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


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FreeBSD/Linux Kernel Cross Reference
sys/kern/sys_generic.c

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    1 /*-
    2  * Copyright (c) 1982, 1986, 1989, 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  *      @(#)sys_generic.c       8.5 (Berkeley) 1/21/94
   35  */
   36 
   37 #include <sys/cdefs.h>
   38 __FBSDID("$FreeBSD: releng/6.1/sys/kern/sys_generic.c 158179 2006-04-30 16:44:43Z cvs2svn $");
   39 
   40 #include "opt_compat.h"
   41 #include "opt_ktrace.h"
   42 
   43 #include <sys/param.h>
   44 #include <sys/systm.h>
   45 #include <sys/sysproto.h>
   46 #include <sys/filedesc.h>
   47 #include <sys/filio.h>
   48 #include <sys/fcntl.h>
   49 #include <sys/file.h>
   50 #include <sys/proc.h>
   51 #include <sys/signalvar.h>
   52 #include <sys/socketvar.h>
   53 #include <sys/uio.h>
   54 #include <sys/kernel.h>
   55 #include <sys/limits.h>
   56 #include <sys/malloc.h>
   57 #include <sys/poll.h>
   58 #include <sys/resourcevar.h>
   59 #include <sys/selinfo.h>
   60 #include <sys/sleepqueue.h>
   61 #include <sys/syscallsubr.h>
   62 #include <sys/sysctl.h>
   63 #include <sys/sysent.h>
   64 #include <sys/vnode.h>
   65 #include <sys/bio.h>
   66 #include <sys/buf.h>
   67 #include <sys/condvar.h>
   68 #ifdef KTRACE
   69 #include <sys/ktrace.h>
   70 #endif
   71 #include <vm/vm.h>
   72 #include <vm/vm_page.h>
   73 
   74 static MALLOC_DEFINE(M_IOCTLOPS, "ioctlops", "ioctl data buffer");
   75 static MALLOC_DEFINE(M_SELECT, "select", "select() buffer");
   76 MALLOC_DEFINE(M_IOV, "iov", "large iov's");
   77 
   78 static int      pollscan(struct thread *, struct pollfd *, u_int);
   79 static int      selscan(struct thread *, fd_mask **, fd_mask **, int);
   80 static int      dofileread(struct thread *, int, struct file *, struct uio *,
   81                     off_t, int);
   82 static int      dofilewrite(struct thread *, int, struct file *, struct uio *,
   83                     off_t, int);
   84 static void     doselwakeup(struct selinfo *, int);
   85 
   86 /*
   87  * Read system call.
   88  */
   89 #ifndef _SYS_SYSPROTO_H_
   90 struct read_args {
   91         int     fd;
   92         void    *buf;
   93         size_t  nbyte;
   94 };
   95 #endif
   96 /*
   97  * MPSAFE
   98  */
   99 int
  100 read(td, uap)
  101         struct thread *td;
  102         struct read_args *uap;
  103 {
  104         struct uio auio;
  105         struct iovec aiov;
  106         int error;
  107 
  108         if (uap->nbyte > INT_MAX)
  109                 return (EINVAL);
  110         aiov.iov_base = uap->buf;
  111         aiov.iov_len = uap->nbyte;
  112         auio.uio_iov = &aiov;
  113         auio.uio_iovcnt = 1;
  114         auio.uio_resid = uap->nbyte;
  115         auio.uio_segflg = UIO_USERSPACE;
  116         error = kern_readv(td, uap->fd, &auio);
  117         return(error);
  118 }
  119 
  120 /*
  121  * Positioned read system call
  122  */
  123 #ifndef _SYS_SYSPROTO_H_
  124 struct pread_args {
  125         int     fd;
  126         void    *buf;
  127         size_t  nbyte;
  128         int     pad;
  129         off_t   offset;
  130 };
  131 #endif
  132 /*
  133  * MPSAFE
  134  */
  135 int
  136 pread(td, uap)
  137         struct thread *td;
  138         struct pread_args *uap;
  139 {
  140         struct uio auio;
  141         struct iovec aiov;
  142         int error;
  143 
  144         if (uap->nbyte > INT_MAX)
  145                 return (EINVAL);
  146         aiov.iov_base = uap->buf;
  147         aiov.iov_len = uap->nbyte;
  148         auio.uio_iov = &aiov;
  149         auio.uio_iovcnt = 1;
  150         auio.uio_resid = uap->nbyte;
  151         auio.uio_segflg = UIO_USERSPACE;
  152         error = kern_preadv(td, uap->fd, &auio, uap->offset);
  153         return(error);
  154 }
  155 
  156 /*
  157  * Scatter read system call.
