hurd/intr-msg.c

   1 /* Replacement for mach_msg used in interruptible Hurd RPCs.
   2    Copyright (C) 1995,96,97,98,99,2000,2001,2002,2005
   3         Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <mach.h>
  22 #include <mach/mig_errors.h>
  23 #include <mach/mig_support.h>
  24 #include <hurd/signal.h>
  25 #include <assert.h>
  26
  27 #include "intr-msg.h"
  28
  29 #ifdef NDR_CHAR_ASCII           /* OSF Mach flavors have different names.  */
  30 # define mig_reply_header_t     mig_reply_error_t
  31 #endif
  32
  33 error_t
  34 _hurd_intr_rpc_mach_msg (mach_msg_header_t *msg,
  35                          mach_msg_option_t option,
  36                          mach_msg_size_t send_size,
  37                          mach_msg_size_t rcv_size,
  38                          mach_port_t rcv_name,
  39                          mach_msg_timeout_t timeout,
  40                          mach_port_t notify)
  41 {
  42   error_t err;
  43   struct hurd_sigstate *ss;
  44   const mach_msg_option_t user_option = option;
  45   const mach_msg_timeout_t user_timeout = timeout;
  46
  47   struct clobber
  48   {
  49 #ifdef NDR_CHAR_ASCII
  50     NDR_record_t ndr;
  51 #else
  52     mach_msg_type_t type;
  53 #endif
  54     error_t err;
  55   };
  56   union msg
  57   {
  58     mach_msg_header_t header;
  59     mig_reply_header_t reply;
  60     struct
  61     {
  62       mach_msg_header_t header;
  63 #ifdef NDR_CHAR_ASCII
  64       NDR_record_t ndr;
  65 #else
  66       int type;
  67 #endif
  68       int code;
  69     } check;
  70     struct
  71     {
  72       mach_msg_header_t header;
  73       struct clobber data;
  74     } request;
  75   };
  76   union msg *const m = (void *) msg;
  77   mach_msg_bits_t msgh_bits;
  78   mach_port_t remote_port;
  79   mach_msg_id_t msgid;
  80   struct clobber save_data;
  81
  82   if ((option & (MACH_SEND_MSG|MACH_RCV_MSG)) != (MACH_SEND_MSG|MACH_RCV_MSG)
  83       || _hurd_msgport_thread == MACH_PORT_NULL)
  84     {
  85       /* Either this is not an RPC (i.e., only a send or only a receive),
  86          so it can't be interruptible; or, the signal thread is not set up
  87          yet, so we cannot do the normal signal magic.  Do a normal,
  88          uninterruptible mach_msg call instead.  */
  89       return __mach_msg (&m->header, option, send_size, rcv_size, rcv_name,
  90                          timeout, notify);
  91     }
  92
  93   ss = _hurd_self_sigstate ();
  94
  95   /* Save state that gets clobbered by an EINTR reply message.
  96      We will need to restore it if we want to retry the RPC.  */
  97   msgh_bits = m->header.msgh_bits;
  98   remote_port = m->header.msgh_remote_port;
  99   msgid = m->header.msgh_id;
 100   assert (rcv_size >= sizeof m->request);
 101   save_data = m->request.data;
 102
 103   /* Tell the signal thread that we are doing an interruptible RPC on
 104      this port.  If we get a signal and should return EINTR, the signal
 105      thread will set this variable to MACH_PORT_NULL.  The RPC might
 106      return EINTR when some other thread gets a signal, in which case we
 107      want to restart our call.  */
 108   ss->intr_port = m->header.msgh_remote_port;
 109
 110   /* A signal may arrive here, after intr_port is set, but before the
 111      mach_msg system call.  The signal handler might do an interruptible
 112      RPC, and clobber intr_port; then it would not be set properly when we
 113      actually did send the RPC, and a later signal wouldn't interrupt that
 114      RPC.  So, _hurd_setup_sighandler saves intr_port in the sigcontext,
 115      and sigreturn restores it.  */
 116
 117  message:
 118
 119   /* XXX
 120      At all points here (once SS->intr_port is set), the signal thread
 121      thinks we are "about to enter the syscall", and might mutate our
 122      return-value register.  This is bogus.
