[commit] master: don't UID EXPUNGE too many messages

[Oswald B. <os...@us...>]

commit 95a22739fa16435d5d709c5a3bfc8e466ee8d1d2
Author: Oswald Buddenhagen <os...@us...>
Date:   Wed Dec 29 14:42:22 2021 +0100

    don't UID EXPUNGE too many messages
    
    we didn't check that the UIDs are adjacent, so we might have caught
    not fetched deleted messages between two fetched messages below the
    bulk load range.
    
    checking adjacency of UIDs would make expunges in the bulk range (which
    is likely to be full of holes) rather inefficient. so we use sequence
    numbers instead.
    
    this is admittedly a rather academical fix ...
    
    amends 18225344.

 src/drv_imap.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/drv_imap.c b/src/drv_imap.c
index b58828ce..55192ff5 100644
--- a/src/drv_imap.c
+++ b/src/drv_imap.c
@@ -3128,7 +3128,18 @@ imap_close_box( store_t *gctx,
 					buf[bl++] = ',';
 				bl += sprintf( buf + bl, "%u", msg->uid );
 				fmsg = msg;
-				for (; (nmsg = msg->next) && (nmsg->flags & F_DELETED); msg = nmsg) {}
+				for (; (nmsg = msg->next); msg = nmsg) {
+					if (nmsg->status & M_DEAD) {
+						// Messages that jump a gap interrupt the range, even expunged ones.
+						if (nmsg->seq)
+							break;
+					} else {
+						if (nmsg->seq > 1)
+							break;
+						if (!(nmsg->flags & F_DELETED))
+							break;
+					}
+				}
 				if (msg != fmsg)
 					bl += sprintf( buf + bl, ":%u", msg->uid );
 			}