  158  */
  159 #ifndef _SYS_SYSPROTO_H_
  160 struct readv_args {
  161         int     fd;
  162         struct  iovec *iovp;
  163         u_int   iovcnt;
  164 };
  165 #endif
  166 /*
  167  * MPSAFE
  168  */
  169 int
  170 readv(struct thread *td, struct readv_args *uap)
  171 {
  172         struct uio *auio;
  173         int error;
  174 
  175         error = copyinuio(uap->iovp, uap->iovcnt, &auio);
  176         if (error)
  177                 return (error);
  178         error = kern_readv(td, uap->fd, auio);
  179         free(auio, M_IOV);
  180         return (error);
  181 }
  182 
  183 int
  184 kern_readv(struct thread *td, int fd, struct uio *auio)
  185 {
  186         struct file *fp;
  187         int error;
  188 
  189         error = fget_read(td, fd, &fp);
  190         if (error)
  191                 return (error);
  192         error = dofileread(td, fd, fp, auio, (off_t)-1, 0);
  193         fdrop(fp, td);
  194         return (error);
  195 }
  196 
  197 /*
  198  * Scatter positioned read system call.
  199  */
  200 #ifndef _SYS_SYSPROTO_H_
  201 struct preadv_args {
  202         int     fd;
  203         struct  iovec *iovp;
  204         u_int   iovcnt;
  205         off_t   offset;
  206 };
  207 #endif
  208 /*
  209  * MPSAFE
  210  */
  211 int
  212 preadv(struct thread *td, struct preadv_args *uap)
  213 {
  214         struct uio *auio;
  215         int error;
  216 
  217         error = copyinuio(uap->iovp, uap->iovcnt, &auio);
  218         if (error)
  219                 return (error);
  220         error = kern_preadv(td, uap->fd, auio, uap->offset);
  221         free(auio, M_IOV);
  222         return (error);
  223 }
  224 
  225 int
  226 kern_preadv(td, fd, auio, offset)
  227         struct thread *td;
  228         int fd;
  229         struct uio *auio;
  230         off_t offset;
  231 {
  232         struct file *fp;
  233         int error;
  234 
  235         error = fget_read(td, fd, &fp);
  236         if (error)
  237                 return (error);
  238         if (!(fp->f_ops->fo_flags & DFLAG_SEEKABLE))
  239                 error = ESPIPE;
  240         else if (offset < 0 && fp->f_vnode->v_type != VCHR)
  241                 error = EINVAL;
  242         else
  243                 error = dofileread(td, fd, fp, auio, offset, FOF_OFFSET);
  244         fdrop(fp, td);
  245         return (error);
  246 }
  247 
  248 /*
  249  * Common code for readv and preadv that reads data in
  250  * from a file using the passed in uio, offset, and flags.
  251  */
  252 static int
  253 dofileread(td, fd, fp, auio, offset, flags)
  254         struct thread *td;
  255         int fd;
  256         struct file *fp;
  257         struct uio *auio;
  258         off_t offset;
  259         int flags;
  260 {
  261         ssize_t cnt;
  262         int error;
  263 #ifdef KTRACE
  264         struct uio *ktruio = NULL;
  265 #endif
  266 
  267         /* Finish zero length reads right here */
  268         if (auio->uio_resid == 0) {
  269                 td->td_retval[0] = 0;
  270                 return(0);
  271         }
  272         auio->uio_rw = UIO_READ;
  273         auio->uio_offset = offset;
  274         auio->uio_td = td;
  275 #ifdef KTRACE
  276         if (KTRPOINT(td, KTR_GENIO)) 
  277                 ktruio = cloneuio(auio);
  278 #endif
  279         cnt = auio->uio_resid;
  280         if ((error = fo_read(fp, auio, td->td_ucred, flags, td))) {
  281                 if (auio->uio_resid != cnt && (error == ERESTART ||
  282                     error == EINTR || error == EWOULDBLOCK))
  283                         error = 0;
  284         }
  285         cnt -= auio->uio_resid;
  286 #ifdef KTRACE
  287         if (ktruio != NULL) {
  288                 ktruio->uio_resid = cnt;
  289                 ktrgenio(fd, UIO_READ, ktruio, error);
  290         }
  291 #endif
  292         td->td_retval[0] = cnt;
  293         return (error);
  294 }
  295 
  296 /*
  297  * Write system call
  298  */
  299 #ifndef _SYS_SYSPROTO_H_
  300 struct write_args {
  301         int     fd;
  302         const void *buf;
  303         size_t  nbyte;
  304 };
  305 #endif
  306 /*
  307  * MPSAFE
  308  */
  309 int
  310 write(td, uap)
