diff --git a/mozilla/string/obsolete/nsStr.cpp b/mozilla/string/obsolete/nsStr.cpp
index 28e641f585c..e099759c818 100644
--- a/mozilla/string/obsolete/nsStr.cpp
+++ b/mozilla/string/obsolete/nsStr.cpp
@@ -438,23 +438,31 @@ void nsStr::CompressSet(nsStr& aDest,const char* aSet,PRUint32 aChar,PRBool aEli
 
 
 PRInt32 nsStr::FindSubstr(const nsStr& aDest,const nsStr& aTarget, PRBool aIgnoreCase,PRUint32 anOffset) {
-  PRInt32 index=anOffset-1;
-  PRInt32 theMax=aDest.mLength-aTarget.mLength;
-  if((aDest.mLength>0) && (aTarget.mLength>0)){
-    PRInt32 theNewStartPos=-1;
-    PRUnichar theFirstTargetChar=GetCharAt(aTarget,0);
-    PRUnichar theLastTargetChar=GetCharAt(aTarget,aTarget.mLength-1);
-    PRInt32   theTargetMax=aTarget.mLength;
-    while(++index<=theMax) {
-      PRInt32 theSubIndex=-1;
-      PRBool  matches=PR_TRUE;
-      while((++theSubIndex<theTargetMax) && (matches)){
-        PRUnichar theChar=GetCharAt(aDest,index+theSubIndex);
-        PRUnichar theTargetChar=GetCharAt(aTarget,theSubIndex);
-        matches=PRBool(theChar==theTargetChar);
+  if((aDest.mLength>0) && (aTarget.mLength>0) && (anOffset<aTarget.mLength)){
+
+      //This little block of code builds up the boyer-moore skip table.
+      //It might be nicer if this could be generated externally as passed in to improve performance.
+    const int theSize=100;
+    int theSkipTable[theSize];
+    PRUint32 theIndex=0;
+    for (theIndex=0;theIndex<theSize;++theIndex) {
+      theSkipTable[theIndex]=aTarget.mLength;
+    }
+    for(theIndex=0;theIndex<aTarget.mLength-1;++theIndex) {
+      theSkipTable[(PRUint32)GetCharAt(aTarget,theIndex)]=(aTarget.mLength-theIndex-1);
+    }
+
+      //and now we do the actual searching.      
+    PRUint32 theMaxIndex=aDest.mLength-anOffset;
+    for (theIndex=aTarget.mLength-1; theIndex< theMaxIndex; theIndex+= theSkipTable[(unsigned char)GetCharAt(aDest,theIndex)]) {
+      int theBufIndex=theIndex;
+      int thePatIndex=aTarget.mLength-1;
+      while (thePatIndex >= 0 && GetCharAt(aDest,theBufIndex)==GetCharAt(aTarget,thePatIndex)){
+        --theBufIndex;
+        --thePatIndex;
       }
-      if(matches) {
-        return index;
+      if(-1==thePatIndex){
+        return anOffset+theBufIndex+1;
       }
     }
   }//if
@@ -514,12 +522,22 @@ PRInt32 nsStr::RFindSubstr(const nsStr& aDest,const nsStr& aTarget, PRBool aIgno
       if(anOffset+aTarget.mLength<=aDest.mLength) {
         while((++theSubIndex<theTargetMax) && (matches)){
           PRUnichar theChar=GetCharAt(aDest,index+theSubIndex);
+          if(theSubIndex>0) {
+            if(theFirstTargetChar==theChar){
+              PRUnichar theDestJumpChar=GetCharAt(aDest,index+theTargetMax);
+              if(theDestJumpChar==theLastTargetChar) {
+                theNewStartPos=index; //this lets us jump ahead during our search where possible.
+              }//if
+            }//if
+          }//if
           PRUnichar theTargetChar=GetCharAt(aTarget,theSubIndex);
           matches=PRBool(theChar==theTargetChar);
         } //while
       } //if
-      if(matches) {
+      if(matches)
         return index;
+      if(-1<theNewStartPos){
+        index=theNewStartPos-1;
       }
     }
   }//if
diff --git a/mozilla/string/obsolete/nsString.h b/mozilla/string/obsolete/nsString.h
index 178307ca416..2c755a643c3 100644
--- a/mozilla/string/obsolete/nsString.h
+++ b/mozilla/string/obsolete/nsString.h
@@ -130,6 +130,15 @@ virtual void SizeOf(nsISizeOfHandler* aHandler) const;
  */
 PRBool IsOrdered(void) const;
 