 123    */
 124
 125   if (ss->cancel)
 126     {
 127       /* We have been cancelled.  Don't do an RPC at all.  */
 128       ss->intr_port = MACH_PORT_NULL;
 129       ss->cancel = 0;
 130       return EINTR;
 131     }
 132
 133   /* Note that the signal trampoline code might modify our OPTION!  */
 134   err = INTR_MSG_TRAP (msg, option, send_size,
 135                        rcv_size, rcv_name, timeout, notify);
 136
 137   switch (err)
 138     {
 139     case MACH_RCV_TIMED_OUT:
 140       if (user_option & MACH_RCV_TIMEOUT)
 141         /* The real user RPC timed out.  */
 142         break;
 143       else
 144         /* The operation was supposedly interrupted, but still has
 145            not returned.  Declare it interrupted.  */
 146         goto interrupted;
 147
 148     case MACH_SEND_INTERRUPTED: /* RPC didn't get out.  */
 149       if (!(option & MACH_SEND_MSG))
 150         {
 151           /* Oh yes, it did!  Since we were not doing a message send,
 152              this return code cannot have come from the kernel!
 153              Instead, it was the signal thread mutating our state to tell
 154              us not to enter this RPC.  However, we are already in the receive!
 155              Since the signal thread thought we weren't in the RPC yet,
 156              it didn't do an interrupt_operation.
 157              XXX */
 158           goto retry_receive;
 159         }
 160       /* FALLTHROUGH */
 161
 162       /* These are the other codes that mean a pseudo-receive modified
 163          the message buffer and we might need to clean up the port rights.  */
 164     case MACH_SEND_TIMED_OUT:
 165     case MACH_SEND_INVALID_NOTIFY:
 166 #ifdef MACH_SEND_NO_NOTIFY
 167     case MACH_SEND_NO_NOTIFY:
 168 #endif
 169 #ifdef MACH_SEND_NOTIFY_IN_PROGRESS
 170     case MACH_SEND_NOTIFY_IN_PROGRESS:
 171 #endif
 172       if (MACH_MSGH_BITS_REMOTE (msg->msgh_bits) == MACH_MSG_TYPE_MOVE_SEND)
 173         {
 174           __mach_port_deallocate (__mach_task_self (), msg->msgh_remote_port);
 175           msg->msgh_bits
 176             = (MACH_MSGH_BITS (MACH_MSG_TYPE_COPY_SEND,
 177                                MACH_MSGH_BITS_LOCAL (msg->msgh_bits))
 178                | MACH_MSGH_BITS_OTHER (msg->msgh_bits));
 179         }
 180       if (msg->msgh_bits & MACH_MSGH_BITS_COMPLEX)
 181         {
 182 #ifndef MACH_MSG_PORT_DESCRIPTOR
 183           /* Check for MOVE_SEND rights in the message.  These hold refs
 184              that we need to release in case the message is in fact never
 185              re-sent later.  Since it might in fact be re-sent, we turn
 186              these into COPY_SEND's after deallocating the extra user ref;
 187              the caller is responsible for still holding a ref to go with
 188              the original COPY_SEND right, so the resend copies it again.  */
 189
 190           mach_msg_type_long_t *ty = (void *) (msg + 1);
 191           while ((void *) ty < (void *) msg + msg->msgh_size)
 192             {
 193               mach_msg_type_name_t name;
 194               mach_msg_type_size_t size;
 195               mach_msg_type_number_t number;
 196
 197               inline void clean_ports (mach_port_t *ports, int dealloc)
 198                 {
 199                   mach_msg_type_number_t i;
 200                   switch (name)
 201                     {
 202                     case MACH_MSG_TYPE_MOVE_SEND:
 203                       for (i = 0; i < number; i++)
 204                         __mach_port_deallocate (__mach_task_self (), *ports++);
 205                       if (ty->msgtl_header.msgt_longform)
 206                         ty->msgtl_name = MACH_MSG_TYPE_COPY_SEND;
 207                       else
 208                         ty->msgtl_header.msgt_name = MACH_MSG_TYPE_COPY_SEND;
 209                       break;
 210                     case MACH_MSG_TYPE_COPY_SEND:
 211                     case MACH_MSG_TYPE_MOVE_RECEIVE:
 212                       break;
 213                     default:
 214                       if (MACH_MSG_TYPE_PORT_ANY (name))
 215                         assert (! "unexpected port type in interruptible RPC");
 216                     }
 217                   if (dealloc)
 218                     __vm_deallocate (__mach_task_self (),
 219                                      (vm_address_t) ports,
 220                                      number * sizeof (mach_port_t));
 221                 }
 222
 223               if (ty->msgtl_header.msgt_longform)
