fix loading of some messages' sizes in some partial sync scenarios

we need to pass a different "boundary" UID to driver_t::load_box() for
every OPEN_* flag that queries a partial range:
- OPEN_FIND refers to messages newer than all we know about
- OPEN_OLD_IDS refers to messages which are paired
- OPEN_{OLD,NEW}_SIZE refers to messages (not) above the committed
  boundary of already propagated messages

we treated the 3rd like the 2nd, which was just wrong - the actual
boundary may be lower or higher, so we'd produce wrong results when
MaxSize was set and only one of New and ReNew was requested.

src/driver.h

@@ -206,12 +206,12 @@ struct driver {
 	 * Consider only messages with UIDs between minuid and maxuid (inclusive)
 	 * and those named in the excs array (smaller than minuid).
 	 * The driver takes ownership of the excs array.
-	 * Messages starting with newuid need to have the TUID populated when OPEN_FIND is set.
-	 * Messages up to seenuid need to have the Message-Id populated when OPEN_OLD_IDS is set.
-	 * Messages up to seenuid need to have the size populated when OPEN_OLD_SIZE is set;
-	 * likewise messages above seenuid when OPEN_NEW_SIZE is set.
+	 * Messages starting with finduid need to have the TUID populated when OPEN_FIND is set.
+	 * Messages up to pairuid need to have the Message-Id populated when OPEN_OLD_IDS is set.
+	 * Messages up to newuid need to have the size populated when OPEN_OLD_SIZE is set;
+	 * likewise messages above newuid when OPEN_NEW_SIZE is set.
 	 * The returned message list remains owned by the driver. */
-	void (*load_box)( store_t *ctx, uint minuid, uint maxuid, uint newuid, uint seenuid, uint_array_t excs,
+	void (*load_box)( store_t *ctx, uint minuid, uint maxuid, uint finduid, uint pairuid, uint newuid, uint_array_t excs,
 	                  void (*cb)( int sts, message_t *msgs, int total_msgs, int recent_msgs, void *aux ), void *aux );
 
 	/* Fetch the contents and flags of the given message from the current mailbox. */

src/drv_imap.c

@@ -2683,7 +2683,7 @@ static void imap_submit_load( imap_store_t *, const char *, int, imap_load_box_s
 static void imap_submit_load_p3( imap_store_t *ctx, imap_load_box_state_t * );
 
 static void
-imap_load_box( store_t *gctx, uint minuid, uint maxuid, uint newuid, uint seenuid, uint_array_t excs,
+imap_load_box( store_t *gctx, uint minuid, uint maxuid, uint finduid, uint pairuid, uint newuid, uint_array_t excs,
                void (*cb)( int sts, message_t *msgs, int total_msgs, int recent_msgs, void *aux ), void *aux )
 {
 	imap_store_t *ctx = (imap_store_t *)gctx;
@@ -2716,11 +2716,11 @@ imap_load_box( store_t *gctx, uint minuid, uint maxuid, uint newuid, uint seenui
 			uint nranges = 1;
 			if (ctx->opts & (OPEN_OLD_SIZE | OPEN_NEW_SIZE))
 				imap_set_range( ranges, &nranges, shifted_bit( ctx->opts, OPEN_OLD_SIZE, WantSize),
-				                                  shifted_bit( ctx->opts, OPEN_NEW_SIZE, WantSize), seenuid );
+				                                  shifted_bit( ctx->opts, OPEN_NEW_SIZE, WantSize), newuid );
 			if (ctx->opts & OPEN_FIND)
-				imap_set_range( ranges, &nranges, 0, WantTuids, newuid - 1 );
+				imap_set_range( ranges, &nranges, 0, WantTuids, finduid - 1 );
 			if (ctx->opts & OPEN_OLD_IDS)
-				imap_set_range( ranges, &nranges, WantMsgids, 0, seenuid );
+				imap_set_range( ranges, &nranges, WantMsgids, 0, pairuid );
 			for (uint r = 0; r < nranges; r++) {
 				sprintf( buf, "%u:%u", ranges[r].first, ranges[r].last );
 				imap_submit_load( ctx, buf, ranges[r].flags, sts );

