385                 /* mtx_assert(&Giant, MA_NOTOWNED); */
  386                 td->td_retval[0] = (*pop & UF_EXCLOSE) ? FD_CLOEXEC : 0;
  387                 FILEDESC_UNLOCK(fdp);
  388                 break;
  389 
  390         case F_SETFD:
  391                 /* mtx_assert(&Giant, MA_NOTOWNED); */
  392                 *pop = (*pop &~ UF_EXCLOSE) |
  393                     (arg & FD_CLOEXEC ? UF_EXCLOSE : 0);
  394                 FILEDESC_UNLOCK(fdp);
  395                 break;
  396 
  397         case F_GETFL:
  398                 /* mtx_assert(&Giant, MA_NOTOWNED); */
  399                 FILE_LOCK(fp);
  400                 FILEDESC_UNLOCK(fdp);
  401                 td->td_retval[0] = OFLAGS(fp->f_flag);
  402                 FILE_UNLOCK(fp);
  403                 break;
  404 
  405         case F_SETFL:
  406                 mtx_assert(&Giant, MA_OWNED);
  407                 FILE_LOCK(fp);
  408                 FILEDESC_UNLOCK(fdp);
  409                 fhold_locked(fp);
  410                 fp->f_flag &= ~FCNTLFLAGS;
  411                 fp->f_flag |= FFLAGS(arg & ~O_ACCMODE) & FCNTLFLAGS;
  412                 FILE_UNLOCK(fp);
  413                 tmp = fp->f_flag & FNONBLOCK;
  414                 error = fo_ioctl(fp, FIONBIO, &tmp, td->td_ucred, td);
  415                 if (error) {
  416                         fdrop(fp, td);
  417                         break;
  418                 }
  419                 tmp = fp->f_flag & FASYNC;
  420                 error = fo_ioctl(fp, FIOASYNC, &tmp, td->td_ucred, td);
  421                 if (error == 0) {
  422                         fdrop(fp, td);
  423                         break;
  424                 }
  425                 FILE_LOCK(fp);
  426                 fp->f_flag &= ~FNONBLOCK;
  427                 FILE_UNLOCK(fp);
  428                 tmp = 0;
  429                 (void)fo_ioctl(fp, FIONBIO, &tmp, td->td_ucred, td);
  430                 fdrop(fp, td);
  431                 break;
  432 
  433         case F_GETOWN:
  434                 mtx_assert(&Giant, MA_OWNED);
  435                 fhold(fp);
  436                 FILEDESC_UNLOCK(fdp);
  437                 error = fo_ioctl(fp, FIOGETOWN, &tmp, td->td_ucred, td);
  438                 if (error == 0)
  439                         td->td_retval[0] = tmp;
  440                 fdrop(fp, td);
  441                 break;
  442 
  443         case F_SETOWN:
  444                 mtx_assert(&Giant, MA_OWNED);
  445                 fhold(fp);
  446                 FILEDESC_UNLOCK(fdp);
  447                 tmp = arg;
  448                 error = fo_ioctl(fp, FIOSETOWN, &tmp, td->td_ucred, td);
  449                 fdrop(fp, td);
  450                 break;
  451 
  452         case F_SETLKW:
  453                 mtx_assert(&Giant, MA_OWNED);
  454                 flg |= F_WAIT;
  455                 /* FALLTHROUGH F_SETLK */
  456 
  457         case F_SETLK:
  458                 mtx_assert(&Giant, MA_OWNED);
  459                 if (fp->f_type != DTYPE_VNODE) {
  460                         FILEDESC_UNLOCK(fdp);
  461                         error = EBADF;
  462                         break;
  463                 }
  464 
  465                 flp = (struct flock *)arg;
  466                 if (flp->l_whence == SEEK_CUR) {
  467                         if (fp->f_offset < 0 ||
  468                             (flp->l_start > 0 &&
  469                              fp->f_offset > OFF_MAX - flp->l_start)) {
  470                                 FILEDESC_UNLOCK(fdp);
  471                                 error = EOVERFLOW;
  472                                 break;
  473                         }
  474                         flp->l_start += fp->f_offset;
  475                 }
  476 
  477                 /*
  478                  * VOP_ADVLOCK() may block.
  479                  */
  480                 fhold(fp);
  481                 FILEDESC_UNLOCK(fdp);
  482                 vp = fp->f_vnode;
  483 
  484                 switch (flp->l_type) {
  485                 case F_RDLCK:
  486                         if ((fp->f_flag & FREAD) == 0) {
  487                                 error = EBADF;
  488                                 break;
  489                         }
  490                         PROC_LOCK(p->p_leader);
  491                         p->p_leader->p_flag |= P_ADVLOCK;
  492                         PROC_UNLOCK(p->p_leader);
  493                         error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK,
  494                             flp, flg);
  495                         break;
  496                 case F_WRLCK:
  497                         if ((fp->f_flag & FWRITE) == 0) {
  498                                 error = EBADF;
  499                                 break;
  500                         }
  501                         PROC_LOCK(p->p_leader);
  502                         p->p_leader->p_flag |= P_ADVLOCK;
  503                         PROC_UNLOCK(p->p_leader);
  504                         error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK,
  505                             flp, flg);
  506                         break;
  507                 case F_UNLCK:
  508                         error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK,
  509                             flp, F_POSIX);
  510                         break;
  511                 default:
  512                         error = EINVAL;
  513                         break;
  514                 }
  515                 /* Check for race with close */
  516                 FILEDESC_LOCK(fdp);
  517                 if ((unsigned) fd >= fdp->fd_nfiles ||
  518                     fp != fdp->fd_ofiles[fd]) {
  519                         FILEDESC_UNLOCK(fdp);
  520                         flp->l_whence = SEEK_SET;
  521                         flp->l_start = 0;
  522                         flp->l_len = 0;
  523                         flp->l_type = F_UNLCK;
  524                         (void) VOP_ADVLOCK(vp, (caddr_t)p->p_leader,
  525                                            F_UNLCK, flp, F_POSIX);
  526                 } else
  527                         FILEDESC_UNLOCK(fdp);
  528                 fdrop(fp, td);
  529                 break;
  530 
  531         case F_GETLK:
  532                 mtx_assert(&Giant, MA_OWNED);
  533                 if (fp->f_type != DTYPE_VNODE) {
  534                         FILEDESC_UNLOCK(fdp);
  535                         error = EBADF;
  536                         break;
  537                 }
  538                 flp = (struct flock *)arg;
  539                 if (flp->l_type != F_RDLCK && flp->l_type != F_WRLCK &&
  540                     flp->l_type != F_UNLCK) {
  541                         FILEDESC_UNLOCK(fdp);
  542                         error = EINVAL;
  543                         break;
  544                 }
  545                 if (flp->l_whence == SEEK_CUR) {
  546                         if ((flp->l_start > 0 &&
  547                             fp->f_offset > OFF_MAX - flp->l_start) ||
  548                             (flp->l_start < 0 &&
  549                              fp->f_offset < OFF_MIN - flp->l_start)) {
  550                                 FILEDESC_UNLOCK(fdp);
  551                                 error = EOVERFLOW;
  552                                 break;
  553                         }
  554                         flp->l_start += fp->f_offset;
  555                 }
  556                 /*
  557                  * VOP_ADVLOCK() may block.
  558                  */
  559                 fhold(fp);
  560                 FILEDESC_UNLOCK(fdp);
  561                 vp = fp->f_vnode;
  562                 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_GETLK, flp,
  563                     F_POSIX);
  564                 fdrop(fp, td);
  565                 break;
  566         default:
  567                 FILEDESC_UNLOCK(fdp);
  568                 error = EINVAL;
  569                 break;
  570         }
  571 done2:
  572         if (giant_locked)
  573                 mtx_unlock(&Giant);
  574         return (error);
  575 }
  576 
  577 /*
  578  * Common code for dup, dup2, and fcntl(F_DUPFD).
  579  */
  580 static int
  581 do_dup(td, type, old, new, retval)
  582         enum dup_type type;
  583         int old, new;
  584         register_t *retval;
  585         struct thread *td;
  586 {
  587         struct filedesc *fdp;
  588         struct proc *p;
  589         struct file *fp;
  590         struct file *delfp;
  591         int error, holdleaders, maxfd;
  592 
  593         KASSERT((type == DUP_VARIABLE || type == DUP_FIXED),
  594             ("invalid dup type %d", type));
  595 
  596         p = td->td_proc;
  597         fdp = p->p_fd;
  598 
  599         /*
  600          * Verify we have a valid descriptor to dup from and possibly to
  601          * dup to.
  602          */
  603         if (old < 0 || new < 0)
  604                 return (EBADF);
  605         PROC_LOCK(p);
  606         maxfd = min((int)lim_cur(p, RLIMIT_NOFILE), maxfilesperproc);
  607         PROC_UNLOCK(p);
  608         if (new >= maxfd)
  609                 return (EMFILE);
  610 
  611         FILEDESC_LOCK(fdp);
  612         if (old >= fdp->fd_nfiles || fdp->fd_ofiles[old] == NULL) {
  613                 FILEDESC_UNLOCK(fdp);
  614                 return (EBADF);
  615         }
  616         if (type == DUP_FIXED && old == new) {
  617                 *retval = new;
  618                 FILEDESC_UNLOCK(fdp);
  619                 return (0);
  620         }
  621         fp = fdp->fd_ofiles[old];
  622         fhold(fp);
  623 
  624         /*
  625          * If the caller specified a file descriptor, make sure the file
  626          * table is large enough to hold it, and grab it.  Otherwise, just
  627          * allocate a new descriptor the usual way.  Since the filedesc
  628          * lock may be temporarily dropped in the process, we have to look
  629          * out for a race.
  630          */
  631         if (type == DUP_FIXED) {
  632                 if (new >= fdp->fd_nfiles)
  633                         fdgrowtable(fdp, new + 1);
  634                 if (fdp->fd_ofiles[new] == NULL)
  635                         fdused(fdp, new);
  636         } else {
  637                 if ((error = fdalloc(td, new, &new)) != 0) {
  638                         FILEDESC_UNLOCK(fdp);
  639                         fdrop(fp, td);
  640                         return (error);
  641                 }
  642         }
  643 
  644         /*
  645          * If the old file changed out from under us then treat it as a
  646          * bad file descriptor.  Userland should do its own locking to
  647          * avoid this case.
