Sentinel: fix SENTINEL SET error reporting.

Thanks to @shenlongxing for reporting the problem.
Related to #5062.

src/sentinel.c

@@ -3380,7 +3380,8 @@ void sentinelRoleCommand(client *c) {
 void sentinelSetCommand(client *c) {
     sentinelRedisInstance *ri;
     int j, changes = 0;
-    char *option, *value;
+    int badarg = 0; /* Bad argument position for error reporting. */
+    char *option;
 
     if ((ri = sentinelGetMasterByNameOrReplyError(c,c->argv[2]))
         == NULL) return;
@@ -3395,28 +3396,34 @@ void sentinelSetCommand(client *c) {
         if (!strcasecmp(option,"down-after-milliseconds") && moreargs > 0) {
             /* down-after-millisecodns <milliseconds> */
             robj *o = c->argv[++j];
-            if (getLongLongFromObject(o,&ll) == C_ERR || ll <= 0)
+            if (getLongLongFromObject(o,&ll) == C_ERR || ll <= 0) {
+                badarg = j;
                 goto badfmt;
+            }
             ri->down_after_period = ll;
             sentinelPropagateDownAfterPeriod(ri);
             changes++;
         } else if (!strcasecmp(option,"failover-timeout") && moreargs > 0) {
             /* failover-timeout <milliseconds> */
             robj *o = c->argv[++j];
-            if (getLongLongFromObject(o,&ll) == C_ERR || ll <= 0)
+            if (getLongLongFromObject(o,&ll) == C_ERR || ll <= 0) {
+                badarg = j;
                 goto badfmt;
+            }
             ri->failover_timeout = ll;
             changes++;
         } else if (!strcasecmp(option,"parallel-syncs") && moreargs > 0) {
             /* parallel-syncs <milliseconds> */
             robj *o = c->argv[++j];
-            if (getLongLongFromObject(o,&ll) == C_ERR || ll <= 0)
+            if (getLongLongFromObject(o,&ll) == C_ERR || ll <= 0) {
+                badarg = j;
                 goto badfmt;
+            }
             ri->parallel_syncs = ll;
             changes++;
         } else if (!strcasecmp(option,"notification-script") && moreargs > 0) {
             /* notification-script <path> */
-            value = c->argv[++j]->ptr;
+            char *value = c->argv[++j]->ptr;
             if (sentinel.deny_scripts_reconfig) {
                 addReplyError(c,
                     "Reconfiguration of scripts path is denied for "
@@ -3436,7 +3443,7 @@ void sentinelSetCommand(client *c) {
             changes++;
         } else if (!strcasecmp(option,"client-reconfig-script") && moreargs > 0) {
             /* client-reconfig-script <path> */
-            value = c->argv[++j]->ptr;
+            char *value = c->argv[++j]->ptr;
             if (sentinel.deny_scripts_reconfig) {
                 addReplyError(c,
                     "Reconfiguration of scripts path is denied for "
@@ -3457,15 +3464,17 @@ void sentinelSetCommand(client *c) {
             changes++;
         } else if (!strcasecmp(option,"auth-pass") && moreargs > 0) {
             /* auth-pass <password> */
-            value = c->argv[++j]->ptr;
+            char *value = c->argv[++j]->ptr;
             sdsfree(ri->auth_pass);
             ri->auth_pass = strlen(value) ? sdsnew(value) : NULL;
             changes++;
         } else if (!strcasecmp(option,"quorum") && moreargs > 0) {
             /* quorum <count> */
             robj *o = c->argv[++j];
-            if (getLongLongFromObject(o,&ll) == C_ERR || ll <= 0)
+            if (getLongLongFromObject(o,&ll) == C_ERR || ll <= 0) {
+                badarg = j;
                 goto badfmt;
+            }
             ri->quorum = ll;
             changes++;
         } else if (!strcasecmp(option,"rename-command") && moreargs > 1) {
@@ -3516,7 +3525,7 @@ void sentinelSetCommand(client *c) {
 badfmt: /* Bad format errors */
     if (changes) sentinelFlushConfig();
     addReplyErrorFormat(c,"Invalid argument '%s' for SENTINEL SET '%s'",
-            value, option);
+        c->argv[badarg]->ptr,option);
 }
 
 /* Our fake PUBLISH command: it is actually useful only to receive hello messages