lib-storage: When logging corrupted mail size, disable logging Messag…

…e-ID for now

This was causing crashes in some situations. It was originally added to
figure out if there were problems with dovecot.index.cache containing
data for wrong messages. This was never found to happen, although now
thinking about it, the problem may have been
7412871. So perhaps this code could be
removed permanently as well.

6b44fc7 also attempted to fix this, but it
wasn't enough. There was still some code path that lead to recursive header
parsing.

src/lib-storage/index/istream-mail.c

@@ -32,8 +32,13 @@ static bool i_stream_mail_try_get_cached_size(struct mail_istream *mstream)
 }
 
 static const char *
-i_stream_mail_get_cached_mail_id(struct mail_istream *mstream)
+i_stream_mail_get_cached_mail_id(struct mail_istream *mstream ATTR_UNUSED)
 {
+#if 0
+	/* FIXME: This function may get called in the middle of header parsing,
+	   which then goes into parsing cached headers and causes crashes.
+	   So disable this for now. Eventually it would be nice if recursion
+	   was possible by each parser using its own private struct. */
 	static const char *headers[] = {
 		"Message-Id",
 		"Date",
@@ -54,6 +59,9 @@ i_stream_mail_get_cached_mail_id(struct mail_istream *mstream)
 	}
 	mail->lookup_abort = orig_lookup_abort;
 	return ret;
+#else
+	return "";
+#endif
 }
 
 static void