  311         struct thread *td;
  312         struct write_args *uap;
  313 {
  314         struct uio auio;
  315         struct iovec aiov;
  316         int error;
  317 
  318         if (uap->nbyte > INT_MAX)
  319                 return (EINVAL);
  320         aiov.iov_base = (void *)(uintptr_t)uap->buf;
  321         aiov.iov_len = uap->nbyte;
  322         auio.uio_iov = &aiov;
  323         auio.uio_iovcnt = 1;
  324         auio.uio_resid = uap->nbyte;
  325         auio.uio_segflg = UIO_USERSPACE;
  326         error = kern_writev(td, uap->fd, &auio);
  327         return(error);
  328 }
  329 
  330 /*
  331  * Positioned write system call
  332  */
  333 #ifndef _SYS_SYSPROTO_H_
  334 struct pwrite_args {
  335         int     fd;
  336         const void *buf;
  337         size_t  nbyte;
  338         int     pad;
  339         off_t   offset;
  340 };
  341 #endif
  342 /*
  343  * MPSAFE
  344  */
  345 int
  346 pwrite(td, uap)
  347         struct thread *td;
  348         struct pwrite_args *uap;
  349 {
  350         struct uio auio;
  351         struct iovec aiov;
  352         int error;
  353 
  354         if (uap->nbyte > INT_MAX)
  355                 return (EINVAL);
  356         aiov.iov_base = (void *)(uintptr_t)uap->buf;
  357         aiov.iov_len = uap->nbyte;
  358         auio.uio_iov = &aiov;
  359         auio.uio_iovcnt = 1;
  360         auio.uio_resid = uap->nbyte;
  361         auio.uio_segflg = UIO_USERSPACE;
  362         error = kern_pwritev(td, uap->fd, &auio, uap->offset);
  363         return(error);
  364 }
  365 
  366 /*
  367  * Gather write system call
  368  */
  369 #ifndef _SYS_SYSPROTO_H_
  370 struct writev_args {
  371         int     fd;
  372         struct  iovec *iovp;
  373         u_int   iovcnt;
  374 };
  375 #endif
  376 /*
  377  * MPSAFE
  378  */
  379 int
  380 writev(struct thread *td, struct writev_args *uap)
  381 {
  382         struct uio *auio;
  383         int error;
  384 
  385         error = copyinuio(uap->iovp, uap->iovcnt, &auio);
  386         if (error)
  387                 return (error);
  388         error = kern_writev(td, uap->fd, auio);
  389         free(auio, M_IOV);
  390         return (error);
  391 }
  392 
  393 int
  394 kern_writev(struct thread *td, int fd, struct uio *auio)
  395 {
  396         struct file *fp;
  397         int error;
  398 
  399         error = fget_write(td, fd, &fp);
  400         if (error)
  401                 return (EBADF); /* XXX this can't be right */
  402         error = dofilewrite(td, fd, fp, auio, (off_t)-1, 0);
  403         fdrop(fp, td);
  404         return (error);
  405 }
  406 
  407 /*
  408  * Gather positioned write system call
  409  */
  410 #ifndef _SYS_SYSPROTO_H_
  411 struct pwritev_args {
  412         int     fd;
  413         struct  iovec *iovp;
  414         u_int   iovcnt;
  415         off_t   offset;
  416 };
  417 #endif
  418 /*
  419  * MPSAFE
  420  */
  421 int
  422 pwritev(struct thread *td, struct pwritev_args *uap)
  423 {
  424         struct uio *auio;
  425         int error;
  426 
  427         error = copyinuio(uap->iovp, uap->iovcnt, &auio);
  428         if (error)
  429                 return (error);
  430         error = kern_pwritev(td, uap->fd, auio, uap->offset);
  431         free(auio, M_IOV);
  432         return (error);
  433 }
  434 
  435 int
  436 kern_pwritev(td, fd, auio, offset)
  437         struct thread *td;
  438         struct uio *auio;
  439         int fd;
  440         off_t offset;
  441 {
  442         struct file *fp;
  443         int error;
  444 
  445         error = fget_write(td, fd, &fp);
  446         if (error)
  447                 return (EBADF); /* XXX this can't be right */
  448         if (!(fp->f_ops->fo_flags & DFLAG_SEEKABLE))
  449                 error = ESPIPE;
  450         else if (offset < 0 && fp->f_vnode->v_type != VCHR)
  451                 error = EINVAL;
  452         else
  453                 error = dofilewrite(td, fd, fp, auio, offset, FOF_OFFSET);
  454         fdrop(fp, td);
  455         return (error);
  456 }
  457 
  458 /*
  459  * Common code for writev and pwritev that writes data to
  460  * a file using the passed in uio, offset, and flags.
