[Hdf-forum] Following external links - permissions

[Allen Sanderson]

Thanks Quincy,

Over the holidays I did some checking and I think it is a case of too  
many objects opened and not properly closed that is leading to the  
failure. The HDF5 calls were part of a larger API which I decided to  
scrap because trying to follow it was too difficult and use a simpler  
API. The simpler API worked as expected so I was able to make  
everything work for writing - unfortunately the API needs to be used  
for reading. And has some other issues with the external links. But I  
think I know what needs to fixed there.

Cheers,

Allen




On Jan 4, 2010, at 7:40 AM, Quincey Koziol wrote:

> Hi Allen,
>
> On Dec 19, 2009, at 1:33 PM, allen wrote:
>
>> Hi Quincey,
>>
>> I am currently using 1.8.2.
>>
>> One other clue, this only happens when I utilize one particular  
>> piece of code (a third party lib). If I skip it then the link is  
>> followed fine later (I access it in multiple places). So I think  
>> the link and the permissions are okay but how this third party code  
>> opens the link initially tends to make it inaccessible later on. So  
>> my guess is that this particular piece of code pooches something. I  
>> have not started looking at it yet. (Probably will be able to as my  
>> hard drive on that machine died Friday night).
>>
>> Some random thoughts if the file was initially opened as RDONLY  
>> with that link accessed. If opening the file again as RDWR would  
>> that force the access to that link to fail?
>
> 	Yes, that would cause the second access to fail.
>
>> If there a way to see what groups are currently  open?
>
> 	You can use the H5Fget_obj_count/H5Fget_obj_ids routines to  
> investigate this.
>
> 	Quincey
>
>
>> Cheers,
>>
>> Allen
>>
>>
>> Allen Sanderson
>> SCI Institute
>> University of Utah
>> www.sci.utah.edu
>>
>>
>>
>> On Dec 18, 2009, at 10:22 PM, Quincey Koziol wrote:
>>
>>> Hi Allen,
>>>
>>> On Dec 18, 2009, at 7:07 PM, Allen Sanderson wrote:
>>>
>>>> One followup could this problem be related to perhaps already  
>>>> having the one link open ??? and then trying to open it again???
>>>
>>> 	Hmm, are you using the latest release (1.8.4)?
>>>
>>> 	Quincey
>>>
>>>>
>>>>
>>>> Cheers,
>>>>
>>>> Allen
>>>>
>>>>
>>>>
>>>>
>>>> On Dec 18, 2009, at 6:02 PM, Allen Sanderson wrote:
>>>>
>>>>> I have a file with two external links that at are both at the  
>>>>> top level:
>>>>>
>>>>> HDF5 "DATA.h5" {
>>>>> GROUP "/" {
>>>>>     EXTERNAL_LINK "Mesh" {
>>>>>       TARGETFILE "Mesh.h5"
>>>>>       TARGETPATH "/Mesh"
>>>>>          GROUP "/Mesh" {
>>>>>       }
>>>>>     }
>>>>>    EXTERNAL_LINK "Step#0" {
>>>>>       TARGETFILE "step_0.h5"
>>>>>       TARGETPATH "/Step#0"
>>>>>          GROUP "/Step#0" {
>>>>>       }
>>>>>     }
>>>>>   }
>>>>> }
>>>>>
>>>>> When I open the main file, DATA.h5 as RDONLY I am able to  
>>>>> traverse both links as one would expect.
>>>>>
>>>>> However, when I open the main file, DATA.h5 as RDWR the group "/ 
>>>>> Mesh" succeeds but the "Step#0" fails. Both links are created in  
>>>>> the exact same manner.
>>>>>
>>>>>  if( H5Lcreate_external(MESH_NAME, "/Mesh",
>>>>> 			 file_id, "Mesh",
>>>>> 			 H5P_DEFAULT, H5P_DEFAULT) < 0 ) {
>>>>>  }
>>>>>
>>>>> So I am at a loss as to why the access is different. I tried to  
>>>>> follow through and understand more on the Property list that is  
>>>>> set to teh default. ie this var:
>>>>> hid_t lapl_id	IN: Link access property list identifier.
>>>>>
>>>>> but I did not get far. Should I be setting something here????
>>>>>
>>>>>
>>>>> Cheers,
>>>>>
>>>>> Allen
>>>>>
>>>>>
>>>>> Allen Sanderson
>>>>> SCI Institute
>>>>> University of Utah
>>>>> www.sci.utah.edu
>>>>>
>>>>>
>>>>>
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>
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