  648          */
  649         if (fdp->fd_ofiles[old] != fp) {
  650                 /* we've allocated a descriptor which we won't use */
  651                 if (fdp->fd_ofiles[new] == NULL)
  652                         fdunused(fdp, new);
  653                 FILEDESC_UNLOCK(fdp);
  654                 fdrop(fp, td);
  655                 return (EBADF);
  656         }
  657         KASSERT(old != new,
  658             ("new fd is same as old"));
  659 
  660         /*
  661          * Save info on the descriptor being overwritten.  We cannot close
  662          * it without introducing an ownership race for the slot, since we
  663          * need to drop the filedesc lock to call closef().
  664          *
  665          * XXX this duplicates parts of close().
  666          */
  667         delfp = fdp->fd_ofiles[new];
  668         holdleaders = 0;
  669         if (delfp != NULL) {
  670                 if (td->td_proc->p_fdtol != NULL) {
  671                         /*
  672                          * Ask fdfree() to sleep to ensure that all relevant
  673                          * process leaders can be traversed in closef().
  674                          */
  675                         fdp->fd_holdleaderscount++;
  676                         holdleaders = 1;
  677                 }
  678         }
  679 
  680         /*
  681          * Duplicate the source descriptor
  682          */
  683         fdp->fd_ofiles[new] = fp;
  684         fdp->fd_ofileflags[new] = fdp->fd_ofileflags[old] &~ UF_EXCLOSE;
  685         if (new > fdp->fd_lastfile)
  686                 fdp->fd_lastfile = new;
  687         *retval = new;
  688 
  689         /*
  690          * If we dup'd over a valid file, we now own the reference to it
  691          * and must dispose of it using closef() semantics (as if a
  692          * close() were performed on it).
  693          *
  694          * XXX this duplicates parts of close().
  695          */
  696         if (delfp != NULL) {
  697                 knote_fdclose(td, new);
  698                 FILEDESC_UNLOCK(fdp);
  699                 mtx_lock(&Giant);
  700                 (void) closef(delfp, td);
  701                 mtx_unlock(&Giant);
  702                 if (holdleaders) {
  703                         FILEDESC_LOCK(fdp);
  704                         fdp->fd_holdleaderscount--;
  705                         if (fdp->fd_holdleaderscount == 0 &&
  706                             fdp->fd_holdleaderswakeup != 0) {
  707                                 fdp->fd_holdleaderswakeup = 0;
  708                                 wakeup(&fdp->fd_holdleaderscount);
  709                         }
  710                         FILEDESC_UNLOCK(fdp);
  711                 }
  712         } else {
  713                 FILEDESC_UNLOCK(fdp);
  714         }
  715         return (0);
  716 }
  717 
  718 /*
  719  * If sigio is on the list associated with a process or process group,
  720  * disable signalling from the device, remove sigio from the list and
  721  * free sigio.
  722  */
  723 void
  724 funsetown(sigiop)
  725         struct sigio **sigiop;
  726 {
  727         struct sigio *sigio;
  728 
  729         SIGIO_LOCK();
  730         sigio = *sigiop;
  731         if (sigio == NULL) {
  732                 SIGIO_UNLOCK();
  733                 return;
  734         }
  735         *(sigio->sio_myref) = NULL;
  736         if ((sigio)->sio_pgid < 0) {
  737                 struct pgrp *pg = (sigio)->sio_pgrp;
  738                 PGRP_LOCK(pg);
  739                 SLIST_REMOVE(&sigio->sio_pgrp->pg_sigiolst, sigio,
  740                              sigio, sio_pgsigio);
  741                 PGRP_UNLOCK(pg);
  742         } else {
  743                 struct proc *p = (sigio)->sio_proc;
  744                 PROC_LOCK(p);
  745                 SLIST_REMOVE(&sigio->sio_proc->p_sigiolst, sigio,
  746                              sigio, sio_pgsigio);
  747                 PROC_UNLOCK(p);
  748         }
  749         SIGIO_UNLOCK();
  750         crfree(sigio->sio_ucred);
  751         FREE(sigio, M_SIGIO);
  752 }
  753 
  754 /*
  755  * Free a list of sigio structures.
  756  * We only need to lock the SIGIO_LOCK because we have made ourselves
  757  * inaccessable to callers of fsetown and therefore do not need to lock
  758  * the proc or pgrp struct for the list manipulation.
  759  */
  760 void
  761 funsetownlst(sigiolst)
  762         struct sigiolst *sigiolst;
  763 {
  764         struct proc *p;
  765         struct pgrp *pg;
  766         struct sigio *sigio;
  767 
  768         sigio = SLIST_FIRST(sigiolst);
  769         if (sigio == NULL)
  770                 return;
  771         p = NULL;
  772         pg = NULL;
  773 
  774         /*
  775          * Every entry of the list should belong
  776          * to a single proc or pgrp.
  777          */
  778         if (sigio->sio_pgid < 0) {
  779                 pg = sigio->sio_pgrp;
  780                 PGRP_LOCK_ASSERT(pg, MA_NOTOWNED);
  781         } else /* if (sigio->sio_pgid > 0) */ {
  782                 p = sigio->sio_proc;
  783                 PROC_LOCK_ASSERT(p, MA_NOTOWNED);
  784         }
  785 
  786         SIGIO_LOCK();
  787         while ((sigio = SLIST_FIRST(sigiolst)) != NULL) {
  788                 *(sigio->sio_myref) = NULL;
  789                 if (pg != NULL) {
  790                         KASSERT(sigio->sio_pgid < 0,
  791                             ("Proc sigio in pgrp sigio list"));
  792                         KASSERT(sigio->sio_pgrp == pg,
  793                             ("Bogus pgrp in sigio list"));
  794                         PGRP_LOCK(pg);
  795                         SLIST_REMOVE(&pg->pg_sigiolst, sigio, sigio,
  796                             sio_pgsigio);
  797                         PGRP_UNLOCK(pg);
  798                 } else /* if (p != NULL) */ {
  799                         KASSERT(sigio->sio_pgid > 0,
  800                             ("Pgrp sigio in proc sigio list"));
  801                         KASSERT(sigio->sio_proc == p,
  802                             ("Bogus proc in sigio list"));
  803                         PROC_LOCK(p);
  804                         SLIST_REMOVE(&p->p_sigiolst, sigio, sigio,
  805                             sio_pgsigio);
  806                         PROC_UNLOCK(p);
  807                 }
  808                 SIGIO_UNLOCK();
  809                 crfree(sigio->sio_ucred);
  810                 FREE(sigio, M_SIGIO);
  811                 SIGIO_LOCK();
  812         }
  813         SIGIO_UNLOCK();
  814 }
  815 
  816 /*
  817  * This is common code for FIOSETOWN ioctl called by fcntl(fd, F_SETOWN, arg).
  818  *
  819  * After permission checking, add a sigio structure to the sigio list for
  820  * the process or process group.
  821  */
  822 int
  823 fsetown(pgid, sigiop)
  824         pid_t pgid;
  825         struct sigio **sigiop;
  826 {
  827         struct proc *proc;
  828         struct pgrp *pgrp;
  829         struct sigio *sigio;
  830         int ret;
  831 
  832         if (pgid == 0) {
  833                 funsetown(sigiop);
  834                 return (0);
  835         }
  836 
  837         ret = 0;
  838 
  839         /* Allocate and fill in the new sigio out of locks. */
  840         MALLOC(sigio, struct sigio *, sizeof(struct sigio), M_SIGIO, M_WAITOK);
  841         sigio->sio_pgid = pgid;
  842         sigio->sio_ucred = crhold(curthread->td_ucred);
  843         sigio->sio_myref = sigiop;
  844 
  845         sx_slock(&proctree_lock);
  846         if (pgid > 0) {
  847                 proc = pfind(pgid);
  848                 if (proc == NULL) {
  849                         ret = ESRCH;
  850                         goto fail;
  851                 }
  852 
  853                 /*
  854                  * Policy - Don't allow a process to FSETOWN a process
  855                  * in another session.
  856                  *
  857                  * Remove this test to allow maximum flexibility or
  858                  * restrict FSETOWN to the current process or process
  859                  * group for maximum safety.
  860                  */
  861                 PROC_UNLOCK(proc);
  862                 if (proc->p_session != curthread->td_proc->p_session) {
  863                         ret = EPERM;
  864                         goto fail;
  865                 }
  866 
  867                 pgrp = NULL;
  868         } else /* if (pgid < 0) */ {
  869                 pgrp = pgfind(-pgid);
  870                 if (pgrp == NULL) {
  871                         ret = ESRCH;
  872                         goto fail;
  873                 }
  874                 PGRP_UNLOCK(pgrp);
  875 
  876                 /*
  877                  * Policy - Don't allow a process to FSETOWN a process
  878                  * in another session.
  879                  *
  880                  * Remove this test to allow maximum flexibility or
  881                  * restrict FSETOWN to the current process or process
  882                  * group for maximum safety.
  883                  */
  884                 if (pgrp->pg_session != curthread->td_proc->p_session) {
  885                         ret = EPERM;
  886                         goto fail;
  887                 }
  888 
  889                 proc = NULL;
  890         }
  891         funsetown(sigiop);
  892         if (pgid > 0) {
  893                 PROC_LOCK(proc);
  894                 /*
  895                  * Since funsetownlst() is called without the proctree
  896                  * locked, we need to check for P_WEXIT.
  897                  * XXX: is ESRCH correct?
  898                  */
  899                 if ((proc->p_flag & P_WEXIT) != 0) {
  900                         PROC_UNLOCK(proc);
  901                         ret = ESRCH;
  902                         goto fail;
  903                 }
  904                 SLIST_INSERT_HEAD(&proc->p_sigiolst, sigio, sio_pgsigio);
  905                 sigio->sio_proc = proc;
  906                 PROC_UNLOCK(proc);
  907         } else {
  908                 PGRP_LOCK(pgrp);
  909                 SLIST_INSERT_HEAD(&pgrp->pg_sigiolst, sigio, sio_pgsigio);
  910                 sigio->sio_pgrp = pgrp;
  911                 PGRP_UNLOCK(pgrp);
  912         }
  913         sx_sunlock(&proctree_lock);
  914         SIGIO_LOCK();
  915         *sigiop = sigio;
  916         SIGIO_UNLOCK();
  917         return (0);
  918 
  919 fail:
  920         sx_sunlock(&proctree_lock);
  921         crfree(sigio->sio_ucred);
  922         FREE(sigio, M_SIGIO);
  923         return (ret);
  924 }
  925 
  926 /*
  927  * This is common code for FIOGETOWN ioctl called by fcntl(fd, F_GETOWN, arg).