+/**
+ *  Determine whether or not this string has a length of 0
+ *  
+ *  @return  TRUE if empty.
+ */
+PRBool IsEmpty(void) const {
+  return PRBool(0==mLength);
+}
+
 /**********************************************************************
   Accessor methods...
  *********************************************************************/
diff --git a/mozilla/string/obsolete/nsString2.cpp b/mozilla/string/obsolete/nsString2.cpp
index 594dfc346fb..1e049866978 100644
--- a/mozilla/string/obsolete/nsString2.cpp
+++ b/mozilla/string/obsolete/nsString2.cpp
@@ -1787,16 +1787,18 @@ nsAutoString2::nsAutoString2(const char* aCString,eCharSize aCharSize) : nsStrin
  * Copy construct from ascii c-string
  * @param   aCString is a ptr to a 1-byte cstr
  */
-nsAutoString2::nsAutoString2(char* aCString,PRUint32 aCapacity,eCharSize aCharSize,PRBool assumeOwnership) : nsString2(aCharSize) {
+nsAutoString2::nsAutoString2(char* aCString,PRInt32 aCapacity,eCharSize aCharSize,PRBool assumeOwnership) : nsString2(aCharSize) {
   mAgent=0;
-  if(assumeOwnership) {
-    nsStr::Initialize(*this,aCString,aCapacity,0,eOneByte,PR_TRUE);
+  if(assumeOwnership && aCString) {
+    aCapacity = (-1==aCapacity) ? strlen(aCString) : aCapacity-1;
+    nsStr::Initialize(*this,aCString,aCapacity,aCapacity,eOneByte,PR_TRUE);
+    AddNullTerminator(*this);
   }
   else {
     nsStr::Initialize(*this,mBuffer,(sizeof(mBuffer)>>aCharSize)-1,0,aCharSize,PR_FALSE);
+    AddNullTerminator(*this);
+    Assign(aCString);
   }
-  AddNullTerminator(*this);
-  Assign(aCString);
 }
 
 /**
@@ -1814,16 +1816,18 @@ nsAutoString2::nsAutoString2(const PRUnichar* aString,eCharSize aCharSize) : nsS
  * Copy construct from uni-string
  * @param   aString is a ptr to a unistr
  */
-nsAutoString2::nsAutoString2(PRUnichar* aString,PRUint32 aCapacity,eCharSize aCharSize,PRBool assumeOwnership) : nsString2(aCharSize) {
+nsAutoString2::nsAutoString2(PRUnichar* aString,PRInt32 aCapacity,eCharSize aCharSize,PRBool assumeOwnership) : nsString2(aCharSize) {
   mAgent=0;
-  if(assumeOwnership) {
-    nsStr::Initialize(*this,(char*)aString,aCapacity,0,eTwoByte,PR_TRUE);
+  if(assumeOwnership && aString) {
+    aCapacity = (-1==aCapacity) ? nsCRT::strlen(aString) : aCapacity-1;
+    nsStr::Initialize(*this,(char*)aString,aCapacity,aCapacity,eTwoByte,PR_TRUE);
+    AddNullTerminator(*this);
   }
   else {
     nsStr::Initialize(*this,mBuffer,(sizeof(mBuffer)>>aCharSize)-1,0,aCharSize,PR_FALSE);
+    AddNullTerminator(*this);
+    Assign(aString);
   }
-  AddNullTerminator(*this);
-  Assign(aString);
 }
 
 
@@ -1904,12 +1908,19 @@ nsSubsumeStr::nsSubsumeStr(nsStr& aString) : nsString2((eCharSize)aString.mCharS
   Subsume(*this,aString);
 }
 
-nsSubsumeStr::nsSubsumeStr(const PRUnichar* aString) : nsString2(aString,eTwoByte) {
+nsSubsumeStr::nsSubsumeStr(PRUnichar* aString,PRBool assumeOwnership,PRInt32 aLength) : nsString2(eTwoByte) {
+  mUStr=aString;
+  mCapacity=mLength=(-1==aLength) ? nsCRT::strlen(aString) : aLength-1;
+  mOwnsBuffer=assumeOwnership;
 }
 
-nsSubsumeStr::nsSubsumeStr(const char* aString) : nsString2(aString,eOneByte) {
+nsSubsumeStr::nsSubsumeStr(char* aString,PRBool assumeOwnership,PRInt32 aLength) : nsString2(eOneByte) {
+  mStr=aString;
+  mCapacity=mLength=(-1==aLength) ? strlen(aString) : aLength-1;
+  mOwnsBuffer=assumeOwnership;
 }
 
