CONFIG REWRITE: don't wipe unknown options.

With this commit options not explicitly rewritten by CONFIG REWRITE are
not touched at all. These include new options that may not have support
for REWRITE, and other special cases like rename-command and include.

src/config.c

@@ -1169,17 +1169,27 @@ void dictListDestructor(void *privdata, void *val);
 void rewriteConfigSentinelOption(struct rewriteConfigState *state);
 
 dictType optionToLineDictType = {
-    dictSdsHash,                /* hash function */
+    dictSdsCaseHash,            /* hash function */
     NULL,                       /* key dup */
     NULL,                       /* val dup */
-    dictSdsKeyCompare,          /* key compare */
+    dictSdsKeyCaseCompare,      /* key compare */
     dictSdsDestructor,          /* key destructor */
     dictListDestructor          /* val destructor */
 };
 
+dictType optionSetDictType = {
+    dictSdsCaseHash,            /* hash function */
+    NULL,                       /* key dup */
+    NULL,                       /* val dup */
+    dictSdsKeyCaseCompare,      /* key compare */
+    dictSdsDestructor,          /* key destructor */
+    NULL                        /* val destructor */
+};
+
 /* The config rewrite state. */
 struct rewriteConfigState {
     dict *option_to_line; /* Option -> list of config file lines map */
+    dict *rewritten;      /* Dictionary of already processed options */
     int numlines;         /* Number of lines in current config */
     sds *lines;           /* Current lines as an array of sds strings */
     int has_tail;         /* True if we already added directives that were
@@ -1203,6 +1213,16 @@ void rewriteConfigAddLineNumberToOption(struct rewriteConfigState *state, sds op
     listAddNodeTail(l,(void*)(long)linenum);
 }
 
+/* Add the specified option to the set of processed options.
+ * This is useful as only unused lines of processed options will be blanked
+ * in the config file, while options the rewrite process does not understand
+ * remain untouched. */
+void rewriteConfigMarkAsProcessed(struct rewriteConfigState *state, char *option) {
+    sds opt = sdsnew(option);
+
+    if (dictAdd(state->rewritten,opt) != DICT_OK) sdsfree(opt);
+}
+
 /* Read the old file, split it into lines to populate a newly created
  * config rewrite state, and return it to the caller.
  *
@@ -1217,6 +1237,7 @@ struct rewriteConfigState *rewriteConfigReadOldFile(char *path) {
     if (fp == NULL && errno != ENOENT) return NULL;
 
     state->option_to_line = dictCreate(&optionToLineDictType,NULL);
+    state->rewritten = dictCreate(&optionSetDictType,NULL);
     state->numlines = 0;
     state->lines = NULL;
     state->has_tail = 0;
@@ -1284,6 +1305,8 @@ void rewriteConfigRewriteLine(struct rewriteConfigState *state, char *option, sd
     sds o = sdsnew(option);
     list *l = dictFetchValue(state->option_to_line,o);
 
+    rewriteConfigMarkAsProcessed(state,option);
+
     if (!l && !force) {
         /* Option not used previously, and we are not forced to use it. */
         sdsfree(line);
@@ -1340,7 +1363,6 @@ void rewriteConfigBytesOption(struct rewriteConfigState *state, char *option, lo
     rewriteConfigFormatMemory(buf,sizeof(buf),value);
     line = sdscatprintf(sdsempty(),"%s %s",option,buf);
     rewriteConfigRewriteLine(state,option,line,force);
-
 }
 
 /* Rewrite a yes/no option. */
@@ -1359,7 +1381,10 @@ void rewriteConfigStringOption(struct rewriteConfigState *state, char *option, c
 
     /* String options set to NULL need to be not present at all in the
      * configuration file to be set to NULL again at the next reboot. */
-    if (value == NULL) return;
+    if (value == NULL) {
+        rewriteConfigMarkAsProcessed(state,option);
+        return;
+    }
 
     /* Compare the strings as sds strings to have a binary safe comparison. */
     if (defvalue && strcmp(value,defvalue) == 0) force = 0;
@@ -1449,7 +1474,10 @@ void rewriteConfigSaveOption(struct rewriteConfigState *state) {
 void rewriteConfigDirOption(struct rewriteConfigState *state) {
     char cwd[1024];
 
-    if (getcwd(cwd,sizeof(cwd)) == NULL) return; /* no rewrite on error. */
+    if (getcwd(cwd,sizeof(cwd)) == NULL) {
+        rewriteConfigMarkAsProcessed(state,"dir");
+        return; /* no rewrite on error. */
+    }
     rewriteConfigStringOption(state,"dir",cwd,NULL);
 }
 
@@ -1460,7 +1488,10 @@ void rewriteConfigSlaveofOption(struct rewriteConfigState *state) {
 
     /* If this is a master, we want all the slaveof config options
      * in the file to be removed. */
-    if (server.masterhost == NULL) return;
+    if (server.masterhost == NULL) {
+        rewriteConfigMarkAsProcessed(state,"slaveof");
+        return;
+    }
     line = sdscatprintf(sdsempty(),"%s %s %d", option,
         server.masterhost, server.masterport);
     rewriteConfigRewriteLine(state,option,line,1);
@@ -1525,7 +1556,10 @@ void rewriteConfigBindOption(struct rewriteConfigState *state) {
     char *option = "bind";
 
     /* Nothing to rewrite if we don't have bind addresses. */
-    if (server.bindaddr_count == 0) return;
+    if (server.bindaddr_count == 0) {
+        rewriteConfigMarkAsProcessed(state,option);
+        return;
+    }
 
     /* Rewrite as bind <addr1> <addr2> ... <addrN> */
     addresses = sdsjoin(server.bindaddr,server.bindaddr_count," ");
@@ -1561,6 +1595,7 @@ sds rewriteConfigGetContentFromState(struct rewriteConfigState *state) {
 void rewriteConfigReleaseState(struct rewriteConfigState *state) {
     sdsfreesplitres(state->lines,state->numlines);
     dictRelease(state->option_to_line);
+    dictRelease(state->rewritten);
     zfree(state);
 }
 
@@ -1578,6 +1613,14 @@ void rewriteConfigRemoveOrphaned(struct rewriteConfigState *state) {
 
     while((de = dictNext(di)) != NULL) {
         list *l = dictGetVal(de);
+        sds option = dictGetKey(de);
+
+        /* Don't blank lines about options the rewrite process
+         * don't understand. */
+        if (dictFetch(state->rewritten,option) == NULL) {
+            redisLog(REDIS_DEBUG,"Not rewritten option: %s", option);
+            continue;
+        }
 
         while(listLength(l)) {
             listNode *ln = listFirst(l);
@@ -1667,8 +1710,6 @@ int rewriteConfig(char *path) {
     /* Step 2: rewrite every single option, replacing or appending it inside
      * the rewrite state. */
 
-    /* TODO: Turn every default into a define, use it also in
-     * initServerConfig(). */
     rewriteConfigYesNoOption(state,"daemonize",server.daemonize,0);
     rewriteConfigStringOption(state,"pidfile",server.pidfile,REDIS_DEFAULT_PID_FILE);
     rewriteConfigNumericalOption(state,"port",server.port,REDIS_SERVERPORT);