 224                 {
 225                   name = ty->msgtl_name;
 226                   size = ty->msgtl_size;
 227                   number = ty->msgtl_number;
 228                   ty = (void *) ty + sizeof (mach_msg_type_long_t);
 229                 }
 230               else
 231                 {
 232                   name = ty->msgtl_header.msgt_name;
 233                   size = ty->msgtl_header.msgt_size;
 234                   number = ty->msgtl_header.msgt_number;
 235                   ty = (void *) ty + sizeof (mach_msg_type_t);
 236                 }
 237
 238               if (ty->msgtl_header.msgt_inline)
 239                 {
 240                   clean_ports ((void *) ty, 0);
 241                   /* calculate length of data in bytes, rounding up */
 242                   ty = (void *) ty + (((((number * size) + 7) >> 3)
 243                                        + sizeof (mach_msg_type_t) - 1)
 244                                       &~ (sizeof (mach_msg_type_t) - 1));
 245                 }
 246               else
 247                 {
 248                   clean_ports (*(void **) ty,
 249                                ty->msgtl_header.msgt_deallocate);
 250                   ty = (void *) ty + sizeof (void *);
 251                 }
 252             }
 253 #else  /* Untyped Mach IPC flavor. */
 254           mach_msg_body_t *body = (void *) (msg + 1);
 255           mach_msg_descriptor_t *desc = (void *) (body + 1);
 256           mach_msg_descriptor_t *desc_end = desc + body->msgh_descriptor_count;
 257           for (; desc < desc_end; ++desc)
 258             switch (desc->type.type)
 259               {
 260               case MACH_MSG_PORT_DESCRIPTOR:
 261                 switch (desc->port.disposition)
 262                   {
 263                   case MACH_MSG_TYPE_MOVE_SEND:
 264                     __mach_port_deallocate (mach_task_self (),
 265                                             desc->port.name);
 266                     desc->port.disposition = MACH_MSG_TYPE_COPY_SEND;
 267                     break;
 268                   case MACH_MSG_TYPE_COPY_SEND:
 269                   case MACH_MSG_TYPE_MOVE_RECEIVE:
 270                     break;
 271                   default:
 272                     assert (! "unexpected port type in interruptible RPC");
 273                   }
 274                 break;
 275               case MACH_MSG_OOL_DESCRIPTOR:
 276                 if (desc->out_of_line.deallocate)
 277                   __vm_deallocate (__mach_task_self (),
 278                                    (vm_address_t) desc->out_of_line.address,
 279                                    desc->out_of_line.size);
 280                 break;
 281               case MACH_MSG_OOL_PORTS_DESCRIPTOR:
 282                 switch (desc->ool_ports.disposition)
 283                   {
 284                   case MACH_MSG_TYPE_MOVE_SEND:
 285                     {
 286                       mach_msg_size_t i;
 287                       const mach_port_t *ports = desc->ool_ports.address;
 288                       for (i = 0; i < desc->ool_ports.count; ++i)
 289                         __mach_port_deallocate (__mach_task_self (), ports[i]);
 290                       desc->ool_ports.disposition = MACH_MSG_TYPE_COPY_SEND;
 291                       break;
 292                     }
 293                   case MACH_MSG_TYPE_COPY_SEND:
 294                   case MACH_MSG_TYPE_MOVE_RECEIVE:
 295                     break;
 296                   default:
 297                     assert (! "unexpected port type in interruptible RPC");
 298                   }
 299                 if (desc->ool_ports.deallocate)
 300                   __vm_deallocate (__mach_task_self (),
 301                                    (vm_address_t) desc->ool_ports.address,
 302                                    desc->ool_ports.count
 303                                    * sizeof (mach_port_t));
 304                 break;
 305               default:
 306                 assert (! "unexpected descriptor type in interruptible RPC");
 307               }
 308 #endif
 309         }
 310       break;
 311
 312     case EINTR:
 313       /* Either the process was stopped and continued,
 314          or the server doesn't support interrupt_operation.  */
 315       if (ss->intr_port != MACH_PORT_NULL)
 316         /* If this signal was for us and it should interrupt calls, the
 317            signal thread will have cleared SS->intr_port.
