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

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    1 /*-
    2  * SPDX-License-Identifier: BSD-3-Clause
    3  *
    4  * Copyright (c) 1982, 1986, 1989, 1993
    5  *      The Regents of the University of California.  All rights reserved.
    6  * (c) UNIX System Laboratories, Inc.
    7  * All or some portions of this file are derived from material licensed
    8  * to the University of California by American Telephone and Telegraph
    9  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
   10  * the permission of UNIX System Laboratories, Inc.
   11  *
   12  * Redistribution and use in source and binary forms, with or without
   13  * modification, are permitted provided that the following conditions
   14  * are met:
   15  * 1. Redistributions of source code must retain the above copyright
   16  *    notice, this list of conditions and the following disclaimer.
   17  * 2. Redistributions in binary form must reproduce the above copyright
   18  *    notice, this list of conditions and the following disclaimer in the
   19  *    documentation and/or other materials provided with the distribution.
   20  * 3. Neither the name of the University nor the names of its contributors
   21  *    may be used to endorse or promote products derived from this software
   22  *    without specific prior written permission.
   23  *
   24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   34  * SUCH DAMAGE.
   35  *
   36  *      @(#)sys_generic.c       8.5 (Berkeley) 1/21/94
   37  */
   38 
   39 #include <sys/cdefs.h>
   40 __FBSDID("$FreeBSD$");
   41 
   42 #include "opt_capsicum.h"
   43 #include "opt_ktrace.h"
   44 
   45 #include <sys/param.h>
   46 #include <sys/systm.h>
   47 #include <sys/sysproto.h>
   48 #include <sys/capsicum.h>
   49 #include <sys/filedesc.h>
   50 #include <sys/filio.h>
   51 #include <sys/fcntl.h>
   52 #include <sys/file.h>
   53 #include <sys/lock.h>
   54 #include <sys/proc.h>
   55 #include <sys/signalvar.h>
   56 #include <sys/socketvar.h>
   57 #include <sys/uio.h>
   58 #include <sys/eventfd.h>
   59 #include <sys/kernel.h>
   60 #include <sys/ktr.h>
   61 #include <sys/limits.h>
   62 #include <sys/malloc.h>
   63 #include <sys/poll.h>
   64 #include <sys/resourcevar.h>
   65 #include <sys/selinfo.h>
   66 #include <sys/sleepqueue.h>
   67 #include <sys/specialfd.h>
   68 #include <sys/syscallsubr.h>
   69 #include <sys/sysctl.h>
   70 #include <sys/sysent.h>
   71 #include <sys/vnode.h>
   72 #include <sys/bio.h>
   73 #include <sys/buf.h>
   74 #include <sys/condvar.h>
   75 #ifdef KTRACE
   76 #include <sys/ktrace.h>
   77 #endif
   78 
   79 #include <security/audit/audit.h>
   80 
   81 /*
   82  * The following macro defines how many bytes will be allocated from
   83  * the stack instead of memory allocated when passing the IOCTL data
   84  * structures from userspace and to the kernel. Some IOCTLs having
   85  * small data structures are used very frequently and this small
   86  * buffer on the stack gives a significant speedup improvement for
   87  * those requests. The value of this define should be greater or equal
   88  * to 64 bytes and should also be power of two. The data structure is
   89  * currently hard-aligned to a 8-byte boundary on the stack. This
   90  * should currently be sufficient for all supported platforms.
   91  */
   92 #define SYS_IOCTL_SMALL_SIZE    128     /* bytes */
   93 #define SYS_IOCTL_SMALL_ALIGN   8       /* bytes */
   94 
   95 #ifdef __LP64__
   96 static int iosize_max_clamp = 0;
   97 SYSCTL_INT(_debug, OID_AUTO, iosize_max_clamp, CTLFLAG_RW,
   98     &iosize_max_clamp, 0, "Clamp max i/o size to INT_MAX");
   99 static int devfs_iosize_max_clamp = 1;
  100 SYSCTL_INT(_debug, OID_AUTO, devfs_iosize_max_clamp, CTLFLAG_RW,
  101     &devfs_iosize_max_clamp, 0, "Clamp max i/o size to INT_MAX for devices");
  102 #endif
  103 
  104 /*
  105  * Assert that the return value of read(2) and write(2) syscalls fits
  106  * into a register.  If not, an architecture will need to provide the
  107  * usermode wrappers to reconstruct the result.
  108  */
  109 CTASSERT(sizeof(register_t) >= sizeof(size_t));
  110 
  111 static MALLOC_DEFINE(M_IOCTLOPS, "ioctlops", "ioctl data buffer");
  112 static MALLOC_DEFINE(M_SELECT, "select", "select() buffer");
  113 MALLOC_DEFINE(M_IOV, "iov", "large iov's");
  114 
  115 static int      pollout(struct thread *, struct pollfd *, struct pollfd *,
  116                     u_int);
  117 static int      pollscan(struct thread *, struct pollfd *, u_int);
  118 static int      pollrescan(struct thread *);
  119 static int      selscan(struct thread *, fd_mask **, fd_mask **, int);
  120 static int      selrescan(struct thread *, fd_mask **, fd_mask **);
  121 static void     selfdalloc(struct thread *, void *);
  122 static void     selfdfree(struct seltd *, struct selfd *);
  123 static int      dofileread(struct thread *, int, struct file *, struct uio *,
  124                     off_t, int);
  125 static int      dofilewrite(struct thread *, int, struct file *, struct uio *,
  126                     off_t, int);
  127 static void     doselwakeup(struct selinfo *, int);
  128 static void     seltdinit(struct thread *);
  129 static int      seltdwait(struct thread *, sbintime_t, sbintime_t);
  130 static void     seltdclear(struct thread *);
  131 
  132 /*
  133  * One seltd per-thread allocated on demand as needed.
  134  *
  135  *      t - protected by st_mtx
  136  *      k - Only accessed by curthread or read-only
  137  */
  138 struct seltd {
  139         STAILQ_HEAD(, selfd)    st_selq;        /* (k) List of selfds. */
  140         struct selfd            *st_free1;      /* (k) free fd for read set. */
  141         struct selfd            *st_free2;      /* (k) free fd for write set. */
  142         struct mtx              st_mtx;         /* Protects struct seltd */
  143         struct cv               st_wait;        /* (t) Wait channel. */
  144         int                     st_flags;       /* (t) SELTD_ flags. */
  145 };
  146 
  147 #define SELTD_PENDING   0x0001                  /* We have pending events. */
  148 #define SELTD_RESCAN    0x0002                  /* Doing a rescan. */
  149 
  150 /*
  151  * One selfd allocated per-thread per-file-descriptor.
  152  *      f - protected by sf_mtx
  153  */
  154 struct selfd {
  155         STAILQ_ENTRY(selfd)     sf_link;        /* (k) fds owned by this td. */
  156         TAILQ_ENTRY(selfd)      sf_threads;     /* (f) fds on this selinfo. */
  157         struct selinfo          *sf_si;         /* (f) selinfo when linked. */
  158         struct mtx              *sf_mtx;        /* Pointer to selinfo mtx. */
  159         struct seltd            *sf_td;         /* (k) owning seltd. */
  160         void                    *sf_cookie;     /* (k) fd or pollfd. */
  161 };
  162 
  163 MALLOC_DEFINE(M_SELFD, "selfd", "selfd");
  164 static struct mtx_pool *mtxpool_select;
  165 
  166 #ifdef __LP64__
  167 size_t
  168 devfs_iosize_max(void)
  169 {
  170 
  171         return (devfs_iosize_max_clamp || SV_CURPROC_FLAG(SV_ILP32) ?
  172             INT_MAX : SSIZE_MAX);
  173 }
  174 
  175 size_t
  176 iosize_max(void)
  177 {
  178 
  179         return (iosize_max_clamp || SV_CURPROC_FLAG(SV_ILP32) ?
  180             INT_MAX : SSIZE_MAX);
  181 }
  182 #endif
  183 
  184 #ifndef _SYS_SYSPROTO_H_
  185 struct read_args {
  186         int     fd;
  187         void    *buf;
  188         size_t  nbyte;
  189 };
  190 #endif
  191 int
  192 sys_read(struct thread *td, struct read_args *uap)
  193 {
  194         struct uio auio;
  195         struct iovec aiov;
  196         int error;
  197 
  198         if (uap->nbyte > IOSIZE_MAX)
  199                 return (EINVAL);
  200         aiov.iov_base = uap->buf;
  201         aiov.iov_len = uap->nbyte;
  202         auio.uio_iov = &aiov;
  203         auio.uio_iovcnt = 1;
  204         auio.uio_resid = uap->nbyte;
  205         auio.uio_segflg = UIO_USERSPACE;
  206         error = kern_readv(td, uap->fd, &auio);
  207         return (error);
  208 }
  209 
  210 /*
  211  * Positioned read system call
  212  */
  213 #ifndef _SYS_SYSPROTO_H_
  214 struct pread_args {
  215         int     fd;
  216         void    *buf;
  217         size_t  nbyte;
  218         int     pad;
  219         off_t   offset;
  220 };
  221 #endif
  222 int
  223 sys_pread(struct thread *td, struct pread_args *uap)
  224 {
  225 
  226         return (kern_pread(td, uap->fd, uap->buf, uap->nbyte, uap->offset));
  227 }
  228 
  229 int
  230 kern_pread(struct thread *td, int fd, void *buf, size_t nbyte, off_t offset)
  231 {
  232         struct uio auio;
  233         struct iovec aiov;
  234         int error;
  235 
  236         if (nbyte > IOSIZE_MAX)
  237                 return (EINVAL);
  238         aiov.iov_base = buf;
  239         aiov.iov_len = nbyte;
  240         auio.uio_iov = &aiov;
  241         auio.uio_iovcnt = 1;
  242         auio.uio_resid = nbyte;
  243         auio.uio_segflg = UIO_USERSPACE;
  244         error = kern_preadv(td, fd, &auio, offset);
  245         return (error);
  246 }
  247 
  248 #if defined(COMPAT_FREEBSD6)
  249 int
  250 freebsd6_pread(struct thread *td, struct freebsd6_pread_args *uap)
  251 {
  252 
  253         return (kern_pread(td, uap->fd, uap->buf, uap->nbyte, uap->offset));
  254 }
  255 #endif
  256 
  257 /*
  258  * Scatter read system call.
