Replace the static error string in ZIP_Put_In_Cache0 with on stack memory

[Sean Chou]

Hi David,

    To free the error string in ZIP_Open is a result of discussion with
hotspot. They said the error string is never used and they do not want to
do the free work in hotspot for ZIP_Open...

    strdup would cause a NULL error string if memory allocation is failed.
If strdup is not used, another choice may be asking the caller to reserve
the space for error string. Caller can reserve the space on stack, so *pmsg
can still be set to NULL in ZIP_Put_In_Cache0 and caller can keep the code
for error handling. But this is also strange. Do you have any better
solutions?

    It will not cause SEGV, there are NULL checks before free.

On Tue, Apr 17, 2012 at 10:48 AM, David Holmes <david.holmes at oracle.com>wrote:

> Certainly the string management in this code is a bit of a mess, but I
> don't understand why the strdup's of string literals have been introduced.
> Even if for a good reason this seems to imply that an allocation failure
> will result in a NULL where before the caller was guaranteed never to get
> NULL in the error case, and that could lead to SEGV.
>
> Also with the change to avoid changes on the hotspot side, the actual
> cause of the open failure has been lost in ZIP_Open
>
> David
>
>
> On 13/04/2012 1:14 AM, Sean Chou wrote:
>
>> Hi Alan,
>>
>>     I made a new webrev, added the comments and the 2 other modification.
>> It's now : http://cr.openjdk.java.net/~**zhouyx/7159982/webrev.02/<http://cr.openjdk.java.net/~zhouyx/7159982/webrev.02/>
>>
>> On Thu, Apr 12, 2012 at 4:24 PM, Alan Bateman<Alan.Bateman at oracle.**com<Alan.Bateman at oracle.com>
>> >wrote:
>>
>>  On 12/04/2012 06:40, Sean Chou wrote:
>>>
>>>  Hi Alan,
>>>>
>>>>    Many thanks.
>>>>
>>>>    I updated the patch, ZIP_Open frees the error message and set "Zip
>>>> file open error".
>>>>
>>>> The new webrev is : http://cr.openjdk.java.net/~**
>>>> zhouyx/7159982/webrev.01/<http**://cr.openjdk.java.net/%**
>>>> 7Ezhouyx/7159982/webrev.01/<http://cr.openjdk.java.net/%7Ezhouyx/7159982/webrev.01/>
>>>> ><
>>>> http://cr.openjdk.java.net/%****7Ezhouyx/7159982/webrev.01/<ht**
>>>> tp://cr.openjdk.java.net/%**7Ezhouyx/7159982/webrev.01/<http://cr.openjdk.java.net/%7Ezhouyx/7159982/webrev.01/>
>>>> >
>>>>
>>>>
>>>>>
>>>>
>>>>    Please take a look once more.
>>>>
>>>>  This looks much better. I think we'll need to add comments to the ZIP_*
>>> functions so that it's clear to anyone using them when they need to free
>>> the error message and then they don't.
>>>
>>> One implementation nit at zip_util.c L876 where it should check if pmsg
>>> is
>>> NULL and I think the tests should be reversed so that its:
>>>
>>> if (file != NULL&&  pmsg != NULL&&  *pmsg != NULL)  { ... }
>>>
>>>
>>> One other minor nit is L875 where there is a space on either side of the
>>> "*", best to keep the style consistent.
>>>
>>> -Alan.
>>>
>>>
>>
>>
>>


-- 
Best Regards,
Sean Chou