Review Request JDK-7119643: It is not possible to read files with a path longer than 2048 characters

[Dmitry Samersoff]

Poonam,

As far as I understand, MAX_PATH is here for a while but later we start
using MAXPATHLEN.

I would recommend to replace all usage of MAX_PATH and PATH_MAX
to MAXPATHLEN

if you fill that these changes is go out of scope of JDK-7119643, please
replace it inside os:stat() only to solve immediate needs and file a
separate CR to have it cleaned up.

-Dmitry


On 2014-03-24 06:55, Poonam Bajaj wrote:
> Hi Dmitry,
> 
> On 3/24/2014 12:49 AM, Dmitry Samersoff wrote:
>> Poonam,
>>
>> 1.
>>
>> MAXPATHLEN == PATH_MAX and it's a system constant that comes from
>> sys/param.h and linux/limits.h so current behavior of hotspot is
>> absolutely correct.
>>
>> Moreover, we uses MAXPATHLEN in many places in os_*.cpp files, so this
>> patch makes hotspot behavior inconsistent.
>>
>> Typical value of PATH_MAX is 4096 so it's unclean for me why we have
>> problems with 2048 bytes file.
>>
>> We probably should check our reference build platform.
> The purpose of this change is to revert back to the same behavior as it
> was before the  fix for 6348631 where we didn't have any path limitation
> in os::open() and os::stat() functions.
> 
> But yes, you are right. We have the following in sys/param.h and
> linux/limits.h for the maximum allowed path length on linux platforms:
> #define PATH_MAX        4096    /* # chars in a path name including nul */
> #define MAXPATHLEN      PATH_MAX
> 
> and MAXPATHLEN is also used in os_linux.cpp. So, if we have to insert
> the path limitation in os::open() and os::stat(), we should be using
> MAXPATHLEN at all the places in os_linux.cpp. Why was MAX_PATH defined
> and to a different value than MAXPATHLEN which is inconsistent with the
> linux definition?
> 
>> 2.
>>
>> Test could be a pure java.
> Ok, will do.
> 
> Thanks,
> Poonam
>>
>> -Dmitry
>>
>> On 2014-03-21 16:52, Poonam Bajaj wrote:
>>> Hi,
>>>
>>> Review request for:
>>> JDK-7119643<https://bugs.openjdk.java.net/browse/JDK-7119643>: It is
>>> not possible to read files with a path longer than 2048 characters
>>>
>>> Problem and Fix: This bug is a regression from 6u29 and exists only on
>>> Linux platform. With the fix for 6348631, a limit of MAX_PATH (2K) got
>>> introduced on the file path length in the os::open() and os::stat()
>>> functions in os_linux.cpp. These changes remove that limit. These
>>> changes also add a regression test case to check that the files having
>>> path longer than 2048 are read without any error.
>>>
>>> Webrev: http://cr.openjdk.java.net/~poonam/7119643/webrev.00/
>>>
>>> This fix needs to go into 9, 8u, 7u and 6u.
>>>
>>> Thanks,
>>> Poonam
>>>
>>


-- 
Dmitry Samersoff
Oracle Java development team, Saint Petersburg, Russia
* I would love to change the world, but they won't give me the source code.