  461  */
  462 static int
  463 dofilewrite(td, fd, fp, auio, offset, flags)
  464         struct thread *td;
  465         int fd;
  466         struct file *fp;
  467         struct uio *auio;
  468         off_t offset;
  469         int flags;
  470 {
  471         ssize_t cnt;
  472         int error;
  473 #ifdef KTRACE
  474         struct uio *ktruio = NULL;
  475 #endif
  476 
  477         auio->uio_rw = UIO_WRITE;
  478         auio->uio_td = td;
  479         auio->uio_offset = offset;
  480 #ifdef KTRACE
  481         if (KTRPOINT(td, KTR_GENIO))
  482                 ktruio = cloneuio(auio);
  483 #endif
  484         cnt = auio->uio_resid;
  485         if (fp->f_type == DTYPE_VNODE)
  486                 bwillwrite();
  487         if ((error = fo_write(fp, auio, td->td_ucred, flags, td))) {
  488                 if (auio->uio_resid != cnt && (error == ERESTART ||
  489                     error == EINTR || error == EWOULDBLOCK))
  490                         error = 0;
  491                 /* Socket layer is responsible for issuing SIGPIPE. */
  492                 if (error == EPIPE) {
  493                         PROC_LOCK(td->td_proc);
  494                         psignal(td->td_proc, SIGPIPE);
  495                         PROC_UNLOCK(td->td_proc);
  496                 }
  497         }
  498         cnt -= auio->uio_resid;
  499 #ifdef KTRACE
  500         if (ktruio != NULL) {
  501                 ktruio->uio_resid = cnt;
  502                 ktrgenio(fd, UIO_WRITE, ktruio, error);
  503         }
  504 #endif
  505         td->td_retval[0] = cnt;
  506         return (error);
  507 }
  508 
  509 /*
  510  * Ioctl system call
  511  */
  512 #ifndef _SYS_SYSPROTO_H_
  513 struct ioctl_args {
  514         int     fd;
  515         u_long  com;
  516         caddr_t data;
  517 };
  518 #endif
  519 /*
  520  * MPSAFE
  521  */
  522 /* ARGSUSED */
  523 int
  524 ioctl(struct thread *td, struct ioctl_args *uap)
  525 {
  526         struct file *fp;
  527         struct filedesc *fdp;
  528         u_long com;
  529         int error = 0;
  530         u_int size;
  531         caddr_t data, memp;
  532         int tmp;
  533 
  534         if (uap->com > 0xffffffff) {
  535                 printf(
  536                     "WARNING pid %d (%s): ioctl sign-extension ioctl %lx\n",
  537                     td->td_proc->p_pid, td->td_proc->p_comm, uap->com);
  538                 uap->com &= 0xffffffff;
  539         }
  540         if ((error = fget(td, uap->fd, &fp)) != 0)
  541                 return (error);
  542         if ((fp->f_flag & (FREAD | FWRITE)) == 0) {
  543                 fdrop(fp, td);
  544                 return (EBADF);
  545         }
  546         fdp = td->td_proc->p_fd;
  547         switch (com = uap->com) {
  548         case FIONCLEX:
  549                 FILEDESC_LOCK_FAST(fdp);
  550                 fdp->fd_ofileflags[uap->fd] &= ~UF_EXCLOSE;
  551                 FILEDESC_UNLOCK_FAST(fdp);
  552                 fdrop(fp, td);
  553                 return (0);
  554         case FIOCLEX:
  555                 FILEDESC_LOCK_FAST(fdp);
  556                 fdp->fd_ofileflags[uap->fd] |= UF_EXCLOSE;
  557                 FILEDESC_UNLOCK_FAST(fdp);
  558                 fdrop(fp, td);
  559                 return (0);
  560         }
  561 
  562         /*
  563          * Interpret high order word to find amount of data to be
  564          * copied to/from the user's address space.
  565          */
  566         size = IOCPARM_LEN(com);
  567         if ((size > IOCPARM_MAX) ||
  568             ((com & (IOC_VOID  | IOC_IN | IOC_OUT)) == 0) ||
  569 #if defined(COMPAT_FREEBSD5) || defined(COMPAT_FREEBSD4) || defined(COMPAT_43)
  570             ((com & IOC_OUT) && size == 0) ||
  571 #else
  572             ((com & (IOC_IN | IOC_OUT)) && size == 0) ||
  573 #endif
  574             ((com & IOC_VOID) && size > 0)) {
  575                 fdrop(fp, td);
  576                 return (ENOTTY);
  577         }
  578 
  579         if (size > 0) {
  580                 memp = malloc((u_long)size, M_IOCTLOPS, M_WAITOK);
  581                 data = memp;
  582         } else {
  583                 memp = NULL;
  584                 data = (void *)&uap->data;
  585         }
  586         if (com & IOC_IN) {
  587                 error = copyin(uap->data, data, (u_int)size);
  588                 if (error) {
  589                         free(memp, M_IOCTLOPS);
  590                         fdrop(fp, td);
  591                         return (error);
  592                 }
  593         } else if (com & IOC_OUT) {
  594                 /*
  595                  * Zero the buffer so the user always
  596                  * gets back something deterministic.
  597                  */
  598                 bzero(data, size);
  599         }
  600 
  601         if (com == FIONBIO) {
  602                 FILE_LOCK(fp);
  603                 if ((tmp = *(int *)data))
  604                         fp->f_flag |= FNONBLOCK;
  605                 else
  606                         fp->f_flag &= ~FNONBLOCK;
  607                 FILE_UNLOCK(fp);
  608                 data = (void *)&tmp;
  609         } else if (com == FIOASYNC) {
  610                 FILE_LOCK(fp);
  611                 if ((tmp = *(int *)data))
  612                         fp->f_flag |= FASYNC;
  613                 else
  614                         fp->f_flag &= ~FASYNC;
  615                 FILE_UNLOCK(fp);
  616                 data = (void *)&tmp;
  617         }
  618 
  619         error = fo_ioctl(fp, com, data, td->td_ucred, td);
  620 
  621         if (error == 0 && (com & IOC_OUT))
  622                 error = copyout(data, uap->data, (u_int)size);
  623 
  624         if (memp != NULL)
  625                 free(memp, M_IOCTLOPS);
  626         fdrop(fp, td);
  627         return (error);
  628 }
  629 
  630 /*
  631  * sellock and selwait are initialized in selectinit() via SYSINIT.