  259  */
  260 #ifndef _SYS_SYSPROTO_H_
  261 struct readv_args {
  262         int     fd;
  263         struct  iovec *iovp;
  264         u_int   iovcnt;
  265 };
  266 #endif
  267 int
  268 sys_readv(struct thread *td, struct readv_args *uap)
  269 {
  270         struct uio *auio;
  271         int error;
  272 
  273         error = copyinuio(uap->iovp, uap->iovcnt, &auio);
  274         if (error)
  275                 return (error);
  276         error = kern_readv(td, uap->fd, auio);
  277         free(auio, M_IOV);
  278         return (error);
  279 }
  280 
  281 int
  282 kern_readv(struct thread *td, int fd, struct uio *auio)
  283 {
  284         struct file *fp;
  285         int error;
  286 
  287         error = fget_read(td, fd, &cap_read_rights, &fp);
  288         if (error)
  289                 return (error);
  290         error = dofileread(td, fd, fp, auio, (off_t)-1, 0);
  291         fdrop(fp, td);
  292         return (error);
  293 }
  294 
  295 /*
  296  * Scatter positioned read system call.
  297  */
  298 #ifndef _SYS_SYSPROTO_H_
  299 struct preadv_args {
  300         int     fd;
  301         struct  iovec *iovp;
  302         u_int   iovcnt;
  303         off_t   offset;
  304 };
  305 #endif
  306 int
  307 sys_preadv(struct thread *td, struct preadv_args *uap)
  308 {
  309         struct uio *auio;
  310         int error;
  311 
  312         error = copyinuio(uap->iovp, uap->iovcnt, &auio);
  313         if (error)
  314                 return (error);
  315         error = kern_preadv(td, uap->fd, auio, uap->offset);
  316         free(auio, M_IOV);
  317         return (error);
  318 }
  319 
  320 int
  321 kern_preadv(struct thread *td, int fd, struct uio *auio, off_t offset)
  322 {
  323         struct file *fp;
  324         int error;
  325 
  326         error = fget_read(td, fd, &cap_pread_rights, &fp);
  327         if (error)
  328                 return (error);
  329         if (!(fp->f_ops->fo_flags & DFLAG_SEEKABLE))
  330                 error = ESPIPE;
  331         else if (offset < 0 &&
  332             (fp->f_vnode == NULL || fp->f_vnode->v_type != VCHR))
  333                 error = EINVAL;
  334         else
  335                 error = dofileread(td, fd, fp, auio, offset, FOF_OFFSET);
  336         fdrop(fp, td);
  337         return (error);
  338 }
  339 
  340 /*
  341  * Common code for readv and preadv that reads data in
  342  * from a file using the passed in uio, offset, and flags.
  343  */
  344 static int
  345 dofileread(struct thread *td, int fd, struct file *fp, struct uio *auio,
  346     off_t offset, int flags)
  347 {
  348         ssize_t cnt;
  349         int error;
  350 #ifdef KTRACE
  351         struct uio *ktruio = NULL;
  352 #endif
  353 
  354         AUDIT_ARG_FD(fd);
  355 
  356         /* Finish zero length reads right here */
  357         if (auio->uio_resid == 0) {
  358                 td->td_retval[0] = 0;
  359                 return (0);
  360         }
  361         auio->uio_rw = UIO_READ;
  362         auio->uio_offset = offset;
  363         auio->uio_td = td;
  364 #ifdef KTRACE
  365         if (KTRPOINT(td, KTR_GENIO)) 
  366                 ktruio = cloneuio(auio);
  367 #endif
  368         cnt = auio->uio_resid;
  369         if ((error = fo_read(fp, auio, td->td_ucred, flags, td))) {
  370                 if (auio->uio_resid != cnt && (error == ERESTART ||
  371                     error == EINTR || error == EWOULDBLOCK))
  372                         error = 0;
  373         }
  374         cnt -= auio->uio_resid;
  375 #ifdef KTRACE
  376         if (ktruio != NULL) {
  377                 ktruio->uio_resid = cnt;
  378                 ktrgenio(fd, UIO_READ, ktruio, error);
  379         }
  380 #endif
  381         td->td_retval[0] = cnt;
  382         return (error);
  383 }
  384 
  385 #ifndef _SYS_SYSPROTO_H_
  386 struct write_args {
  387         int     fd;
  388         const void *buf;
  389         size_t  nbyte;
  390 };
  391 #endif
  392 int
  393 sys_write(struct thread *td, struct write_args *uap)
  394 {
  395         struct uio auio;
  396         struct iovec aiov;
  397         int error;
  398 
  399         if (uap->nbyte > IOSIZE_MAX)
  400                 return (EINVAL);
  401         aiov.iov_base = (void *)(uintptr_t)uap->buf;
  402         aiov.iov_len = uap->nbyte;
  403         auio.uio_iov = &aiov;
  404         auio.uio_iovcnt = 1;
  405         auio.uio_resid = uap->nbyte;
  406         auio.uio_segflg = UIO_USERSPACE;
  407         error = kern_writev(td, uap->fd, &auio);
  408         return (error);
  409 }
  410 
  411 /*
  412  * Positioned write system call.
  413  */
  414 #ifndef _SYS_SYSPROTO_H_
  415 struct pwrite_args {
  416         int     fd;
  417         const void *buf;
  418         size_t  nbyte;
  419         int     pad;
  420         off_t   offset;
  421 };
  422 #endif
  423 int
  424 sys_pwrite(struct thread *td, struct pwrite_args *uap)
  425 {
  426 
  427         return (kern_pwrite(td, uap->fd, uap->buf, uap->nbyte, uap->offset));
  428 }
  429 
  430 int
  431 kern_pwrite(struct thread *td, int fd, const void *buf, size_t nbyte,
  432     off_t offset)
  433 {
  434         struct uio auio;
  435         struct iovec aiov;
  436         int error;
  437 
  438         if (nbyte > IOSIZE_MAX)
  439                 return (EINVAL);
  440         aiov.iov_base = (void *)(uintptr_t)buf;
  441         aiov.iov_len = nbyte;
  442         auio.uio_iov = &aiov;
  443         auio.uio_iovcnt = 1;
  444         auio.uio_resid = nbyte;
  445         auio.uio_segflg = UIO_USERSPACE;
  446         error = kern_pwritev(td, fd, &auio, offset);
  447         return (error);
  448 }
  449 
  450 #if defined(COMPAT_FREEBSD6)
  451 int
  452 freebsd6_pwrite(struct thread *td, struct freebsd6_pwrite_args *uap)
  453 {
  454 
  455         return (kern_pwrite(td, uap->fd, uap->buf, uap->nbyte, uap->offset));
  456 }
  457 #endif
  458 
  459 /*
  460  * Gather write system call.
  461  */
  462 #ifndef _SYS_SYSPROTO_H_
  463 struct writev_args {
  464         int     fd;
  465         struct  iovec *iovp;
  466         u_int   iovcnt;
  467 };
  468 #endif
  469 int
  470 sys_writev(struct thread *td, struct writev_args *uap)
  471 {
  472         struct uio *auio;
  473         int error;
  474 
  475         error = copyinuio(uap->iovp, uap->iovcnt, &auio);
  476         if (error)
  477                 return (error);
  478         error = kern_writev(td, uap->fd, auio);
  479         free(auio, M_IOV);
  480         return (error);
  481 }
  482 
  483 int
  484 kern_writev(struct thread *td, int fd, struct uio *auio)
  485 {
  486         struct file *fp;
  487         int error;
  488 
  489         error = fget_write(td, fd, &cap_write_rights, &fp);
  490         if (error)
  491                 return (error);
  492         error = dofilewrite(td, fd, fp, auio, (off_t)-1, 0);
  493         fdrop(fp, td);
  494         return (error);
  495 }
  496 
  497 /*
  498  * Gather positioned write system call.
  499  */
  500 #ifndef _SYS_SYSPROTO_H_
  501 struct pwritev_args {
  502         int     fd;
  503         struct  iovec *iovp;
  504         u_int   iovcnt;
  505         off_t   offset;
  506 };
  507 #endif
  508 int
  509 sys_pwritev(struct thread *td, struct pwritev_args *uap)
  510 {
  511         struct uio *auio;
  512         int error;
  513 
  514         error = copyinuio(uap->iovp, uap->iovcnt, &auio);
  515         if (error)
  516                 return (error);
  517         error = kern_pwritev(td, uap->fd, auio, uap->offset);
  518         free(auio, M_IOV);
  519         return (error);
  520 }
  521 
  522 int
  523 kern_pwritev(struct thread *td, int fd, struct uio *auio, off_t offset)
  524 {
  525         struct file *fp;
  526         int error;
  527 
  528         error = fget_write(td, fd, &cap_pwrite_rights, &fp);
  529         if (error)
  530                 return (error);
  531         if (!(fp->f_ops->fo_flags & DFLAG_SEEKABLE))
  532                 error = ESPIPE;
  533         else if (offset < 0 &&
  534             (fp->f_vnode == NULL || fp->f_vnode->v_type != VCHR))
  535                 error = EINVAL;
  536         else
  537                 error = dofilewrite(td, fd, fp, auio, offset, FOF_OFFSET);
  538         fdrop(fp, td);
  539         return (error);
  540 }
  541 
  542 /*
  543  * Common code for writev and pwritev that writes data to
  544  * a file using the passed in uio, offset, and flags.