+
 #ifdef  RICKG_DEBUG
 /***********************************************************************
   IMPLEMENTATION of CStringTester...
@@ -1928,6 +1939,14 @@ CStringTester::CStringTester() {
       nsString2 theString0("foo",theSize);  //watch it construct and destruct
     }
 
+    {
+      //this test makes sure that autostrings who assume ownership of a buffer, 
+      //don't also try to copy that buffer onto itself... (was a bug)
+      char* theStr="hello rick";      
+      nsAutoString2(theStr,5,eOneByte,PR_FALSE);
+
+    }
+
     {
       nsString2 theString("hello");
       nsString2 temp1=theString+" there!";
diff --git a/mozilla/string/obsolete/nsString2.h b/mozilla/string/obsolete/nsString2.h
index 4d9bab7bcab..bd7b74fad1d 100644
--- a/mozilla/string/obsolete/nsString2.h
+++ b/mozilla/string/obsolete/nsString2.h
@@ -52,8 +52,8 @@ class nsISizeOfHandler;
 #define nsAutoString2 nsAutoString
 #endif
 
-class NS_COM nsSubsumeStr;
 
+class NS_COM nsSubsumeStr;
 class NS_COM nsString2 : public nsStr {
 
   public: 
@@ -744,9 +744,9 @@ public:
 
 
     nsAutoString2(const char* aCString,eCharSize aCharSize=kDefaultCharSize);
-    nsAutoString2(char* aCString,PRUint32 aLength,eCharSize aCharSize=kDefaultCharSize,PRBool assumeOwnership=PR_FALSE);
+    nsAutoString2(char* aCString,PRInt32 aCapacity=-1,eCharSize aCharSize=kDefaultCharSize,PRBool assumeOwnership=PR_FALSE);
     nsAutoString2(const PRUnichar* aString,eCharSize aCharSize=kDefaultCharSize);
-    nsAutoString2(PRUnichar* aString,PRUint32 aLength,eCharSize aCharSize=kDefaultCharSize,PRBool assumeOwnership=PR_FALSE);
+    nsAutoString2(PRUnichar* aString,PRInt32 aCapacity=-1,eCharSize aCharSize=kDefaultCharSize,PRBool assumeOwnership=PR_FALSE);
     
     nsAutoString2(const nsStr& aString,eCharSize aCharSize=kDefaultCharSize);
     nsAutoString2(const nsString2& aString,eCharSize aCharSize=kDefaultCharSize);
@@ -790,8 +790,8 @@ class NS_COM nsSubsumeStr : public nsString2 {
 public:
   nsSubsumeStr(nsString2& aString);
   nsSubsumeStr(nsStr& aString);
-  nsSubsumeStr(const PRUnichar* aString);
-  nsSubsumeStr(const char* aString);
+  nsSubsumeStr(PRUnichar* aString,PRBool assumeOwnership,PRInt32 aLength=-1);
+  nsSubsumeStr(char* aString,PRBool assumeOwnership,PRInt32 aLength=-1);
 };
 
 #endif
diff --git a/mozilla/xpcom/ds/nsStr.cpp b/mozilla/xpcom/ds/nsStr.cpp
index 28e641f585c..e099759c818 100644
--- a/mozilla/xpcom/ds/nsStr.cpp
+++ b/mozilla/xpcom/ds/nsStr.cpp
@@ -438,23 +438,31 @@ void nsStr::CompressSet(nsStr& aDest,const char* aSet,PRUint32 aChar,PRBool aEli
 