  632  */
  633 struct mtx      sellock;
  634 struct cv       selwait;
  635 u_int           nselcoll;       /* Select collisions since boot */
  636 SYSCTL_UINT(_kern, OID_AUTO, nselcoll, CTLFLAG_RD, &nselcoll, 0, "");
  637 
  638 /*
  639  * Select system call.
  640  */
  641 #ifndef _SYS_SYSPROTO_H_
  642 struct select_args {
  643         int     nd;
  644         fd_set  *in, *ou, *ex;
  645         struct  timeval *tv;
  646 };
  647 #endif
  648 /*
  649  * MPSAFE
  650  */
  651 int
  652 select(td, uap)
  653         register struct thread *td;
  654         register struct select_args *uap;
  655 {
  656         struct timeval tv, *tvp;
  657         int error;
  658 
  659         if (uap->tv != NULL) {
  660                 error = copyin(uap->tv, &tv, sizeof(tv));
  661                 if (error)
  662                         return (error);
  663                 tvp = &tv;
  664         } else
  665                 tvp = NULL;
  666 
  667         return (kern_select(td, uap->nd, uap->in, uap->ou, uap->ex, tvp));
  668 }
  669 
  670 int
  671 kern_select(struct thread *td, int nd, fd_set *fd_in, fd_set *fd_ou,
  672     fd_set *fd_ex, struct timeval *tvp)
  673 {
  674         struct filedesc *fdp;
  675         /*
  676          * The magic 2048 here is chosen to be just enough for FD_SETSIZE
  677          * infds with the new FD_SETSIZE of 1024, and more than enough for
  678          * FD_SETSIZE infds, outfds and exceptfds with the old FD_SETSIZE
  679          * of 256.
  680          */
  681         fd_mask s_selbits[howmany(2048, NFDBITS)];
  682         fd_mask *ibits[3], *obits[3], *selbits, *sbp;
  683         struct timeval atv, rtv, ttv;
  684         int error, timo;
  685         u_int ncoll, nbufbytes, ncpbytes, nfdbits;
  686 
  687         if (nd < 0)
  688                 return (EINVAL);
  689         fdp = td->td_proc->p_fd;
  690         
  691         FILEDESC_LOCK_FAST(fdp);
  692 
  693         if (nd > td->td_proc->p_fd->fd_nfiles)
  694                 nd = td->td_proc->p_fd->fd_nfiles;   /* forgiving; slightly wrong */
  695         FILEDESC_UNLOCK_FAST(fdp);
  696 
  697         /*
  698          * Allocate just enough bits for the non-null fd_sets.  Use the
  699          * preallocated auto buffer if possible.
  700          */
  701         nfdbits = roundup(nd, NFDBITS);
  702         ncpbytes = nfdbits / NBBY;
  703         nbufbytes = 0;
  704         if (fd_in != NULL)
  705                 nbufbytes += 2 * ncpbytes;
  706         if (fd_ou != NULL)
  707                 nbufbytes += 2 * ncpbytes;
  708         if (fd_ex != NULL)
  709                 nbufbytes += 2 * ncpbytes;
  710         if (nbufbytes <= sizeof s_selbits)
  711                 selbits = &s_selbits[0];
  712         else
  713                 selbits = malloc(nbufbytes, M_SELECT, M_WAITOK);
  714 
  715         /*
  716          * Assign pointers into the bit buffers and fetch the input bits.
  717          * Put the output buffers together so that they can be bzeroed
  718          * together.
  719          */
  720         sbp = selbits;
  721 #define getbits(name, x) \
  722         do {                                                            \
  723                 if (name == NULL)                                       \
  724                         ibits[x] = NULL;                                \
  725                 else {                                                  \
  726                         ibits[x] = sbp + nbufbytes / 2 / sizeof *sbp;   \
  727                         obits[x] = sbp;                                 \
  728                         sbp += ncpbytes / sizeof *sbp;                  \
  729                         error = copyin(name, ibits[x], ncpbytes);       \
  730                         if (error != 0)                                 \
  731                                 goto done_nosellock;                    \
  732                 }                                                       \
  733         } while (0)
  734         getbits(fd_in, 0);
  735         getbits(fd_ou, 1);
  736         getbits(fd_ex, 2);
  737 #undef  getbits
  738         if (nbufbytes != 0)
  739                 bzero(selbits, nbufbytes / 2);
  740 
  741         if (tvp != NULL) {
  742                 atv = *tvp;
  743                 if (itimerfix(&atv)) {
  744                         error = EINVAL;
  745                         goto done_nosellock;
  746                 }
  747                 getmicrouptime(&rtv);
  748                 timevaladd(&atv, &rtv);
  749         } else {
  750                 atv.tv_sec = 0;
  751                 atv.tv_usec = 0;
  752         }
  753         timo = 0;
  754         TAILQ_INIT(&td->td_selq);
  755         mtx_lock(&sellock);
  756 retry:
  757         ncoll = nselcoll;
  758         mtx_lock_spin(&sched_lock);
  759         td->td_flags |= TDF_SELECT;
  760         mtx_unlock_spin(&sched_lock);
  761         mtx_unlock(&sellock);
  762 
  763         error = selscan(td, ibits, obits, nd);
  764         mtx_lock(&sellock);
  765         if (error || td->td_retval[0])
  766                 goto done;
  767         if (atv.tv_sec || atv.tv_usec) {
  768                 getmicrouptime(&rtv);
  769                 if (timevalcmp(&rtv, &atv, >=))
  770                         goto done;
  771                 ttv = atv;
  772                 timevalsub(&ttv, &rtv);
  773                 timo = ttv.tv_sec > 24 * 60 * 60 ?
