Restrict use of escape expansion

Only expand escape sequences like \n and \t in telluser(error) comamnds
that ask for it by preficing the messages by double backslash. Otherwise
backward copatiblity is too severely broken for messages that display
DOS-style filenames.

diff --git a/backend.c b/backend.c
index 46a14c7..bd4bd75 100644 (file)
--- a/backend.c
+++ b/backend.c
@@ -7488,13 +7488,15 @@ if(appData.debugMode) fprintf(debugFP, "nodes = %d, %lld\n", (int) programStats.
      * Look for communication commands
      */
     if (!strncmp(message, "telluser ", 9)) {
-       EscapeExpand(message+9, message+9); // [HGM] esc: allow escape sequences in popup box
+       if(message[9] == '\\' && message[10] == '\\')
+           EscapeExpand(message+9, message+11); // [HGM] esc: allow escape sequences in popup box
        DisplayNote(message + 9);
        return;
     }
     if (!strncmp(message, "tellusererror ", 14)) {
        cps->userError = 1;
-       EscapeExpand(message+14, message+14); // [HGM] esc: allow escape sequences in popup box
+       if(message[14] == '\\' && message[15] == '\\')
+           EscapeExpand(message+14, message+16); // [HGM] esc: allow escape sequences in popup box
        DisplayError(message + 14, 0);
        return;
     }