src/drv_maildir.c

@@ -70,7 +70,7 @@ typedef struct {
 typedef struct {
 	store_t gen;
 	int uvfd, uvok, is_inbox, fresh[3];
-	uint opts, minuid, maxuid, newuid, seenuid, uidvalidity, nuid;
+	uint opts, minuid, maxuid, finduid, pairuid, newuid, uidvalidity, nuid;
 	uint_array_t excs;
 	char *path; /* own */
 	char *trash;
@@ -1139,9 +1139,9 @@ maildir_scan( maildir_store_t *ctx, msg_t_array_alloc_t *msglist )
 				free( entry->base );
 				entry->base = nfstrndup( buf + bl + 4, (size_t)fnl );
 			}
-			int want_size = (uid > ctx->seenuid) ? (ctx->opts & OPEN_NEW_SIZE) : (ctx->opts & OPEN_OLD_SIZE);
-			int want_tuid = ((ctx->opts & OPEN_FIND) && uid >= ctx->newuid);
-			int want_msgid = ((ctx->opts & OPEN_OLD_IDS) && uid <= ctx->seenuid);
+			int want_size = (uid > ctx->newuid) ? (ctx->opts & OPEN_NEW_SIZE) : (ctx->opts & OPEN_OLD_SIZE);
+			int want_tuid = ((ctx->opts & OPEN_FIND) && uid >= ctx->finduid);
+			int want_msgid = ((ctx->opts & OPEN_OLD_IDS) && uid <= ctx->pairuid);
 			if (!want_size && !want_tuid && !want_msgid)
 				continue;
 			if (!fnl)
@@ -1357,7 +1357,7 @@ maildir_confirm_box_empty( store_t *gctx )
 	maildir_store_t *ctx = (maildir_store_t *)gctx;
 	msg_t_array_alloc_t msglist;
 
-	ctx->excs.size = ctx->minuid = ctx->maxuid = ctx->newuid = 0;
+	ctx->excs.size = ctx->minuid = ctx->maxuid = ctx->finduid = 0;
 
 	if (maildir_scan( ctx, &msglist ) != DRV_OK)
 		return DRV_BOX_BAD;
@@ -1435,7 +1435,7 @@ maildir_prepare_load_box( store_t *gctx, uint opts )
 }
 
 static void
-maildir_load_box( store_t *gctx, uint minuid, uint maxuid, uint newuid, uint seenuid, uint_array_t excs,
+maildir_load_box( store_t *gctx, uint minuid, uint maxuid, uint finduid, uint pairuid, uint newuid, uint_array_t excs,
                   void (*cb)( int sts, message_t *msgs, int total_msgs, int recent_msgs, void *aux ), void *aux )
 {
 	maildir_store_t *ctx = (maildir_store_t *)gctx;
@@ -1445,8 +1445,9 @@ maildir_load_box( store_t *gctx, uint minuid, uint maxuid, uint newuid, uint see
 
 	ctx->minuid = minuid;
 	ctx->maxuid = maxuid;
+	ctx->finduid = finduid;
+	ctx->pairuid = pairuid;
 	ctx->newuid = newuid;
-	ctx->seenuid = seenuid;
 	ARRAY_SQUEEZE( &excs );
 	ctx->excs = excs;
 

src/drv_proxy.c

@@ -198,8 +198,8 @@ proxy_@name@( store_t *gctx@decl_args@, void (*cb)( @decl_cb_args@void *aux ), v
 //# DEFINE load_box_pre_print_args
 	static char ubuf[12];
 //# END
-//# DEFINE load_box_print_fmt_args , [%u,%s] (new >= %u, seen <= %u)
-//# DEFINE load_box_print_pass_args , minuid, (maxuid == UINT_MAX) ? "inf" : (nfsnprintf( ubuf, sizeof(ubuf), "%u", maxuid ), ubuf), newuid, seenuid
+//# DEFINE load_box_print_fmt_args , [%u,%s] (find >= %u, paired <= %u, new > %u)
+//# DEFINE load_box_print_pass_args , minuid, (maxuid == UINT_MAX) ? "inf" : (nfsnprintf( ubuf, sizeof(ubuf), "%u", maxuid ), ubuf), finduid, pairuid, newuid
 //# DEFINE load_box_print_args
 	if (excs.size) {
 		debugn( "  excs:" );