  928  */
  929 pid_t
  930 fgetown(sigiop)
  931         struct sigio **sigiop;
  932 {
  933         pid_t pgid;
  934 
  935         SIGIO_LOCK();
  936         pgid = (*sigiop != NULL) ? (*sigiop)->sio_pgid : 0;
  937         SIGIO_UNLOCK();
  938         return (pgid);
  939 }
  940 
  941 /*
  942  * Close a file descriptor.
  943  */
  944 #ifndef _SYS_SYSPROTO_H_
  945 struct close_args {
  946         int     fd;
  947 };
  948 #endif
  949 /*
  950  * MPSAFE
  951  */
  952 /* ARGSUSED */
  953 int
  954 close(td, uap)
  955         struct thread *td;
  956         struct close_args *uap;
  957 {
  958         struct filedesc *fdp;
  959         struct file *fp;
  960         int fd, error;
  961         int holdleaders;
  962 
  963         fd = uap->fd;
  964         error = 0;
  965         holdleaders = 0;
  966         fdp = td->td_proc->p_fd;
  967         mtx_lock(&Giant);
  968         FILEDESC_LOCK(fdp);
  969         if ((unsigned)fd >= fdp->fd_nfiles ||
  970             (fp = fdp->fd_ofiles[fd]) == NULL) {
  971                 FILEDESC_UNLOCK(fdp);
  972                 mtx_unlock(&Giant);
  973                 return (EBADF);
  974         }
  975         fdp->fd_ofiles[fd] = NULL;
  976         fdp->fd_ofileflags[fd] = 0;
  977         fdunused(fdp, fd);
  978         if (td->td_proc->p_fdtol != NULL) {
  979                 /*
  980                  * Ask fdfree() to sleep to ensure that all relevant
  981                  * process leaders can be traversed in closef().
  982                  */
  983                 fdp->fd_holdleaderscount++;
  984                 holdleaders = 1;
  985         }
  986 
  987         /*
  988          * we now hold the fp reference that used to be owned by the descriptor
  989          * array.
  990          * We have to unlock the FILEDESC *AFTER* knote_fdclose to prevent a
  991          * race of the fd getting opened, a knote added, and deleteing a knote
  992          * for the new fd.
  993          */
  994         knote_fdclose(td, fd);
  995         FILEDESC_UNLOCK(fdp);
  996 
  997         error = closef(fp, td);
  998         mtx_unlock(&Giant);
  999         if (holdleaders) {
 1000                 FILEDESC_LOCK(fdp);
 1001                 fdp->fd_holdleaderscount--;
 1002                 if (fdp->fd_holdleaderscount == 0 &&
 1003                     fdp->fd_holdleaderswakeup != 0) {
 1004                         fdp->fd_holdleaderswakeup = 0;
 1005                         wakeup(&fdp->fd_holdleaderscount);
 1006                 }
 1007                 FILEDESC_UNLOCK(fdp);
 1008         }
 1009         return (error);
 1010 }
 1011 
 1012 #if defined(COMPAT_43)
 1013 /*
 1014  * Return status information about a file descriptor.
 1015  */
 1016 #ifndef _SYS_SYSPROTO_H_
 1017 struct ofstat_args {
 1018         int     fd;
 1019         struct  ostat *sb;
 1020 };
 1021 #endif
 1022 /*
 1023  * MPSAFE
 1024  */
 1025 /* ARGSUSED */
 1026 int
 1027 ofstat(td, uap)
 1028         struct thread *td;
 1029         struct ofstat_args *uap;
 1030 {
 1031         struct file *fp;
 1032         struct stat ub;
 1033         struct ostat oub;
 1034         int error;
 1035 
 1036         if ((error = fget(td, uap->fd, &fp)) != 0)
 1037                 goto done2;
 1038         error = fo_stat(fp, &ub, td->td_ucred, td);
 1039         if (error == 0) {
 1040                 cvtstat(&ub, &oub);
 1041                 error = copyout(&oub, uap->sb, sizeof(oub));
 1042         }
 1043         fdrop(fp, td);
 1044 done2:
 1045         return (error);
 1046 }
 1047 #endif /* COMPAT_43 */
 1048 
 1049 /*
 1050  * Return status information about a file descriptor.
 1051  */
 1052 #ifndef _SYS_SYSPROTO_H_
 1053 struct fstat_args {
 1054         int     fd;
 1055         struct  stat *sb;
 1056 };
 1057 #endif
 1058 /*
 1059  * MPSAFE
 1060  */
 1061 /* ARGSUSED */
 1062 int
 1063 fstat(td, uap)
 1064         struct thread *td;
 1065         struct fstat_args *uap;
 1066 {
 1067         struct file *fp;
 1068         struct stat ub;
 1069         int error;
 1070 
 1071         if ((error = fget(td, uap->fd, &fp)) != 0)
 1072                 goto done2;
 1073         error = fo_stat(fp, &ub, td->td_ucred, td);
 1074         if (error == 0)
 1075                 error = copyout(&ub, uap->sb, sizeof(ub));
 1076         fdrop(fp, td);
 1077 done2:
 1078         return (error);
 1079 }
 1080 
 1081 /*
 1082  * Return status information about a file descriptor.
 1083  */
 1084 #ifndef _SYS_SYSPROTO_H_
 1085 struct nfstat_args {
 1086         int     fd;
 1087         struct  nstat *sb;
 1088 };
 1089 #endif
 1090 /*
 1091  * MPSAFE
 1092  */
 1093 /* ARGSUSED */
 1094 int
 1095 nfstat(td, uap)
 1096         struct thread *td;
 1097         struct nfstat_args *uap;
 1098 {
 1099         struct file *fp;
 1100         struct stat ub;
 1101         struct nstat nub;
 1102         int error;
 1103 
 1104         if ((error = fget(td, uap->fd, &fp)) != 0)
 1105                 goto done2;
 1106         error = fo_stat(fp, &ub, td->td_ucred, td);
 1107         if (error == 0) {
 1108                 cvtnstat(&ub, &nub);
 1109                 error = copyout(&nub, uap->sb, sizeof(nub));
 1110         }
 1111         fdrop(fp, td);
 1112 done2:
 1113         return (error);
 1114 }
 1115 
 1116 /*
 1117  * Return pathconf information about a file descriptor.
 1118  */
 1119 #ifndef _SYS_SYSPROTO_H_
 1120 struct fpathconf_args {
 1121         int     fd;
 1122         int     name;
 1123 };
 1124 #endif
 1125 /*
 1126  * MPSAFE
 1127  */
 1128 /* ARGSUSED */
 1129 int
 1130 fpathconf(td, uap)
 1131         struct thread *td;
 1132         struct fpathconf_args *uap;
 1133 {
 1134         struct file *fp;
 1135         struct vnode *vp;
 1136         int error;
 1137 
 1138         if ((error = fget(td, uap->fd, &fp)) != 0)
 1139                 return (error);
 1140 
 1141         /* If asynchronous I/O is available, it works for all descriptors. */
 1142         if (uap->name == _PC_ASYNC_IO) {
 1143                 td->td_retval[0] = async_io_version;
 1144                 goto out;
 1145         }
 1146         vp = fp->f_vnode;
 1147         if (vp != NULL) {
 1148                 mtx_lock(&Giant);
 1149                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
 1150                 error = VOP_PATHCONF(vp, uap->name, td->td_retval);
 1151                 VOP_UNLOCK(vp, 0, td);
 1152                 mtx_unlock(&Giant);
 1153         } else if (fp->f_type == DTYPE_PIPE || fp->f_type == DTYPE_SOCKET) {
 1154                 if (uap->name != _PC_PIPE_BUF) {
 1155                         error = EINVAL;
 1156                 } else {
 1157                         td->td_retval[0] = PIPE_BUF;
 1158                 error = 0;
 1159                 }
 1160         } else {
 1161                 error = EOPNOTSUPP;
 1162         }
 1163 out:
 1164         fdrop(fp, td);
 1165         return (error);
 1166 }
 1167 
 1168 /*
 1169  * Grow the file table to accomodate (at least) nfd descriptors.  This may
 1170  * block and drop the filedesc lock, but it will reacquire it before
 1171  * returing.
 1172  */
 1173 static void
 1174 fdgrowtable(struct filedesc *fdp, int nfd)
 1175 {
 1176         struct file **ntable;
 1177         char *nfileflags;
 1178         int nnfiles, onfiles;
 1179         NDSLOTTYPE *nmap;
 1180 
 1181         FILEDESC_LOCK_ASSERT(fdp, MA_OWNED);
 1182 
 1183         KASSERT(fdp->fd_nfiles > 0,
 1184             ("zero-length file table"));
 1185 
 1186         /* compute the size of the new table */
 1187         onfiles = fdp->fd_nfiles;
 1188         nnfiles = NDSLOTS(nfd) * NDENTRIES; /* round up */
 1189         if (nnfiles <= onfiles)
 1190                 /* the table is already large enough */
 1191                 return;
 1192 
 1193         /* allocate a new table and (if required) new bitmaps */
 1194         FILEDESC_UNLOCK(fdp);
 1195         MALLOC(ntable, struct file **, nnfiles * OFILESIZE,
 1196             M_FILEDESC, M_ZERO | M_WAITOK);
 1197         nfileflags = (char *)&ntable[nnfiles];
 1198         if (NDSLOTS(nnfiles) > NDSLOTS(onfiles))
 1199                 MALLOC(nmap, NDSLOTTYPE *, NDSLOTS(nnfiles) * NDSLOTSIZE,
 1200                     M_FILEDESC, M_ZERO | M_WAITOK);
 1201         else
 1202                 nmap = NULL;
 1203         FILEDESC_LOCK(fdp);
 1204 
 1205         /*
 1206          * We now have new tables ready to go.  Since we dropped the
 1207          * filedesc lock to call malloc(), watch out for a race.
 1208          */
 1209         onfiles = fdp->fd_nfiles;
 1210         if (onfiles >= nnfiles) {
 1211                 /* we lost the race, but that's OK */
 1212                 free(ntable, M_FILEDESC);
 1213                 if (nmap != NULL)
 1214                         free(nmap, M_FILEDESC);
 1215                 return;
 1216         }
 1217         bcopy(fdp->fd_ofiles, ntable, onfiles * sizeof(*ntable));
 1218         bcopy(fdp->fd_ofileflags, nfileflags, onfiles);
 1219         if (onfiles > NDFILE)
 1220                 free(fdp->fd_ofiles, M_FILEDESC);
 1221         fdp->fd_ofiles = ntable;
 1222         fdp->fd_ofileflags = nfileflags;
 1223         if (NDSLOTS(nnfiles) > NDSLOTS(onfiles)) {
 1224                 bcopy(fdp->fd_map, nmap, NDSLOTS(onfiles) * sizeof(*nmap));
 1225                 if (NDSLOTS(onfiles) > NDSLOTS(NDFILE))
 1226                         free(fdp->fd_map, M_FILEDESC);
 1227                 fdp->fd_map = nmap;
 1228         }
 1229         fdp->fd_nfiles = nnfiles;
 1230 }
 1231 
 1232 /*
 1233  * Allocate a file descriptor for the process.
