fixing bug 9560.

install.DiskSpaceAvailable() now returns the correct value, as much as a
unsigned 32bit type can hold.  It should really be stored in a unsigned
64bit type.  I'll file it as a seperate bug against nsFileSpec.

xpinstall/src/nsInstall.cpp

@@ -616,7 +616,7 @@ nsInstall::DeleteFile(const nsString& aFolder, const nsString& aRelativeFileName
 }
 
 PRInt32    
-nsInstall::DiskSpaceAvailable(const nsString& aFolder, PRInt32* aReturn)
+nsInstall::DiskSpaceAvailable(const nsString& aFolder, PRUint32* aReturn)
 {
     nsFileSpec fsFolder(aFolder);
 

xpinstall/src/nsInstall.h

@@ -180,7 +180,7 @@ class nsInstall
         
         PRInt32    DeleteComponent(const nsString& aRegistryName, PRInt32* aReturn);
         PRInt32    DeleteFile(const nsString& aFolder, const nsString& aRelativeFileName, PRInt32* aReturn);
-        PRInt32    DiskSpaceAvailable(const nsString& aFolder, PRInt32* aReturn);
+        PRInt32    DiskSpaceAvailable(const nsString& aFolder, PRUint32* aReturn);
         PRInt32    Execute(const nsString& aJarSource, const nsString& aArgs, PRInt32* aReturn);
         PRInt32    Execute(const nsString& aJarSource, PRInt32* aReturn);
         PRInt32    FinalizeInstall(PRInt32* aReturn);

xpinstall/src/nsJSInstall.cpp

@@ -629,7 +629,7 @@ PR_STATIC_CALLBACK(JSBool)
 InstallDiskSpaceAvailable(JSContext *cx, JSObject *obj, uintN argc, jsval *argv, jsval *rval)
 {
   nsInstall *nativeThis = (nsInstall*)JS_GetPrivate(cx, obj);
-  PRInt32 nativeRet;
+  PRUint32 nativeRet;
   nsAutoString b0;
 
   *rval = JSVAL_NULL;
@@ -650,7 +650,18 @@ InstallDiskSpaceAvailable(JSContext *cx, JSObject *obj, uintN argc, jsval *argv,
       return JS_FALSE;
     }
 
-    *rval = INT_TO_JSVAL(nativeRet);
+    if ( nativeRet <= JSVAL_INT_MAX )
+      *rval = INT_TO_JSVAL(nativeRet);
+    else
+    {
+      JSInt64 l;
+      jsdouble d;
+
+      JSLL_UI2L( l, nativeRet );
+      JSLL_L2D( d, l );
+
+      JS_NewDoubleValue( cx, d, rval );
+    }
   }
   else
   {