  774                     24 * 60 * 60 * hz : tvtohz(&ttv);
  775         }
  776 
  777         /*
  778          * An event of interest may occur while we do not hold
  779          * sellock, so check TDF_SELECT and the number of
  780          * collisions and rescan the file descriptors if
  781          * necessary.
  782          */
  783         mtx_lock_spin(&sched_lock);
  784         if ((td->td_flags & TDF_SELECT) == 0 || nselcoll != ncoll) {
  785                 mtx_unlock_spin(&sched_lock);
  786                 goto retry;
  787         }
  788         mtx_unlock_spin(&sched_lock);
  789 
  790         if (timo > 0)
  791                 error = cv_timedwait_sig(&selwait, &sellock, timo);
  792         else
  793                 error = cv_wait_sig(&selwait, &sellock);
  794         
  795         if (error == 0)
  796                 goto retry;
  797 
  798 done:
  799         clear_selinfo_list(td);
  800         mtx_lock_spin(&sched_lock);
  801         td->td_flags &= ~TDF_SELECT;
  802         mtx_unlock_spin(&sched_lock);
  803         mtx_unlock(&sellock);
  804 
  805 done_nosellock:
  806         /* select is not restarted after signals... */
  807         if (error == ERESTART)
  808                 error = EINTR;
  809         if (error == EWOULDBLOCK)
  810                 error = 0;
  811 #define putbits(name, x) \
  812         if (name && (error2 = copyout(obits[x], name, ncpbytes))) \
  813                 error = error2;
  814         if (error == 0) {
  815                 int error2;
  816 
  817                 putbits(fd_in, 0);
  818                 putbits(fd_ou, 1);
  819                 putbits(fd_ex, 2);
  820 #undef putbits
  821         }
  822         if (selbits != &s_selbits[0])
  823                 free(selbits, M_SELECT);
  824 
  825         return (error);
  826 }
  827 
  828 static int
  829 selscan(td, ibits, obits, nfd)
  830         struct thread *td;
  831         fd_mask **ibits, **obits;
  832         int nfd;
  833 {
  834         int msk, i, fd;
  835         fd_mask bits;
  836         struct file *fp;
  837         int n = 0;
  838         /* Note: backend also returns POLLHUP/POLLERR if appropriate. */
  839         static int flag[3] = { POLLRDNORM, POLLWRNORM, POLLRDBAND };
  840         struct filedesc *fdp = td->td_proc->p_fd;
  841 
  842         FILEDESC_LOCK(fdp);
  843         for (msk = 0; msk < 3; msk++) {
  844                 if (ibits[msk] == NULL)
  845                         continue;
  846                 for (i = 0; i < nfd; i += NFDBITS) {
  847                         bits = ibits[msk][i/NFDBITS];
  848                         /* ffs(int mask) not portable, fd_mask is long */
  849                         for (fd = i; bits && fd < nfd; fd++, bits >>= 1) {
  850                                 if (!(bits & 1))
  851                                         continue;
  852                                 if ((fp = fget_locked(fdp, fd)) == NULL) {
  853                                         FILEDESC_UNLOCK(fdp);
  854                                         return (EBADF);
  855                                 }
  856                                 if (fo_poll(fp, flag[msk], td->td_ucred,
  857                                     td)) {
  858                                         obits[msk][(fd)/NFDBITS] |=
  859                                             ((fd_mask)1 << ((fd) % NFDBITS));
  860                                         n++;
  861                                 }
  862                         }
  863                 }
  864         }
  865         FILEDESC_UNLOCK(fdp);
  866         td->td_retval[0] = n;
  867         return (0);
  868 }
  869 
  870 /*
  871  * Poll system call.
  872  */
  873 #ifndef _SYS_SYSPROTO_H_
  874 struct poll_args {
  875         struct pollfd *fds;
  876         u_int   nfds;
  877         int     timeout;
  878 };
  879 #endif
  880 /*
  881  * MPSAFE
  882  */
  883 int
  884 poll(td, uap)
  885         struct thread *td;
  886         struct poll_args *uap;
  887 {
  888         struct pollfd *bits;
  889         struct pollfd smallbits[32];
  890         struct timeval atv, rtv, ttv;
  891         int error = 0, timo;
  892         u_int ncoll, nfds;
  893         size_t ni;
  894 
  895         nfds = uap->nfds;
  896 
  897         /*
  898          * This is kinda bogus.  We have fd limits, but that is not
  899          * really related to the size of the pollfd array.  Make sure
  900          * we let the process use at least FD_SETSIZE entries and at
  901          * least enough for the current limits.  We want to be reasonably
  902          * safe, but not overly restrictive.