  545  */
  546 static int
  547 dofilewrite(struct thread *td, int fd, struct file *fp, struct uio *auio,
  548     off_t offset, int flags)
  549 {
  550         ssize_t cnt;
  551         int error;
  552 #ifdef KTRACE
  553         struct uio *ktruio = NULL;
  554 #endif
  555 
  556         AUDIT_ARG_FD(fd);
  557         auio->uio_rw = UIO_WRITE;
  558         auio->uio_td = td;
  559         auio->uio_offset = offset;
  560 #ifdef KTRACE
  561         if (KTRPOINT(td, KTR_GENIO))
  562                 ktruio = cloneuio(auio);
  563 #endif
  564         cnt = auio->uio_resid;
  565         error = fo_write(fp, auio, td->td_ucred, flags, td);
  566         /*
  567          * Socket layer is responsible for special error handling,
  568          * see sousrsend().
  569          */
  570         if (error != 0 && fp->f_type != DTYPE_SOCKET) {
  571                 if (auio->uio_resid != cnt && (error == ERESTART ||
  572                     error == EINTR || error == EWOULDBLOCK))
  573                         error = 0;
  574                 if (error == EPIPE) {
  575                         PROC_LOCK(td->td_proc);
  576                         tdsignal(td, SIGPIPE);
  577                         PROC_UNLOCK(td->td_proc);
  578                 }
  579         }
  580         cnt -= auio->uio_resid;
  581 #ifdef KTRACE
  582         if (ktruio != NULL) {
  583                 ktruio->uio_resid = cnt;
  584                 ktrgenio(fd, UIO_WRITE, ktruio, error);
  585         }
  586 #endif
  587         td->td_retval[0] = cnt;
  588         return (error);
  589 }
  590 
  591 /*
  592  * Truncate a file given a file descriptor.
  593  *
  594  * Can't use fget_write() here, since must return EINVAL and not EBADF if the
  595  * descriptor isn't writable.
  596  */
  597 int
  598 kern_ftruncate(struct thread *td, int fd, off_t length)
  599 {
  600         struct file *fp;
  601         int error;
  602 
  603         AUDIT_ARG_FD(fd);
  604         if (length < 0)
  605                 return (EINVAL);
  606         error = fget(td, fd, &cap_ftruncate_rights, &fp);
  607         if (error)
  608                 return (error);
  609         AUDIT_ARG_FILE(td->td_proc, fp);
  610         if (!(fp->f_flag & FWRITE)) {
  611                 fdrop(fp, td);
  612                 return (EINVAL);
  613         }
  614         error = fo_truncate(fp, length, td->td_ucred, td);
  615         fdrop(fp, td);
  616         return (error);
  617 }
  618 
  619 #ifndef _SYS_SYSPROTO_H_
  620 struct ftruncate_args {
  621         int     fd;
  622         int     pad;
  623         off_t   length;
  624 };
  625 #endif
  626 int
  627 sys_ftruncate(struct thread *td, struct ftruncate_args *uap)
  628 {
  629 
  630         return (kern_ftruncate(td, uap->fd, uap->length));
  631 }
  632 
  633 #if defined(COMPAT_43)
  634 #ifndef _SYS_SYSPROTO_H_
  635 struct oftruncate_args {
  636         int     fd;
  637         long    length;
  638 };
  639 #endif
  640 int
  641 oftruncate(struct thread *td, struct oftruncate_args *uap)
  642 {
  643 
  644         return (kern_ftruncate(td, uap->fd, uap->length));
  645 }
  646 #endif /* COMPAT_43 */
  647 
  648 #ifndef _SYS_SYSPROTO_H_
  649 struct ioctl_args {
  650         int     fd;
  651         u_long  com;
  652         caddr_t data;
  653 };
  654 #endif
  655 /* ARGSUSED */
  656 int
  657 sys_ioctl(struct thread *td, struct ioctl_args *uap)
  658 {
  659         u_char smalldata[SYS_IOCTL_SMALL_SIZE] __aligned(SYS_IOCTL_SMALL_ALIGN);
  660         uint32_t com;
  661         int arg, error;
  662         u_int size;
  663         caddr_t data;
  664 
  665 #ifdef INVARIANTS
  666         if (uap->com > 0xffffffff) {
  667                 printf(
  668                     "WARNING pid %d (%s): ioctl sign-extension ioctl %lx\n",
  669                     td->td_proc->p_pid, td->td_name, uap->com);
  670         }
  671 #endif
  672         com = (uint32_t)uap->com;
  673 
  674         /*
  675          * Interpret high order word to find amount of data to be
  676          * copied to/from the user's address space.
  677          */
  678         size = IOCPARM_LEN(com);
  679         if ((size > IOCPARM_MAX) ||
  680             ((com & (IOC_VOID  | IOC_IN | IOC_OUT)) == 0) ||
  681 #if defined(COMPAT_FREEBSD5) || defined(COMPAT_FREEBSD4) || defined(COMPAT_43)
  682             ((com & IOC_OUT) && size == 0) ||
  683 #else
  684             ((com & (IOC_IN | IOC_OUT)) && size == 0) ||
  685 #endif
  686             ((com & IOC_VOID) && size > 0 && size != sizeof(int)))
  687                 return (ENOTTY);
  688 
  689         if (size > 0) {
  690                 if (com & IOC_VOID) {
  691                         /* Integer argument. */
  692                         arg = (intptr_t)uap->data;
  693                         data = (void *)&arg;
  694                         size = 0;
  695                 } else {
  696                         if (size > SYS_IOCTL_SMALL_SIZE)
  697                                 data = malloc((u_long)size, M_IOCTLOPS, M_WAITOK);
  698                         else
  699                                 data = smalldata;
  700                 }
  701         } else
  702                 data = (void *)&uap->data;
  703         if (com & IOC_IN) {
  704                 error = copyin(uap->data, data, (u_int)size);
  705                 if (error != 0)
  706                         goto out;
  707         } else if (com & IOC_OUT) {
  708                 /*
  709                  * Zero the buffer so the user always
  710                  * gets back something deterministic.
  711                  */
  712                 bzero(data, size);
  713         }
  714 
  715         error = kern_ioctl(td, uap->fd, com, data);
  716 
  717         if (error == 0 && (com & IOC_OUT))
  718                 error = copyout(data, uap->data, (u_int)size);
  719 
  720 out:
  721         if (size > SYS_IOCTL_SMALL_SIZE)
  722                 free(data, M_IOCTLOPS);
  723         return (error);
  724 }
  725 
  726 int
  727 kern_ioctl(struct thread *td, int fd, u_long com, caddr_t data)
  728 {
  729         struct file *fp;
  730         struct filedesc *fdp;
  731         int error, tmp, locked;
  732 
  733         AUDIT_ARG_FD(fd);
  734         AUDIT_ARG_CMD(com);
  735 
  736         fdp = td->td_proc->p_fd;
  737 
  738         switch (com) {
  739         case FIONCLEX:
  740         case FIOCLEX:
  741                 FILEDESC_XLOCK(fdp);
  742                 locked = LA_XLOCKED;
  743                 break;
  744         default:
  745 #ifdef CAPABILITIES
  746                 FILEDESC_SLOCK(fdp);
  747                 locked = LA_SLOCKED;
  748 #else
  749                 locked = LA_UNLOCKED;
  750 #endif
  751                 break;
  752         }
  753 
  754 #ifdef CAPABILITIES
  755         if ((fp = fget_noref(fdp, fd)) == NULL) {
  756                 error = EBADF;
  757                 goto out;
  758         }
  759         if ((error = cap_ioctl_check(fdp, fd, com)) != 0) {
  760                 fp = NULL;      /* fhold() was not called yet */
  761                 goto out;
  762         }
  763         if (!fhold(fp)) {
  764                 error = EBADF;
  765                 fp = NULL;
  766                 goto out;
  767         }
  768         if (locked == LA_SLOCKED) {
  769                 FILEDESC_SUNLOCK(fdp);
  770                 locked = LA_UNLOCKED;
  771         }
  772 #else
  773         error = fget(td, fd, &cap_ioctl_rights, &fp);
  774         if (error != 0) {
  775                 fp = NULL;
  776                 goto out;
  777         }
  778 #endif
  779         if ((fp->f_flag & (FREAD | FWRITE)) == 0) {
  780                 error = EBADF;
  781                 goto out;
  782         }
  783 
  784         switch (com) {
  785         case FIONCLEX:
  786                 fdp->fd_ofiles[fd].fde_flags &= ~UF_EXCLOSE;
  787                 goto out;
  788         case FIOCLEX:
  789                 fdp->fd_ofiles[fd].fde_flags |= UF_EXCLOSE;
  790                 goto out;
  791         case FIONBIO:
  792                 if ((tmp = *(int *)data))
  793                         atomic_set_int(&fp->f_flag, FNONBLOCK);
  794                 else
  795                         atomic_clear_int(&fp->f_flag, FNONBLOCK);
  796                 data = (void *)&tmp;
  797                 break;
  798         case FIOASYNC:
  799                 if ((tmp = *(int *)data))
  800                         atomic_set_int(&fp->f_flag, FASYNC);
  801                 else
  802                         atomic_clear_int(&fp->f_flag, FASYNC);
  803                 data = (void *)&tmp;
  804                 break;
  805         }
  806 
  807         error = fo_ioctl(fp, com, data, td->td_ucred, td);
  808 out:
  809         switch (locked) {
  810         case LA_XLOCKED:
  811                 FILEDESC_XUNLOCK(fdp);
  812                 break;
  813 #ifdef CAPABILITIES
  814         case LA_SLOCKED:
  815                 FILEDESC_SUNLOCK(fdp);
  816                 break;
  817 #endif
  818         default:
  819                 FILEDESC_UNLOCK_ASSERT(fdp);
  820                 break;
  821         }
  822         if (fp != NULL)
  823                 fdrop(fp, td);