 1234  */
 1235 int
 1236 fdalloc(struct thread *td, int minfd, int *result)
 1237 {
 1238         struct proc *p = td->td_proc;
 1239         struct filedesc *fdp = p->p_fd;
 1240         int fd = -1, maxfd;
 1241 
 1242         FILEDESC_LOCK_ASSERT(fdp, MA_OWNED);
 1243 
 1244         PROC_LOCK(p);
 1245         maxfd = min((int)lim_cur(p, RLIMIT_NOFILE), maxfilesperproc);
 1246         PROC_UNLOCK(p);
 1247 
 1248         /*
 1249          * Search the bitmap for a free descriptor.  If none is found, try
 1250          * to grow the file table.  Keep at it until we either get a file
 1251          * descriptor or run into process or system limits; fdgrowtable()
 1252          * may drop the filedesc lock, so we're in a race.
 1253          */
 1254         for (;;) {
 1255                 fd = fd_first_free(fdp, minfd, fdp->fd_nfiles);
 1256                 if (fd >= maxfd)
 1257                         return (EMFILE);
 1258                 if (fd < fdp->fd_nfiles)
 1259                         break;
 1260                 fdgrowtable(fdp, min(fdp->fd_nfiles * 2, maxfd));
 1261         }
 1262 
 1263         /*
 1264          * Perform some sanity checks, then mark the file descriptor as
 1265          * used and return it to the caller.
 1266          */
 1267         KASSERT(!fdisused(fdp, fd),
 1268             ("fd_first_free() returned non-free descriptor"));
 1269         KASSERT(fdp->fd_ofiles[fd] == NULL,
 1270             ("free descriptor isn't"));
 1271         fdp->fd_ofileflags[fd] = 0; /* XXX needed? */
 1272         fdused(fdp, fd);
 1273         fdp->fd_freefile = fd_first_free(fdp, fd, fdp->fd_nfiles);
 1274         *result = fd;
 1275         return (0);
 1276 }
 1277 
 1278 /*
 1279  * Check to see whether n user file descriptors
 1280  * are available to the process p.
 1281  */
 1282 int
 1283 fdavail(td, n)
 1284         struct thread *td;
 1285         int n;
 1286 {
 1287         struct proc *p = td->td_proc;
 1288         struct filedesc *fdp = td->td_proc->p_fd;
 1289         struct file **fpp;
 1290         int i, lim, last;
 1291 
 1292         FILEDESC_LOCK_ASSERT(fdp, MA_OWNED);
 1293 
 1294         PROC_LOCK(p);
 1295         lim = min((int)lim_cur(p, RLIMIT_NOFILE), maxfilesperproc);
 1296         PROC_UNLOCK(p);
 1297         if ((i = lim - fdp->fd_nfiles) > 0 && (n -= i) <= 0)
 1298                 return (1);
 1299         last = min(fdp->fd_nfiles, lim);
 1300         fpp = &fdp->fd_ofiles[fdp->fd_freefile];
 1301         for (i = last - fdp->fd_freefile; --i >= 0; fpp++) {
 1302                 if (*fpp == NULL && --n <= 0)
 1303                         return (1);
 1304         }
 1305         return (0);
 1306 }
 1307 
 1308 /*
 1309  * Create a new open file structure and allocate
 1310  * a file decriptor for the process that refers to it.
 1311  * We add one reference to the file for the descriptor table
 1312  * and one reference for resultfp. This is to prevent us being
 1313  * prempted and the entry in the descriptor table closed after
 1314  * we release the FILEDESC lock.
 1315  */
 1316 int
 1317 falloc(td, resultfp, resultfd)
 1318         struct thread *td;
 1319         struct file **resultfp;
 1320         int *resultfd;
 1321 {
 1322         struct proc *p = td->td_proc;
 1323         struct file *fp, *fq;
 1324         int error, i;
 1325         int maxuserfiles = maxfiles - (maxfiles / 20);
 1326         static struct timeval lastfail;
 1327         static int curfail;
 1328 
 1329         fp = uma_zalloc(file_zone, M_WAITOK | M_ZERO);
 1330         sx_xlock(&filelist_lock);
 1331         if ((nfiles >= maxuserfiles && (td->td_ucred->cr_ruid != 0 ||
 1332            jailed(td->td_ucred))) || nfiles >= maxfiles) {
 1333                 if (ppsratecheck(&lastfail, &curfail, 1)) {
 1334                         printf("kern.maxfiles limit exceeded by uid %i, please see tuning(7).\n",
 1335                                 td->td_ucred->cr_ruid);
 1336                 }
 1337                 sx_xunlock(&filelist_lock);
 1338                 uma_zfree(file_zone, fp);
 1339                 return (ENFILE);
 1340         }
 1341         nfiles++;
 1342 
 1343         /*
 1344          * If the process has file descriptor zero open, add the new file
 1345          * descriptor to the list of open files at that point, otherwise
 1346          * put it at the front of the list of open files.
 1347          */
 1348         fp->f_mtxp = mtx_pool_alloc(mtxpool_sleep);
 1349         fp->f_count = 1;
 1350         if (resultfp)
 1351                 fp->f_count++;
 1352         fp->f_cred = crhold(td->td_ucred);
 1353         fp->f_ops = &badfileops;
 1354         fp->f_data = NULL;
 1355         fp->f_vnode = NULL;
 1356         FILEDESC_LOCK(p->p_fd);
 1357         if ((fq = p->p_fd->fd_ofiles[0])) {
 1358                 LIST_INSERT_AFTER(fq, fp, f_list);
 1359         } else {
 1360                 LIST_INSERT_HEAD(&filehead, fp, f_list);
 1361         }
 1362         sx_xunlock(&filelist_lock);
 1363         if ((error = fdalloc(td, 0, &i))) {
 1364                 FILEDESC_UNLOCK(p->p_fd);
 1365                 fdrop(fp, td);
 1366                 if (resultfp)
 1367                         fdrop(fp, td);
 1368                 return (error);
 1369         }
 1370         p->p_fd->fd_ofiles[i] = fp;
 1371         FILEDESC_UNLOCK(p->p_fd);
 1372         if (resultfp)
 1373                 *resultfp = fp;
 1374         if (resultfd)
 1375                 *resultfd = i;
 1376         return (0);
 1377 }
 1378 
 1379 /*
 1380  * Free a file descriptor.
 1381  */
 1382 void
 1383 ffree(fp)
 1384         struct file *fp;
 1385 {
 1386 
 1387         KASSERT(fp->f_count == 0, ("ffree: fp_fcount not 0!"));
 1388         sx_xlock(&filelist_lock);
 1389         LIST_REMOVE(fp, f_list);
 1390         nfiles--;
 1391         sx_xunlock(&filelist_lock);
 1392         crfree(fp->f_cred);
 1393         uma_zfree(file_zone, fp);
 1394 }
 1395 
 1396 /*
 1397  * Build a new filedesc structure from another.
 1398  * Copy the current, root, and jail root vnode references.
 1399  */
 1400 struct filedesc *
 1401 fdinit(fdp)
 1402         struct filedesc *fdp;
 1403 {
 1404         struct filedesc0 *newfdp;
 1405 
 1406         FILEDESC_LOCK_ASSERT(fdp, MA_OWNED);
 1407 
 1408         FILEDESC_UNLOCK(fdp);
 1409         MALLOC(newfdp, struct filedesc0 *, sizeof(struct filedesc0),
 1410             M_FILEDESC, M_WAITOK | M_ZERO);
 1411         FILEDESC_LOCK(fdp);
 1412         mtx_init(&newfdp->fd_fd.fd_mtx, FILEDESC_LOCK_DESC, NULL, MTX_DEF);
 1413         newfdp->fd_fd.fd_cdir = fdp->fd_cdir;
 1414         if (newfdp->fd_fd.fd_cdir)
 1415                 VREF(newfdp->fd_fd.fd_cdir);
 1416         newfdp->fd_fd.fd_rdir = fdp->fd_rdir;
 1417         if (newfdp->fd_fd.fd_rdir)
 1418                 VREF(newfdp->fd_fd.fd_rdir);
 1419         newfdp->fd_fd.fd_jdir = fdp->fd_jdir;
 1420         if (newfdp->fd_fd.fd_jdir)
 1421                 VREF(newfdp->fd_fd.fd_jdir);
 1422 
 1423         /* Create the file descriptor table. */
 1424         newfdp->fd_fd.fd_refcnt = 1;
 1425         newfdp->fd_fd.fd_cmask = CMASK;
 1426         newfdp->fd_fd.fd_ofiles = newfdp->fd_dfiles;
 1427         newfdp->fd_fd.fd_ofileflags = newfdp->fd_dfileflags;
 1428         newfdp->fd_fd.fd_nfiles = NDFILE;
 1429         newfdp->fd_fd.fd_map = newfdp->fd_dmap;
 1430         return (&newfdp->fd_fd);
 1431 }
 1432 
 1433 /*
 1434  * Share a filedesc structure.
 1435  */
 1436 struct filedesc *
 1437 fdshare(fdp)
 1438         struct filedesc *fdp;
 1439 {
 1440         FILEDESC_LOCK(fdp);
 1441         fdp->fd_refcnt++;
 1442         FILEDESC_UNLOCK(fdp);
 1443         return (fdp);
 1444 }
 1445 
 1446 /*
 1447  * Copy a filedesc structure.
 1448  * A NULL pointer in returns a NULL reference, this is to ease callers,
 1449  * not catch errors.
