+++ /dev/null
-/*
- * Copyright (c) 2000-2001 Apple Computer, Inc. All Rights Reserved.
- *
- * The contents of this file constitute Original Code as defined in and are
- * subject to the Apple Public Source License Version 1.2 (the 'License').
- * You may not use this file except in compliance with the License. Please obtain
- * a copy of the License at http://www.apple.com/publicsource and read it before
- * using this file.
- *
- * This 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.
- */
-
-
-//
-// globalizer - multiscope globalization services.
-//
-// This is a tentative, partial implementation.
-// Status:
-// module scope: constructs, optional cleanup
-// thread scope: constructs, optional cleanup
-// process scope: not implemented (obsolete implementation, unused)
-// system scope: not implemented (probably never will)
-//
-// @@@ Assumption: {bool,T*} atomic unless PTHREAD_STRICT
-//
-#include <Security/globalizer.h>
-#include <Security/debugging.h>
-#include <cstdlib>
-
-
-//
-// The Error class thrown if Nexus operations fail
-//
-GlobalNexus::Error::~Error() throw()
-{
-}
-
-
-//
-// The long (and possibly contentious) path of ModuleNexus()
-//
-// Briefly, the trick here is to go through a three-stage sequence
-// to lazily construct a unique singleton object, no matter how many
-// threads all of a sudden decide they need it.
-// State sequence:
-// State 0: pointer == 0, not initialized, idle
-// State 1: pointer == mutexp | 0x1, where mutexp points to a Mutex
-// used to serialize construction of the singleton object
-// State 2: pointer == &singleton, and we're done
-//
-// TAKE NOTE:
-// This code is optimized with a particular issue in mind: when placed
-// into static storage (as ModuleNexi are wont to), it should not require
-// dynamic initialization. This is important because our code is, in effect,
-// linked into just about every program in the system. The price we pay
-// for this coolness is
-// (a) This won't work *except* in static storage (not on stack or heap)
-// (b) We slightly fracture portability (see below)
-// This has been considered Worth It, at least for now. Before you throw
-// up and throw this code out, please try to figure out whether you know
-// the Whole Story. Thank you.
-//
-// WARNING:
-// This code makes the following non-portable assumptions:
-// (a) NULL == 0 (binary representation of NULL pointer is zero value)
-// (b) Pointers acquired from new have at least their LSB zero (are at
-// least two-byte aligned).
-// It seems like it's been a while since anyone made a machine/runtime that
-// violated either of those. But you have been warned.
-//
-#if defined(_HAVE_ATOMIC_OPERATIONS)
-
-AtomicWord ModuleNexusCommon::create(void *(*make)())
-{
- sync++; // keep mutex alive if needed
- retry:
- AtomicWord initialPointer = pointer; // latch pointer
- if (!initialPointer || (initialPointer & 0x1)) {
- Mutex *mutex;
- if (initialPointer == 0) {
- mutex = new Mutex(false); // don't bother debugging this one
- mutex->lock();
- if (atomicStore(pointer, AtomicWord(mutex) | 0x1, 0) != 0) {
- // somebody beat us to the lead - back off
- mutex->unlock();
- delete mutex;
- goto retry;
- }
- // we have the ball
- try {
- void *singleton = make();
- pointer = AtomicWord(singleton);
- // we need a write barrier here, but the mutex->unlock below provides it for free
- } catch (...) {
- secdebug("nexus", "ModuleNexus %p construction failed", this);
- mutex->unlock();
- if (--sync == 0) {
- delete mutex;
- pointer = 0;
- }
- throw;
- }
- } else {
- mutex = reinterpret_cast<Mutex *>(initialPointer & ~0x1);
- mutex->lock(); // we'll wait here
- }
- mutex->unlock();
- //@@@ retry if not resolved -- or fail here (with "object can't be built")
- if (--sync == 0)
- delete mutex;
- }
- return pointer;
-}
-
-#endif //_HAVE_ATOMIC_OPERATIONS
-
-
-//
-// Process nexus operation
-//
-ProcessNexusBase::ProcessNexusBase(const char *identifier)
-{
- const char *env = getenv(identifier);
- if (env == NULL) { // perhaps we're first...
- auto_ptr<Store> store(new Store);
- char form[2*sizeof(Store *) + 2];
- sprintf(form, "*%p", &store);
- setenv(identifier, form, 0); // do NOT overwrite...
- env = getenv(identifier); // ... and refetch to resolve races
- if (sscanf(env, "*%p", &mStore) != 1)
- CssmError::throwMe(CSSM_ERRCODE_INTERNAL_ERROR /*"environment communication failed" */);
- if (mStore == store.get()) // we won the race...
- store.release(); // ... so keep the store
- } else
- if (sscanf(env, "*%p", &mStore) != 1)
- CssmError::throwMe(CSSM_ERRCODE_INTERNAL_ERROR /*"environment communication failed"*/);
-}
projects / apple / security.git / blobdiff