OSObject.cpp

/*
 * Copyright (c) 2000 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_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. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * 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
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 */
/* OSObject.cpp created by gvdl on Fri 1998-11-17 */

#include <libkern/c++/OSObject.h>
#include <libkern/c++/OSString.h>
#include <libkern/c++/OSArray.h>
#include <libkern/c++/OSSerialize.h>
#include <libkern/c++/OSLib.h>
#include <libkern/OSDebug.h>
#include <libkern/c++/OSCPPDebug.h>
#include <IOKit/IOKitDebug.h>
#include <libkern/OSAtomic.h>

#include <libkern/c++/OSCollection.h>

#include <kern/queue.h>

__BEGIN_DECLS
int debug_ivars_size;
__END_DECLS


// OSDefineMetaClassAndAbstractStructors(OSObject, 0);
/* Class global data */
OSObject::MetaClass OSObject::gMetaClass;
const OSMetaClass * const OSObject::metaClass = &OSObject::gMetaClass;
const OSMetaClass * const OSObject::superClass = 0;

/* Class member functions - Can't use defaults */
OSObject::~OSObject()			{ }
const OSMetaClass * OSObject::getMetaClass() const
    { return &gMetaClass; }
OSObject *OSObject::MetaClass::alloc() const { return 0; }

/* The OSObject::MetaClass constructor */
OSObject::MetaClass::MetaClass()
    : OSMetaClass("OSObject", OSObject::superClass, sizeof(OSObject))
    { }

// Virtual Padding
OSMetaClassDefineReservedUnused(OSObject,  0);
OSMetaClassDefineReservedUnused(OSObject,  1);
OSMetaClassDefineReservedUnused(OSObject,  2);
OSMetaClassDefineReservedUnused(OSObject,  3);
OSMetaClassDefineReservedUnused(OSObject,  4);
OSMetaClassDefineReservedUnused(OSObject,  5);
OSMetaClassDefineReservedUnused(OSObject,  6);
OSMetaClassDefineReservedUnused(OSObject,  7);
OSMetaClassDefineReservedUnused(OSObject,  8);
OSMetaClassDefineReservedUnused(OSObject,  9);
OSMetaClassDefineReservedUnused(OSObject, 10);
OSMetaClassDefineReservedUnused(OSObject, 11);
OSMetaClassDefineReservedUnused(OSObject, 12);
OSMetaClassDefineReservedUnused(OSObject, 13);
OSMetaClassDefineReservedUnused(OSObject, 14);
OSMetaClassDefineReservedUnused(OSObject, 15);

static const char *getClassName(const OSObject *obj)
{
    const OSMetaClass *meta = obj->getMetaClass();
    return (meta) ? meta->getClassName() : "unknown class?";
}

int OSObject::getRetainCount() const
{
    return (int) ((UInt16) retainCount);
}

void OSObject::taggedRetain(const void *tag) const
{
    volatile UInt32 *countP = (volatile UInt32 *) &retainCount;
    UInt32 inc = 1;
    UInt32 origCount;
    UInt32 newCount;

    // Increment the collection bucket.
    if ((const void *) OSTypeID(OSCollection) == tag)
	inc |= (1UL<<16);

    do {
	origCount = *countP;
        if ( ((UInt16) origCount | 0x1) == 0xffff ) {
            const char *msg;
            if (origCount & 0x1) {
                // If count == 0xffff that means we are freeing now so we can
                // just return obviously somebody is cleaning up dangling
                // references.
                msg = "Attempting to retain a freed object";
            }
            else {
                // If count == 0xfffe then we have wrapped our reference count.
                // We should stop counting now as this reference must be
                // leaked rather than accidently wrapping around the clock and
                // freeing a very active object later.

#if !DEBUG
		break;	// Break out of update loop which pegs the reference
#else /* DEBUG */
                // @@@ gvdl: eventually need to make this panic optional
                // based on a boot argument i.e. debug= boot flag
                msg = "About to wrap the reference count, reference leak?";
#endif /* !DEBUG */
            }
            panic("OSObject::refcount: %s", msg);
        }

	newCount = origCount + inc;
    } while (!OSCompareAndSwap(origCount, newCount, const_cast<UInt32 *>(countP)));
}

void OSObject::taggedRelease(const void *tag) const
{
    taggedRelease(tag, 1);
}

void OSObject::taggedRelease(const void *tag, const int when) const
{
    volatile UInt32 *countP = (volatile UInt32 *) &retainCount;
    UInt32 dec = 1;
    UInt32 origCount;
    UInt32 newCount;
    UInt32 actualCount;

    // Increment the collection bucket.
    if ((const void *) OSTypeID(OSCollection) == tag)
	dec |= (1UL<<16);

    do {
	origCount = *countP;
        
        if ( ((UInt16) origCount | 0x1) == 0xffff ) {
            if (origCount & 0x1) {
                // If count == 0xffff that means we are freeing now so we can
                // just return obviously somebody is cleaning up some dangling
                // references.  So we blow out immediately.
                return;
            }
            else {
                // If count == 0xfffe then we have wrapped our reference
                // count.  We should stop counting now as this reference must be
                // leaked rather than accidently freeing an active object later.