 1450  */
 1451 struct filedesc *
 1452 fdcopy(fdp)
 1453         struct filedesc *fdp;
 1454 {
 1455         struct filedesc *newfdp;
 1456         int i;
 1457 
 1458         /* Certain daemons might not have file descriptors. */
 1459         if (fdp == NULL)
 1460                 return (NULL);
 1461 
 1462         FILEDESC_LOCK_ASSERT(fdp, MA_OWNED);
 1463         newfdp = fdinit(fdp);
 1464         while (fdp->fd_lastfile >= newfdp->fd_nfiles) {
 1465                 FILEDESC_UNLOCK(fdp);
 1466                 FILEDESC_LOCK(newfdp);
 1467                 fdgrowtable(newfdp, fdp->fd_lastfile + 1);
 1468                 FILEDESC_UNLOCK(newfdp);
 1469                 FILEDESC_LOCK(fdp);
 1470         }
 1471         /* copy everything except kqueue descriptors */
 1472         newfdp->fd_freefile = -1;
 1473         for (i = 0; i <= fdp->fd_lastfile; ++i) {
 1474                 if (fdisused(fdp, i) &&
 1475                     fdp->fd_ofiles[i]->f_type != DTYPE_KQUEUE) {
 1476                         newfdp->fd_ofiles[i] = fdp->fd_ofiles[i];
 1477                         newfdp->fd_ofileflags[i] = fdp->fd_ofileflags[i];
 1478                         fhold(newfdp->fd_ofiles[i]);
 1479                         newfdp->fd_lastfile = i;
 1480                 } else {
 1481                         if (newfdp->fd_freefile == -1)
 1482                                 newfdp->fd_freefile = i;
 1483                 }
 1484         }
 1485         FILEDESC_UNLOCK(fdp);
 1486         FILEDESC_LOCK(newfdp);
 1487         for (i = 0; i <= newfdp->fd_lastfile; ++i)
 1488                 if (newfdp->fd_ofiles[i] != NULL)
 1489                         fdused(newfdp, i);
 1490         FILEDESC_UNLOCK(newfdp);
 1491         FILEDESC_LOCK(fdp);
 1492         if (newfdp->fd_freefile == -1)
 1493                 newfdp->fd_freefile = i;
 1494         newfdp->fd_cmask = fdp->fd_cmask;
 1495         return (newfdp);
 1496 }
 1497 
 1498 /* A mutex to protect the association between a proc and filedesc. */
 1499 struct mtx      fdesc_mtx;
 1500 MTX_SYSINIT(fdesc, &fdesc_mtx, "fdesc", MTX_DEF);
 1501 
 1502 /*
 1503  * Release a filedesc structure.
 1504  */
 1505 void
 1506 fdfree(td)
 1507         struct thread *td;
 1508 {
 1509         struct filedesc *fdp;
 1510         struct file **fpp;
 1511         int i;
 1512         struct filedesc_to_leader *fdtol;
 1513         struct file *fp;
 1514         struct vnode *vp;
 1515         struct flock lf;
 1516 
 1517         GIANT_REQUIRED;         /* VFS */
 1518 
 1519         /* Certain daemons might not have file descriptors. */
 1520         fdp = td->td_proc->p_fd;
 1521         if (fdp == NULL)
 1522                 return;
 1523 
 1524         /* Check for special need to clear POSIX style locks */
 1525         fdtol = td->td_proc->p_fdtol;
 1526         if (fdtol != NULL) {
 1527                 FILEDESC_LOCK(fdp);
 1528                 KASSERT(fdtol->fdl_refcount > 0,
 1529                         ("filedesc_to_refcount botch: fdl_refcount=%d",
 1530                          fdtol->fdl_refcount));
 1531                 if (fdtol->fdl_refcount == 1 &&
 1532                     (td->td_proc->p_leader->p_flag & P_ADVLOCK) != 0) {
 1533                         i = 0;
 1534                         fpp = fdp->fd_ofiles;
 1535                         for (i = 0, fpp = fdp->fd_ofiles;
 1536                              i <= fdp->fd_lastfile;
 1537                              i++, fpp++) {
 1538                                 if (*fpp == NULL ||
 1539                                     (*fpp)->f_type != DTYPE_VNODE)
 1540                                         continue;
 1541                                 fp = *fpp;
 1542                                 fhold(fp);
 1543                                 FILEDESC_UNLOCK(fdp);
 1544                                 lf.l_whence = SEEK_SET;
 1545                                 lf.l_start = 0;
 1546                                 lf.l_len = 0;
 1547                                 lf.l_type = F_UNLCK;
 1548                                 vp = fp->f_vnode;
 1549                                 (void) VOP_ADVLOCK(vp,
 1550                                                    (caddr_t)td->td_proc->
 1551                                                    p_leader,
 1552                                                    F_UNLCK,
 1553                                                    &lf,
 1554                                                    F_POSIX);
 1555                                 FILEDESC_LOCK(fdp);
 1556                                 fdrop(fp, td);
 1557                                 fpp = fdp->fd_ofiles + i;
 1558                         }
 1559                 }
 1560         retry:
 1561                 if (fdtol->fdl_refcount == 1) {
 1562                         if (fdp->fd_holdleaderscount > 0 &&
 1563                             (td->td_proc->p_leader->p_flag & P_ADVLOCK) != 0) {
 1564                                 /*
 1565                                  * close() or do_dup() has cleared a reference
 1566                                  * in a shared file descriptor table.
 1567                                  */
 1568                                 fdp->fd_holdleaderswakeup = 1;
 1569                                 msleep(&fdp->fd_holdleaderscount, &fdp->fd_mtx,
 1570                                        PLOCK, "fdlhold", 0);
 1571                                 goto retry;
 1572                         }
 1573                         if (fdtol->fdl_holdcount > 0) {
 1574                                 /*
 1575                                  * Ensure that fdtol->fdl_leader
 1576                                  * remains valid in closef().
 1577                                  */
 1578                                 fdtol->fdl_wakeup = 1;
 1579                                 msleep(fdtol, &fdp->fd_mtx,
 1580                                        PLOCK, "fdlhold", 0);
 1581                                 goto retry;
 1582                         }
 1583                 }
 1584                 fdtol->fdl_refcount--;
 1585                 if (fdtol->fdl_refcount == 0 &&
 1586                     fdtol->fdl_holdcount == 0) {
 1587                         fdtol->fdl_next->fdl_prev = fdtol->fdl_prev;
 1588                         fdtol->fdl_prev->fdl_next = fdtol->fdl_next;
 1589                 } else
 1590                         fdtol = NULL;
 1591                 td->td_proc->p_fdtol = NULL;
 1592                 FILEDESC_UNLOCK(fdp);
 1593                 if (fdtol != NULL)
 1594                         FREE(fdtol, M_FILEDESC_TO_LEADER);
 1595         }
 1596         FILEDESC_LOCK(fdp);
 1597         if (--fdp->fd_refcnt > 0) {
 1598                 FILEDESC_UNLOCK(fdp);
 1599                 return;
 1600         }
 1601 
 1602         /*
 1603          * We are the last reference to the structure, so we can
 1604          * safely assume it will not change out from under us.
 1605          */
 1606         FILEDESC_UNLOCK(fdp);
 1607         fpp = fdp->fd_ofiles;
 1608         for (i = fdp->fd_lastfile; i-- >= 0; fpp++) {
 1609                 if (*fpp)
 1610                         (void) closef(*fpp, td);
 1611         }
 1612 
 1613         /* XXX This should happen earlier. */
 1614         mtx_lock(&fdesc_mtx);
 1615         td->td_proc->p_fd = NULL;
 1616         mtx_unlock(&fdesc_mtx);
 1617 
 1618         if (fdp->fd_nfiles > NDFILE)
 1619                 FREE(fdp->fd_ofiles, M_FILEDESC);
 1620         if (NDSLOTS(fdp->fd_nfiles) > NDSLOTS(NDFILE))
 1621                 FREE(fdp->fd_map, M_FILEDESC);
 1622         if (fdp->fd_cdir)
 1623                 vrele(fdp->fd_cdir);
 1624         if (fdp->fd_rdir)
 1625                 vrele(fdp->fd_rdir);
 1626         if (fdp->fd_jdir)
 1627                 vrele(fdp->fd_jdir);
 1628         mtx_destroy(&fdp->fd_mtx);
 1629         FREE(fdp, M_FILEDESC);
 1630 }
 1631 
 1632 /*
 1633  * For setugid programs, we don't want to people to use that setugidness
 1634  * to generate error messages which write to a file which otherwise would
 1635  * otherwise be off-limits to the process.  We check for filesystems where
 1636  * the vnode can change out from under us after execve (like [lin]procfs).
 1637  *
 1638  * Since setugidsafety calls this only for fd 0, 1 and 2, this check is
 1639  * sufficient.  We also don't for check setugidness since we know we are.
 1640  */
 1641 static int
 1642 is_unsafe(struct file *fp)
 1643 {
 1644         if (fp->f_type == DTYPE_VNODE) {
 1645                 struct vnode *vp = fp->f_vnode;
 1646 
 1647                 if ((vp->v_vflag & VV_PROCDEP) != 0)
 1648                         return (1);
 1649         }
 1650         return (0);
 1651 }
 1652 
 1653 /*
 1654  * Make this setguid thing safe, if at all possible.
 1655  */
 1656 void
 1657 setugidsafety(td)
 1658         struct thread *td;
 1659 {
 1660         struct filedesc *fdp;
 1661         int i;
 1662 
 1663         /* Certain daemons might not have file descriptors. */
 1664         fdp = td->td_proc->p_fd;
 1665         if (fdp == NULL)
 1666                 return;
 1667 
 1668         /*
 1669          * Note: fdp->fd_ofiles may be reallocated out from under us while
 1670          * we are blocked in a close.  Be careful!
 1671          */
 1672         FILEDESC_LOCK(fdp);
 1673         for (i = 0; i <= fdp->fd_lastfile; i++) {
 1674                 if (i > 2)
 1675                         break;
 1676                 if (fdp->fd_ofiles[i] && is_unsafe(fdp->fd_ofiles[i])) {
 1677                         struct file *fp;
 1678 
 1679                         knote_fdclose(td, i);
 1680                         /*
 1681                          * NULL-out descriptor prior to close to avoid
 1682                          * a race while close blocks.
 1683                          */
 1684                         fp = fdp->fd_ofiles[i];
 1685                         fdp->fd_ofiles[i] = NULL;
 1686                         fdp->fd_ofileflags[i] = 0;
 1687                         fdunused(fdp, i);
 1688                         FILEDESC_UNLOCK(fdp);
 1689                         (void) closef(fp, td);
 1690                         FILEDESC_LOCK(fdp);
 1691                 }
 1692         }
 1693         FILEDESC_UNLOCK(fdp);
 1694 }
 1695 
 1696 /*
 1697  * Close any files on exec?
 1698  */
 1699 void
 1700 fdcloseexec(td)
 1701         struct thread *td;
 1702 {
 1703         struct filedesc *fdp;
 1704         int i;
 1705 
 1706         /* Certain daemons might not have file descriptors. */
 1707         fdp = td->td_proc->p_fd;
 1708         if (fdp == NULL)
 1709                 return;
 1710 
 1711         FILEDESC_LOCK(fdp);
 1712 
 1713         /*
 1714          * We cannot cache fd_ofiles or fd_ofileflags since operations
 1715          * may block and rip them out from under us.
