sysdeps/mach/hurd/select.c

   1 /* Copyright (C) 1991, 92, 93, 94, 95, 96 Free Software Foundation, Inc.
   2 This file is part of the GNU C Library.
   3
   4 The GNU C Library is free software; you can redistribute it and/or
   5 modify it under the terms of the GNU Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 License, or (at your option) any later version.
   8
   9 The GNU C Library is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <ansidecl.h>
  20 #include <sys/types.h>
  21 #include <hurd.h>
  22 #include <hurd/fd.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <assert.h>
  26
  27 /* All user select types.  */
  28 #define SELECT_ALL (SELECT_READ | SELECT_WRITE | SELECT_URG)
  29
  30 /* Used to record that a particular select rpc returned. Must be distinct
  31    from SELECT_ALL (which better not have the high bit set).  */
  32 #define SELECT_RETURNED ((SELECT_ALL << 1) & ~SELECT_ALL)
  33
  34 /* Check the first NFDS descriptors each in READFDS (if not NULL) for read
  35    readiness, in WRITEFDS (if not NULL) for write readiness, and in EXCEPTFDS
  36    (if not NULL) for exceptional conditions.  If TIMEOUT is not NULL, time out
  37    after waiting the interval specified therein.  Returns the number of ready
  38    descriptors, or -1 for errors.  */
  39 int
  40 DEFUN(__select, (nfds, readfds, writefds, exceptfds, timeout),
  41       int nfds AND fd_set *readfds AND fd_set *writefds AND
  42       fd_set *exceptfds AND struct timeval *timeout)
  43 {
  44   int i;
  45   mach_port_t portset;
  46   int got;
  47   error_t err;
  48   fd_set rfds, wfds, xfds;
  49   int firstfd, lastfd;
  50   mach_msg_timeout_t to = (timeout != NULL ?
  51                            (timeout->tv_sec * 1000 +
  52                             timeout->tv_usec / 1000) :
  53                            0);
  54   struct
  55     {
  56       struct hurd_userlink ulink;
  57       struct hurd_fd *cell;
  58       mach_port_t io_port;
  59       int type;
  60       mach_port_t reply_port;
  61     } d[nfds];
  62
  63   /* Use local copies so we can't crash from user bogosity.  */
  64   if (readfds == NULL)
  65     FD_ZERO (&rfds);
  66   else
  67     rfds = *readfds;
  68   if (writefds == NULL)
  69     FD_ZERO (&wfds);
  70   else
  71     wfds = *writefds;
  72   if (exceptfds == NULL)
  73     FD_ZERO (&xfds);
  74   else
  75     xfds = *exceptfds;
  76
  77   HURD_CRITICAL_BEGIN;
  78   __mutex_lock (&_hurd_dtable_lock);
  79
  80   if (nfds > _hurd_dtablesize)
  81     nfds = _hurd_dtablesize;
  82
  83   /* Collect the ports for interesting FDs.  */
  84   firstfd = lastfd = -1;
  85   for (i = 0; i < nfds; ++i)
  86     {
  87       int type = 0;
  88       if (readfds != NULL && FD_ISSET (i, &rfds))
  89         type |= SELECT_READ;
  90       if (writefds != NULL && FD_ISSET (i, &wfds))
  91         type |= SELECT_WRITE;
  92       if (exceptfds != NULL && FD_ISSET (i, &xfds))
  93         type |= SELECT_URG;
  94       d[i].type = type;
  95       if (type)
  96         {
  97           d[i].cell = _hurd_dtable[i];
  98           d[i].io_port = _hurd_port_get (&d[i].cell->port, &d[i].ulink);
  99           if (d[i].io_port == MACH_PORT_NULL)
 100             {
 101               /* If one descriptor is bogus, we fail completely.  */
 102               while (i-- > 0)
 103                 _hurd_port_free (&d[i].cell->port, &d[i].ulink, d[i].io_port);
 104               errno = EBADF;
 105               break;
 106             }
 107           lastfd = i;
 108           if (firstfd == -1)
 109             firstfd = i;
 110         }
 111     }
 112
 113   __mutex_unlock (&_hurd_dtable_lock);
 114   HURD_CRITICAL_END;
 115
 116   if (i < nfds)
 117     return -1;
 118
 119   /* Send them all io_select request messages.  */
 120   err = 0;
 121   got = 0;
 122   portset = MACH_PORT_NULL;
 123   for (i = firstfd; i <= lastfd; ++i)
 124     if (d[i].type)
 125       {
 126         int type = d[i].type;
 127         d[i].reply_port = __mach_reply_port ();
 128         err = __io_select (d[i].io_port, d[i].reply_port,
 129                            /* Poll for each but the last.  */
 130                            (i == lastfd && got == 0) ? to : 0,
 131                            &type);
 132         switch (err)
 133           {
 134           case MACH_RCV_TIMED_OUT:
 135             /* No immediate response.  This is normal.  */
 136             err = 0;
 137             if (got == 0)
 138               {
 139                 /* We will wait again for a reply later.  */
 140                 if (portset == MACH_PORT_NULL)
 141                   /* Create the portset to receive all the replies on.  */
 142                   err = __mach_port_allocate (__mach_task_self (),
 143                                               MACH_PORT_RIGHT_PORT_SET,
 144                                               &portset);
 145                 if (! err)
 146                   /* Put this reply port in the port set.  */
 147                   __mach_port_move_member (__mach_task_self (),
 148                                            d[i].reply_port, portset);
 149               }
 150             break;
 151
 152           default:
 153             /* No other error should happen.  Callers of select don't
 154                expect to see errors, so we simulate readiness of the erring
 155                object and the next call hopefully will get the error again.  */
 156             type = SELECT_ALL;
 157             /* FALLTHROUGH */
 158
 159           case 0:
 160             /* We got an answer.  */
 161             if ((type & SELECT_ALL) == 0)
 162               /* Bogus answer; treat like an error, as a fake positive.  */