 
 PRInt32 nsStr::FindSubstr(const nsStr& aDest,const nsStr& aTarget, PRBool aIgnoreCase,PRUint32 anOffset) {
-  PRInt32 index=anOffset-1;
-  PRInt32 theMax=aDest.mLength-aTarget.mLength;
-  if((aDest.mLength>0) && (aTarget.mLength>0)){
-    PRInt32 theNewStartPos=-1;
-    PRUnichar theFirstTargetChar=GetCharAt(aTarget,0);
-    PRUnichar theLastTargetChar=GetCharAt(aTarget,aTarget.mLength-1);
-    PRInt32   theTargetMax=aTarget.mLength;
-    while(++index<=theMax) {
-      PRInt32 theSubIndex=-1;
-      PRBool  matches=PR_TRUE;
-      while((++theSubIndex<theTargetMax) && (matches)){
-        PRUnichar theChar=GetCharAt(aDest,index+theSubIndex);
-        PRUnichar theTargetChar=GetCharAt(aTarget,theSubIndex);
-        matches=PRBool(theChar==theTargetChar);
+  if((aDest.mLength>0) && (aTarget.mLength>0) && (anOffset<aTarget.mLength)){
+
+      //This little block of code builds up the boyer-moore skip table.
+      //It might be nicer if this could be generated externally as passed in to improve performance.
+    const int theSize=100;
+    int theSkipTable[theSize];
+    PRUint32 theIndex=0;
+    for (theIndex=0;theIndex<theSize;++theIndex) {
+      theSkipTable[theIndex]=aTarget.mLength;
+    }
+    for(theIndex=0;theIndex<aTarget.mLength-1;++theIndex) {
+      theSkipTable[(PRUint32)GetCharAt(aTarget,theIndex)]=(aTarget.mLength-theIndex-1);
+    }
+
+      //and now we do the actual searching.      
+    PRUint32 theMaxIndex=aDest.mLength-anOffset;
+    for (theIndex=aTarget.mLength-1; theIndex< theMaxIndex; theIndex+= theSkipTable[(unsigned char)GetCharAt(aDest,theIndex)]) {
+      int theBufIndex=theIndex;
+      int thePatIndex=aTarget.mLength-1;
+      while (thePatIndex >= 0 && GetCharAt(aDest,theBufIndex)==GetCharAt(aTarget,thePatIndex)){
+        --theBufIndex;
+        --thePatIndex;
       }
-      if(matches) {
-        return index;
+      if(-1==thePatIndex){
+        return anOffset+theBufIndex+1;
       }
     }
   }//if
@@ -514,12 +522,22 @@ PRInt32 nsStr::RFindSubstr(const nsStr& aDest,const nsStr& aTarget, PRBool aIgno
       if(anOffset+aTarget.mLength<=aDest.mLength) {
         while((++theSubIndex<theTargetMax) && (matches)){
           PRUnichar theChar=GetCharAt(aDest,index+theSubIndex);
+          if(theSubIndex>0) {
+            if(theFirstTargetChar==theChar){
+              PRUnichar theDestJumpChar=GetCharAt(aDest,index+theTargetMax);
+              if(theDestJumpChar==theLastTargetChar) {
+                theNewStartPos=index; //this lets us jump ahead during our search where possible.
+              }//if
+            }//if
+          }//if
           PRUnichar theTargetChar=GetCharAt(aTarget,theSubIndex);
           matches=PRBool(theChar==theTargetChar);
         } //while
       } //if
-      if(matches) {
+      if(matches)
         return index;
+      if(-1<theNewStartPos){
+        index=theNewStartPos-1;
       }
     }
   }//if
diff --git a/mozilla/xpcom/ds/nsString.h b/mozilla/xpcom/ds/nsString.h
index 178307ca416..2c755a643c3 100644
--- a/mozilla/xpcom/ds/nsString.h
+++ b/mozilla/xpcom/ds/nsString.h
@@ -130,6 +130,15 @@ virtual void SizeOf(nsISizeOfHandler* aHandler) const;
  */
 PRBool IsOrdered(void) const;
 
+/**
+ *  Determine whether or not this string has a length of 0
+ *  
+ *  @return  TRUE if empty.
+ */
+PRBool IsEmpty(void) const {
+  return PRBool(0==mLength);
+}
+
 /**********************************************************************
   Accessor methods...
  *********************************************************************/
diff --git a/mozilla/xpcom/ds/nsString2.cpp b/mozilla/xpcom/ds/nsString2.cpp
index 594dfc346fb..1e049866978 100644
--- a/mozilla/xpcom/ds/nsString2.cpp
+++ b/mozilla/xpcom/ds/nsString2.cpp
@@ -1787,16 +1787,18 @@ nsAutoString2::nsAutoString2(const char* aCString,eCharSize aCharSize) : nsStrin
  * Copy construct from ascii c-string
  * @param   aCString is a ptr to a 1-byte cstr
  */
-nsAutoString2::nsAutoString2(char* aCString,PRUint32 aCapacity,eCharSize aCharSize,PRBool assumeOwnership) : nsString2(aCharSize) {
+nsAutoString2::nsAutoString2(char* aCString,PRInt32 aCapacity,eCharSize aCharSize,PRBool assumeOwnership) : nsString2(aCharSize) {
   mAgent=0;
-  if(assumeOwnership) {
-    nsStr::Initialize(*this,aCString,aCapacity,0,eOneByte,PR_TRUE);
+  if(assumeOwnership && aCString) {
+    aCapacity = (-1==aCapacity) ? strlen(aCString) : aCapacity-1;
+    nsStr::Initialize(*this,aCString,aCapacity,aCapacity,eOneByte,PR_TRUE);
+    AddNullTerminator(*this);
   }
   else {
     nsStr::Initialize(*this,mBuffer,(sizeof(mBuffer)>>aCharSize)-1,0,aCharSize,PR_FALSE);
+    AddNullTerminator(*this);
+    Assign(aCString);
   }
-  AddNullTerminator(*this);
-  Assign(aCString);
 }
 
