[PATCH 3/4] compact: Provide user with more error feedback

[Ben Gamari <bgamari.foss@gmail.com>]

Provide instructions on what to do when we couldn't move the compacted
database into place.

Signed-off-by: Ben Gamari <bgamari.foss@gmail.com>
---
 lib/database.cc | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/lib/database.cc b/lib/database.cc
index 57c2292..34753ab 100644
--- a/lib/database.cc
+++ b/lib/database.cc
@@ -938,7 +938,25 @@ notmuch_database_compact (const char* path,
     }
 
     if (rename(compact_xapian_path, xapian_path)) {
-	fprintf (stderr, "Error moving compacted database\n");
+	fprintf (stderr, "Error moving compacted database into place: %s\n", strerror(errno));
+	fprintf (stderr, "\n");
+	fprintf (stderr, "Encountered error while moving the compacted database\n");
+	fprintf (stderr, "\n");
+	fprintf (stderr, "    %s\n", compact_xapian_path);
+	fprintf (stderr, "\n");
+	fprintf (stderr, "to\n");
+	fprintf (stderr, "\n");
+	fprintf (stderr, "    %s\n", xapian_path);
+	fprintf (stderr, "\n");
+	fprintf (stderr, "Please identify the reason for this and move the compacted database\n");
+	fprintf (stderr, "into place manually.\n");
+	if (old_xapian_path != NULL) {
+	    fprintf (stderr, "\n");
+	    fprintf (stderr, "Alternatively you can revert to the uncompacted database with\n");
+	    fprintf (stderr, "\n");
+	    fprintf (stderr, "    mv %s %s\n", old_xapian_path, xapian_path);
+	    fprintf (stderr, "\n");
+	}
 	ret = NOTMUCH_STATUS_FILE_ERROR;
 	goto DONE;
     }
-- 
1.8.3.2