Best way to apply textconv to a working tree file

Hello,

In order to add textconv support to "git-gui blame", we have to run
textconv on a file which is in the working tree.
Currently, "git-gui blame" uses the Tcl function 'open' to display the
content of the working-tree file. This doesn't allow us to run textconv on
it.

We are wondering what is the best way to do the textconv. Here are some
solutions we thought about:

- For revisions, "git-gui blame" is based on "git cat-file blob
<sha1:path>". Therefore, we thought of adding a "--textconv" option on
cat-file as well as a "--working-tree" option ("git cat-file --working-tree
<file>" will display the content of <file> in the working-tree)

- Use the "-p" (pretty print) cat-file's option, with a path beginning by
./ (to avoid ambiguous name like HEAD)

- Create a "git textconv" command, to easily run textconv on any object.

Which way you think is the best?

Thanks for your time and comments.
Regards