  824         return (error);
  825 }
  826 
  827 int
  828 sys_posix_fallocate(struct thread *td, struct posix_fallocate_args *uap)
  829 {
  830         int error;
  831 
  832         error = kern_posix_fallocate(td, uap->fd, uap->offset, uap->len);
  833         return (kern_posix_error(td, error));
  834 }
  835 
  836 int
  837 kern_posix_fallocate(struct thread *td, int fd, off_t offset, off_t len)
  838 {
  839         struct file *fp;
  840         int error;
  841 
  842         AUDIT_ARG_FD(fd);
  843         if (offset < 0 || len <= 0)
  844                 return (EINVAL);
  845         /* Check for wrap. */
  846         if (offset > OFF_MAX - len)
  847                 return (EFBIG);
  848         AUDIT_ARG_FD(fd);
  849         error = fget(td, fd, &cap_pwrite_rights, &fp);
  850         if (error != 0)
  851                 return (error);
  852         AUDIT_ARG_FILE(td->td_proc, fp);
  853         if ((fp->f_ops->fo_flags & DFLAG_SEEKABLE) == 0) {
  854                 error = ESPIPE;
  855                 goto out;
  856         }
  857         if ((fp->f_flag & FWRITE) == 0) {
  858                 error = EBADF;
  859                 goto out;
  860         }
  861 
  862         error = fo_fallocate(fp, offset, len, td);
  863  out:
  864         fdrop(fp, td);
  865         return (error);
  866 }
  867 
  868 int
  869 sys_fspacectl(struct thread *td, struct fspacectl_args *uap)
  870 {
  871         struct spacectl_range rqsr, rmsr;
  872         int error, cerror;
  873 
  874         error = copyin(uap->rqsr, &rqsr, sizeof(rqsr));
  875         if (error != 0)
  876                 return (error);
  877 
  878         error = kern_fspacectl(td, uap->fd, uap->cmd, &rqsr, uap->flags,
  879             &rmsr);
  880         if (uap->rmsr != NULL) {
  881                 cerror = copyout(&rmsr, uap->rmsr, sizeof(rmsr));
  882                 if (error == 0)
  883                         error = cerror;
  884         }
  885         return (error);
  886 }
  887 
  888 int
  889 kern_fspacectl(struct thread *td, int fd, int cmd,
  890     const struct spacectl_range *rqsr, int flags, struct spacectl_range *rmsrp)
  891 {
  892         struct file *fp;
  893         struct spacectl_range rmsr;
  894         int error;
  895 
  896         AUDIT_ARG_FD(fd);
  897         AUDIT_ARG_CMD(cmd);
  898         AUDIT_ARG_FFLAGS(flags);
  899 
  900         if (rqsr == NULL)
  901                 return (EINVAL);
  902         rmsr = *rqsr;
  903         if (rmsrp != NULL)
  904                 *rmsrp = rmsr;
  905 
  906         if (cmd != SPACECTL_DEALLOC ||
  907             rqsr->r_offset < 0 || rqsr->r_len <= 0 ||
  908             rqsr->r_offset > OFF_MAX - rqsr->r_len ||
  909             (flags & ~SPACECTL_F_SUPPORTED) != 0)
  910                 return (EINVAL);
  911 
  912         error = fget_write(td, fd, &cap_pwrite_rights, &fp);
  913         if (error != 0)
  914                 return (error);
  915         AUDIT_ARG_FILE(td->td_proc, fp);
  916         if ((fp->f_ops->fo_flags & DFLAG_SEEKABLE) == 0) {
  917                 error = ESPIPE;
  918                 goto out;
  919         }
  920         if ((fp->f_flag & FWRITE) == 0) {
  921                 error = EBADF;
  922                 goto out;
  923         }
  924 
  925         error = fo_fspacectl(fp, cmd, &rmsr.r_offset, &rmsr.r_len, flags,
  926             td->td_ucred, td);
  927         /* fspacectl is not restarted after signals if the file is modified. */
  928         if (rmsr.r_len != rqsr->r_len && (error == ERESTART ||
  929             error == EINTR || error == EWOULDBLOCK))
  930                 error = 0;
  931         if (rmsrp != NULL)
  932                 *rmsrp = rmsr;
  933 out:
  934         fdrop(fp, td);
  935         return (error);
  936 }
  937 
  938 int
  939 kern_specialfd(struct thread *td, int type, void *arg)
  940 {
  941         struct file *fp;
  942         struct specialfd_eventfd *ae;
  943         int error, fd, fflags;
  944 
  945         fflags = 0;
  946         error = falloc_noinstall(td, &fp);
  947         if (error != 0)
  948                 return (error);
  949 
  950         switch (type) {
  951         case SPECIALFD_EVENTFD:
  952                 ae = arg;
  953                 if ((ae->flags & EFD_CLOEXEC) != 0)
  954                         fflags |= O_CLOEXEC;
  955                 error = eventfd_create_file(td, fp, ae->initval, ae->flags);
  956                 break;
  957         default:
  958                 error = EINVAL;
  959                 break;
  960         }
  961 
  962         if (error == 0)
  963                 error = finstall(td, fp, &fd, fflags, NULL);
  964         fdrop(fp, td);
  965         if (error == 0)
  966                 td->td_retval[0] = fd;
  967         return (error);
  968 }
  969 
  970 int
  971 sys___specialfd(struct thread *td, struct __specialfd_args *args)
  972 {
  973         struct specialfd_eventfd ae;
  974         int error;
  975 
  976         switch (args->type) {
  977         case SPECIALFD_EVENTFD:
  978                 if (args->len != sizeof(struct specialfd_eventfd)) {
  979                         error = EINVAL;
  980                         break;
  981                 }
  982                 error = copyin(args->req, &ae, sizeof(ae));
  983                 if (error != 0)
  984                         break;
  985                 if ((ae.flags & ~(EFD_CLOEXEC | EFD_NONBLOCK |
  986                     EFD_SEMAPHORE)) != 0) {
  987                         error = EINVAL;
  988                         break;
  989                 }
  990                 error = kern_specialfd(td, args->type, &ae);
  991                 break;
  992         default:
  993                 error = EINVAL;
  994                 break;
  995         }
  996         return (error);
  997 }
  998 
  999 int
 1000 poll_no_poll(int events)
 1001 {
 1002         /*
 1003          * Return true for read/write.  If the user asked for something
 1004          * special, return POLLNVAL, so that clients have a way of
 1005          * determining reliably whether or not the extended
 1006          * functionality is present without hard-coding knowledge
 1007          * of specific filesystem implementations.
 1008          */
 1009         if (events & ~POLLSTANDARD)
 1010                 return (POLLNVAL);
 1011 
 1012         return (events & (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM));
 1013 }
 1014 
 1015 int
 1016 sys_pselect(struct thread *td, struct pselect_args *uap)
 1017 {
 1018         struct timespec ts;
 1019         struct timeval tv, *tvp;
 1020         sigset_t set, *uset;
 1021         int error;
 1022 
 1023         if (uap->ts != NULL) {
 1024                 error = copyin(uap->ts, &ts, sizeof(ts));
 1025                 if (error != 0)
 1026                     return (error);
 1027                 TIMESPEC_TO_TIMEVAL(&tv, &ts);
 1028                 tvp = &tv;
 1029         } else
 1030                 tvp = NULL;
 1031         if (uap->sm != NULL) {
 1032                 error = copyin(uap->sm, &set, sizeof(set));
 1033                 if (error != 0)
 1034                         return (error);
 1035                 uset = &set;
 1036         } else
 1037                 uset = NULL;
 1038         return (kern_pselect(td, uap->nd, uap->in, uap->ou, uap->ex, tvp,
 1039             uset, NFDBITS));
 1040 }
 1041 
 1042 int
 1043 kern_pselect(struct thread *td, int nd, fd_set *in, fd_set *ou, fd_set *ex,
 1044     struct timeval *tvp, sigset_t *uset, int abi_nfdbits)
 1045 {
 1046         int error;
 1047 
 1048         if (uset != NULL) {
 1049                 error = kern_sigprocmask(td, SIG_SETMASK, uset,
 1050                     &td->td_oldsigmask, 0);
 1051                 if (error != 0)
 1052                         return (error);
 1053                 td->td_pflags |= TDP_OLDMASK;
 1054                 /*
 1055                  * Make sure that ast() is called on return to
 1056                  * usermode and TDP_OLDMASK is cleared, restoring old
 1057                  * sigmask.
 1058                  */
 1059                 ast_sched(td, TDA_SIGSUSPEND);
 1060         }
 1061         error = kern_select(td, nd, in, ou, ex, tvp, abi_nfdbits);
 1062         return (error);
 1063 }
 1064 
 1065 #ifndef _SYS_SYSPROTO_H_
 1066 struct select_args {
 1067         int     nd;
 1068         fd_set  *in, *ou, *ex;
 1069         struct  timeval *tv;
 1070 };
 1071 #endif
 1072 int
 1073 sys_select(struct thread *td, struct select_args *uap)
 1074 {
 1075         struct timeval tv, *tvp;
 1076         int error;
 1077 
 1078         if (uap->tv != NULL) {
 1079                 error = copyin(uap->tv, &tv, sizeof(tv));
 1080                 if (error)
 1081                         return (error);
 1082                 tvp = &tv;
 1083         } else
 1084                 tvp = NULL;
 1085 
 1086         return (kern_select(td, uap->nd, uap->in, uap->ou, uap->ex, tvp,
 1087             NFDBITS));
 1088 }
 1089 
 1090 /*
 1091  * In the unlikely case when user specified n greater then the last
 1092  * open file descriptor, check that no bits are set after the last
 1093  * valid fd.  We must return EBADF if any is set.