 /**
@@ -1814,16 +1816,18 @@ nsAutoString2::nsAutoString2(const PRUnichar* aString,eCharSize aCharSize) : nsS
  * Copy construct from uni-string
  * @param   aString is a ptr to a unistr
  */
-nsAutoString2::nsAutoString2(PRUnichar* aString,PRUint32 aCapacity,eCharSize aCharSize,PRBool assumeOwnership) : nsString2(aCharSize) {
+nsAutoString2::nsAutoString2(PRUnichar* aString,PRInt32 aCapacity,eCharSize aCharSize,PRBool assumeOwnership) : nsString2(aCharSize) {
   mAgent=0;
-  if(assumeOwnership) {
-    nsStr::Initialize(*this,(char*)aString,aCapacity,0,eTwoByte,PR_TRUE);
+  if(assumeOwnership && aString) {
+    aCapacity = (-1==aCapacity) ? nsCRT::strlen(aString) : aCapacity-1;
+    nsStr::Initialize(*this,(char*)aString,aCapacity,aCapacity,eTwoByte,PR_TRUE);
+    AddNullTerminator(*this);
   }
   else {
     nsStr::Initialize(*this,mBuffer,(sizeof(mBuffer)>>aCharSize)-1,0,aCharSize,PR_FALSE);
+    AddNullTerminator(*this);
+    Assign(aString);
   }
-  AddNullTerminator(*this);
-  Assign(aString);
 }
 
 
@@ -1904,12 +1908,19 @@ nsSubsumeStr::nsSubsumeStr(nsStr& aString) : nsString2((eCharSize)aString.mCharS
   Subsume(*this,aString);
 }
 
-nsSubsumeStr::nsSubsumeStr(const PRUnichar* aString) : nsString2(aString,eTwoByte) {
+nsSubsumeStr::nsSubsumeStr(PRUnichar* aString,PRBool assumeOwnership,PRInt32 aLength) : nsString2(eTwoByte) {
+  mUStr=aString;
+  mCapacity=mLength=(-1==aLength) ? nsCRT::strlen(aString) : aLength-1;
+  mOwnsBuffer=assumeOwnership;
 }
 
-nsSubsumeStr::nsSubsumeStr(const char* aString) : nsString2(aString,eOneByte) {
+nsSubsumeStr::nsSubsumeStr(char* aString,PRBool assumeOwnership,PRInt32 aLength) : nsString2(eOneByte) {
+  mStr=aString;
+  mCapacity=mLength=(-1==aLength) ? strlen(aString) : aLength-1;
+  mOwnsBuffer=assumeOwnership;
 }
 
+
 #ifdef  RICKG_DEBUG
 /***********************************************************************
   IMPLEMENTATION of CStringTester...
@@ -1928,6 +1939,14 @@ CStringTester::CStringTester() {
       nsString2 theString0("foo",theSize);  //watch it construct and destruct
     }
 
+    {
+      //this test makes sure that autostrings who assume ownership of a buffer, 
+      //don't also try to copy that buffer onto itself... (was a bug)
+      char* theStr="hello rick";      
+      nsAutoString2(theStr,5,eOneByte,PR_FALSE);
+
+    }
+
     {
       nsString2 theString("hello");
       nsString2 temp1=theString+" there!";
diff --git a/mozilla/xpcom/ds/nsString2.h b/mozilla/xpcom/ds/nsString2.h
index 4d9bab7bcab..bd7b74fad1d 100644
--- a/mozilla/xpcom/ds/nsString2.h
+++ b/mozilla/xpcom/ds/nsString2.h
@@ -52,8 +52,8 @@ class nsISizeOfHandler;
 #define nsAutoString2 nsAutoString
 #endif
 
-class NS_COM nsSubsumeStr;
 
