--- xnu/xnu-201.5/libkern/c++/OSSymbol.cpp
+++ xnu/xnu-792.6.70/libkern/c++/OSSymbol.cpp
@@ -21,6 +21,7 @@
  */
 /* IOSymbol.cpp created by gvdl on Fri 1998-11-17 */
 
+#include <string.h>
 #include <sys/cdefs.h>
 
 __BEGIN_DECLS
@@ -29,6 +30,7 @@
 
 #include <libkern/c++/OSSymbol.h>
 #include <libkern/c++/OSLib.h>
+#include <string.h>
 
 #define super OSString
 
@@ -93,7 +95,7 @@
 
     OSSymbol *findSymbol(const char *cString) const;
     OSSymbol *insertSymbol(OSSymbol *sym);
-    void removeSymbol(const char *cString);
+    void removeSymbol(OSSymbol *sym);
 
     OSSymbolPoolState initHashState();
     OSSymbol *nextHashState(OSSymbolPoolState *stateP);
@@ -225,18 +227,15 @@
         probeSymbol = (OSSymbol *) thisBucket->symbolP;
 
         if (inLen == probeSymbol->length
-        &&  (strcmp(probeSymbol->string, cString) == 0)
-        &&  (probeSymbol->getRetainCount() >= 1))	// WRONG need when
+        &&  (strcmp(probeSymbol->string, cString) == 0))
             return probeSymbol;
-        else
-            return 0;
+	return 0;
     }
 
     for (list = thisBucket->symbolP; j--; list++) {
         probeSymbol = *list;
         if (inLen == probeSymbol->length
-        &&  (strcmp(probeSymbol->string, cString) == 0)
-        &&  (probeSymbol->getRetainCount() >= 1))	// WRONG need when
+        &&  (strcmp(probeSymbol->string, cString) == 0))
             return probeSymbol;
     }
 
@@ -258,7 +257,7 @@
         thisBucket->symbolP = (OSSymbol **) sym;
         thisBucket->count++;
         count++;
-        return 0;
+        return sym;
     }
 
     if (j == 1) {
@@ -279,7 +278,7 @@
         if (count > nBuckets)
             reconstructSymbols();
 
-        return 0;
+        return sym;
     }
 
     for (list = thisBucket->symbolP; j--; list++) {
@@ -302,16 +301,16 @@
     if (count > nBuckets)
         reconstructSymbols();
 
-    return 0;
-}
-
-void OSSymbolPool::removeSymbol(const char *cString)
+    return sym;
+}
+
+void OSSymbolPool::removeSymbol(OSSymbol *sym)
 {
     Bucket *thisBucket;
     unsigned int j, inLen, hash;
     OSSymbol *probeSymbol, **list;
 
-    hashSymbol(cString, &hash, &inLen); inLen++;
+    hashSymbol(sym->string, &hash, &inLen); inLen++;
     thisBucket = &buckets[hash % nBuckets];
     j = thisBucket->count;
     list = thisBucket->symbolP;
@@ -322,8 +321,7 @@
     if (j == 1) {
         probeSymbol = (OSSymbol *) list;
 
-        if (inLen == probeSymbol->length
-        &&  strcmp(probeSymbol->string, cString) == 0) {
+        if (probeSymbol == sym) {
             thisBucket->symbolP = 0;
             count--;
             thisBucket->count--;
@@ -334,8 +332,7 @@
 
     if (j == 2) {
         probeSymbol = list[0];
-        if (inLen == probeSymbol->length
-        &&  strcmp(probeSymbol->string, cString) == 0) {
+        if (probeSymbol == sym) {
             thisBucket->symbolP = (OSSymbol **) list[1];
             kfree((vm_offset_t)list, 2 * sizeof(OSSymbol *));
 	    ACCUMSIZE(-(2 * sizeof(OSSymbol *)));
@@ -345,8 +342,7 @@
         }
 