 1094  *
 1095  * There are applications that rely on the behaviour.
 1096  *
 1097  * nd is fd_nfiles.
 1098  */
 1099 static int
 1100 select_check_badfd(fd_set *fd_in, int nd, int ndu, int abi_nfdbits)
 1101 {
 1102         char *addr, *oaddr;
 1103         int b, i, res;
 1104         uint8_t bits;
 1105 
 1106         if (nd >= ndu || fd_in == NULL)
 1107                 return (0);
 1108 
 1109         oaddr = NULL;
 1110         bits = 0; /* silence gcc */
 1111         for (i = nd; i < ndu; i++) {
 1112                 b = i / NBBY;
 1113 #if BYTE_ORDER == LITTLE_ENDIAN
 1114                 addr = (char *)fd_in + b;
 1115 #else
 1116                 addr = (char *)fd_in;
 1117                 if (abi_nfdbits == NFDBITS) {
 1118                         addr += rounddown(b, sizeof(fd_mask)) +
 1119                             sizeof(fd_mask) - 1 - b % sizeof(fd_mask);
 1120                 } else {
 1121                         addr += rounddown(b, sizeof(uint32_t)) +
 1122                             sizeof(uint32_t) - 1 - b % sizeof(uint32_t);
 1123                 }
 1124 #endif
 1125                 if (addr != oaddr) {
 1126                         res = fubyte(addr);
 1127                         if (res == -1)
 1128                                 return (EFAULT);
 1129                         oaddr = addr;
 1130                         bits = res;
 1131                 }
 1132                 if ((bits & (1 << (i % NBBY))) != 0)
 1133                         return (EBADF);
 1134         }
 1135         return (0);
 1136 }
 1137 
 1138 int
 1139 kern_select(struct thread *td, int nd, fd_set *fd_in, fd_set *fd_ou,
 1140     fd_set *fd_ex, struct timeval *tvp, int abi_nfdbits)
 1141 {
 1142         struct filedesc *fdp;
 1143         /*
 1144          * The magic 2048 here is chosen to be just enough for FD_SETSIZE
 1145          * infds with the new FD_SETSIZE of 1024, and more than enough for
 1146          * FD_SETSIZE infds, outfds and exceptfds with the old FD_SETSIZE
 1147          * of 256.
 1148          */
 1149         fd_mask s_selbits[howmany(2048, NFDBITS)];
 1150         fd_mask *ibits[3], *obits[3], *selbits, *sbp;
 1151         struct timeval rtv;
 1152         sbintime_t asbt, precision, rsbt;
 1153         u_int nbufbytes, ncpbytes, ncpubytes, nfdbits;
 1154         int error, lf, ndu;
 1155 
 1156         if (nd < 0)
 1157                 return (EINVAL);
 1158         fdp = td->td_proc->p_fd;
 1159         ndu = nd;
 1160         lf = fdp->fd_nfiles;
 1161         if (nd > lf)
 1162                 nd = lf;
 1163 
 1164         error = select_check_badfd(fd_in, nd, ndu, abi_nfdbits);
 1165         if (error != 0)
 1166                 return (error);
 1167         error = select_check_badfd(fd_ou, nd, ndu, abi_nfdbits);
 1168         if (error != 0)
 1169                 return (error);
 1170         error = select_check_badfd(fd_ex, nd, ndu, abi_nfdbits);
 1171         if (error != 0)
 1172                 return (error);
 1173 
 1174         /*
 1175          * Allocate just enough bits for the non-null fd_sets.  Use the
 1176          * preallocated auto buffer if possible.
 1177          */
 1178         nfdbits = roundup(nd, NFDBITS);
 1179         ncpbytes = nfdbits / NBBY;
 1180         ncpubytes = roundup(nd, abi_nfdbits) / NBBY;
 1181         nbufbytes = 0;
 1182         if (fd_in != NULL)
 1183                 nbufbytes += 2 * ncpbytes;
 1184         if (fd_ou != NULL)
 1185                 nbufbytes += 2 * ncpbytes;
 1186         if (fd_ex != NULL)
 1187                 nbufbytes += 2 * ncpbytes;
 1188         if (nbufbytes <= sizeof s_selbits)
 1189                 selbits = &s_selbits[0];
 1190         else
 1191                 selbits = malloc(nbufbytes, M_SELECT, M_WAITOK);
 1192 
 1193         /*
 1194          * Assign pointers into the bit buffers and fetch the input bits.
 1195          * Put the output buffers together so that they can be bzeroed
 1196          * together.
 1197          */
 1198         sbp = selbits;
 1199 #define getbits(name, x) \
 1200         do {                                                            \
 1201                 if (name == NULL) {                                     \
 1202                         ibits[x] = NULL;                                \
 1203                         obits[x] = NULL;                                \
 1204                 } else {                                                \
 1205                         ibits[x] = sbp + nbufbytes / 2 / sizeof *sbp;   \
 1206                         obits[x] = sbp;                                 \
 1207                         sbp += ncpbytes / sizeof *sbp;                  \
 1208                         error = copyin(name, ibits[x], ncpubytes);      \
 1209                         if (error != 0)                                 \
 1210                                 goto done;                              \
 1211                         if (ncpbytes != ncpubytes)                      \
 1212                                 bzero((char *)ibits[x] + ncpubytes,     \
 1213                                     ncpbytes - ncpubytes);              \
 1214                 }                                                       \
 1215         } while (0)
 1216         getbits(fd_in, 0);
 1217         getbits(fd_ou, 1);
 1218         getbits(fd_ex, 2);
 1219 #undef  getbits
 1220 
 1221 #if BYTE_ORDER == BIG_ENDIAN && defined(__LP64__)
 1222         /*
 1223          * XXX: swizzle_fdset assumes that if abi_nfdbits != NFDBITS,
 1224          * we are running under 32-bit emulation. This should be more
 1225          * generic.
 1226          */
 1227 #define swizzle_fdset(bits)                                             \
 1228         if (abi_nfdbits != NFDBITS && bits != NULL) {                   \
 1229                 int i;                                                  \
 1230                 for (i = 0; i < ncpbytes / sizeof *sbp; i++)            \
 1231                         bits[i] = (bits[i] >> 32) | (bits[i] << 32);    \
 1232         }
 1233 #else
 1234 #define swizzle_fdset(bits)
 1235 #endif
 1236 
 1237         /* Make sure the bit order makes it through an ABI transition */
 1238         swizzle_fdset(ibits[0]);
 1239         swizzle_fdset(ibits[1]);
 1240         swizzle_fdset(ibits[2]);
 1241 
 1242         if (nbufbytes != 0)
 1243                 bzero(selbits, nbufbytes / 2);
 1244 
 1245         precision = 0;
 1246         if (tvp != NULL) {
 1247                 rtv = *tvp;
 1248                 if (rtv.tv_sec < 0 || rtv.tv_usec < 0 ||
 1249                     rtv.tv_usec >= 1000000) {
 1250                         error = EINVAL;
 1251                         goto done;
 1252                 }
 1253                 if (!timevalisset(&rtv))
 1254                         asbt = 0;
 1255                 else if (rtv.tv_sec <= INT32_MAX) {
 1256                         rsbt = tvtosbt(rtv);
 1257                         precision = rsbt;
 1258                         precision >>= tc_precexp;
 1259                         if (TIMESEL(&asbt, rsbt))
 1260                                 asbt += tc_tick_sbt;
 1261                         if (asbt <= SBT_MAX - rsbt)
 1262                                 asbt += rsbt;
 1263                         else
 1264                                 asbt = -1;
 1265                 } else
 1266                         asbt = -1;
 1267         } else
 1268                 asbt = -1;
 1269         seltdinit(td);
 1270         /* Iterate until the timeout expires or descriptors become ready. */
 1271         for (;;) {
 1272                 error = selscan(td, ibits, obits, nd);
 1273                 if (error || td->td_retval[0] != 0)
 1274                         break;
 1275                 error = seltdwait(td, asbt, precision);
 1276                 if (error)
 1277                         break;
 1278                 error = selrescan(td, ibits, obits);
 1279                 if (error || td->td_retval[0] != 0)
 1280                         break;
 1281         }
 1282         seltdclear(td);
 1283 
 1284 done:
 1285         /* select is not restarted after signals... */
 1286         if (error == ERESTART)
 1287                 error = EINTR;
 1288         if (error == EWOULDBLOCK)
 1289                 error = 0;
 1290 
 1291         /* swizzle bit order back, if necessary */
 1292         swizzle_fdset(obits[0]);
 1293         swizzle_fdset(obits[1]);
 1294         swizzle_fdset(obits[2]);
 1295 #undef swizzle_fdset
 1296 
 1297 #define putbits(name, x) \
 1298         if (name && (error2 = copyout(obits[x], name, ncpubytes))) \
 1299                 error = error2;
 1300         if (error == 0) {
 1301                 int error2;
 1302 
 1303                 putbits(fd_in, 0);
 1304                 putbits(fd_ou, 1);
 1305                 putbits(fd_ex, 2);
 1306 #undef putbits
 1307         }
 1308         if (selbits != &s_selbits[0])
 1309                 free(selbits, M_SELECT);
 1310 
 1311         return (error);
 1312 }
 1313 /* 
 1314  * Convert a select bit set to poll flags.
 1315  *
 1316  * The backend always returns POLLHUP/POLLERR if appropriate and we
 1317  * return this as a set bit in any set.
