lib-index: Fixed potential assert-crash when view syncing sees a reset marker.

It should never try to use main index map at that point, because
view_sync_have_expunges() looks changes only before the reset marker.
Fixes:

Error: Index .../dovecot.index lost messages without expunging (36 -> 27)

diff --git a/src/lib-index/mail-index-view-sync.c b/src/lib-index/mail-index-view-sync.c
index 2911d9d04b59e04617570a61d80be567b8105892..c6ba75d1761cc65990b19fa259a693f3cb3000fe 100644 (file)
--- a/src/lib-index/mail-index-view-sync.c
+++ b/src/lib-index/mail-index-view-sync.c
@@ -42,7 +42,7 @@ struct mail_index_view_sync_ctx {
 
 static int
 view_sync_set_log_view_range(struct mail_index_view *view, bool sync_expunges,
-                            bool *reset_r)
+                            bool *reset_r, bool *partial_sync_r)
 {
        const struct mail_index_header *hdr = &view->index->map->hdr;
        uint32_t start_seq, end_seq;
@@ -50,6 +50,8 @@ view_sync_set_log_view_range(struct mail_index_view *view, bool sync_expunges,
        const char *reason;
        int ret;
 
+       *partial_sync_r = FALSE;
+
        start_seq = view->log_file_expunge_seq;
        start_offset = view->log_file_expunge_offset;
        end_seq = hdr->log_file_seq;
@@ -89,6 +91,7 @@ view_sync_set_log_view_range(struct mail_index_view *view, bool sync_expunges,
                                view->log_file_expunge_seq);
                        break;
                }
+               *partial_sync_r = TRUE;
        }
        return 1;
 }
@@ -523,7 +526,7 @@ mail_index_view_sync_begin(struct mail_index_view *view,
        struct mail_index_view_sync_ctx *ctx;
        struct mail_index_map *tmp_map;
        unsigned int expunge_count = 0;
-       bool reset, sync_expunges, have_expunges;
+       bool reset, partial_sync, sync_expunges, have_expunges;
        int ret;
 
        i_assert(!view->syncing);
@@ -556,7 +559,7 @@ mail_index_view_sync_begin(struct mail_index_view *view,
                return ctx;
        }
 
-       ret = view_sync_set_log_view_range(view, sync_expunges, &reset);
+       ret = view_sync_set_log_view_range(view, sync_expunges, &reset, &partial_sync);
        if (ret < 0) {
                ctx->failed = TRUE;
                return ctx;
@@ -600,7 +603,7 @@ mail_index_view_sync_begin(struct mail_index_view *view,
                                     view->index->filepath);
        }
 
-       if (!have_expunges) {
+       if (!have_expunges && !partial_sync) {
                /* no expunges, we can just replace the map */
                if (view->index->map->hdr.messages_count <
                    ctx->finish_min_msg_count) {
@@ -617,9 +620,12 @@ mail_index_view_sync_begin(struct mail_index_view *view,
                mail_index_unmap(&view->map);
                view->map = view->index->map;
        } else {
-               /* expunges seen. create a private map which we update.
-                  if we're syncing expunges the map will finally be replaced
-                  with the head map to remove the expunged messages. */
+               /* a) expunges seen. b) doing a partial sync because we saw
+                  a reset.
+
+                  Create a private map which we update. If we're syncing
+                  expunges the map will finally be replaced with the head map
+                  to remove the expunged messages. */
                ctx->sync_map_update = TRUE;
 
                if (view->map->refcount > 1) {