mach/msgserver.c

   1 /* Copyright (C) 1993-2021 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 Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the 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    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 /* Based on CMU's mach_msg_server.c revision 2.4 of 91/05/14, and thus
  19    under the following copyright.  Rewritten by Roland McGrath (FSF)
  20    93/12/06 to use stack space instead of malloc, and to handle
  21    large messages with MACH_RCV_LARGE.  */
  22
  23 /*
  24  * Mach Operating System
  25  * Copyright (c) 1991,1990 Carnegie Mellon University
  26  * All Rights Reserved.
  27  *
  28  * Permission to use, copy, modify and distribute this software and its
  29  * documentation is hereby granted, provided that both the copyright
  30  * notice and this permission notice appear in all copies of the
  31  * software, derivative works or modified versions, and any portions
  32  * thereof, and that both notices appear in supporting documentation.
  33  *
  34  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  35  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  36  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  37  *
  38  * Carnegie Mellon requests users of this software to return to
  39  *
  40  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  41  *  School of Computer Science
  42  *  Carnegie Mellon University
  43  *  Pittsburgh PA 15213-3890
  44  *
  45  * any improvements or extensions that they make and grant Carnegie Mellon
  46  * the rights to redistribute these changes.
  47  */
  48 /*
  49  * (pre-GNU) HISTORY
  50  *
  51  * Revision 2.4  91/05/14  17:53:22  mrt
  52  *      Correcting copyright
  53  *
  54  * Revision 2.3  91/02/14  14:17:47  mrt
  55  *      Added new Mach copyright
  56  *      [91/02/13  12:44:20  mrt]
  57  *
  58  * Revision 2.2  90/08/06  17:23:58  rpd
  59  *      Created.
  60  *
  61  */
  62
  63
  64 #include <mach.h>
  65 #include <mach/mig_errors.h>
  66 #include <stdlib.h>             /* For malloc and free.  */
  67 #include <assert.h>
  68
  69 #ifdef NDR_CHAR_ASCII           /* OSF Mach flavors have different names.  */
  70 # define mig_reply_header_t     mig_reply_error_t
  71 #endif
  72
  73 mach_msg_return_t
  74 __mach_msg_server_timeout (boolean_t (*demux) (mach_msg_header_t *request,
  75                                                mach_msg_header_t *reply),
  76                            mach_msg_size_t max_size,
  77                            mach_port_t rcv_name,
  78                            mach_msg_option_t option,
  79                            mach_msg_timeout_t timeout)
  80 {
  81   mig_reply_header_t *request, *reply;
  82   mach_msg_return_t mr;
  83
  84   if (max_size == 0)
  85     {
  86 #ifdef MACH_RCV_LARGE
  87       option |= MACH_RCV_LARGE;
  88       max_size = 2 * __vm_page_size; /* Generic.  Good? XXX */
  89 #else
  90       max_size = 4 * __vm_page_size; /* XXX */
  91 #endif
  92     }
  93
  94   request = __alloca (max_size);
  95   reply = __alloca (max_size);
  96
  97   while (1)
  98     {
  99     get_request:
 100       mr = __mach_msg (&request->Head, MACH_RCV_MSG|option,
 101                        0, max_size, rcv_name,
 102                        timeout, MACH_PORT_NULL);
 103       while (mr == MACH_MSG_SUCCESS)
 104         {
 105           /* We have a request message.
 106              Pass it to DEMUX for processing.  */
 107
 108           (void) (*demux) (&request->Head, &reply->Head);
 109           assert (reply->Head.msgh_size <= max_size);
 110
 111           switch (reply->RetCode)
 112             {
 113             case KERN_SUCCESS:
 114               /* Hunky dory.  */
 115               break;
 116
 117             case MIG_NO_REPLY:
 118               /* The server function wanted no reply sent.
 119                  Loop for another request.  */
 120               goto get_request;
 121
 122             default:
 123               /* Some error; destroy the request message to release any
 124                  port rights or VM it holds.  Don't destroy the reply port
 125                  right, so we can send an error message.  */
 126               request->Head.msgh_remote_port = MACH_PORT_NULL;
 127               __mach_msg_destroy (&request->Head);
 128               break;
 129             }
 130
 131           if (reply->Head.msgh_remote_port == MACH_PORT_NULL)
 132             {
 133               /* No reply port, so destroy the reply.  */
 134               if (reply->Head.msgh_bits & MACH_MSGH_BITS_COMPLEX)
 135                 __mach_msg_destroy (&reply->Head);
 136               goto get_request;
 137             }
 138
 139           /* Send the reply and the get next request.  */
 140
 141           {
 142             /* Swap the request and reply buffers.  mach_msg will read the
 143                reply message from the buffer we pass and write the new
 144                request message to the same buffer.  */
 145             void *tmp = request;
 146             request = reply;
 147             reply = tmp;
 148           }
 149
 150           mr = __mach_msg (&request->Head,
 151                            MACH_SEND_MSG|MACH_RCV_MSG|option,
 152                            request->Head.msgh_size, max_size, rcv_name,
 153                            timeout, MACH_PORT_NULL);
 154         }
 155
 156       /* A message error occurred.  */
 157
 158       switch (mr)
 159         {
 160         case MACH_RCV_TOO_LARGE:
 161 #ifdef MACH_RCV_LARGE
 162           /* The request message is larger than MAX_SIZE, and has not
 163              been dequeued.  The message header has the actual size of
 164              the message.  We recurse here in hopes that the compiler
 165              will optimize the tail-call and allocate some more stack
 166              space instead of way too much.  */
 167           return __mach_msg_server_timeout (demux, request->Head.msgh_size,
 168                                             rcv_name, option, timeout);
 169 #else
 170           /* XXX the kernel has destroyed the msg */
 171           break;
 172 #endif
 173
 174         case MACH_SEND_INVALID_DEST:
 175           /* The reply can't be delivered, so destroy it.  This error
 176              indicates only that the requester went away, so we
 177              continue and get the next request.  */
 178           __mach_msg_destroy (&request->Head);
 179           break;
 180
 181         default:
 182           /* Some other form of lossage; return to caller.  */
 183           return mr;
 184         }
 185     }
 186 }
 187 weak_alias (__mach_msg_server_timeout, mach_msg_server_timeout)
 188
 189 mach_msg_return_t
 190 __mach_msg_server (boolean_t (*demux) (mach_msg_header_t *in,
 191                                        mach_msg_header_t *out),
 192                    mach_msg_size_t max_size,
 193                    mach_port_t rcv_name)
 194 {
 195   return __mach_msg_server_timeout (demux, max_size, rcv_name,
 196                                     MACH_MSG_OPTION_NONE,
 197                                     MACH_MSG_TIMEOUT_NONE);
 198 }
 199 weak_alias (__mach_msg_server, mach_msg_server)