 1318  */
 1319 static const int select_flags[3] = {
 1320     POLLRDNORM | POLLHUP | POLLERR,
 1321     POLLWRNORM | POLLHUP | POLLERR,
 1322     POLLRDBAND | POLLERR
 1323 };
 1324 
 1325 /*
 1326  * Compute the fo_poll flags required for a fd given by the index and
 1327  * bit position in the fd_mask array.
 1328  */
 1329 static __inline int
 1330 selflags(fd_mask **ibits, int idx, fd_mask bit)
 1331 {
 1332         int flags;
 1333         int msk;
 1334 
 1335         flags = 0;
 1336         for (msk = 0; msk < 3; msk++) {
 1337                 if (ibits[msk] == NULL)
 1338                         continue;
 1339                 if ((ibits[msk][idx] & bit) == 0)
 1340                         continue;
 1341                 flags |= select_flags[msk];
 1342         }
 1343         return (flags);
 1344 }
 1345 
 1346 /*
 1347  * Set the appropriate output bits given a mask of fired events and the
 1348  * input bits originally requested.
 1349  */
 1350 static __inline int
 1351 selsetbits(fd_mask **ibits, fd_mask **obits, int idx, fd_mask bit, int events)
 1352 {
 1353         int msk;
 1354         int n;
 1355 
 1356         n = 0;
 1357         for (msk = 0; msk < 3; msk++) {
 1358                 if ((events & select_flags[msk]) == 0)
 1359                         continue;
 1360                 if (ibits[msk] == NULL)
 1361                         continue;
 1362                 if ((ibits[msk][idx] & bit) == 0)
 1363                         continue;
 1364                 /*
 1365                  * XXX Check for a duplicate set.  This can occur because a
 1366                  * socket calls selrecord() twice for each poll() call
 1367                  * resulting in two selfds per real fd.  selrescan() will
 1368                  * call selsetbits twice as a result.
 1369                  */
 1370                 if ((obits[msk][idx] & bit) != 0)
 1371                         continue;
 1372                 obits[msk][idx] |= bit;
 1373                 n++;
 1374         }
 1375 
 1376         return (n);
 1377 }
 1378 
 1379 /*
 1380  * Traverse the list of fds attached to this thread's seltd and check for
 1381  * completion.
 1382  */
 1383 static int
 1384 selrescan(struct thread *td, fd_mask **ibits, fd_mask **obits)
 1385 {
 1386         struct filedesc *fdp;
 1387         struct selinfo *si;
 1388         struct seltd *stp;
 1389         struct selfd *sfp;
 1390         struct selfd *sfn;
 1391         struct file *fp;
 1392         fd_mask bit;
 1393         int fd, ev, n, idx;
 1394         int error;
 1395         bool only_user;
 1396 
 1397         fdp = td->td_proc->p_fd;
 1398         stp = td->td_sel;
 1399         n = 0;
 1400         only_user = FILEDESC_IS_ONLY_USER(fdp);
 1401         STAILQ_FOREACH_SAFE(sfp, &stp->st_selq, sf_link, sfn) {
 1402                 fd = (int)(uintptr_t)sfp->sf_cookie;
 1403                 si = sfp->sf_si;
 1404                 selfdfree(stp, sfp);
 1405                 /* If the selinfo wasn't cleared the event didn't fire. */
 1406                 if (si != NULL)
 1407                         continue;
 1408                 if (only_user)
 1409                         error = fget_only_user(fdp, fd, &cap_event_rights, &fp);
 1410                 else
 1411                         error = fget_unlocked(td, fd, &cap_event_rights, &fp);
 1412                 if (__predict_false(error != 0))
 1413                         return (error);
 1414                 idx = fd / NFDBITS;
 1415                 bit = (fd_mask)1 << (fd % NFDBITS);
 1416                 ev = fo_poll(fp, selflags(ibits, idx, bit), td->td_ucred, td);
 1417                 if (only_user)
 1418                         fput_only_user(fdp, fp);
 1419                 else
 1420                         fdrop(fp, td);
 1421                 if (ev != 0)
 1422                         n += selsetbits(ibits, obits, idx, bit, ev);
 1423         }
 1424         stp->st_flags = 0;
 1425         td->td_retval[0] = n;
 1426         return (0);
 1427 }
 1428 
 1429 /*
 1430  * Perform the initial filedescriptor scan and register ourselves with
 1431  * each selinfo.
 1432  */
 1433 static int
 1434 selscan(struct thread *td, fd_mask **ibits, fd_mask **obits, int nfd)
 1435 {
 1436         struct filedesc *fdp;
 1437         struct file *fp;
 1438         fd_mask bit;
 1439         int ev, flags, end, fd;
 1440         int n, idx;
 1441         int error;
 1442         bool only_user;
 1443 
 1444         fdp = td->td_proc->p_fd;
 1445         n = 0;
 1446         only_user = FILEDESC_IS_ONLY_USER(fdp);
 1447         for (idx = 0, fd = 0; fd < nfd; idx++) {
 1448                 end = imin(fd + NFDBITS, nfd);
 1449                 for (bit = 1; fd < end; bit <<= 1, fd++) {
 1450                         /* Compute the list of events we're interested in. */
 1451                         flags = selflags(ibits, idx, bit);
 1452                         if (flags == 0)
 1453                                 continue;
 1454                         if (only_user)
 1455                                 error = fget_only_user(fdp, fd, &cap_event_rights, &fp);
 1456                         else
 1457                                 error = fget_unlocked(td, fd, &cap_event_rights, &fp);
 1458                         if (__predict_false(error != 0))
 1459                                 return (error);
 1460                         selfdalloc(td, (void *)(uintptr_t)fd);
 1461                         ev = fo_poll(fp, flags, td->td_ucred, td);
 1462                         if (only_user)
 1463                                 fput_only_user(fdp, fp);
 1464                         else
 1465                                 fdrop(fp, td);
 1466                         if (ev != 0)
 1467                                 n += selsetbits(ibits, obits, idx, bit, ev);
 1468                 }
 1469         }
 1470 
 1471         td->td_retval[0] = n;
 1472         return (0);
 1473 }
 1474 
 1475 int
 1476 sys_poll(struct thread *td, struct poll_args *uap)
 1477 {
 1478         struct timespec ts, *tsp;
 1479 
 1480         if (uap->timeout != INFTIM) {
 1481                 if (uap->timeout < 0)
 1482                         return (EINVAL);
 1483                 ts.tv_sec = uap->timeout / 1000;
 1484                 ts.tv_nsec = (uap->timeout % 1000) * 1000000;
 1485                 tsp = &ts;
 1486         } else
 1487                 tsp = NULL;
 1488 
 1489         return (kern_poll(td, uap->fds, uap->nfds, tsp, NULL));
 1490 }
 1491 
 1492 /*
 1493  * kfds points to an array in the kernel.
 1494  */
 1495 int
 1496 kern_poll_kfds(struct thread *td, struct pollfd *kfds, u_int nfds,
 1497     struct timespec *tsp, sigset_t *uset)
 1498 {
 1499         sbintime_t sbt, precision, tmp;
 1500         time_t over;
 1501         struct timespec ts;
 1502         int error;
 1503 
 1504         precision = 0;
 1505         if (tsp != NULL) {
 1506                 if (!timespecvalid_interval(tsp))
 1507                         return (EINVAL);
 1508                 if (tsp->tv_sec == 0 && tsp->tv_nsec == 0)
 1509                         sbt = 0;
 1510                 else {
 1511                         ts = *tsp;
 1512                         if (ts.tv_sec > INT32_MAX / 2) {
 1513                                 over = ts.tv_sec - INT32_MAX / 2;
 1514                                 ts.tv_sec -= over;
 1515                         } else
 1516                                 over = 0;
 1517                         tmp = tstosbt(ts);
 1518                         precision = tmp;
 1519                         precision >>= tc_precexp;
 1520                         if (TIMESEL(&sbt, tmp))
 1521                                 sbt += tc_tick_sbt;
 1522                         sbt += tmp;
 1523                 }
 1524         } else
 1525                 sbt = -1;
 1526 
 1527         if (uset != NULL) {
 1528                 error = kern_sigprocmask(td, SIG_SETMASK, uset,
 1529                     &td->td_oldsigmask, 0);
 1530                 if (error)
 1531                         return (error);
 1532                 td->td_pflags |= TDP_OLDMASK;
 1533                 /*
 1534                  * Make sure that ast() is called on return to
 1535                  * usermode and TDP_OLDMASK is cleared, restoring old
 1536                  * sigmask.
 1537                  */
 1538                 ast_sched(td, TDA_SIGSUSPEND);
 1539         }
 1540 
 1541         seltdinit(td);
 1542         /* Iterate until the timeout expires or descriptors become ready. */
 1543         for (;;) {
 1544                 error = pollscan(td, kfds, nfds);
 1545                 if (error || td->td_retval[0] != 0)
 1546                         break;
 1547                 error = seltdwait(td, sbt, precision);
 1548                 if (error)
 1549                         break;
 1550                 error = pollrescan(td);
 1551                 if (error || td->td_retval[0] != 0)
 1552                         break;
 1553         }
 1554         seltdclear(td);
 1555 
 1556         /* poll is not restarted after signals... */
 1557         if (error == ERESTART)
 1558                 error = EINTR;
 1559         if (error == EWOULDBLOCK)
 1560                 error = 0;
 1561         return (error);
 1562 }
 1563 
 1564 int
 1565 sys_ppoll(struct thread *td, struct ppoll_args *uap)
 1566 {
 1567         struct timespec ts, *tsp;
 1568         sigset_t set, *ssp;
 1569         int error;
 1570 
 1571         if (uap->ts != NULL) {
 1572                 error = copyin(uap->ts, &ts, sizeof(ts));
 1573                 if (error)
 1574                         return (error);
 1575                 tsp = &ts;
 1576         } else
 1577                 tsp = NULL;
 1578         if (uap->set != NULL) {
 1579                 error = copyin(uap->set, &set, sizeof(set));
 1580                 if (error)
 1581                         return (error);
 1582                 ssp = &set;
 1583         } else
 1584                 ssp = NULL;
 1585         return (kern_poll(td, uap->fds, uap->nfds, tsp, ssp));
 1586 }
 1587 
 1588 /*
 1589  * ufds points to an array in user space.