 1716          */
 1717         for (i = 0; i <= fdp->fd_lastfile; i++) {
 1718                 if (fdp->fd_ofiles[i] != NULL &&
 1719                     (fdp->fd_ofileflags[i] & UF_EXCLOSE)) {
 1720                         struct file *fp;
 1721 
 1722                         knote_fdclose(td, i);
 1723                         /*
 1724                          * NULL-out descriptor prior to close to avoid
 1725                          * a race while close blocks.
 1726                          */
 1727                         fp = fdp->fd_ofiles[i];
 1728                         fdp->fd_ofiles[i] = NULL;
 1729                         fdp->fd_ofileflags[i] = 0;
 1730                         fdunused(fdp, i);
 1731                         FILEDESC_UNLOCK(fdp);
 1732                         (void) closef(fp, td);
 1733                         FILEDESC_LOCK(fdp);
 1734                 }
 1735         }
 1736         FILEDESC_UNLOCK(fdp);
 1737 }
 1738 
 1739 /*
 1740  * It is unsafe for set[ug]id processes to be started with file
 1741  * descriptors 0..2 closed, as these descriptors are given implicit
 1742  * significance in the Standard C library.  fdcheckstd() will create a
 1743  * descriptor referencing /dev/null for each of stdin, stdout, and
 1744  * stderr that is not already open.
 1745  */
 1746 int
 1747 fdcheckstd(td)
 1748         struct thread *td;
 1749 {
 1750         struct nameidata nd;
 1751         struct filedesc *fdp;
 1752         struct file *fp;
 1753         register_t retval;
 1754         int fd, i, error, flags, devnull;
 1755 
 1756         GIANT_REQUIRED;         /* VFS */
 1757 
 1758         fdp = td->td_proc->p_fd;
 1759         if (fdp == NULL)
 1760                 return (0);
 1761         KASSERT(fdp->fd_refcnt == 1, ("the fdtable should not be shared"));
 1762         devnull = -1;
 1763         error = 0;
 1764         for (i = 0; i < 3; i++) {
 1765                 if (fdp->fd_ofiles[i] != NULL)
 1766                         continue;
 1767                 if (devnull < 0) {
 1768                         error = falloc(td, &fp, &fd);
 1769                         if (error != 0)
 1770                                 break;
 1771                         /* Note extra ref on `fp' held for us by falloc(). */
 1772                         KASSERT(fd == i, ("oof, we didn't get our fd"));
 1773                         NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, "/dev/null",
 1774                             td);
 1775                         flags = FREAD | FWRITE;
 1776                         error = vn_open(&nd, &flags, 0, -1);
 1777                         if (error != 0) {
 1778                                 /*
 1779                                  * Someone may have closed the entry in the
 1780                                  * file descriptor table, so check it hasn't
 1781                                  * changed before dropping the reference count.
 1782                                  */
 1783                                 FILEDESC_LOCK(fdp);
 1784                                 KASSERT(fdp->fd_ofiles[fd] == fp,
 1785                                     ("table not shared, how did it change?"));
 1786                                 fdp->fd_ofiles[fd] = NULL;
 1787                                 fdunused(fdp, fd);
 1788                                 FILEDESC_UNLOCK(fdp);
 1789                                 fdrop(fp, td);
 1790                                 fdrop(fp, td);
 1791                                 break;
 1792                         }
 1793                         NDFREE(&nd, NDF_ONLY_PNBUF);
 1794                         fp->f_vnode = nd.ni_vp;
 1795                         fp->f_data = nd.ni_vp;
 1796                         fp->f_flag = flags;
 1797                         fp->f_ops = &vnops;
 1798                         fp->f_type = DTYPE_VNODE;
 1799                         VOP_UNLOCK(nd.ni_vp, 0, td);
 1800                         devnull = fd;
 1801                         fdrop(fp, td);
 1802                 } else {
 1803                         error = do_dup(td, DUP_FIXED, devnull, i, &retval);
 1804                         if (error != 0)
 1805                                 break;
 1806                 }
 1807         }
 1808         return (error);
 1809 }
 1810 
 1811 /*
 1812  * Internal form of close.
 1813  * Decrement reference count on file structure.
 1814  * Note: td may be NULL when closing a file
 1815  * that was being passed in a message.
 1816  */
 1817 int
 1818 closef(fp, td)
 1819         struct file *fp;
 1820         struct thread *td;
 1821 {
 1822         struct vnode *vp;
 1823         struct flock lf;
 1824         struct filedesc_to_leader *fdtol;
 1825         struct filedesc *fdp;
 1826 
 1827         if (fp == NULL)
 1828                 return (0);
 1829         /*
 1830          * POSIX record locking dictates that any close releases ALL
 1831          * locks owned by this process.  This is handled by setting
 1832          * a flag in the unlock to free ONLY locks obeying POSIX
 1833          * semantics, and not to free BSD-style file locks.
 1834          * If the descriptor was in a message, POSIX-style locks
 1835          * aren't passed with the descriptor.
 1836          */
 1837         if (td != NULL &&
 1838             fp->f_type == DTYPE_VNODE) {
 1839                 if ((td->td_proc->p_leader->p_flag & P_ADVLOCK) != 0) {
 1840                         lf.l_whence = SEEK_SET;
 1841                         lf.l_start = 0;
 1842                         lf.l_len = 0;
 1843                         lf.l_type = F_UNLCK;
 1844                         vp = fp->f_vnode;
 1845                         (void) VOP_ADVLOCK(vp, (caddr_t)td->td_proc->p_leader,
 1846                                            F_UNLCK, &lf, F_POSIX);
 1847                 }
 1848                 fdtol = td->td_proc->p_fdtol;
 1849                 if (fdtol != NULL) {
 1850                         /*
 1851                          * Handle special case where file descriptor table
 1852                          * is shared between multiple process leaders.
 1853                          */
 1854                         fdp = td->td_proc->p_fd;
 1855                         FILEDESC_LOCK(fdp);
 1856                         for (fdtol = fdtol->fdl_next;
 1857                              fdtol != td->td_proc->p_fdtol;
 1858                              fdtol = fdtol->fdl_next) {
 1859                                 if ((fdtol->fdl_leader->p_flag &
 1860                                      P_ADVLOCK) == 0)
 1861                                         continue;
 1862                                 fdtol->fdl_holdcount++;
 1863                                 FILEDESC_UNLOCK(fdp);
 1864                                 lf.l_whence = SEEK_SET;
 1865                                 lf.l_start = 0;
 1866                                 lf.l_len = 0;
 1867                                 lf.l_type = F_UNLCK;
 1868                                 vp = fp->f_vnode;
 1869                                 (void) VOP_ADVLOCK(vp,
 1870                                                    (caddr_t)fdtol->fdl_leader,
 1871                                                    F_UNLCK, &lf, F_POSIX);
 1872                                 FILEDESC_LOCK(fdp);
 1873                                 fdtol->fdl_holdcount--;
 1874                                 if (fdtol->fdl_holdcount == 0 &&
 1875                                     fdtol->fdl_wakeup != 0) {
 1876                                         fdtol->fdl_wakeup = 0;
 1877                                         wakeup(fdtol);
 1878                                 }
 1879                         }
 1880                         FILEDESC_UNLOCK(fdp);
 1881                 }
 1882         }
 1883         return (fdrop(fp, td));
 1884 }
 1885 
 1886 /*
 1887  * Drop reference on struct file passed in, may call closef if the
 1888  * reference hits zero.
 1889  */
 1890 int
 1891 fdrop(fp, td)
 1892         struct file *fp;
 1893         struct thread *td;
 1894 {
 1895 
 1896         FILE_LOCK(fp);
 1897         return (fdrop_locked(fp, td));
 1898 }
 1899 
 1900 /*
 1901  * Extract the file pointer associated with the specified descriptor for
 1902  * the current user process.
 1903  *
 1904  * If the descriptor doesn't exist, EBADF is returned.
 1905  *
 1906  * If the descriptor exists but doesn't match 'flags' then
 1907  * return EBADF for read attempts and EINVAL for write attempts.
 1908  *
 1909  * If 'hold' is set (non-zero) the file's refcount will be bumped on return.
 1910  * It should be droped with fdrop().
 1911  * If it is not set, then the refcount will not be bumped however the
 1912  * thread's filedesc struct will be returned locked (for fgetsock).
 1913  *
 1914  * If an error occured the non-zero error is returned and *fpp is set to NULL.
 1915  * Otherwise *fpp is set and zero is returned.
 1916  */
 1917 static __inline int
 1918 _fget(struct thread *td, int fd, struct file **fpp, int flags, int hold)
 1919 {
 1920         struct filedesc *fdp;
 1921         struct file *fp;
 1922 
 1923         *fpp = NULL;
 1924         if (td == NULL || (fdp = td->td_proc->p_fd) == NULL)
 1925                 return (EBADF);
 1926         FILEDESC_LOCK(fdp);
 1927         if ((fp = fget_locked(fdp, fd)) == NULL || fp->f_ops == &badfileops) {
 1928                 FILEDESC_UNLOCK(fdp);
 1929                 return (EBADF);
 1930         }
 1931 
 1932         /*
 1933          * Note: FREAD failures returns EBADF to maintain backwards
 1934          * compatibility with what routines returned before.
 1935          *
 1936          * Only one flag, or 0, may be specified.
 1937          */
 1938         if (flags == FREAD && (fp->f_flag & FREAD) == 0) {
 1939                 FILEDESC_UNLOCK(fdp);
 1940                 return (EBADF);
 1941         }
 1942         if (flags == FWRITE && (fp->f_flag & FWRITE) == 0) {
 1943                 FILEDESC_UNLOCK(fdp);
 1944                 return (EINVAL);
 1945         }
 1946         if (hold) {
 1947                 fhold(fp);
 1948                 FILEDESC_UNLOCK(fdp);
 1949         }
 1950         *fpp = fp;
 1951         return (0);
 1952 }
 1953 
 1954 int
 1955 fget(struct thread *td, int fd, struct file **fpp)
 1956 {
 1957 
 1958         return(_fget(td, fd, fpp, 0, 1));
 1959 }
 1960 
 1961 int
 1962 fget_read(struct thread *td, int fd, struct file **fpp)
 1963 {
 1964 
 1965         return(_fget(td, fd, fpp, FREAD, 1));
 1966 }
 1967 
 1968 int
 1969 fget_write(struct thread *td, int fd, struct file **fpp)
 1970 {
 1971 
 1972         return(_fget(td, fd, fpp, FWRITE, 1));
 1973 }
 1974 
 1975 /*
 1976  * Like fget() but loads the underlying vnode, or returns an error if
 1977  * the descriptor does not represent a vnode.  Note that pipes use vnodes
 1978  * but never have VM objects (so VOP_GETVOBJECT() calls will return an
 1979  * error).  The returned vnode will be vref()d.
