src/kits/network/netresolv/isc/ev_files.c

   1 /*
   2  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (c) 1995-1999 by Internet Software Consortium
   4  *
   5  * Permission to use, copy, modify, and distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
  10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  11  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
  12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  15  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 /* ev_files.c - implement asynch file IO for the eventlib
  19  * vix 11sep95 [initial]
  20  */
  21
  22 #if !defined(LINT) && !defined(CODECENTER)
  23 static const char rcsid[] = "$Id: ev_files.c,v 1.8 2005/07/28 06:51:48 marka Exp $";
  24 #endif
  25
  26 #include "port_before.h"
  27 #include "fd_setsize.h"
  28
  29 #include <sys/types.h>
  30 #include <sys/time.h>
  31 #include <sys/ioctl.h>
  32
  33 #include <errno.h>
  34 #include <fcntl.h>
  35 #include <unistd.h>
  36
  37 #include <isc/eventlib.h>
  38 #include "eventlib_p.h"
  39
  40 #include "port_after.h"
  41
  42 static evFile *FindFD(const evContext_p *ctx, int fd, int eventmask);
  43
  44 int
  45 evSelectFD(evContext opaqueCtx,
  46            int fd,
  47            int eventmask,
  48            evFileFunc func,
  49            void *uap,
  50            evFileID *opaqueID
  51 ) {
  52         evContext_p *ctx = opaqueCtx.opaque;
  53         evFile *id;
  54         int mode;
  55
  56         evPrintf(ctx, 1,
  57                  "evSelectFD(ctx %p, fd %d, mask 0x%x, func %p, uap %p)\n",
  58                  ctx, fd, eventmask, func, uap);
  59         if (eventmask == 0 || (eventmask & ~EV_MASK_ALL) != 0)
  60                 EV_ERR(EINVAL);
  61 #ifndef USE_POLL
  62         if (fd > ctx->highestFD)
  63                 EV_ERR(EINVAL);
  64 #endif
  65         OK(mode = fcntl(fd, F_GETFL, NULL));    /*%< side effect: validate fd. */
  66         /*
  67          * The first time we touch a file descriptor, we need to check to see
  68          * if the application already had it in O_NONBLOCK mode and if so, all
  69          * of our deselect()'s have to leave it in O_NONBLOCK.  If not, then
  70          * all but our last deselect() has to leave it in O_NONBLOCK.
  71          */
  72 #ifdef USE_POLL
  73         /* Make sure both ctx->pollfds[] and ctx->fdTable[] are large enough */
  74         if (fd >= ctx->maxnfds && evPollfdRealloc(ctx, 1, fd) != 0)
  75                 EV_ERR(ENOMEM);
  76 #endif /* USE_POLL */
  77         id = FindFD(ctx, fd, EV_MASK_ALL);
  78         if (id == NULL) {
  79                 if (mode & PORT_NONBLOCK)
  80                         FD_SET(fd, &ctx->nonblockBefore);
  81                 else {
  82 #ifdef USE_FIONBIO_IOCTL
  83                         int on = 1;
  84                         OK(ioctl(fd, FIONBIO, (char *)&on));
  85 #else
  86                         OK(fcntl(fd, F_SETFL, mode | PORT_NONBLOCK));
  87 #endif
  88                         FD_CLR(fd, &ctx->nonblockBefore);
  89                 }
  90         }
  91
  92         /*
  93          * If this descriptor is already in use, search for it again to see
  94          * if any of the eventmask bits we want to set are already captured.
  95          * We cannot usefully capture the same fd event more than once in the
  96          * same context.
  97          */
  98         if (id != NULL && FindFD(ctx, fd, eventmask) != NULL)
  99                 EV_ERR(ETOOMANYREFS);
 100
 101         /* Allocate and fill. */
 102         OKNEW(id);
 103         id->func = func;
 104         id->uap = uap;
 105         id->fd = fd;
 106         id->eventmask = eventmask;
 107
 108         /*
 109          * Insert at head.  Order could be important for performance if we
 110          * believe that evGetNext()'s accesses to the fd_sets will be more
 111          * serial and therefore more cache-lucky if the list is ordered by
 112          * ``fd.''  We do not believe these things, so we don't do it.
 113          *
 114          * The interesting sequence is where GetNext() has cached a select()
 115          * result and the caller decides to evSelectFD() on some descriptor.
 116          * Since GetNext() starts at the head, it can miss new entries we add
 117          * at the head.  This is not a serious problem since the event being
 118          * evSelectFD()'d for has to occur before evSelectFD() is called for
 119          * the file event to be considered "missed" -- a real corner case.
 120          * Maintaining a "tail" pointer for ctx->files would fix this, but I'm
 121          * not sure it would be ``more correct.''