         probeSymbol = list[1];
-        if (inLen == probeSymbol->length
-        &&  strcmp(probeSymbol->string, cString) == 0) {
+        if (probeSymbol == sym) {
             thisBucket->symbolP = (OSSymbol **) list[0];
             kfree((vm_offset_t)list, 2 * sizeof(OSSymbol *));
 	    ACCUMSIZE(-(2 * sizeof(OSSymbol *)));
@@ -359,8 +355,7 @@
 
     for (; j--; list++) {
         probeSymbol = *list;
-        if (inLen == probeSymbol->length
-        &&  strcmp(probeSymbol->string, cString) == 0) {
+        if (probeSymbol == sym) {
 
             list = (OSSymbol **)
                 kalloc((thisBucket->count-1) * sizeof(OSSymbol *));
@@ -432,40 +427,60 @@
 {
     pool->closeGate();
 
-    OSSymbol *newSymb = pool->findSymbol(cString);
-    if (newSymb)
-        newSymb->retain();
-    else if ( (newSymb = new OSSymbol) ) {
+    OSSymbol *oldSymb = pool->findSymbol(cString);
+    if (!oldSymb) {
+        OSSymbol *newSymb = new OSSymbol;
+        if (!newSymb) {
+            pool->openGate();
+            return newSymb;
+        }
+
 	if (newSymb->OSString::initWithCString(cString))
-	    pool->insertSymbol(newSymb);
-	else {
-	    newSymb->free();
-	    newSymb = 0;
-	}
-    }
+	    oldSymb = pool->insertSymbol(newSymb);
+        
+        if (newSymb == oldSymb) {
+            pool->openGate();
+            return newSymb;	// return the newly created & inserted symbol.
+        }
+        else
+            // Somebody else inserted the new symbol so free our copy
+	    newSymb->OSString::free();
+    }
+    
+    oldSymb->retain();	// Retain the old symbol before releasing the lock.
+
     pool->openGate();
-
-    return newSymb;
+    return oldSymb;
 }
 
 const OSSymbol *OSSymbol::withCStringNoCopy(const char *cString)
 {
     pool->closeGate();
 
-    OSSymbol *newSymb = pool->findSymbol(cString);
-    if (newSymb)
-        newSymb->retain();
-    else if ( (newSymb = new OSSymbol) ) {
+    OSSymbol *oldSymb = pool->findSymbol(cString);
+    if (!oldSymb) {
+        OSSymbol *newSymb = new OSSymbol;
+        if (!newSymb) {
+            pool->openGate();
+            return newSymb;
+        }
+
 	if (newSymb->OSString::initWithCStringNoCopy(cString))
-	    pool->insertSymbol(newSymb);
-	else {
-	    newSymb->free();
-	    newSymb = 0;
-	}
-    }
+	    oldSymb = pool->insertSymbol(newSymb);
+        
+        if (newSymb == oldSymb) {
+            pool->openGate();
+            return newSymb;	// return the newly created & inserted symbol.
+        }
+        else
+            // Somebody else inserted the new symbol so free our copy
+	    newSymb->OSString::free();
+    }
+    
+    oldSymb->retain();	// Retain the old symbol before releasing the lock.
+
     pool->openGate();
-
-    return newSymb;
+    return oldSymb;
 }
 
 void OSSymbol::checkForPageUnload(void *startAddr, void *endAddr)
@@ -488,12 +503,21 @@
     pool->openGate();
 }
 
+void OSSymbol::taggedRelease(const void *tag) const
+{
+    super::taggedRelease(tag);
+}
+
+void OSSymbol::taggedRelease(const void *tag, const int when) const
+{
+    pool->closeGate();
+    super::taggedRelease(tag, when);
+    pool->openGate();
+}
+
 void OSSymbol::free()
 {
-    pool->closeGate();
-    pool->removeSymbol(string);
-    pool->openGate();
-    
+    pool->removeSymbol(this);
     super::free();
 }