 1980  */
 1981 static __inline int
 1982 _fgetvp(struct thread *td, int fd, struct vnode **vpp, int flags)
 1983 {
 1984         struct file *fp;
 1985         int error;
 1986 
 1987         GIANT_REQUIRED;         /* VFS */
 1988 
 1989         *vpp = NULL;
 1990         if ((error = _fget(td, fd, &fp, 0, 0)) != 0)
 1991                 return (error);
 1992         if (fp->f_vnode == NULL) {
 1993                 error = EINVAL;
 1994         } else {
 1995                 *vpp = fp->f_vnode;
 1996                 vref(*vpp);
 1997         }
 1998         FILEDESC_UNLOCK(td->td_proc->p_fd);
 1999         return (error);
 2000 }
 2001 
 2002 int
 2003 fgetvp(struct thread *td, int fd, struct vnode **vpp)
 2004 {
 2005 
 2006         return (_fgetvp(td, fd, vpp, 0));
 2007 }
 2008 
 2009 int
 2010 fgetvp_read(struct thread *td, int fd, struct vnode **vpp)
 2011 {
 2012 
 2013         return (_fgetvp(td, fd, vpp, FREAD));
 2014 }
 2015 
 2016 int
 2017 fgetvp_write(struct thread *td, int fd, struct vnode **vpp)
 2018 {
 2019 
 2020         return (_fgetvp(td, fd, vpp, FWRITE));
 2021 }
 2022 
 2023 /*
 2024  * Like fget() but loads the underlying socket, or returns an error if
 2025  * the descriptor does not represent a socket.
 2026  *
 2027  * We bump the ref count on the returned socket.  XXX Also obtain the SX
 2028  * lock in the future.
 2029  */
 2030 int
 2031 fgetsock(struct thread *td, int fd, struct socket **spp, u_int *fflagp)
 2032 {
 2033         struct file *fp;
 2034         int error;
 2035 
 2036         NET_ASSERT_GIANT();
 2037 
 2038         *spp = NULL;
 2039         if (fflagp != NULL)
 2040                 *fflagp = 0;
 2041         if ((error = _fget(td, fd, &fp, 0, 0)) != 0)
 2042                 return (error);
 2043         if (fp->f_type != DTYPE_SOCKET) {
 2044                 error = ENOTSOCK;
 2045         } else {
 2046                 *spp = fp->f_data;
 2047                 if (fflagp)
 2048                         *fflagp = fp->f_flag;
 2049                 SOCK_LOCK(*spp);
 2050                 soref(*spp);
 2051                 SOCK_UNLOCK(*spp);
 2052         }
 2053         FILEDESC_UNLOCK(td->td_proc->p_fd);
 2054         return (error);
 2055 }
 2056 
 2057 /*
 2058  * Drop the reference count on the the socket and XXX release the SX lock in
 2059  * the future.  The last reference closes the socket.
 2060  */
 2061 void
 2062 fputsock(struct socket *so)
 2063 {
 2064 
 2065         NET_ASSERT_GIANT();
 2066         ACCEPT_LOCK();
 2067         SOCK_LOCK(so);
 2068         sorele(so);
 2069 }
 2070 
 2071 /*
 2072  * Drop reference on struct file passed in, may call closef if the
 2073  * reference hits zero.
 2074  * Expects struct file locked, and will unlock it.
 2075  */
 2076 int
 2077 fdrop_locked(fp, td)
 2078         struct file *fp;
 2079         struct thread *td;
 2080 {
 2081         int error;
 2082 
 2083         FILE_LOCK_ASSERT(fp, MA_OWNED);
 2084 
 2085         if (--fp->f_count > 0) {
 2086                 FILE_UNLOCK(fp);
 2087                 return (0);
 2088         }
 2089         /* We have the last ref so we can proceed without the file lock. */
 2090         FILE_UNLOCK(fp);
 2091         if (fp->f_count < 0)
 2092                 panic("fdrop: count < 0");
 2093         if (fp->f_ops != &badfileops)
 2094                 error = fo_close(fp, td);
 2095         else
 2096                 error = 0;
 2097         ffree(fp);
 2098         return (error);
 2099 }
 2100 
 2101 /*
 2102  * Apply an advisory lock on a file descriptor.
 2103  *
 2104  * Just attempt to get a record lock of the requested type on
 2105  * the entire file (l_whence = SEEK_SET, l_start = 0, l_len = 0).
 2106  */
 2107 #ifndef _SYS_SYSPROTO_H_
 2108 struct flock_args {
 2109         int     fd;
 2110         int     how;
 2111 };
 2112 #endif
 2113 /*
 2114  * MPSAFE
 2115  */
 2116 /* ARGSUSED */
 2117 int
 2118 flock(td, uap)
 2119         struct thread *td;
 2120         struct flock_args *uap;
 2121 {
 2122         struct file *fp;
 2123         struct vnode *vp;
 2124         struct flock lf;
 2125         int error;
 2126 
 2127         if ((error = fget(td, uap->fd, &fp)) != 0)
 2128                 return (error);
 2129         if (fp->f_type != DTYPE_VNODE) {
 2130                 fdrop(fp, td);
 2131                 return (EOPNOTSUPP);
 2132         }
 2133 
 2134         mtx_lock(&Giant);
 2135         vp = fp->f_vnode;
 2136         lf.l_whence = SEEK_SET;
 2137         lf.l_start = 0;
 2138         lf.l_len = 0;
 2139         if (uap->how & LOCK_UN) {
 2140                 lf.l_type = F_UNLCK;
 2141                 FILE_LOCK(fp);
 2142                 fp->f_flag &= ~FHASLOCK;
 2143                 FILE_UNLOCK(fp);
 2144                 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, F_FLOCK);
 2145                 goto done2;
 2146         }
 2147         if (uap->how & LOCK_EX)
 2148                 lf.l_type = F_WRLCK;
 2149         else if (uap->how & LOCK_SH)
 2150                 lf.l_type = F_RDLCK;
 2151         else {
 2152                 error = EBADF;
 2153                 goto done2;
 2154         }
 2155         FILE_LOCK(fp);
 2156         fp->f_flag |= FHASLOCK;
 2157         FILE_UNLOCK(fp);
 2158         error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf,
 2159             (uap->how & LOCK_NB) ? F_FLOCK : F_FLOCK | F_WAIT);
 2160 done2:
 2161         fdrop(fp, td);
 2162         mtx_unlock(&Giant);
 2163         return (error);
 2164 }
 2165 
 2166 /*
 2167  * File Descriptor pseudo-device driver (/dev/fd/).
 2168  *
 2169  * Opening minor device N dup()s the file (if any) connected to file
 2170  * descriptor N belonging to the calling process.  Note that this driver
 2171  * consists of only the ``open()'' routine, because all subsequent
 2172  * references to this file will be direct to the other driver.
 2173  */
 2174 /* ARGSUSED */
 2175 static int
 2176 fdopen(dev, mode, type, td)
 2177         struct cdev *dev;
 2178         int mode, type;
 2179         struct thread *td;
 2180 {
 2181 
 2182         /*
 2183          * XXX Kludge: set curthread->td_dupfd to contain the value of the
 2184          * the file descriptor being sought for duplication. The error
 2185          * return ensures that the vnode for this device will be released
 2186          * by vn_open. Open will detect this special error and take the
 2187          * actions in dupfdopen below. Other callers of vn_open or VOP_OPEN
 2188          * will simply report the error.
 2189          */
 2190         td->td_dupfd = dev2unit(dev);
 2191         return (ENODEV);
 2192 }
 2193 
 2194 /*
 2195  * Duplicate the specified descriptor to a free descriptor.
 2196  */
 2197 int
 2198 dupfdopen(td, fdp, indx, dfd, mode, error)
 2199         struct thread *td;
 2200         struct filedesc *fdp;
 2201         int indx, dfd;
 2202         int mode;
 2203         int error;
 2204 {
 2205         struct file *wfp;
 2206         struct file *fp;
 2207 
 2208         /*
 2209          * If the to-be-dup'd fd number is greater than the allowed number
 2210          * of file descriptors, or the fd to be dup'd has already been
 2211          * closed, then reject.
 2212          */
 2213         FILEDESC_LOCK(fdp);
 2214         if (dfd < 0 || dfd >= fdp->fd_nfiles ||
 2215             (wfp = fdp->fd_ofiles[dfd]) == NULL) {
 2216                 FILEDESC_UNLOCK(fdp);
 2217                 return (EBADF);
 2218         }
 2219 
 2220         /*
 2221          * There are two cases of interest here.
 2222          *
 2223          * For ENODEV simply dup (dfd) to file descriptor
 2224          * (indx) and return.
 2225          *
 2226          * For ENXIO steal away the file structure from (dfd) and
 2227          * store it in (indx).  (dfd) is effectively closed by
 2228          * this operation.
 2229          *
 2230          * Any other error code is just returned.
 2231          */
 2232         switch (error) {
 2233         case ENODEV:
 2234                 /*
 2235                  * Check that the mode the file is being opened for is a
 2236                  * subset of the mode of the existing descriptor.
 2237                  */
 2238                 FILE_LOCK(wfp);
 2239                 if (((mode & (FREAD|FWRITE)) | wfp->f_flag) != wfp->f_flag) {
 2240                         FILE_UNLOCK(wfp);
 2241                         FILEDESC_UNLOCK(fdp);
 2242                         return (EACCES);
 2243                 }
 2244                 fp = fdp->fd_ofiles[indx];
 2245                 fdp->fd_ofiles[indx] = wfp;
 2246                 fdp->fd_ofileflags[indx] = fdp->fd_ofileflags[dfd];
 2247                 if (fp == NULL)
 2248                         fdused(fdp, indx);
 2249                 fhold_locked(wfp);
 2250                 FILE_UNLOCK(wfp);
 2251                 if (fp != NULL)
 2252                         FILE_LOCK(fp);
 2253                 FILEDESC_UNLOCK(fdp);
 2254                 /*
 2255                  * We now own the reference to fp that the ofiles[] array
 2256                  * used to own.  Release it.
 2257                  */
 2258                 if (fp != NULL)
 2259                         fdrop_locked(fp, td);
 2260                 return (0);
 2261 
 2262         case ENXIO:
 2263                 /*
 2264                  * Steal away the file pointer from dfd and stuff it into indx.