 318            Since it's not cleared, the signal was for another thread,
 319            or SA_RESTART is set.  Restart the interrupted call.  */
 320         {
 321           /* Make sure we have a valid reply port.  The one we were using
 322              may have been destroyed by interruption.  */
 323           m->header.msgh_local_port = rcv_name = __mig_get_reply_port ();
 324           m->header.msgh_bits = msgh_bits;
 325           option = user_option;
 326           timeout = user_timeout;
 327           goto message;
 328         }
 329       /* FALLTHROUGH */
 330
 331     case MACH_RCV_PORT_DIED:
 332       /* Server didn't respond to interrupt_operation,
 333          so the signal thread destroyed the reply port.  */
 334       /* FALLTHROUGH */
 335
 336     interrupted:
 337       err = EINTR;
 338
 339       /* The EINTR return indicates cancellation, so clear the flag.  */
 340       ss->cancel = 0;
 341       break;
 342
 343     case MACH_RCV_INTERRUPTED:  /* RPC sent; no reply.  */
 344       option &= ~MACH_SEND_MSG; /* Don't send again.  */
 345     retry_receive:
 346       if (ss->intr_port == MACH_PORT_NULL)
 347         {
 348           /* This signal or cancellation was for us.  We need to wait for
 349              the reply, but not hang forever.  */
 350           option |= MACH_RCV_TIMEOUT;
 351           /* Never decrease the user's timeout.  */
 352           if (!(user_option & MACH_RCV_TIMEOUT)
 353               || timeout > _hurd_interrupted_rpc_timeout)
 354             timeout = _hurd_interrupted_rpc_timeout;
 355         }
 356       else
 357         {
 358           option = user_option;
 359           timeout = user_timeout;
 360         }
 361       goto message;             /* Retry the receive.  */
 362
 363     case MACH_MSG_SUCCESS:
 364       {
 365         /* We got a reply.  Was it EINTR?  */
 366 #ifdef MACH_MSG_TYPE_BIT
 367         const union
 368         {
 369           mach_msg_type_t t;
 370           int i;
 371         } check =
 372           { t: { MACH_MSG_TYPE_INTEGER_T, sizeof (integer_t) * 8,
 373                  1, TRUE, FALSE, FALSE, 0 } };
 374 #endif
 375
 376         if (m->reply.RetCode == EINTR &&
 377             m->header.msgh_size == sizeof m->reply &&
 378 #ifdef MACH_MSG_TYPE_BIT
 379             m->check.type == check.i &&
 380 #endif
 381             !(m->header.msgh_bits & MACH_MSGH_BITS_COMPLEX))
 382           {
 383             /* It is indeed EINTR.  Is the interrupt for us?  */
 384             if (ss->intr_port != MACH_PORT_NULL)
 385               {
 386                 /* Nope; repeat the RPC.
 387                    XXX Resources moved? */
 388
 389                 assert (m->header.msgh_id == msgid + 100);
 390
 391                 /* We know we have a valid reply port, because we just
 392                    received the EINTR reply on it.  Restore it and the
 393                    other fields in the message header needed for send,
 394                    since the header now reflects receipt of the reply.  */
 395                 m->header.msgh_local_port = rcv_name;
 396                 m->header.msgh_remote_port = remote_port;
 397                 m->header.msgh_id = msgid;
 398                 m->header.msgh_bits = msgh_bits;
 399                 /* Restore the two words clobbered by the reply data.  */
 400                 m->request.data = save_data;
 401
 402                 /* Restore the original mach_msg options.
 403                    OPTION may have had MACH_RCV_TIMEOUT added,
 404                    and/or MACH_SEND_MSG removed.  */
 405                 option = user_option;
 406                 timeout = user_timeout;
 407
 408                 /* Now we are ready to repeat the original message send.  */
 409                 goto message;
 410               }
 411             else
 412               /* The EINTR return indicates cancellation,
 413                  so clear the flag.  */
 414               ss->cancel = 0;
 415           }
 416       }
 417       break;
 418
 419     default:                    /* Quiet -Wswitch-enum.  */
 420       break;
 421     }
 422
 423   ss->intr_port = MACH_PORT_NULL;
 424
 425   return err;
 426 }