 1590  */
 1591 int
 1592 kern_poll(struct thread *td, struct pollfd *ufds, u_int nfds,
 1593     struct timespec *tsp, sigset_t *set)
 1594 {
 1595         struct pollfd *kfds;
 1596         struct pollfd stackfds[32];
 1597         int error;
 1598 
 1599         if (kern_poll_maxfds(nfds))
 1600                 return (EINVAL);
 1601         if (nfds > nitems(stackfds))
 1602                 kfds = mallocarray(nfds, sizeof(*kfds), M_TEMP, M_WAITOK);
 1603         else
 1604                 kfds = stackfds;
 1605         error = copyin(ufds, kfds, nfds * sizeof(*kfds));
 1606         if (error != 0)
 1607                 goto out;
 1608 
 1609         error = kern_poll_kfds(td, kfds, nfds, tsp, set);
 1610         if (error == 0)
 1611                 error = pollout(td, kfds, ufds, nfds);
 1612 
 1613 out:
 1614         if (nfds > nitems(stackfds))
 1615                 free(kfds, M_TEMP);
 1616         return (error);
 1617 }
 1618 
 1619 bool
 1620 kern_poll_maxfds(u_int nfds)
 1621 {
 1622 
 1623         /*
 1624          * This is kinda bogus.  We have fd limits, but that is not
 1625          * really related to the size of the pollfd array.  Make sure
 1626          * we let the process use at least FD_SETSIZE entries and at
 1627          * least enough for the system-wide limits.  We want to be reasonably
 1628          * safe, but not overly restrictive.
 1629          */
 1630         return (nfds > maxfilesperproc && nfds > FD_SETSIZE);
 1631 }
 1632 
 1633 static int
 1634 pollrescan(struct thread *td)
 1635 {
 1636         struct seltd *stp;
 1637         struct selfd *sfp;
 1638         struct selfd *sfn;
 1639         struct selinfo *si;
 1640         struct filedesc *fdp;
 1641         struct file *fp;
 1642         struct pollfd *fd;
 1643         int n, error;
 1644         bool only_user;
 1645 
 1646         n = 0;
 1647         fdp = td->td_proc->p_fd;
 1648         stp = td->td_sel;
 1649         only_user = FILEDESC_IS_ONLY_USER(fdp);
 1650         STAILQ_FOREACH_SAFE(sfp, &stp->st_selq, sf_link, sfn) {
 1651                 fd = (struct pollfd *)sfp->sf_cookie;
 1652                 si = sfp->sf_si;
 1653                 selfdfree(stp, sfp);
 1654                 /* If the selinfo wasn't cleared the event didn't fire. */
 1655                 if (si != NULL)
 1656                         continue;
 1657                 if (only_user)
 1658                         error = fget_only_user(fdp, fd->fd, &cap_event_rights, &fp);
 1659                 else
 1660                         error = fget_unlocked(td, fd->fd, &cap_event_rights, &fp);
 1661                 if (__predict_false(error != 0)) {
 1662                         fd->revents = POLLNVAL;
 1663                         n++;
 1664                         continue;
 1665                 }
 1666                 /*
 1667                  * Note: backend also returns POLLHUP and
 1668                  * POLLERR if appropriate.
 1669                  */
 1670                 fd->revents = fo_poll(fp, fd->events, td->td_ucred, td);
 1671                 if (only_user)
 1672                         fput_only_user(fdp, fp);
 1673                 else
 1674                         fdrop(fp, td);
 1675                 if (fd->revents != 0)
 1676                         n++;
 1677         }
 1678         stp->st_flags = 0;
 1679         td->td_retval[0] = n;
 1680         return (0);
 1681 }
 1682 
 1683 static int
 1684 pollout(struct thread *td, struct pollfd *fds, struct pollfd *ufds, u_int nfd)
 1685 {
 1686         int error = 0;
 1687         u_int i = 0;
 1688         u_int n = 0;
 1689 
 1690         for (i = 0; i < nfd; i++) {
 1691                 error = copyout(&fds->revents, &ufds->revents,
 1692                     sizeof(ufds->revents));
 1693                 if (error)
 1694                         return (error);
 1695                 if (fds->revents != 0)
 1696                         n++;
 1697                 fds++;
 1698                 ufds++;
 1699         }
 1700         td->td_retval[0] = n;
 1701         return (0);
 1702 }
 1703 
 1704 static int
 1705 pollscan(struct thread *td, struct pollfd *fds, u_int nfd)
 1706 {
 1707         struct filedesc *fdp;
 1708         struct file *fp;
 1709         int i, n, error;
 1710         bool only_user;
 1711 
 1712         n = 0;
 1713         fdp = td->td_proc->p_fd;
 1714         only_user = FILEDESC_IS_ONLY_USER(fdp);
 1715         for (i = 0; i < nfd; i++, fds++) {
 1716                 if (fds->fd < 0) {
 1717                         fds->revents = 0;
 1718                         continue;
 1719                 }
 1720                 if (only_user)
 1721                         error = fget_only_user(fdp, fds->fd, &cap_event_rights, &fp);
 1722                 else
 1723                         error = fget_unlocked(td, fds->fd, &cap_event_rights, &fp);
 1724                 if (__predict_false(error != 0)) {
 1725                         fds->revents = POLLNVAL;
 1726                         n++;
 1727                         continue;
 1728                 }
 1729                 /*
 1730                  * Note: backend also returns POLLHUP and
 1731                  * POLLERR if appropriate.
 1732                  */
 1733                 selfdalloc(td, fds);
 1734                 fds->revents = fo_poll(fp, fds->events,
 1735                     td->td_ucred, td);
 1736                 if (only_user)
 1737                         fput_only_user(fdp, fp);
 1738                 else
 1739                         fdrop(fp, td);
 1740                 /*
 1741                  * POSIX requires POLLOUT to be never
 1742                  * set simultaneously with POLLHUP.
 1743                  */
 1744                 if ((fds->revents & POLLHUP) != 0)
 1745                         fds->revents &= ~POLLOUT;
 1746 
 1747                 if (fds->revents != 0)
 1748                         n++;
 1749         }
 1750         td->td_retval[0] = n;
 1751         return (0);
 1752 }
 1753 
 1754 /*
 1755  * XXX This was created specifically to support netncp and netsmb.  This
 1756  * allows the caller to specify a socket to wait for events on.  It returns
 1757  * 0 if any events matched and an error otherwise.  There is no way to
 1758  * determine which events fired.
 1759  */
 1760 int
 1761 selsocket(struct socket *so, int events, struct timeval *tvp, struct thread *td)
 1762 {
 1763         struct timeval rtv;
 1764         sbintime_t asbt, precision, rsbt;
 1765         int error;
 1766 
 1767         precision = 0;  /* stupid gcc! */
 1768         if (tvp != NULL) {
 1769                 rtv = *tvp;
 1770                 if (rtv.tv_sec < 0 || rtv.tv_usec < 0 || 
 1771                     rtv.tv_usec >= 1000000)
 1772                         return (EINVAL);
 1773                 if (!timevalisset(&rtv))
 1774                         asbt = 0;
 1775                 else if (rtv.tv_sec <= INT32_MAX) {
 1776                         rsbt = tvtosbt(rtv);
 1777                         precision = rsbt;
 1778                         precision >>= tc_precexp;
 1779                         if (TIMESEL(&asbt, rsbt))
 1780                                 asbt += tc_tick_sbt;
 1781                         if (asbt <= SBT_MAX - rsbt)
 1782                                 asbt += rsbt;
 1783                         else
 1784                                 asbt = -1;
 1785                 } else
 1786                         asbt = -1;
 1787         } else
 1788                 asbt = -1;
 1789         seltdinit(td);
 1790         /*
 1791          * Iterate until the timeout expires or the socket becomes ready.
 1792          */
 1793         for (;;) {
 1794                 selfdalloc(td, NULL);
 1795                 if (sopoll(so, events, NULL, td) != 0) {
 1796                         error = 0;
 1797                         break;
 1798                 }
 1799                 error = seltdwait(td, asbt, precision);
 1800                 if (error)
 1801                         break;
 1802         }
 1803         seltdclear(td);
 1804         /* XXX Duplicates ncp/smb behavior. */
 1805         if (error == ERESTART)
 1806                 error = 0;
 1807         return (error);
 1808 }
 1809 
 1810 /*
 1811  * Preallocate two selfds associated with 'cookie'.  Some fo_poll routines
 1812  * have two select sets, one for read and another for write.
 1813  */
 1814 static void
 1815 selfdalloc(struct thread *td, void *cookie)
 1816 {
 1817         struct seltd *stp;
 1818 
 1819         stp = td->td_sel;
 1820         if (stp->st_free1 == NULL)
 1821                 stp->st_free1 = malloc(sizeof(*stp->st_free1), M_SELFD, M_WAITOK|M_ZERO);
 1822         stp->st_free1->sf_td = stp;
 1823         stp->st_free1->sf_cookie = cookie;
 1824         if (stp->st_free2 == NULL)
 1825                 stp->st_free2 = malloc(sizeof(*stp->st_free2), M_SELFD, M_WAITOK|M_ZERO);
 1826         stp->st_free2->sf_td = stp;
 1827         stp->st_free2->sf_cookie = cookie;
 1828 }
 1829 
 1830 static void
 1831 selfdfree(struct seltd *stp, struct selfd *sfp)
 1832 {
 1833         STAILQ_REMOVE(&stp->st_selq, sfp, selfd, sf_link);
 1834         /*
 1835          * Paired with doselwakeup.