  903          */
  904         PROC_LOCK(td->td_proc);
  905         if ((nfds > lim_cur(td->td_proc, RLIMIT_NOFILE)) &&
  906             (nfds > FD_SETSIZE)) {
  907                 PROC_UNLOCK(td->td_proc);
  908                 error = EINVAL;
  909                 goto done2;
  910         }
  911         PROC_UNLOCK(td->td_proc);
  912         ni = nfds * sizeof(struct pollfd);
  913         if (ni > sizeof(smallbits))
  914                 bits = malloc(ni, M_TEMP, M_WAITOK);
  915         else
  916                 bits = smallbits;
  917         error = copyin(uap->fds, bits, ni);
  918         if (error)
  919                 goto done_nosellock;
  920         if (uap->timeout != INFTIM) {
  921                 atv.tv_sec = uap->timeout / 1000;
  922                 atv.tv_usec = (uap->timeout % 1000) * 1000;
  923                 if (itimerfix(&atv)) {
  924                         error = EINVAL;
  925                         goto done_nosellock;
  926                 }
  927                 getmicrouptime(&rtv);
  928                 timevaladd(&atv, &rtv);
  929         } else {
  930                 atv.tv_sec = 0;
  931                 atv.tv_usec = 0;
  932         }
  933         timo = 0;
  934         TAILQ_INIT(&td->td_selq);
  935         mtx_lock(&sellock);
  936 retry:
  937         ncoll = nselcoll;
  938         mtx_lock_spin(&sched_lock);
  939         td->td_flags |= TDF_SELECT;
  940         mtx_unlock_spin(&sched_lock);
  941         mtx_unlock(&sellock);
  942 
  943         error = pollscan(td, bits, nfds);
  944         mtx_lock(&sellock);
  945         if (error || td->td_retval[0])
  946                 goto done;
  947         if (atv.tv_sec || atv.tv_usec) {
  948                 getmicrouptime(&rtv);
  949                 if (timevalcmp(&rtv, &atv, >=))
  950                         goto done;
  951                 ttv = atv;
  952                 timevalsub(&ttv, &rtv);
  953                 timo = ttv.tv_sec > 24 * 60 * 60 ?
  954                     24 * 60 * 60 * hz : tvtohz(&ttv);
  955         }
  956         /*
  957          * An event of interest may occur while we do not hold
  958          * sellock, so check TDF_SELECT and the number of collisions
  959          * and rescan the file descriptors if necessary.
  960          */
  961         mtx_lock_spin(&sched_lock);
  962         if ((td->td_flags & TDF_SELECT) == 0 || nselcoll != ncoll) {
  963                 mtx_unlock_spin(&sched_lock);
  964                 goto retry;
  965         }
  966         mtx_unlock_spin(&sched_lock);
  967 
  968         if (timo > 0)
  969                 error = cv_timedwait_sig(&selwait, &sellock, timo);
  970         else
  971                 error = cv_wait_sig(&selwait, &sellock);
  972 
  973         if (error == 0)
  974                 goto retry;
  975 
  976 done:
  977         clear_selinfo_list(td);
  978         mtx_lock_spin(&sched_lock);
  979         td->td_flags &= ~TDF_SELECT;
  980         mtx_unlock_spin(&sched_lock);
  981         mtx_unlock(&sellock);
  982 
  983 done_nosellock:
  984         /* poll is not restarted after signals... */
  985         if (error == ERESTART)
  986                 error = EINTR;
  987         if (error == EWOULDBLOCK)
  988                 error = 0;
  989         if (error == 0) {
  990                 error = copyout(bits, uap->fds, ni);
  991                 if (error)
  992                         goto out;
  993         }
  994 out:
  995         if (ni > sizeof(smallbits))
  996                 free(bits, M_TEMP);
  997 done2:
  998         return (error);
  999 }
 1000 
 1001 static int
 1002 pollscan(td, fds, nfd)
 1003         struct thread *td;
 1004         struct pollfd *fds;
 1005         u_int nfd;
 1006 {
 1007         register struct filedesc *fdp = td->td_proc->p_fd;
 1008         int i;
 1009         struct file *fp;
 1010         int n = 0;
 1011 
 1012         FILEDESC_LOCK(fdp);
 1013         for (i = 0; i < nfd; i++, fds++) {
 1014                 if (fds->fd >= fdp->fd_nfiles) {
 1015                         fds->revents = POLLNVAL;
 1016                         n++;
 1017                 } else if (fds->fd < 0) {
 1018                         fds->revents = 0;
 1019                 } else {
 1020                         fp = fdp->fd_ofiles[fds->fd];
 1021                         if (fp == NULL) {
 1022                                 fds->revents = POLLNVAL;
 1023                                 n++;
 1024                         } else {
 1025                                 /*
 1026                                  * Note: backend also returns POLLHUP and
 1027                                  * POLLERR if appropriate.
