libsystem_asl.tproj/src/asl_mt_shim.c

   1 /*
   2  * Copyright (c) 2019 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #include <asl_msg.h>
  25 #include <os/lock_private.h>
  26 #include <xpc/private.h>
  27
  28 #if TARGET_OS_OSX
  29
  30 #define MT_SHIM_SERVICE_NAME "com.apple.analyticsd.messagetracer"
  31
  32 static os_unfair_lock _mt_shim_lock = OS_UNFAIR_LOCK_INIT;
  33 static xpc_pipe_t _mt_shim_pipe;
  34
  35 void
  36 _asl_mt_shim_fork_child(void)
  37 {
  38     if (_mt_shim_pipe) {
  39         xpc_pipe_invalidate(_mt_shim_pipe);
  40         xpc_release(_mt_shim_pipe);
  41         _mt_shim_pipe = NULL;
  42     }
  43     _mt_shim_lock = OS_UNFAIR_LOCK_INIT;
  44 }
  45
  46 static xpc_pipe_t
  47 _asl_mt_shim_pipe_copy(OS_OBJECT_CONSUMED xpc_pipe_t prev)
  48 {
  49     xpc_pipe_t pipe;
  50
  51     os_unfair_lock_lock_with_options(&_mt_shim_lock,
  52             OS_UNFAIR_LOCK_DATA_SYNCHRONIZATION);
  53     pipe = _mt_shim_pipe;
  54     if (prev) {
  55         if (pipe == prev) {
  56             xpc_release(pipe);
  57             pipe = NULL;
  58         }
  59         xpc_release(prev);
  60     }
  61     if (!pipe) {
  62         uint64_t flags = XPC_PIPE_PRIVILEGED | XPC_PIPE_USE_SYNC_IPC_OVERRIDE;
  63         _mt_shim_pipe = pipe = xpc_pipe_create(MT_SHIM_SERVICE_NAME, flags);
  64     }
  65     if (pipe) xpc_retain(pipe);
  66     os_unfair_lock_unlock(&_mt_shim_lock);
  67     return pipe;
  68 }
  69
  70 static xpc_object_t
  71 _asl_mt_shim_send_with_reply(xpc_object_t msg)
  72 {
  73     xpc_object_t reply = NULL;
  74     xpc_pipe_t pipe = _asl_mt_shim_pipe_copy(NULL);
  75
  76     if (pipe && xpc_pipe_routine(pipe, msg, &reply) == EPIPE) {
  77         pipe = _asl_mt_shim_pipe_copy(pipe);
  78         if (pipe) (void)xpc_pipe_routine(pipe, msg, &reply);
  79     }
  80     if (pipe) xpc_release(pipe);
  81     return reply;
  82 }
  83
  84 void
  85 _asl_mt_shim_send_message(asl_msg_t *msg)
  86 {
  87     /* don't send messages that were already shimmed by the caller */
  88     const char *val = NULL;
  89     if ((asl_msg_lookup(msg, "com.apple.message.__source__", &val, NULL) == 0) && (val != NULL)) {
  90         if (!strcmp(val, "SPI")) return;
  91     }
  92
  93     xpc_object_t xmsg = xpc_dictionary_create(NULL, NULL, 0);
  94     _asl_log_args_to_xpc(NULL, (asl_object_t)msg, xmsg);
  95     xpc_object_t reply = _asl_mt_shim_send_with_reply(xmsg);
  96     if (reply) xpc_release(reply);
  97     xpc_release(xmsg);
  98 }
  99
 100 #endif /* TARGET_OS_OSX */