Index setter of HTMLSelectElement and HTMLOptionsCollection should do nothing if the requested size…

Source/core/html/HTMLSelectElement.cpp

Index: Source/core/html/HTMLSelectElement.cpp
diff --git a/Source/core/html/HTMLSelectElement.cpp b/Source/core/html/HTMLSelectElement.cpp
index a1305e285839e0d4f038c3507a3a0a1f5e45925e..1bef20c0c2f99d43711097921588c970112ad1e1 100644
--- a/Source/core/html/HTMLSelectElement.cpp
+++ b/Source/core/html/HTMLSelectElement.cpp
@@ -51,6 +51,7 @@
 #include "core/html/HTMLOptionElement.h"
 #include "core/html/forms/FormController.h"
 #include "core/input/EventHandler.h"
+#include "core/inspector/ConsoleMessage.h"
 #include "core/layout/HitTestRequest.h"
 #include "core/layout/HitTestResult.h"
 #include "core/layout/LayoutListBox.h"
@@ -467,8 +468,11 @@ HTMLOptionElement* HTMLSelectElement::item(unsigned index)
 
 void HTMLSelectElement::setOption(unsigned index, HTMLOptionElement* option, ExceptionState& exceptionState)
 {
-    if (index > maxSelectItems - 1)
-        index = maxSelectItems - 1;
+    if (index >= length() && index >= maxSelectItems) {

[davve, 2015/08/20 07:40:43]

I like that you added the comparison to current length()!

That means that a parser-generated list with more than maxSelectItems (10000)
will not be silently clamped when using these setters.

Does this change in behavior warrant a note in the description perhaps?

[tkent, 2015/08/20 08:05:47]

Yeah, I'll add this to the description.
Shrinking the existing options is not reasonable.  IMO, this 10,000 limitation
itself doesn't make much sense.

+        document().addConsoleMessage(ConsoleMessage::create(JSMessageSource, WarningMessageLevel,
+            String::format("A request to update an option at index=%u is ignored.  The maximum length is %u.", index, maxSelectItems)));

[keishi, 2015/08/20 07:39:46]

nit: Other messages seemed to be like "Failed to blah blah", "Blocked blah
blah". Maybe it would be more consistent if the subject was the UserAgent.

[tkent, 2015/08/20 08:05:47]

will do.

+        return;
+    }
     int diff = index - length();
     HTMLOptionElementOrHTMLOptGroupElement element;
     element.setHTMLOptionElement(option);
@@ -491,8 +495,11 @@ void HTMLSelectElement::setOption(unsigned index, HTMLOptionElement* option, Exc
 
 void HTMLSelectElement::setLength(unsigned newLen, ExceptionState& exceptionState)
 {
-    if (newLen > maxSelectItems)
+    if (newLen > length() && newLen > maxSelectItems) {
+        document().addConsoleMessage(ConsoleMessage::create(JSMessageSource, WarningMessageLevel,
+            String::format("A request to update the option length to %u is ignored.  The maximum length is %u.", newLen, maxSelectItems)));
         return;
+    }
     int diff = length() - newLen;
 
     if (diff < 0) { // Add dummy elements.