+class NS_COM nsSubsumeStr;
 class NS_COM nsString2 : public nsStr {
 
   public: 
@@ -744,9 +744,9 @@ public:
 
 
     nsAutoString2(const char* aCString,eCharSize aCharSize=kDefaultCharSize);
-    nsAutoString2(char* aCString,PRUint32 aLength,eCharSize aCharSize=kDefaultCharSize,PRBool assumeOwnership=PR_FALSE);
+    nsAutoString2(char* aCString,PRInt32 aCapacity=-1,eCharSize aCharSize=kDefaultCharSize,PRBool assumeOwnership=PR_FALSE);
     nsAutoString2(const PRUnichar* aString,eCharSize aCharSize=kDefaultCharSize);
-    nsAutoString2(PRUnichar* aString,PRUint32 aLength,eCharSize aCharSize=kDefaultCharSize,PRBool assumeOwnership=PR_FALSE);
+    nsAutoString2(PRUnichar* aString,PRInt32 aCapacity=-1,eCharSize aCharSize=kDefaultCharSize,PRBool assumeOwnership=PR_FALSE);
     
     nsAutoString2(const nsStr& aString,eCharSize aCharSize=kDefaultCharSize);
     nsAutoString2(const nsString2& aString,eCharSize aCharSize=kDefaultCharSize);
@@ -790,8 +790,8 @@ class NS_COM nsSubsumeStr : public nsString2 {
 public:
   nsSubsumeStr(nsString2& aString);
   nsSubsumeStr(nsStr& aString);
-  nsSubsumeStr(const PRUnichar* aString);
-  nsSubsumeStr(const char* aString);
+  nsSubsumeStr(PRUnichar* aString,PRBool assumeOwnership,PRInt32 aLength=-1);
+  nsSubsumeStr(char* aString,PRBool assumeOwnership,PRInt32 aLength=-1);
 };
 
 #endif
diff --git a/mozilla/xpcom/string/obsolete/nsStr.cpp b/mozilla/xpcom/string/obsolete/nsStr.cpp
index 28e641f585c..e099759c818 100644
--- a/mozilla/xpcom/string/obsolete/nsStr.cpp
+++ b/mozilla/xpcom/string/obsolete/nsStr.cpp
@@ -438,23 +438,31 @@ void nsStr::CompressSet(nsStr& aDest,const char* aSet,PRUint32 aChar,PRBool aEli
 
 
 PRInt32 nsStr::FindSubstr(const nsStr& aDest,const nsStr& aTarget, PRBool aIgnoreCase,PRUint32 anOffset) {
-  PRInt32 index=anOffset-1;
-  PRInt32 theMax=aDest.mLength-aTarget.mLength;
-  if((aDest.mLength>0) && (aTarget.mLength>0)){
-    PRInt32 theNewStartPos=-1;
-    PRUnichar theFirstTargetChar=GetCharAt(aTarget,0);
-    PRUnichar theLastTargetChar=GetCharAt(aTarget,aTarget.mLength-1);
-    PRInt32   theTargetMax=aTarget.mLength;
-    while(++index<=theMax) {
-      PRInt32 theSubIndex=-1;
-      PRBool  matches=PR_TRUE;
-      while((++theSubIndex<theTargetMax) && (matches)){
-        PRUnichar theChar=GetCharAt(aDest,index+theSubIndex);
-        PRUnichar theTargetChar=GetCharAt(aTarget,theSubIndex);
-        matches=PRBool(theChar==theTargetChar);
+  if((aDest.mLength>0) && (aTarget.mLength>0) && (anOffset<aTarget.mLength)){
+
+      //This little block of code builds up the boyer-moore skip table.
+      //It might be nicer if this could be generated externally as passed in to improve performance.
+    const int theSize=100;
+    int theSkipTable[theSize];
+    PRUint32 theIndex=0;
+    for (theIndex=0;theIndex<theSize;++theIndex) {
+      theSkipTable[theIndex]=aTarget.mLength;
+    }
+    for(theIndex=0;theIndex<aTarget.mLength-1;++theIndex) {
+      theSkipTable[(PRUint32)GetCharAt(aTarget,theIndex)]=(aTarget.mLength-theIndex-1);
+    }
+
+      //and now we do the actual searching.      
+    PRUint32 theMaxIndex=aDest.mLength-anOffset;
+    for (theIndex=aTarget.mLength-1; theIndex< theMaxIndex; theIndex+= theSkipTable[(unsigned char)GetCharAt(aDest,theIndex)]) {
+      int theBufIndex=theIndex;
+      int thePatIndex=aTarget.mLength-1;
+      while (thePatIndex >= 0 && GetCharAt(aDest,theBufIndex)==GetCharAt(aTarget,thePatIndex)){
+        --theBufIndex;
+        --thePatIndex;
       }
-      if(matches) {
-        return index;
+      if(-1==thePatIndex){
+        return anOffset+theBufIndex+1;
       }
     }
   }//if
@@ -514,12 +522,22 @@ PRInt32 nsStr::RFindSubstr(const nsStr& aDest,const nsStr& aTarget, PRBool aIgno
       if(anOffset+aTarget.mLength<=aDest.mLength) {
         while((++theSubIndex<theTargetMax) && (matches)){
           PRUnichar theChar=GetCharAt(aDest,index+theSubIndex);
+          if(theSubIndex>0) {
+            if(theFirstTargetChar==theChar){
+              PRUnichar theDestJumpChar=GetCharAt(aDest,index+theTargetMax);
+              if(theDestJumpChar==theLastTargetChar) {
+                theNewStartPos=index; //this lets us jump ahead during our search where possible.
+              }//if
+            }//if
+          }//if
           PRUnichar theTargetChar=GetCharAt(aTarget,theSubIndex);
           matches=PRBool(theChar==theTargetChar);
         } //while
       } //if
-      if(matches) {
+      if(matches)
         return index;
+      if(-1<theNewStartPos){
+        index=theNewStartPos-1;
       }
     }
   }//if
diff --git a/mozilla/xpcom/string/obsolete/nsString.h b/mozilla/xpcom/string/obsolete/nsString.h
index 178307ca416..2c755a643c3 100644
--- a/mozilla/xpcom/string/obsolete/nsString.h
+++ b/mozilla/xpcom/string/obsolete/nsString.h
@@ -130,6 +130,15 @@ virtual void SizeOf(nsISizeOfHandler* aHandler) const;
  */
 PRBool IsOrdered(void) const;
 