 122          */
 123         if (ctx->files != NULL)
 124                 ctx->files->prev = id;
 125         id->prev = NULL;
 126         id->next = ctx->files;
 127         ctx->files = id;
 128
 129         /* Insert into fd table. */
 130         if (ctx->fdTable[fd] != NULL)
 131                 ctx->fdTable[fd]->fdprev = id;
 132         id->fdprev = NULL;
 133         id->fdnext = ctx->fdTable[fd];
 134         ctx->fdTable[fd] = id;
 135
 136         /* Turn on the appropriate bits in the {rd,wr,ex}Next fd_set's. */
 137         if (eventmask & EV_READ)
 138                 FD_SET(fd, &ctx->rdNext);
 139         if (eventmask & EV_WRITE)
 140                 FD_SET(fd, &ctx->wrNext);
 141         if (eventmask & EV_EXCEPT)
 142                 FD_SET(fd, &ctx->exNext);
 143
 144         /* Update fdMax. */
 145         if (fd > ctx->fdMax)
 146                 ctx->fdMax = fd;
 147
 148         /* Remember the ID if the caller provided us a place for it. */
 149         if (opaqueID)
 150                 opaqueID->opaque = id;
 151
 152         return (0);
 153 }
 154
 155 int
 156 evDeselectFD(evContext opaqueCtx, evFileID opaqueID) {
 157         evContext_p *ctx = opaqueCtx.opaque;
 158         evFile *del = opaqueID.opaque;
 159         evFile *cur;
 160         int mode, eventmask;
 161
 162         if (!del) {
 163                 evPrintf(ctx, 11, "evDeselectFD(NULL) ignored\n");
 164                 errno = EINVAL;
 165                 return (-1);
 166         }
 167
 168         evPrintf(ctx, 1, "evDeselectFD(fd %d, mask 0x%x)\n",
 169                  del->fd, del->eventmask);
 170
 171         /* Get the mode.  Unless the file has been closed, errors are bad. */
 172         mode = fcntl(del->fd, F_GETFL, NULL);
 173         if (mode == -1 && errno != EBADF)
 174                 EV_ERR(errno);
 175
 176         /* Remove from the list of files. */
 177         if (del->prev != NULL)
 178                 del->prev->next = del->next;
 179         else
 180                 ctx->files = del->next;
 181         if (del->next != NULL)
 182                 del->next->prev = del->prev;
 183
 184         /* Remove from the fd table. */
 185         if (del->fdprev != NULL)
 186                 del->fdprev->fdnext = del->fdnext;
 187         else
 188                 ctx->fdTable[del->fd] = del->fdnext;
 189         if (del->fdnext != NULL)
 190                 del->fdnext->fdprev = del->fdprev;
 191
 192         /*
 193          * If the file descriptor does not appear in any other select() entry,
 194          * and if !EV_WASNONBLOCK, and if we got no EBADF when we got the mode
 195          * earlier, then: restore the fd to blocking status.
 196          */
 197         if (!(cur = FindFD(ctx, del->fd, EV_MASK_ALL)) &&
 198             !FD_ISSET(del->fd, &ctx->nonblockBefore) &&
 199             mode != -1) {
 200                 /*
 201                  * Note that we won't return an error status to the caller if
 202                  * this fcntl() fails since (a) we've already done the work
 203                  * and (b) the caller didn't ask us anything about O_NONBLOCK.
 204                  */
 205 #ifdef USE_FIONBIO_IOCTL
 206                 int off = 0;
 207                 (void) ioctl(del->fd, FIONBIO, (char *)&off);
 208 #else
 209                 (void) fcntl(del->fd, F_SETFL, mode & ~PORT_NONBLOCK);
 210 #endif
 211         }
 212
 213         /*
 214          * Now find all other uses of this descriptor and OR together an event
 215          * mask so that we don't turn off {rd,wr,ex}Next bits that some other
 216          * file event is using.  As an optimization, stop if the event mask
 217          * fills.
 218          */
 219         eventmask = 0;
 220         for ((void)NULL;
 221              cur != NULL && eventmask != EV_MASK_ALL;
 222              cur = cur->next)
 223                 if (cur->fd == del->fd)
 224                         eventmask |= cur->eventmask;
 225
 226         /* OK, now we know which bits we can clear out. */
 227         if (!(eventmask & EV_READ)) {
 228                 FD_CLR(del->fd, &ctx->rdNext);
 229                 if (FD_ISSET(del->fd, &ctx->rdLast)) {
 230                         FD_CLR(del->fd, &ctx->rdLast);
 231                         ctx->fdCount--;
 232                 }
 233         }
 234         if (!(eventmask & EV_WRITE)) {
 235                 FD_CLR(del->fd, &ctx->wrNext);
 236                 if (FD_ISSET(del->fd, &ctx->wrLast)) {
 237                         FD_CLR(del->fd, &ctx->wrLast);
 238                         ctx->fdCount--;
 239                 }
 240         }
 241         if (!(eventmask & EV_EXCEPT)) {
 242                 FD_CLR(del->fd, &ctx->exNext);
 243                 if (FD_ISSET(del->fd, &ctx->exLast)) {
 244                         FD_CLR(del->fd, &ctx->exLast);
 245                         ctx->fdCount--;
 246                 }
 247         }
 248
 249         /* If this was the maxFD, find the new one. */
 250         if (del->fd == ctx->fdMax) {
 251                 ctx->fdMax = -1;
 252                 for (cur = ctx->files; cur; cur = cur->next)
 253                         if (cur->fd > ctx->fdMax)
 254                                 ctx->fdMax = cur->fd;
 255         }
 256
 257         /* If this was the fdNext, cycle that to the next entry. */
 258         if (del == ctx->fdNext)
 259                 ctx->fdNext = del->next;
 260
 261         /* Couldn't free it before now since we were using fields out of it. */
 262         FREE(del);
 263
 264         return (0);
 265 }
 266
 267 static evFile *
 268 FindFD(const evContext_p *ctx, int fd, int eventmask) {
 269         evFile *id;
 270
 271         for (id = ctx->fdTable[fd]; id != NULL; id = id->fdnext)
 272                 if (id->fd == fd && (id->eventmask & eventmask) != 0)
 273                         break;
 274         return (id);
 275 }
 276
 277 /*! \file */