[9front] upas/fs: copy messages between IMAP folders

[risto.salminen@gmx.com]

Dear 9front community,

it is currently not possible to copy messages between
IMAP folders in any way using upas, if I understand
correctly.  upas/fs does not support putting messages
to the mailbox directories in /mail/fs/.  The need for
this arises when someone wants to archive messages
from inbox to another IMAP folder.

The following patch attempts to implement the support
for copying messages between IMAP folders in a similar
way in which flagging and deleting messages are handled.
The same functionality could be extended to other mailbox
types too, although it seems that currently this is only
useful with IMAP.  I have been using this for half a year
now without any problems.

The alternative way to achieve the same result would
be to make upas/fs support writing files to the
/mail/fs/ folders.  Then perhaps upas/mbappend could
be used to write messages to these folders in the same
way as it can currently be used to write messages to
the /mail/box/ folders.  However, the message numbering
schemes are different between these two folder
hierarchies, so there would have to be some special
casing for that, which would complicate things.
Implementing the feature that way would seem to be
more challenging in other ways too, which is why I am
presenting a simpler approach.

Would this be useful for the broader audience?

Thanks,
rsal

diff -r 7c895ae504fa sys/man/4/upasfs
--- a/sys/man/4/upasfs	Fri May 28 13:02:58 2021 +0200
+++ b/sys/man/4/upasfs	Fri May 28 16:40:56 2021 +0300
@@ -206,7 +206,7 @@
 .I fs
 to open, close, rename, create or remove new mailboxes,
 and also to
-delete or flag groups of messages atomically.
+delete, flag, or copy groups of messages atomically.
 The messages that can be written to this file are:
 .TP 2i
 .PD 0
@@ -260,6 +260,13 @@
 .TP
 .B "flag \fImboxname flags number ...\fP
 flag the given messages.
+.TP
+.B "copy \fImboxname number ... target\fP
+Copy the given messages from
+.IR mboxname
+to mailbox named
+.IR target.
+At the moment only supported with IMAP mailboxes.
 .PD
 .PP
 The
diff -r 7c895ae504fa sys/src/cmd/upas/fs/dat.h
--- a/sys/src/cmd/upas/fs/dat.h	Fri May 28 13:02:58 2021 +0200
+++ b/sys/src/cmd/upas/fs/dat.h	Fri May 28 16:40:56 2021 +0300
@@ -174,6 +174,7 @@
 	void	(*decache)(Mailbox*, Message*);
 	int	(*fetch)(Mailbox*, Message*, uvlong, ulong);
 	void	(*delete)(Mailbox*, Message*);
+	char	*(*copy)(Mailbox*, Message*, char*);
 	char	*(*ctl)(Mailbox*, int, char**);
 	char	*(*remove)(Mailbox *, int);
 	char	*(*rename)(Mailbox*, char*, int);
@@ -215,6 +216,7 @@
 void		unnewmessage(Mailbox*, Message*, Message*);
 char*		delmessages(int, char**);
 char		*flagmessages(int, char**);
+char*		copymessages(int, char**);
 void		digestmessage(Mailbox*, Message*);

 int		wraptls(int, char*);
diff -r 7c895ae504fa sys/src/cmd/upas/fs/fs.c
--- a/sys/src/cmd/upas/fs/fs.c	Fri May 28 13:02:58 2021 +0200
+++ b/sys/src/cmd/upas/fs/fs.c	Fri May 28 16:40:56 2021 +0300
@@ -1242,6 +1242,11 @@
 				return nil;
 			return flagmessages(argc - 1, argv + 1);
 		}
+		if(strcmp(argv[0], "copy") == 0){
+			if(argc < 4)
+				return nil;
+			return copymessages(argc - 1, argv + 1);
+		}
 		if(strcmp(argv[0], "remove") == 0){
 			v0 = argv0;
 			flags = 0;
diff -r 7c895ae504fa sys/src/cmd/upas/fs/imap.c
--- a/sys/src/cmd/upas/fs/imap.c	Fri May 28 13:02:58 2021 +0200
+++ b/sys/src/cmd/upas/fs/imap.c	Fri May 28 16:40:56 2021 +0300
@@ -1025,6 +1025,22 @@
 }

