Cannot add attribute into main attributes of a jar if there is no version

[mandy chung]

On 1/29/18 4:22 PM, Weijun Wang wrote:
> Ping again.
>
>> On Jan 22, 2018, at 1:12 PM, Weijun Wang <weijun.wang at oracle.com> wrote:
>>
>> src/java.base/share/classes/java/util/jar/Attributes.java:
>>
>>    329	    @SuppressWarnings("deprecation")
>>    330	    void writeMain(DataOutputStream out) throws IOException
>>    331	    {
>>    332	        // write out the *-Version header first, if it exists
>>    333	        String vername = Name.MANIFEST_VERSION.toString();
>>    334	        String version = getValue(vername);
>>    335	        if (version == null) {
>>    336	            vername = Name.SIGNATURE_VERSION.toString();
>>    337	            version = getValue(vername);
>>    338	        }
>>    339	
>>    340	        if (version != null) {
>>    341	            out.writeBytes(vername+": "+version+"\r\n");
>>    342	        }
>>    343	
>>    344	        // write out all attributes except for the version
>>    345	        // we wrote out earlier
>>    346	        for (Entry<Object, Object> e : entrySet()) {
>>    347	            String name = ((Name) e.getKey()).toString();
>>    348	            if ((version != null) && !(name.equalsIgnoreCase(vername))) {
>>
>> So, if there is no existing MANIFEST_VERSION or SIGNATURE_VERSION, then version is null and the check above will be false for ever and any other attribute cannot be written out.
>>
>> Is this intended? If so, we can exit with an else block after line 342.

 From code inspection, I agree that this method is a nop if there is no 
Manifest-Version attribute or Signature-Attribute.  This can return 
quickly without iterating the entry set.   I don't see any issue to make 
it an else block.

This method is only called from Manifest::write method which does not 
mention Signature-Version but I don't have the history to tell if this 
is intended or not.

Mandy