 163               type = SELECT_ALL;
 164
 165             /* This port is already ready already.  */
 166             d[i].type &= type;
 167             d[i].type |= SELECT_RETURNED;
 168             ++got;
 169             break;
 170           }
 171         _hurd_port_free (&d[i].cell->port, &d[i].ulink, d[i].io_port);
 172       }
 173
 174   /* Now wait for reply messages.  */
 175   if (!err && got == 0)
 176     {
 177       /* Now wait for io_select_reply messages on PORT,
 178          timing out as appropriate.  */
 179
 180       union
 181         {
 182           mach_msg_header_t head;
 183           struct
 184             {
 185               mach_msg_header_t head;
 186               mach_msg_type_t err_type;
 187               error_t err;
 188             } error;
 189           struct
 190             {
 191               mach_msg_header_t head;
 192               mach_msg_type_t err_type;
 193               error_t err;
 194               mach_msg_type_t result_type;
 195               int result;
 196             } success;
 197         } msg;
 198       mach_msg_option_t options = (timeout == NULL ? 0 : MACH_RCV_TIMEOUT);
 199       error_t msgerr;
 200       while ((msgerr = __mach_msg (&msg.head,
 201                                    MACH_RCV_MSG | options,
 202                                    0, sizeof msg, portset, to,
 203                                    MACH_PORT_NULL)) == MACH_MSG_SUCCESS)
 204         {
 205           /* We got a message.  Decode it.  */
 206 #define IO_SELECT_REPLY_MSGID (21012 + 100) /* XXX */
 207           const mach_msg_type_t inttype =
 208             { MACH_MSG_TYPE_INTEGER_32, 32, 1, 1, 0, 0 };
 209           if (msg.head.msgh_id == IO_SELECT_REPLY_MSGID &&
 210               msg.head.msgh_size >= sizeof msg.error &&
 211               !(msg.head.msgh_bits & MACH_MSGH_BITS_COMPLEX) &&
 212               *(int *) &msg.error.err_type == *(int *) &inttype)
 213             {
 214               /* This is a properly formatted message so far.
 215                  See if it is a success or a failure.  */
 216               if (msg.error.err == EINTR &&
 217                   msg.head.msgh_size == sizeof msg.error)
 218                 {
 219                   /* EINTR response; poll for further responses
 220                      and then return quickly.  */
 221                   err = EINTR;
 222                   goto poll;
 223                 }
 224               if (msg.error.err ||
 225                   msg.head.msgh_size != sizeof msg.success ||
 226                   *(int *) &msg.success.result_type != *(int *) &inttype ||
 227                   (msg.success.result & SELECT_ALL) == 0)
 228                 {
 229                   /* Error or bogus reply.  Simulate readiness.  */
 230                   __mach_msg_destroy (&msg);
 231                   msg.success.result = SELECT_ALL;
 232                 }
 233
 234               /* Look up the respondant's reply port and record its
 235                  readiness.  */
 236               {
 237                 int had = got;
 238                 for (i = firstfd; i <= lastfd; ++i)
 239                   if (d[i].type && d[i].reply_port == msg.head.msgh_local_port)
 240                     {
 241                       d[i].type &= msg.success.result;
 242                       d[i].type |= SELECT_RETURNED;
 243                       ++got;
 244                     }
 245                 assert (got > had);
 246               }
 247             }
 248
 249           if (msg.head.msgh_remote_port != MACH_PORT_NULL)
 250             __mach_port_deallocate (__mach_task_self (),
 251                                     msg.head.msgh_remote_port);
 252
 253           if (got)
 254           poll:
 255             {
 256               /* Poll for another message.  */
 257               to = 0;
 258               options |= MACH_RCV_TIMEOUT;
 259             }
 260         }
 261
 262       if (err == MACH_RCV_TIMED_OUT)
 263         /* This is the normal value for ERR.  We might have timed out and
 264            read no messages.  Otherwise, after receiving the first message,
 265            we poll for more messages.  We receive with a timeout of 0 to
 266            effect a poll, so ERR is MACH_RCV_TIMED_OUT when the poll finds no
 267            message waiting.  */
 268         err = 0;
 269
 270       if (got)
 271         /* At least one descriptor is known to be ready now, so we will
 272            return success.  */
 273         err = 0;
 274     }
 275
 276   for (i = firstfd; i <= lastfd; ++i)
 277     if (d[i].type)
 278       __mach_port_destroy (__mach_task_self (), d[i].reply_port);
 279   if (portset != MACH_PORT_NULL)
 280     __mach_port_destroy (__mach_task_self (), portset);
 281
 282   if (err)
 283     return __hurd_fail (err);
 284
 285   /* Below we recalculate GOT to include an increment for each operation
 286      allowed on each fd.  */
 287   got = 0;
 288
 289   /* Set the user bitarrays.  We only ever have to clear bits, as all desired
 290      ones are initially set.  */
 291   for (i = firstfd; i <= lastfd; ++i)
 292     {
 293       int type = d[i].type;
 294
 295       if ((type & SELECT_RETURNED) == 0)
 296         type = 0;
 297
 298       if (type & SELECT_READ)
 299         got++;
 300       else if (readfds)
 301         FD_CLR (i, readfds);
 302       if (type & SELECT_WRITE)
 303         got++;
 304       else if (writefds)
 305         FD_CLR (i, writefds);
 306       if (type & SELECT_URG)
 307         got++;
 308       else if (exceptfds)
 309         FD_CLR (i, exceptfds);
 310     }
 311
 312   return got;
 313 }
 314
 315 weak_alias (__select, select)