+/**
+ *  Determine whether or not this string has a length of 0
+ *  
+ *  @return  TRUE if empty.
+ */
+PRBool IsEmpty(void) const {
+  return PRBool(0==mLength);
+}
+
 /**********************************************************************
   Accessor methods...
  *********************************************************************/
diff --git a/mozilla/xpcom/string/obsolete/nsString2.cpp b/mozilla/xpcom/string/obsolete/nsString2.cpp
index 594dfc346fb..1e049866978 100644
--- a/mozilla/xpcom/string/obsolete/nsString2.cpp
+++ b/mozilla/xpcom/string/obsolete/nsString2.cpp
@@ -1787,16 +1787,18 @@ nsAutoString2::nsAutoString2(const char* aCString,eCharSize aCharSize) : nsStrin
  * Copy construct from ascii c-string
  * @param   aCString is a ptr to a 1-byte cstr
  */
-nsAutoString2::nsAutoString2(char* aCString,PRUint32 aCapacity,eCharSize aCharSize,PRBool assumeOwnership) : nsString2(aCharSize) {
+nsAutoString2::nsAutoString2(char* aCString,PRInt32 aCapacity,eCharSize aCharSize,PRBool assumeOwnership) : nsString2(aCharSize) {
   mAgent=0;
-  if(assumeOwnership) {
-    nsStr::Initialize(*this,aCString,aCapacity,0,eOneByte,PR_TRUE);
+  if(assumeOwnership && aCString) {
+    aCapacity = (-1==aCapacity) ? strlen(aCString) : aCapacity-1;
+    nsStr::Initialize(*this,aCString,aCapacity,aCapacity,eOneByte,PR_TRUE);
+    AddNullTerminator(*this);
   }
   else {
     nsStr::Initialize(*this,mBuffer,(sizeof(mBuffer)>>aCharSize)-1,0,aCharSize,PR_FALSE);
+    AddNullTerminator(*this);
+    Assign(aCString);
   }
-  AddNullTerminator(*this);
-  Assign(aCString);
 }
 
 /**
@@ -1814,16 +1816,18 @@ nsAutoString2::nsAutoString2(const PRUnichar* aString,eCharSize aCharSize) : nsS
  * Copy construct from uni-string
  * @param   aString is a ptr to a unistr
  */
-nsAutoString2::nsAutoString2(PRUnichar* aString,PRUint32 aCapacity,eCharSize aCharSize,PRBool assumeOwnership) : nsString2(aCharSize) {
+nsAutoString2::nsAutoString2(PRUnichar* aString,PRInt32 aCapacity,eCharSize aCharSize,PRBool assumeOwnership) : nsString2(aCharSize) {
   mAgent=0;
-  if(assumeOwnership) {
-    nsStr::Initialize(*this,(char*)aString,aCapacity,0,eTwoByte,PR_TRUE);
+  if(assumeOwnership && aString) {
+    aCapacity = (-1==aCapacity) ? nsCRT::strlen(aString) : aCapacity-1;
+    nsStr::Initialize(*this,(char*)aString,aCapacity,aCapacity,eTwoByte,PR_TRUE);
+    AddNullTerminator(*this);
   }
   else {
     nsStr::Initialize(*this,mBuffer,(sizeof(mBuffer)>>aCharSize)-1,0,aCharSize,PR_FALSE);
+    AddNullTerminator(*this);
+    Assign(aString);
   }
-  AddNullTerminator(*this);
-  Assign(aString);
 }
 
