Custom IMAP flags

[Vincent B. <be...@lu...>]

Hey!

I am using mbsync to sync IMAP mailboxes. I believe that custom flags
are not supported. Looking at the IMAP driver, I see a list of supported
flags and later a comment about user-tags being ignored.

I am using Gnus which uses some custom tags. With offlineimap, there is
some hack to be able to use them:
 http://lists.gnu.org/archive/html/info-gnus-english/2011-10/msg00052.html

How could we support them in mbsync?

If I would like to support them with an ad hoc modification, I think
this would be easy:

In driver.h (the comment say to keep sort ordering, but then I need to
modify the value of existing flags, are they stored somewhere?):

#define F_DRAFT	     (1<<0) /* Draft */
#define F_EXPIRE     (1<<1) /* gnus-expire */
#define F_FLAGGED    (1<<2) /* Flagged */
#define F_DORMANT    (1<<3) /* gnus-dormant */
#define F_ANSWERED   (1<<4) /* Replied */
#define F_SEEN       (1<<5) /* Seen */
#define F_DELETED    (1<<6) /* Trashed */
#define F_SAVE       (1<<7) /* gnus-save */
#define F_FORWARD    (1<<8) /* gnus-forward */
#define NUM_FLAGS 9

In drv_maildir.c:

static const char Flags[] = { 'D', 'E', 'F', 'Q', 'R', 'S', 'T', 'V', 'W' };

In drv_imap.c:

static const char *Flags[] = {
	"Draft",
        "gnus-expire",
	"Flagged",
        "gnus-dormant",
	"Answered",
	"Seen",
	"Deleted",
        "gnus-save",
        "gnus-forward"
};

However, that's not very extensible. Maybe this can be made
configurable.

My questions :

 1. Would the above steps work correctly?

 2. Do I really need to keep the sort order in maildir's Flags array? It
    would be easier to add flags from configuration file if I didn't
    have to.

Thanks.
-- 
Avoid temporary variables.
            - The Elements of Programming Style (Kernighan & Plauger)