 2265                  */
 2266                 fp = fdp->fd_ofiles[indx];
 2267                 fdp->fd_ofiles[indx] = fdp->fd_ofiles[dfd];
 2268                 fdp->fd_ofiles[dfd] = NULL;
 2269                 fdp->fd_ofileflags[indx] = fdp->fd_ofileflags[dfd];
 2270                 fdp->fd_ofileflags[dfd] = 0;
 2271                 fdunused(fdp, dfd);
 2272                 if (fp == NULL)
 2273                         fdused(fdp, indx);
 2274                 if (fp != NULL)
 2275                         FILE_LOCK(fp);
 2276                 FILEDESC_UNLOCK(fdp);
 2277 
 2278                 /*
 2279                  * we now own the reference to fp that the ofiles[] array
 2280                  * used to own.  Release it.
 2281                  */
 2282                 if (fp != NULL)
 2283                         fdrop_locked(fp, td);
 2284                 return (0);
 2285 
 2286         default:
 2287                 FILEDESC_UNLOCK(fdp);
 2288                 return (error);
 2289         }
 2290         /* NOTREACHED */
 2291 }
 2292 
 2293 struct filedesc_to_leader *
 2294 filedesc_to_leader_alloc(struct filedesc_to_leader *old,
 2295                          struct filedesc *fdp,
 2296                          struct proc *leader)
 2297 {
 2298         struct filedesc_to_leader *fdtol;
 2299 
 2300         MALLOC(fdtol, struct filedesc_to_leader *,
 2301                sizeof(struct filedesc_to_leader),
 2302                M_FILEDESC_TO_LEADER,
 2303                M_WAITOK);
 2304         fdtol->fdl_refcount = 1;
 2305         fdtol->fdl_holdcount = 0;
 2306         fdtol->fdl_wakeup = 0;
 2307         fdtol->fdl_leader = leader;
 2308         if (old != NULL) {
 2309                 FILEDESC_LOCK(fdp);
 2310                 fdtol->fdl_next = old->fdl_next;
 2311                 fdtol->fdl_prev = old;
 2312                 old->fdl_next = fdtol;
 2313                 fdtol->fdl_next->fdl_prev = fdtol;
 2314                 FILEDESC_UNLOCK(fdp);
 2315         } else {
 2316                 fdtol->fdl_next = fdtol;
 2317                 fdtol->fdl_prev = fdtol;
 2318         }
 2319         return (fdtol);
 2320 }
 2321 
 2322 /*
 2323  * Get file structures.
 2324  */
 2325 static int
 2326 sysctl_kern_file(SYSCTL_HANDLER_ARGS)
 2327 {
 2328         struct xfile xf;
 2329         struct filedesc *fdp;
 2330         struct file *fp;
 2331         struct proc *p;
 2332         int error, n;
 2333 
 2334         /*
 2335          * Note: because the number of file descriptors is calculated
 2336          * in different ways for sizing vs returning the data,
 2337          * there is information leakage from the first loop.  However,
 2338          * it is of a similar order of magnitude to the leakage from
 2339          * global system statistics such as kern.openfiles.
 2340          */
 2341         error = sysctl_wire_old_buffer(req, 0);
 2342         if (error != 0)
 2343                 return (error);
 2344         if (req->oldptr == NULL) {
 2345                 n = 16;         /* A slight overestimate. */
 2346                 sx_slock(&filelist_lock);
 2347                 LIST_FOREACH(fp, &filehead, f_list) {
 2348                         /*
 2349                          * We should grab the lock, but this is an
 2350                          * estimate, so does it really matter?
 2351                          */
 2352                         /* mtx_lock(fp->f_mtxp); */
 2353                         n += fp->f_count;
 2354                         /* mtx_unlock(f->f_mtxp); */
 2355                 }
 2356                 sx_sunlock(&filelist_lock);
 2357                 return (SYSCTL_OUT(req, 0, n * sizeof(xf)));
 2358         }
 2359         error = 0;
 2360         bzero(&xf, sizeof(xf));
 2361         xf.xf_size = sizeof(xf);
 2362         sx_slock(&allproc_lock);
 2363         LIST_FOREACH(p, &allproc, p_list) {
 2364                 if (p->p_state == PRS_NEW)
 2365                         continue;
 2366                 PROC_LOCK(p);
 2367                 if (p_cansee(req->td, p) != 0) {
 2368                         PROC_UNLOCK(p);
 2369                         continue;
 2370                 }
 2371                 xf.xf_pid = p->p_pid;
 2372                 xf.xf_uid = p->p_ucred->cr_uid;
 2373                 PROC_UNLOCK(p);
 2374                 mtx_lock(&fdesc_mtx);
 2375                 if ((fdp = p->p_fd) == NULL) {
 2376                         mtx_unlock(&fdesc_mtx);
 2377                         continue;
 2378                 }
 2379                 FILEDESC_LOCK(fdp);
 2380                 for (n = 0; n < fdp->fd_nfiles; ++n) {
 2381                         if ((fp = fdp->fd_ofiles[n]) == NULL)
 2382                                 continue;
 2383                         xf.xf_fd = n;
 2384                         xf.xf_file = fp;
 2385                         xf.xf_data = fp->f_data;
 2386                         xf.xf_vnode = fp->f_vnode;
 2387                         xf.xf_type = fp->f_type;
 2388                         xf.xf_count = fp->f_count;
 2389                         xf.xf_msgcount = fp->f_msgcount;
 2390                         xf.xf_offset = fp->f_offset;
 2391                         xf.xf_flag = fp->f_flag;
 2392                         error = SYSCTL_OUT(req, &xf, sizeof(xf));
 2393                         if (error)
 2394                                 break;
 2395                 }
 2396                 FILEDESC_UNLOCK(fdp);
 2397                 mtx_unlock(&fdesc_mtx);
 2398                 if (error)
 2399                         break;
 2400         }
 2401         sx_sunlock(&allproc_lock);
 2402         return (error);
 2403 }
 2404 
 2405 SYSCTL_PROC(_kern, KERN_FILE, file, CTLTYPE_OPAQUE|CTLFLAG_RD,
 2406     0, 0, sysctl_kern_file, "S,xfile", "Entire file table");
 2407 
 2408 SYSCTL_INT(_kern, KERN_MAXFILESPERPROC, maxfilesperproc, CTLFLAG_RW,
 2409     &maxfilesperproc, 0, "Maximum files allowed open per process");
 2410 
 2411 SYSCTL_INT(_kern, KERN_MAXFILES, maxfiles, CTLFLAG_RW,
 2412     &maxfiles, 0, "Maximum number of files");
 2413 
 2414 SYSCTL_INT(_kern, OID_AUTO, openfiles, CTLFLAG_RD,
 2415     &nfiles, 0, "System-wide number of open files");
 2416 
 2417 static void
 2418 fildesc_drvinit(void *unused)
 2419 {
 2420         struct cdev *dev;
 2421 
 2422         dev = make_dev(&fildesc_cdevsw, 0, UID_ROOT, GID_WHEEL, 0666, "fd/0");
 2423         make_dev_alias(dev, "stdin");
 2424         dev = make_dev(&fildesc_cdevsw, 1, UID_ROOT, GID_WHEEL, 0666, "fd/1");
 2425         make_dev_alias(dev, "stdout");
 2426         dev = make_dev(&fildesc_cdevsw, 2, UID_ROOT, GID_WHEEL, 0666, "fd/2");
 2427         make_dev_alias(dev, "stderr");
 2428 }
 2429 
 2430 static fo_rdwr_t        badfo_readwrite;
 2431 static fo_ioctl_t       badfo_ioctl;
 2432 static fo_poll_t        badfo_poll;
 2433 static fo_kqfilter_t    badfo_kqfilter;
 2434 static fo_stat_t        badfo_stat;
 2435 static fo_close_t       badfo_close;
 2436 
 2437 struct fileops badfileops = {
 2438         .fo_read = badfo_readwrite,
 2439         .fo_write = badfo_readwrite,
 2440         .fo_ioctl = badfo_ioctl,
 2441         .fo_poll = badfo_poll,
 2442         .fo_kqfilter = badfo_kqfilter,
 2443         .fo_stat = badfo_stat,
 2444         .fo_close = badfo_close,
 2445 };
 2446 
 2447 static int
 2448 badfo_readwrite(fp, uio, active_cred, flags, td)
 2449         struct file *fp;
 2450         struct uio *uio;
 2451         struct ucred *active_cred;
 2452         struct thread *td;
 2453         int flags;
 2454 {
 2455 
 2456         return (EBADF);
 2457 }
 2458 
 2459 static int
 2460 badfo_ioctl(fp, com, data, active_cred, td)
 2461         struct file *fp;
 2462         u_long com;
 2463         void *data;
 2464         struct ucred *active_cred;
 2465         struct thread *td;
 2466 {
 2467 
 2468         return (EBADF);
 2469 }
 2470 
 2471 static int
 2472 badfo_poll(fp, events, active_cred, td)
 2473         struct file *fp;
 2474         int events;
 2475         struct ucred *active_cred;
 2476         struct thread *td;
 2477 {
 2478 
 2479         return (0);
 2480 }
 2481 
 2482 static int
 2483 badfo_kqfilter(fp, kn)
 2484         struct file *fp;
 2485         struct knote *kn;
 2486 {
 2487 
 2488         return (0);
 2489 }
 2490 
 2491 static int
 2492 badfo_stat(fp, sb, active_cred, td)
 2493         struct file *fp;
 2494         struct stat *sb;
 2495         struct ucred *active_cred;
 2496         struct thread *td;
 2497 {
 2498 
 2499         return (EBADF);
 2500 }
 2501 
 2502 static int
 2503 badfo_close(fp, td)
 2504         struct file *fp;
 2505         struct thread *td;
 2506 {
 2507 
 2508         return (EBADF);
 2509 }
 2510 
 2511 SYSINIT(fildescdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,
 2512                                         fildesc_drvinit,NULL)
 2513 
 2514 static void filelistinit(void *);
 2515 SYSINIT(select, SI_SUB_LOCK, SI_ORDER_FIRST, filelistinit, NULL)
 2516 
 2517 /* ARGSUSED*/
 2518 static void
 2519 filelistinit(dummy)
 2520         void *dummy;
 2521 {
 2522 
 2523         file_zone = uma_zcreate("Files", sizeof(struct file), NULL, NULL,
 2524             NULL, NULL, UMA_ALIGN_PTR, 0);
 2525         sx_init(&filelist_lock, "filelist lock");
 2526         mtx_init(&sigio_lock, "sigio lock", NULL, MTX_DEF);
 2527 }

Cache object: d7d1929aec1895aa08932f3fb6d10736


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