Security-57031.1.35.tar.gz

[apple/security.git] / securityd / src / child.cpp

diff --git a/securityd/src/child.cpp b/securityd/src/child.cpp
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+/*
+ * Copyright (c) 2004,2007 Apple Inc. All Rights Reserved.
+ * 
+ * @APPLE_LICENSE_HEADER_START@
+ * 
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ * 
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+
+//
+// child - track a single child process and its belongings
+//
+#include "child.h"
+#include "dtrace.h"
+#include <security_utilities/debugging.h>
+
+
+//
+// We use a static Mutex to coordinate checkin
+//
+Mutex ServerChild::mCheckinLock;
+
+
+//
+// Make and break ServerChildren
+//
+ServerChild::ServerChild()
+       : mCheckinCond(mCheckinLock)
+{
+}
+
+
+//
+// If the ServerChild is destroyed, kill its process, nice or hard.
+//
+// In case you wonder about the tango below, it's making sure we
+// get to "It's dead, Jim" with the minimum number of checkChildren()
+// calls while still working correctly if this is the only thread alive.
+//
+//@@@ We *could* define a "soft shutdown" MIG message to send to all
+//@@@ ServerChildren in this situation.
+//
+ServerChild::~ServerChild()
+{
+       mServicePort.destroy();
+       
+       if (state() == alive) {
+               this->kill(SIGTERM);            // shoot it once
+               checkChildren();                        // check for quick death
+               if (state() == alive) {
+                       usleep(300000);                 // give it some grace
+                       if (state() == alive) { // could have been reaped by another thread
+                               checkChildren();        // check again
+                               if (state() == alive) { // it... just... won't... die...
+                                       this->kill(SIGKILL); // take THAT!
+                                       checkChildren();
+                                       if (state() == alive) // stuck zombie
+                                               abandon();      // leave the body behind
+                               }
+                       }
+               }
+       }
+}
+
+
+//
+// Parent action during fork: wait until ready or dead, then return
+//
+void ServerChild::parentAction()
+{
+       // wait for either checkin or (premature) death
+       secdebug("serverchild", "%p (pid %d) waiting for checkin", this, pid());
+       StLock<Mutex> _(mCheckinLock);
+       while (!ready() && state() == alive)
+               mCheckinCond.wait();
+
+       // so what happened?
+       if (state() == dead) {
+               // our child died
+               secdebug("serverchild", "%p (pid %d) died before checking in", this, pid());
+               SECURITYD_CHILD_STILLBORN(this->pid());
+       } else if (ready()) {
+               // child has checked in and is ready for service
+               secdebug("serverchild", "%p (pid %d) ready for service on port %d",
+                       this, pid(), mServicePort.port());
+               SECURITYD_CHILD_READY(this->pid());
+       } else
+               assert(false);          // how did we ever get here?!
+}
+
+
+//
+// Death action during fork: release the waiting creator thread, if any
+//
+void ServerChild::dying()
+{
+       SECURITYD_CHILD_DYING(this->pid());
+       secdebug("serverchild", "%p is dead; resuming parent thread (if any)", this);
+       mCheckinCond.signal();
+}
+
+
+void ServerChild::checkIn(Port servicePort, pid_t pid)
+{
+       if (ServerChild *child = Child::find<ServerChild>(pid)) {
+               // Child was alive when last seen. Store service port and signal parent thread
+               {
+                       StLock<Mutex> _(mCheckinLock);
+                       child->mServicePort = servicePort;
+                       servicePort.modRefs(MACH_PORT_RIGHT_SEND, +1);  // retain send right
+                       secdebug("serverchild", "%p (pid %d) checking in; resuming parent thread",
+                               child, pid);
+               }
+               SECURITYD_CHILD_CHECKIN(pid, servicePort);
+               child->mCheckinCond.signal();
+       } else {
+               // Child has died; is wrong kind; or spurious checkin.
+               // If it was a proper child, death notifications will wake up the parent thread
+               secdebug("serverchild", "pid %d not in child set; checkin ignored", pid);
+               SECURITYD_CHILD_CHECKIN(pid, 0);
+       }
+}