src/sync.c

@@ -170,7 +170,7 @@ typedef struct {
 	uint newmaxuid[2];  // highest UID that is currently being propagated
 	uint uidval[2];     // UID validity value
 	uint newuidval[2];  // UID validity obtained from driver
-	uint newuid[2];     // TUID lookup makes sense only for UIDs >= this
+	uint finduid[2];    // TUID lookup makes sense only for UIDs >= this
 	uint maxxfuid;      // highest expired UID on far side
 	uchar good_flags[2], bad_flags[2];
 } sync_vars_t;
@@ -896,7 +896,7 @@ load_state( sync_vars_t *svars )
 				if (c == 'S')
 					svars->maxuid[t1] = svars->newmaxuid[t1];
 				else if (c == 'F')
-					svars->newuid[t1] = t2;
+					svars->finduid[t1] = t2;
 				else if (c == 'T')
 					*uint_array_append( &svars->trashed_msgs[t1] ) = t2;
 				else if (c == '!')
@@ -1350,27 +1350,19 @@ static void box_loaded( int sts, message_t *msgs, int total_msgs, int recent_msg
 static void
 load_box( sync_vars_t *svars, int t, uint minwuid, uint_array_t mexcs )
 {
-	uint maxwuid, seenuid;
+	uint maxwuid = 0, pairuid = UINT_MAX;
 
 	if (svars->opts[t] & OPEN_NEW) {
 		if (minwuid > svars->maxuid[t] + 1)
 			minwuid = svars->maxuid[t] + 1;
 		maxwuid = UINT_MAX;
-		if (svars->opts[t] & (OPEN_OLD_IDS|OPEN_OLD_SIZE))
-			seenuid = get_seenuid( svars, t );
-		else
-			seenuid = 0;
+		if (svars->opts[t] & OPEN_OLD_IDS)  // Implies OPEN_OLD
+			pairuid = get_seenuid( svars, t );
 	} else if (svars->opts[t] & OPEN_OLD) {
-		maxwuid = seenuid = get_seenuid( svars, t );
-	} else
-		maxwuid = seenuid = 0;
-	if (seenuid < svars->maxuid[t]) {
-		/* We cannot rely on the maxuid, as uni-directional syncing does not update it.
-		 * But if it is there, use it to avoid a possible gap in the fetched range. */
-		seenuid = svars->maxuid[t];
+		maxwuid = get_seenuid( svars, t );
 	}
 	info( "Loading %s box...\n", str_fn[t] );
-	svars->drv[t]->load_box( svars->ctx[t], minwuid, maxwuid, svars->newuid[t], seenuid, mexcs, box_loaded, AUX );
+	svars->drv[t]->load_box( svars->ctx[t], minwuid, maxwuid, svars->finduid[t], pairuid, svars->maxuid[t], mexcs, box_loaded, AUX );
 }
 
 typedef struct {
@@ -1814,8 +1806,8 @@ box_loaded( int sts, message_t *msgs, int total_msgs, int recent_msgs, void *aux
 	if (UseFSync)
 		fdatasync( fileno( svars->jfp ) );
 	for (t = 0; t < 2; t++) {
-		svars->newuid[t] = svars->drv[t]->get_uidnext( svars->ctx[t] );
-		JLOG( "F %d %u", (t, svars->newuid[t]), "save UIDNEXT of %s", str_fn[t] );
+		svars->finduid[t] = svars->drv[t]->get_uidnext( svars->ctx[t] );
+		JLOG( "F %d %u", (t, svars->finduid[t]), "save UIDNEXT of %s", str_fn[t] );
 		svars->new_msgs[t] = svars->msgs[1-t];
 		msgs_copied( svars, t );
 		if (check_cancel( svars ))
@@ -1921,7 +1913,7 @@ msgs_copied( sync_vars_t *svars, int t )
 
 	if (svars->state[t] & ST_FIND_NEW) {
 		debug( "finding just copied messages on %s\n", str_fn[t] );
-		svars->drv[t]->find_new_msgs( svars->ctx[t], svars->newuid[t], msgs_found_new, AUX );
+		svars->drv[t]->find_new_msgs( svars->ctx[t], svars->finduid[t], msgs_found_new, AUX );
 	} else {
 		msgs_new_done( svars, t );
 	}