 1836          */
 1837         if (atomic_load_acq_ptr((uintptr_t *)&sfp->sf_si) != (uintptr_t)NULL) {
 1838                 mtx_lock(sfp->sf_mtx);
 1839                 if (sfp->sf_si != NULL) {
 1840                         TAILQ_REMOVE(&sfp->sf_si->si_tdlist, sfp, sf_threads);
 1841                 }
 1842                 mtx_unlock(sfp->sf_mtx);
 1843         }
 1844         free(sfp, M_SELFD);
 1845 }
 1846 
 1847 /* Drain the waiters tied to all the selfd belonging the specified selinfo. */
 1848 void
 1849 seldrain(struct selinfo *sip)
 1850 {
 1851 
 1852         /*
 1853          * This feature is already provided by doselwakeup(), thus it is
 1854          * enough to go for it.
 1855          * Eventually, the context, should take care to avoid races
 1856          * between thread calling select()/poll() and file descriptor
 1857          * detaching, but, again, the races are just the same as
 1858          * selwakeup().
 1859          */
 1860         doselwakeup(sip, -1);
 1861 }
 1862 
 1863 /*
 1864  * Record a select request.
 1865  */
 1866 void
 1867 selrecord(struct thread *selector, struct selinfo *sip)
 1868 {
 1869         struct selfd *sfp;
 1870         struct seltd *stp;
 1871         struct mtx *mtxp;
 1872 
 1873         stp = selector->td_sel;
 1874         /*
 1875          * Don't record when doing a rescan.
 1876          */
 1877         if (stp->st_flags & SELTD_RESCAN)
 1878                 return;
 1879         /*
 1880          * Grab one of the preallocated descriptors.
 1881          */
 1882         sfp = NULL;
 1883         if ((sfp = stp->st_free1) != NULL)
 1884                 stp->st_free1 = NULL;
 1885         else if ((sfp = stp->st_free2) != NULL)
 1886                 stp->st_free2 = NULL;
 1887         else
 1888                 panic("selrecord: No free selfd on selq");
 1889         mtxp = sip->si_mtx;
 1890         if (mtxp == NULL)
 1891                 mtxp = mtx_pool_find(mtxpool_select, sip);
 1892         /*
 1893          * Initialize the sfp and queue it in the thread.
 1894          */
 1895         sfp->sf_si = sip;
 1896         sfp->sf_mtx = mtxp;
 1897         STAILQ_INSERT_TAIL(&stp->st_selq, sfp, sf_link);
 1898         /*
 1899          * Now that we've locked the sip, check for initialization.
 1900          */
 1901         mtx_lock(mtxp);
 1902         if (sip->si_mtx == NULL) {
 1903                 sip->si_mtx = mtxp;
 1904                 TAILQ_INIT(&sip->si_tdlist);
 1905         }
 1906         /*
 1907          * Add this thread to the list of selfds listening on this selinfo.
 1908          */
 1909         TAILQ_INSERT_TAIL(&sip->si_tdlist, sfp, sf_threads);
 1910         mtx_unlock(sip->si_mtx);
 1911 }
 1912 
 1913 /* Wake up a selecting thread. */
 1914 void
 1915 selwakeup(struct selinfo *sip)
 1916 {
 1917         doselwakeup(sip, -1);
 1918 }
 1919 
 1920 /* Wake up a selecting thread, and set its priority. */
 1921 void
 1922 selwakeuppri(struct selinfo *sip, int pri)
 1923 {
 1924         doselwakeup(sip, pri);
 1925 }
 1926 
 1927 /*
 1928  * Do a wakeup when a selectable event occurs.
 1929  */
 1930 static void
 1931 doselwakeup(struct selinfo *sip, int pri)
 1932 {
 1933         struct selfd *sfp;
 1934         struct selfd *sfn;
 1935         struct seltd *stp;
 1936 
 1937         /* If it's not initialized there can't be any waiters. */
 1938         if (sip->si_mtx == NULL)
 1939                 return;
 1940         /*
 1941          * Locking the selinfo locks all selfds associated with it.
 1942          */
 1943         mtx_lock(sip->si_mtx);
 1944         TAILQ_FOREACH_SAFE(sfp, &sip->si_tdlist, sf_threads, sfn) {
 1945                 /*
 1946                  * Once we remove this sfp from the list and clear the
 1947                  * sf_si seltdclear will know to ignore this si.
 1948                  */
 1949                 TAILQ_REMOVE(&sip->si_tdlist, sfp, sf_threads);
 1950                 stp = sfp->sf_td;
 1951                 mtx_lock(&stp->st_mtx);
 1952                 stp->st_flags |= SELTD_PENDING;
 1953                 cv_broadcastpri(&stp->st_wait, pri);
 1954                 mtx_unlock(&stp->st_mtx);
 1955                 /*
 1956                  * Paired with selfdfree.
 1957                  *
 1958                  * Storing this only after the wakeup provides an invariant that
 1959                  * stp is not used after selfdfree returns.
 1960                  */
 1961                 atomic_store_rel_ptr((uintptr_t *)&sfp->sf_si, (uintptr_t)NULL);
 1962         }
 1963         mtx_unlock(sip->si_mtx);
 1964 }
 1965 
 1966 static void
 1967 seltdinit(struct thread *td)
 1968 {
 1969         struct seltd *stp;
 1970 
 1971         stp = td->td_sel;
 1972         if (stp != NULL) {
 1973                 MPASS(stp->st_flags == 0);
 1974                 MPASS(STAILQ_EMPTY(&stp->st_selq));
 1975                 return;
 1976         }
 1977         stp = malloc(sizeof(*stp), M_SELECT, M_WAITOK|M_ZERO);
 1978         mtx_init(&stp->st_mtx, "sellck", NULL, MTX_DEF);
 1979         cv_init(&stp->st_wait, "select");
 1980         stp->st_flags = 0;
 1981         STAILQ_INIT(&stp->st_selq);
 1982         td->td_sel = stp;
 1983 }
 1984 
 1985 static int
 1986 seltdwait(struct thread *td, sbintime_t sbt, sbintime_t precision)
 1987 {
 1988         struct seltd *stp;
 1989         int error;
 1990 
 1991         stp = td->td_sel;
 1992         /*
 1993          * An event of interest may occur while we do not hold the seltd
 1994          * locked so check the pending flag before we sleep.
 1995          */
 1996         mtx_lock(&stp->st_mtx);
 1997         /*
 1998          * Any further calls to selrecord will be a rescan.
 1999          */
 2000         stp->st_flags |= SELTD_RESCAN;
 2001         if (stp->st_flags & SELTD_PENDING) {
 2002                 mtx_unlock(&stp->st_mtx);
 2003                 return (0);
 2004         }
 2005         if (sbt == 0)
 2006                 error = EWOULDBLOCK;
 2007         else if (sbt != -1)
 2008                 error = cv_timedwait_sig_sbt(&stp->st_wait, &stp->st_mtx,
 2009                     sbt, precision, C_ABSOLUTE);
 2010         else
 2011                 error = cv_wait_sig(&stp->st_wait, &stp->st_mtx);
 2012         mtx_unlock(&stp->st_mtx);
 2013 
 2014         return (error);
 2015 }
 2016 
 2017 void
 2018 seltdfini(struct thread *td)
 2019 {
 2020         struct seltd *stp;
 2021 
 2022         stp = td->td_sel;
 2023         if (stp == NULL)
 2024                 return;
 2025         MPASS(stp->st_flags == 0);
 2026         MPASS(STAILQ_EMPTY(&stp->st_selq));
 2027         if (stp->st_free1)
 2028                 free(stp->st_free1, M_SELFD);
 2029         if (stp->st_free2)
 2030                 free(stp->st_free2, M_SELFD);
 2031         td->td_sel = NULL;
 2032         cv_destroy(&stp->st_wait);
 2033         mtx_destroy(&stp->st_mtx);
 2034         free(stp, M_SELECT);
 2035 }
 2036 
 2037 /*
 2038  * Remove the references to the thread from all of the objects we were
 2039  * polling.
 2040  */
 2041 static void
 2042 seltdclear(struct thread *td)
 2043 {
 2044         struct seltd *stp;
 2045         struct selfd *sfp;
 2046         struct selfd *sfn;
 2047 
 2048         stp = td->td_sel;
 2049         STAILQ_FOREACH_SAFE(sfp, &stp->st_selq, sf_link, sfn)
 2050                 selfdfree(stp, sfp);
 2051         stp->st_flags = 0;
 2052 }
 2053 
 2054 static void selectinit(void *);
 2055 SYSINIT(select, SI_SUB_SYSCALLS, SI_ORDER_ANY, selectinit, NULL);
 2056 static void
 2057 selectinit(void *dummy __unused)
 2058 {
 2059 
 2060         mtxpool_select = mtx_pool_create("select mtxpool", 128, MTX_DEF);
 2061 }
 2062 
 2063 /*
 2064  * Set up a syscall return value that follows the convention specified for
 2065  * posix_* functions.
 2066  */
 2067 int
 2068 kern_posix_error(struct thread *td, int error)
 2069 {
 2070 
 2071         if (error <= 0)
 2072                 return (error);
 2073         td->td_errno = error;
 2074         td->td_pflags |= TDP_NERRNO;
 2075         td->td_retval[0] = error;
 2076         return (0);
 2077 }

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