administering files, data type "file"

Hi,
I want to administer files with postgres.
When I "import" a file to postgres I also
submit certain atributes the file has.
Such as filetype or specific properties I know
about the file (not the standard stuff like
the OS knows about the file as date,and size)
I want that postgres then copies the file to a
save place and write and read protects it.
Once I query for certain attributes I submitted before
and I get a hit I should be able to get the filename
from postgres including a "read" permission.
I also want to be able to create a new file.
After submitting the properties the file has
postgres should give me a filename and write
permission
for that file. After finishing my creation of the file
I want that postgres stops read and write access to
that file.

Can something like that be done with the current
version. Are there any successful implementations of
that and where can I find them?

thanks, daniel

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