 static char*
+imap4copy(Mailbox *mb, Message *m, char *dest)
+{
+	char *r;
+	Imap *imap;
+
+	imap = mb->aux;
+	if((ulong)(m->imapuid>>32) == imap->validity){
+		imap4cmd(imap, "uid copy %lud %s", (ulong)m->imapuid, dest);
+		r = imap4resp(imap);
+		if(!isokay(r))
+			return r;
+	}
+	return 0;
+}
+
+static char*
 imap4sync(Mailbox *mb)
 {
 	char *err;
@@ -1183,6 +1199,7 @@
 	mb->delete = imap4delete;
 	mb->rename = imap4rename;
 	mb->modflags = imap4modflags;
+	mb->copy = imap4copy;
 	mb->addfrom = 1;
 	return nil;
 }
diff -r 7c895ae504fa sys/src/cmd/upas/fs/mbox.c
--- a/sys/src/cmd/upas/fs/mbox.c	Fri May 28 13:02:58 2021 +0200
+++ b/sys/src/cmd/upas/fs/mbox.c	Fri May 28 16:40:56 2021 +0300
@@ -1137,6 +1137,31 @@
 	return rerr;
 }

+char*
+copymessages(int argc, char **argv)
+{
+	char *err, *dest, *rerr;
+	int i;
+	Mailbox *mb;
+	Message *m;
+
+	rerr = 0;
+	for(mb = mbl; mb != nil; mb = mb->next)
+		if(strcmp(*argv, mb->name) == 0)
+			break;
+	if(mb == nil)
+		return "no such mailbox";
+	if(mb->copy == nil)
+		return "copy not supported";
+	dest = argv[argc - 1];
+	for(i = 1; i < argc - 1; i++)
+		for(m = mb->root->part; m; m = m->next)
+			if(strcmp(m->name, argv[i]) == 0)
+				if(err = mb->copy(mb, m, dest))
+					rerr = err;
+	return rerr;
+}
+
 void
 msgincref(Mailbox *mb, Message *m)
 {
diff -r 7c895ae504fa sys/src/cmd/upas/fs/mdir.c
--- a/sys/src/cmd/upas/fs/mdir.c	Fri May 28 13:02:58 2021 +0200
+++ b/sys/src/cmd/upas/fs/mdir.c	Fri May 28 16:40:56 2021 +0300
@@ -294,5 +294,6 @@
 	mb->idxread = idxr;
 	mb->idxwrite = idxw;
 	mb->ctl = mdirctl;
+	mb->copy = nil;
 	return nil;
 }
diff -r 7c895ae504fa sys/src/cmd/upas/fs/plan9.c
--- a/sys/src/cmd/upas/fs/plan9.c	Fri May 28 13:02:58 2021 +0200
+++ b/sys/src/cmd/upas/fs/plan9.c	Fri May 28 16:40:56 2021 +0300
@@ -411,5 +411,6 @@
 	mb->remove = localremove;
 	mb->rename = localrename;
 	mb->decache = plan9decache;
+	mb->copy = nil;
 	return nil;
 }
diff -r 7c895ae504fa sys/src/cmd/upas/fs/pop3.c
--- a/sys/src/cmd/upas/fs/pop3.c	Fri May 28 13:02:58 2021 +0200
+++ b/sys/src/cmd/upas/fs/pop3.c	Fri May 28 16:40:56 2021 +0300
@@ -624,6 +624,7 @@
 	mb->sync = pop3sync;
 	mb->close = pop3close;
 	mb->ctl = pop3ctl;
+	mb->copy = nil;
 	mb->addfrom = 1;
 	return nil;
 }