reject mutable operation when slave readonly mode

src/config.c

@@ -208,6 +208,10 @@ void loadServerConfig(char *filename) {
             if ((server.daemonize = yesnotoi(argv[1])) == -1) {
                 err = "argument must be 'yes' or 'no'"; goto loaderr;
             }
+        } else if (!strcasecmp(argv[0],"slave-readonly") && argc == 2) {
+            if ((server.slave_readonly= yesnotoi(argv[1])) == -1) {
+                err = "argument must be 'yes' or 'no'"; goto loaderr;
+            }
         } else if (!strcasecmp(argv[0],"appendonly") && argc == 2) {
             if ((server.appendonly = yesnotoi(argv[1])) == -1) {
                 err = "argument must be 'yes' or 'no'"; goto loaderr;

src/redis.c

@@ -795,6 +795,7 @@ void initServerConfig() {
     server.syslog_ident = zstrdup("redis");
     server.syslog_facility = LOG_LOCAL0;
     server.daemonize = 0;
+    server.slave_readonly = 0;
     server.appendonly = 0;
     server.appendfsync = APPENDFSYNC_EVERYSEC;
     server.no_appendfsync_on_rewrite = 0;
@@ -1051,6 +1052,12 @@ int processCommand(redisClient *c) {
         return REDIS_OK;
     }
 
+    /* Check readonly flag */
+    if (server.slave_readonly && (c->flags & REDIS_MASTER || c->flags & REDIS_SLAVE) && (cmd->flags & REDIS_CMD_IS_MUTABLE)) {
+        addReplyError(c,"operation is mutable, not permitted");
+        return REDIS_OK;
+    }
+
     /* Handle the maxmemory directive.
      *
      * First we try to free some memory if possible (if there are volatile

src/redis.h

@@ -404,6 +404,7 @@ struct redisServer {
     int no_appendfsync_on_rewrite;
     int shutdown_asap;
     int activerehashing;
+    int slave_readonly;
     char *requirepass;
     /* Persistence */
     long long dirty;            /* changes to DB from the last save */