fix mixing MaxMessages with MaxSize

this is actually a useful combination for resource-constrained devices.

NEWS

@@ -9,6 +9,8 @@ is now the file's containing directory.
 Placeholders will be now created for messages exceeding MaxSize even if
 they are flagged on the source side.
 
+MaxMessages and MaxSize can be used together now.
+
 The unfiltered list of mailboxes in each Store can be printed now.
 
 A proper summary is now printed prior to exiting.

src/run-tests.pl

@@ -1313,6 +1313,131 @@ my @X38 = (
 );
 test("max messages + expunge", \@x38, \@X38, \@O38);
 
+# Expiration with size restriction tests
+
+my @x40 = (
+  P, 0, P,
+
+  A, "**", "*>", "*?",
+  B, "**", "*>", "*S?",
+  C, "**", "*>S", "*S?",
+  D, "*S*", "*>S", "*S?",
+  E, "*S*", "*>", "*S?",
+  F, "*S*", "*>S", "*?",
+  G, "*S*", "*>", "*?",
+  H, "**", "*>S", "*?",
+
+  I, "*F*", "*>", "*?",
+  J, "*F*", "*>", "*S?",
+  K, "*F*", "*>S", "*S?",
+  L, "*FS*", "*>S", "*S?",
+  M, "*FS*", "*>", "*S?",
+  N, "*FS*", "*>S", "*?",
+  O, "*FS*", "*>", "*?",
+  P, "*F*", "*>S", "*?",
+
+  Q, "**", "", "",
+  R, "*FS*", "", "",
+  S, "*S*", "", "",
+
+  T, "**", "", "",
+  U, "*FS*", "", "",
+  V, "*S*", "", "",
+);
+
+my @O41 = ("", "", "MaxSize 1k\nMaxMessages 3\nExpireUnread no\n");
+my @X41 = (
+  V, S, V,
+
+  C, "", "-S", "-S",
+  D, "", "+~", "+T",
+  E, "", "+~S", "+T",
+  F, "-S", "-S", "",
+  G, "", "+~S", "+ST",
+  H, "", "-S", "",
+
+  K, "", "-S", "-S",
+  M, "", "+S", "",
+  N, "-S", "-S", "",
+  O, "", "+S", "+S",
+  P, "", "-S", "",
+
+  Q, "", "*>", "*?",
+  R, "", "*>S", "*S?",
+
+  T, "", "*>", "*?",
+  U, "", "*>S", "*S?",
+  V, "", "*>S", "*S?",
+);
+test("max size without upgrade + max messages", \@x40, \@X41, \@O41);
+
+my @x42 = (
+  T, Q, T,
+
+  A, "**", "*>", "*F?",
+  B, "**", "*>", "*FS?",
+  C, "**", "*>S", "*FS?",
+  D, "*S*", "*>S", "*FS?",
+  E, "*S*", "*>", "*FS?",
+  F, "*S*", "*>S", "*F?",
+  G, "*S*", "*>", "*F?",
+  H, "**", "*>S", "*F?",
+
+  I, "*F*", "*>", "*F?",
+  J, "*F*", "*>", "*FS?",
+  K, "*F*", "*>S", "*FS?",
+  L, "*FS*", "*>S", "*FS?",
+  M, "*FS*", "*>", "*FS?",
+  N, "*FS*", "*>S", "*F?",
+  O, "*FS*", "*>", "*F?",
+  P, "*F*", "*>S", "*F?",
+
+  Q, "*S", "", "",
+
+  R, "*", "*", "*",
+  S, "*", "*", "*",
+  T, "*", "*", "*",
+);
+
+my @X43 = (
+  T, Q, P,
+
+  A, "", ">->", "^*",
+  A, "&", "^", "&1+T",
+  B, "", ">->", "^*",
+  B, "&", "^", "&1+T",
+  C, "", ">->S", "^*",
+  C, "&", "^", "&1+T",
+  D, "", "/", "",
+  D, "&", "^", "&1+T",
+  E, "", "/", "",
+  E, "&", "^", "&1+T",
+  F, "-S", ">->S", "^*",
+  F, "&", "^", "&1+T",
+  G, "", "/", "",
+  G, "&", "^", "&1+T",
+  H, "", ">->S", "^*",
+  H, "&", "^", "&1+T",
+
+  I, "", ">->+F", "^F*",
+  I, "&", "^", "&1+T",
+  J, "", ">->+F", "^F*",
+  J, "&", "^", "&1+T",
+  K, "", ">->S+F", "^F*",
+  K, "&", "^", "&1+T",
+  L, "", ">->+F", "^FS*",
+  L, "&", "^", "&1+T",
+  M, "", ">->+FS", "^FS*",
+  M, "&", "^", "&1+T",
+  N, "-S", ">->S+F", "^F*",
+  N, "&", "^", "&1+T",
+  O, "", ">->+FS", "^FS*",
+  O, "&", "^", "&1+T",
+  P, "", ">->S+F", "^F*",
+  P, "&", "^", "&1+T",
+);
+test("max size with upgrade + max messages", \@x42, \@X43, \@O41);
+
 # Test for legacy/tampered states with inaccurate maxuid tracking
 
 # Joined post-push & post-pull state to have just one test -

src/sync.c

@@ -799,7 +799,9 @@ box_opened2( sync_vars_t *svars, int t )
 		svars->any_expiring = 1;
 	if (svars->any_expiring) {
 		opts[N] |= OPEN_OLD | OPEN_FLAGS;
-		if (chan->ops[N] & (OP_NEW | OP_RENEW))
+		if (any_dummies[N])
+			opts[F] |= OPEN_OLD | OPEN_FLAGS;
+		else if (chan->ops[N] & (OP_NEW | OP_RENEW))
 			opts[F] |= OPEN_FLAGS;
 	}
 	svars->opts[F] = svars->drv[F]->prepare_load_box( ctx[F], opts[F] );
@@ -1284,10 +1286,30 @@ box_loaded( int sts, message_t *msgs, int total_msgs, int recent_msgs, void *aux
 				// to expire in the first place.
 				if (!srec->msg[N])
 					continue;
-				nflags = (srec->msg[N]->flags | srec->aflags[N]) & ~srec->dflags[N];
+				nflags = srec->msg[N]->flags;
+				if (srec->status & S_DUMMY(N)) {
+					if (!srec->msg[F])
+						continue;
+					// We need to pull in the real Flagged and Seen even if flag
+					// propagation was not requested, as the placeholder's ones are
+					// useless (except for un-seeing).
+					// This results in the somewhat weird situation that messages
+					// which are not visibly flagged remain unexpired.
+					sflags = srec->msg[F]->flags;
+					aflags = (sflags & ~srec->flags) & (F_SEEN | F_FLAGGED);
+					dflags = (~sflags & srec->flags) & F_SEEN;
+					nflags = (nflags & (~(F_SEEN | F_FLAGGED) | (srec->flags & F_SEEN)) & ~dflags) | aflags;
+				}
+				nflags = (nflags | srec->aflags[N]) & ~srec->dflags[N];
+			} else {
+				if (srec->status & S_UPGRADE) {
+					// The dummy's F & S flags are mostly masked out anyway,
+					// but we may be pulling in the real ones.
+					nflags = (srec->pflags | srec->aflags[N]) & ~srec->dflags[N];
 				} else {
 					nflags = srec->msg[F]->flags;
 				}
+			}
 			if (!(nflags & F_DELETED) || (srec->status & (S_EXPIRE | S_EXPIRED))) {
 				// The message is not deleted, or it is, but only due to being expired.
 				arecs[alive++] = (alive_srec_t){ srec, nflags };