 1028                                  */
 1029                                 fds->revents = fo_poll(fp, fds->events,
 1030                                     td->td_ucred, td);
 1031                                 if (fds->revents != 0)
 1032                                         n++;
 1033                         }
 1034                 }
 1035         }
 1036         FILEDESC_UNLOCK(fdp);
 1037         td->td_retval[0] = n;
 1038         return (0);
 1039 }
 1040 
 1041 /*
 1042  * OpenBSD poll system call.
 1043  * XXX this isn't quite a true representation..  OpenBSD uses select ops.
 1044  */
 1045 #ifndef _SYS_SYSPROTO_H_
 1046 struct openbsd_poll_args {
 1047         struct pollfd *fds;
 1048         u_int   nfds;
 1049         int     timeout;
 1050 };
 1051 #endif
 1052 /*
 1053  * MPSAFE
 1054  */
 1055 int
 1056 openbsd_poll(td, uap)
 1057         register struct thread *td;
 1058         register struct openbsd_poll_args *uap;
 1059 {
 1060         return (poll(td, (struct poll_args *)uap));
 1061 }
 1062 
 1063 /*
 1064  * Remove the references to the thread from all of the objects
 1065  * we were polling.
 1066  *
 1067  * This code assumes that the underlying owner of the selinfo
 1068  * structure will hold sellock before it changes it, and that
 1069  * it will unlink itself from our list if it goes away.
 1070  */
 1071 void
 1072 clear_selinfo_list(td)
 1073         struct thread *td;
 1074 {
 1075         struct selinfo *si;
 1076 
 1077         mtx_assert(&sellock, MA_OWNED);
 1078         TAILQ_FOREACH(si, &td->td_selq, si_thrlist)
 1079                 si->si_thread = NULL;
 1080         TAILQ_INIT(&td->td_selq);
 1081 }
 1082 
 1083 /*
 1084  * Record a select request.
 1085  */
 1086 void
 1087 selrecord(selector, sip)
 1088         struct thread *selector;
 1089         struct selinfo *sip;
 1090 {
 1091 
 1092         mtx_lock(&sellock);
 1093         /*
 1094          * If the selinfo's thread pointer is NULL then take ownership of it.
 1095          *
 1096          * If the thread pointer is not NULL and it points to another
 1097          * thread, then we have a collision.
 1098          *
 1099          * If the thread pointer is not NULL and points back to us then leave
 1100          * it alone as we've already added pointed it at us and added it to
 1101          * our list.
 1102          */
 1103         if (sip->si_thread == NULL) {
 1104                 sip->si_thread = selector;
 1105                 TAILQ_INSERT_TAIL(&selector->td_selq, sip, si_thrlist);
 1106         } else if (sip->si_thread != selector) {
 1107                 sip->si_flags |= SI_COLL;
 1108         }
 1109 
 1110         mtx_unlock(&sellock);
 1111 }
 1112 
 1113 /* Wake up a selecting thread. */
 1114 void
 1115 selwakeup(sip)
 1116         struct selinfo *sip;
 1117 {
 1118         doselwakeup(sip, -1);
 1119 }
 1120 
 1121 /* Wake up a selecting thread, and set its priority. */
 1122 void
 1123 selwakeuppri(sip, pri)
 1124         struct selinfo *sip;
 1125         int pri;
 1126 {
 1127         doselwakeup(sip, pri);
 1128 }
 1129 
 1130 /*
 1131  * Do a wakeup when a selectable event occurs.
 1132  */
 1133 static void
 1134 doselwakeup(sip, pri)
 1135         struct selinfo *sip;
 1136         int pri;
 1137 {
 1138         struct thread *td;
 1139 
 1140         mtx_lock(&sellock);
 1141         td = sip->si_thread;
 1142         if ((sip->si_flags & SI_COLL) != 0) {
 1143                 nselcoll++;
 1144                 sip->si_flags &= ~SI_COLL;
 1145                 cv_broadcastpri(&selwait, pri);
 1146         }
 1147         if (td == NULL) {
 1148                 mtx_unlock(&sellock);
 1149                 return;
 1150         }
 1151         TAILQ_REMOVE(&td->td_selq, sip, si_thrlist);
 1152         sip->si_thread = NULL;
 1153         mtx_lock_spin(&sched_lock);
 1154         td->td_flags &= ~TDF_SELECT;
 1155         mtx_unlock_spin(&sched_lock);
 1156         sleepq_remove(td, &selwait);
 1157         mtx_unlock(&sellock);
 1158 }
 1159 
 1160 static void selectinit(void *);
 1161 SYSINIT(select, SI_SUB_LOCK, SI_ORDER_FIRST, selectinit, NULL)
 1162 
 1163 /* ARGSUSED*/
 1164 static void
 1165 selectinit(dummy)
 1166         void *dummy;
 1167 {
 1168         cv_init(&selwait, "select");
 1169         mtx_init(&sellock, "sellck", NULL, MTX_DEF);
 1170 }

Cache object: 283754ed65b168d6169dfc0fa6babfe8


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