assuan_read_from_server() and return value

[Ben Kibbey]

On Wed, Dec 12, 2007 at 03:47:18PM +0100, Marcus Brinkmann wrote:
> > After the inquire callback is finished, assuan_transact() sends END to
> > terminate the inquire then calls _assuan_read_from_server() again.
> 
> Are you sure?  That's not my reading of the code:
> 
> assuan-client.c::assuan_transact()
> [...]
> 
>       if (!inquire_cb)
>         {
>           assuan_write_line (ctx, "END"); /* get out of inquire mode */
>           _assuan_read_from_server (ctx, &okay, &off); /* dummy read */
>           rc = _assuan_error (ASSUAN_No_Inquire_Callback);
>         }
>       else
>         {
>           rc = inquire_cb (inquire_cb_arg, line);
>           if (!rc)
>             rc = assuan_send_data (ctx, NULL, 0); /* flush and send END */
>           if (!rc)
>             goto again;
>         }

I do have an inquire callback set. I was referring to the END sent from
assuan_send_data(). Then _assuan_read_from_server() is called to get the
error code (if any) of the inquire (with my patch applied).

> > Without the patch, _assuan_read_from_server()
> > returns the value returned from _assuan_read_line() (zero). I use
> > GPG_ERR codes on the server. Pinentry uses ASSUAN_ errors and there is
> > no way to tell if the error is an GPG_ERR_ or an ASSUAN_ error.
> 
> Not quite correct.  We have a heuristic to differentiate: Values that
> have the high bits set indicate a gpg error with a source set.  All
> our servers set a gpg error source.  On the other hand, low values
> indicate an assuan based error code.  This is not failure proof, but
> covers current and expected usage.  By the way: It is currently
> undefined how assuan error codes can be extended by user defined error
> codes.  In gpg-error, there are reserved values for that.

Breaks when GPG_ERR_SOURCE_UNKNOWN is used, and this is the default.

> 
> > So I
> > guess pinentry has to migrate to use GPG_ERR_ codes, which may break
> > clients, or I have to wait until libassuan removes ASSUAN_ codes
> > completely forcing libassuan users to use GPG_ERR_ codes, which seems
> > unlikely to happen any time soon?
> 
> We can map assuan error codes to gpg error codes (see the function
> _assuan_error in mkerrors).

Has the error source problem above.

I have rewritten my app to handle pinentry specially, although it will
break when pinentry uses gpg-error codes. But I still need the patch
applied in order to get any inquire error code from the server.

-- 
Benjamin J. Kibbey bjk at luxsci.net/jabber/freenode
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