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Re: Identifying sparse files using getattrlist()
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Re: Identifying sparse files using getattrlist()



Why the hard coded value 512 ?

To find the real size of the file I tried this :
RealSize = st_blocks * st_blksize;

st_blksize returned was 4096

And the real size far execeeded the stat size (should be the opposite
for sparse files)

Thanks

On Tue, Nov 3, 2009 at 9:25 PM, Peter O'Gorman <email@hidden> wrote:
> On 11/03/2009 09:35 AM, rohan a wrote:
>>
>> Hello All,
>>
>> Please help me. Need it urgently.
>
> I think you should just be using stat(2) and comparing st_size with
> st_blocks*512.
>
> But UFS seems to have gone away, so I was unable to create a UFS disk image
> to check.
>
> Peter
>
>>
>> Thanks
>>
>> On Tue, Nov 3, 2009 at 4:34 PM, rohan a<email@hidden>  wrote:
>>>
>>> When I use
>>> # mkfile -nv 4g sparse
>>> on a 7GB Apple_UFS partition
>>>
>>> df -k gives me this :
>>>
>>> #df -k
>>> Filesystem   1024-blocks Used Available Capacity  Mounted on
>>> /dev/disk2s3     7390568   40   7021000     1%    /Volumes/UFSVolume
>>>
>>> This indicates that the file created is sparse since it shows Capacity as
>>> 1%
>>>
>>> On Tue, Nov 3, 2009 at 4:27 PM, Alastair Houghton
>>> <email@hidden>  wrote:
>>>>
>>>> On 2 Nov 2009, at 13:37, rohan a wrote:
>>>>
>>>>> I am trying to identify if a particular file is a sparse file using
>>>>> getattrlist()
>>>>>
>>>>> I am using this :     attrList.fileattr    = ATTR_FILE_TOTALSIZE |
>>>>> ATTR_FILE_ALLOCSIZE;
>>>>>
>>>>> According to the man page if  ATTR_FILE_ALLOCSIZE<
>>>>> ATTR_FILE_TOTALSIZE the file is a sparse file.
>>>>>
>>>>> I created the sparse file using dd
>>>>> #dd if=/dev/zero of=sparse-file bs=1 count=0 seek=3g
>>>>>
>>>>> However, both AllocSize and TotalSize are returning the same size
>>>>> while actually AllocSize<  TotalSize
>>>>>
>>>>> I am using UFS
>>>>
>>>> Does Apple UFS even support sparse files?  Remember, UFS is a name used
>>>> by a
>>>> fair number of totally different and usually incompatible filesystems.
>>>>  I
>>>> haven't really ever bothered investigating exactly what Apple's UFS can
>>>> and
>>>> can't do... indeed, I've always had the impression that it was only
>>>> really
>>>> present for the benefit of old-time NeXT users who might have compatible
>>>> filesystems floating around already.
>
>
> --
> Peter O'Gorman
> http://pogma.com
>
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References: 
 >Identifying sparse files using getattrlist() (From: rohan a <email@hidden>)
 >Re: Identifying sparse files using getattrlist() (From: Alastair Houghton <email@hidden>)
 >Re: Identifying sparse files using getattrlist() (From: rohan a <email@hidden>)
 >Re: Identifying sparse files using getattrlist() (From: rohan a <email@hidden>)
 >Re: Identifying sparse files using getattrlist() (From: Peter O'Gorman <email@hidden>)



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