#if !DEBUG
		return;	// return out of function which pegs the reference
#else /* DEBUG */
                // @@@ gvdl: eventually need to make this panic optional
                // based on a boot argument i.e. debug= boot flag
                panic("OSObject::refcount: %s",
                      "About to unreference a pegged object, reference leak?");
#endif /* !DEBUG */
            }
        }
	actualCount = origCount - dec;
        if ((UInt16) actualCount < when)
            newCount = 0xffff;
        else
            newCount = actualCount;

    } while (!OSCompareAndSwap(origCount, newCount, const_cast<UInt32 *>(countP)));

    //
    // This panic means that we have just attempted to release an object
    // whose retain count has gone to less than the number of collections
    // it is a member off.  Take a panic immediately.
    // In fact the panic MAY not be a registry corruption but it is 
    // ALWAYS the wrong thing to do.  I call it a registry corruption 'cause
    // the registry is the biggest single use of a network of collections.
    //
// xxx - this error message is overly-specific;
// xxx - any code in the kernel could trip this,
// xxx - and it applies as noted to all collections, not just the registry
    if ((UInt16) actualCount < (actualCount >> 16)) {
        panic("A kext releasing a(n) %s has corrupted the registry.",
            getClassName(this));
    }

    // Check for a 'free' condition and that if we are first through
    if (newCount == 0xffff) {
        (const_cast<OSObject *>(this))->free();
    }
}

void OSObject::release() const
{
    taggedRelease(0);
}

void OSObject::retain() const
{
    taggedRetain(0);
}

extern "C" void
osobject_retain(void * object)
{
    ((OSObject *)object)->retain();
}

extern "C" void
osobject_release(void * object)
{
    ((OSObject *)object)->release();
}

void OSObject::release(int when) const
{
    taggedRelease(0, when);
}

bool OSObject::serialize(OSSerialize *s) const
{
    char cstr[128];
    bool ok;

    snprintf(cstr, sizeof(cstr), "%s is not serializable", getClassName(this));

    OSString * str;
    str = OSString::withCStringNoCopy(cstr);
    if (!str) return false;

    ok = str->serialize(s);
    str->release();

    return (ok);
}

void *OSObject::operator new(size_t size)
{
#if IOTRACKING
    if (kIOTracking & gIOKitDebug) return (OSMetaClass::trackedNew(size));
#endif

    void * mem = kalloc_tag_bt(size, VM_KERN_MEMORY_LIBKERN);
    assert(mem);
    bzero(mem, size);
    OSIVAR_ACCUMSIZE(size);

    return (void *) mem;
}

void OSObject::operator delete(void * mem, size_t size)
{
    if (!mem) return;

#if IOTRACKING
    if (kIOTracking & gIOKitDebug) return (OSMetaClass::trackedDelete(mem, size));
#endif

    kfree(mem, size);
    OSIVAR_ACCUMSIZE(-size);
}

bool OSObject::init()
{
#if IOTRACKING
    if (kIOTracking & gIOKitDebug) getMetaClass()->trackedInstance(this);
#endif
    return true;
}

void OSObject::free()
{
    const OSMetaClass *meta = getMetaClass();

    if (meta)
    {
	meta->instanceDestructed();
#if IOTRACKING
	if (kIOTracking & gIOKitDebug) getMetaClass()->trackedFree(this);
#endif
    }
    delete this;
}

#if IOTRACKING
void OSObject::trackingAccumSize(size_t size)
{
    if (kIOTracking & gIOKitDebug) getMetaClass()->trackedAccumSize(this, size);
}
#endif

/* Class member functions - Can't use defaults */
/* During constructor vtable is always OSObject's - can't call any subclass */

OSObject::OSObject()
{
    retainCount = 1;
//    if (kIOTracking & gIOKitDebug) getMetaClass()->trackedInstance(this);
}

OSObject::OSObject(const OSMetaClass *)
{
    retainCount = 1;
//    if (kIOTracking & gIOKitDebug) getMetaClass()->trackedInstance(this);
}