 
@@ -1904,12 +1908,19 @@ nsSubsumeStr::nsSubsumeStr(nsStr& aString) : nsString2((eCharSize)aString.mCharS
   Subsume(*this,aString);
 }
 
-nsSubsumeStr::nsSubsumeStr(const PRUnichar* aString) : nsString2(aString,eTwoByte) {
+nsSubsumeStr::nsSubsumeStr(PRUnichar* aString,PRBool assumeOwnership,PRInt32 aLength) : nsString2(eTwoByte) {
+  mUStr=aString;
+  mCapacity=mLength=(-1==aLength) ? nsCRT::strlen(aString) : aLength-1;
+  mOwnsBuffer=assumeOwnership;
 }
 
-nsSubsumeStr::nsSubsumeStr(const char* aString) : nsString2(aString,eOneByte) {
+nsSubsumeStr::nsSubsumeStr(char* aString,PRBool assumeOwnership,PRInt32 aLength) : nsString2(eOneByte) {
+  mStr=aString;
+  mCapacity=mLength=(-1==aLength) ? strlen(aString) : aLength-1;
+  mOwnsBuffer=assumeOwnership;
 }
 
+
 #ifdef  RICKG_DEBUG
 /***********************************************************************
   IMPLEMENTATION of CStringTester...
@@ -1928,6 +1939,14 @@ CStringTester::CStringTester() {
       nsString2 theString0("foo",theSize);  //watch it construct and destruct
     }
 
+    {
+      //this test makes sure that autostrings who assume ownership of a buffer, 
+      //don't also try to copy that buffer onto itself... (was a bug)
+      char* theStr="hello rick";      
+      nsAutoString2(theStr,5,eOneByte,PR_FALSE);
+
+    }
+
     {
       nsString2 theString("hello");
       nsString2 temp1=theString+" there!";
diff --git a/mozilla/xpcom/string/obsolete/nsString2.h b/mozilla/xpcom/string/obsolete/nsString2.h
index 4d9bab7bcab..bd7b74fad1d 100644
--- a/mozilla/xpcom/string/obsolete/nsString2.h
+++ b/mozilla/xpcom/string/obsolete/nsString2.h
@@ -52,8 +52,8 @@ class nsISizeOfHandler;
 #define nsAutoString2 nsAutoString
 #endif
 
-class NS_COM nsSubsumeStr;
 
+class NS_COM nsSubsumeStr;
 class NS_COM nsString2 : public nsStr {
 
   public: 
@@ -744,9 +744,9 @@ public:
 
 
     nsAutoString2(const char* aCString,eCharSize aCharSize=kDefaultCharSize);
-    nsAutoString2(char* aCString,PRUint32 aLength,eCharSize aCharSize=kDefaultCharSize,PRBool assumeOwnership=PR_FALSE);
+    nsAutoString2(char* aCString,PRInt32 aCapacity=-1,eCharSize aCharSize=kDefaultCharSize,PRBool assumeOwnership=PR_FALSE);
     nsAutoString2(const PRUnichar* aString,eCharSize aCharSize=kDefaultCharSize);
-    nsAutoString2(PRUnichar* aString,PRUint32 aLength,eCharSize aCharSize=kDefaultCharSize,PRBool assumeOwnership=PR_FALSE);
+    nsAutoString2(PRUnichar* aString,PRInt32 aCapacity=-1,eCharSize aCharSize=kDefaultCharSize,PRBool assumeOwnership=PR_FALSE);
     
     nsAutoString2(const nsStr& aString,eCharSize aCharSize=kDefaultCharSize);
     nsAutoString2(const nsString2& aString,eCharSize aCharSize=kDefaultCharSize);
@@ -790,8 +790,8 @@ class NS_COM nsSubsumeStr : public nsString2 {
 public:
   nsSubsumeStr(nsString2& aString);
   nsSubsumeStr(nsStr& aString);
-  nsSubsumeStr(const PRUnichar* aString);
-  nsSubsumeStr(const char* aString);
+  nsSubsumeStr(PRUnichar* aString,PRBool assumeOwnership,PRInt32 aLength=-1);
+  nsSubsumeStr(char* aString,PRBool assumeOwnership,PRInt32 aLength=-1);
 };
 
 #endif