Improve RDB error-on-load handling

Previouly if we loaded a corrupt RDB, Redis printed an error report
with a big "REPORT ON GITHUB" message at the bottom.  But, we know
RDB load failures are corrupt data, not corrupt code.

Now when RDB failure is detected (duplicate keys or unknown data
types in the file), we run check-rdb against the RDB then exit.  The
automatic check-rdb hopefully gives the user instant feedback
about what is wrong instead of providing a mysterious stack
trace.

Author: mattsta

src/rdb.c

@@ -44,6 +44,16 @@
 #define RDB_LOAD_ENC    (1<<0)
 #define RDB_LOAD_PLAIN  (1<<1)
 
+#define rdbExitReportCorruptRDB(reason) rdbCheckThenExit(reason, __LINE__);
+
+void rdbCheckThenExit(char *reason, int where) {
+    redisLog(REDIS_WARNING, "Corrupt RDB detected at rdb.c:%d (%s). "
+        "Running 'redis-check-rdb --dbfilename %s'",
+        where, reason, server.rdb_filename);
+    redis_check_rdb(server.rdb_filename);
+    exit(1);
+}
+
 static int rdbWriteRaw(rio *rdb, void *p, size_t len) {
     if (rdb && rioWrite(rdb,p,len) == 0)
         return -1;
@@ -188,7 +198,7 @@ void *rdbLoadIntegerObject(rio *rdb, int enctype, int flags) {
         val = (int32_t)v;
     } else {
         val = 0; /* anti-warning */
-        redisPanic("Unknown RDB integer encoding type");
+        rdbExitReportCorruptRDB("Unknown RDB integer encoding type");
     }
     if (plain) {
         char buf[REDIS_LONGSTR_SIZE], *p;
@@ -394,7 +404,7 @@ void *rdbGenericLoadStringObject(rio *rdb, int flags) {
         case REDIS_RDB_ENC_LZF:
             return rdbLoadLzfStringObject(rdb,flags);
         default:
-            redisPanic("Unknown RDB encoding type");
+            rdbExitReportCorruptRDB("Unknown RDB encoding type");
         }
     }
 
@@ -923,7 +933,7 @@ void rdbRemoveTempFile(pid_t childpid) {
 /* Load a Redis object of the specified type from the specified file.
  * On success a newly allocated object is returned, otherwise NULL. */
 robj *rdbLoadObject(int rdbtype, rio *rdb) {
-    robj *o, *ele, *dec;
+    robj *o = NULL, *ele, *dec;
     size_t len;
     unsigned int i;
 
@@ -1078,7 +1088,9 @@ robj *rdbLoadObject(int rdbtype, rio *rdb) {
 
             /* Add pair to hash table */
             ret = dictAdd((dict*)o->ptr, field, value);
-            redisAssert(ret == DICT_OK);
+            if (ret == DICT_ERR) {
+                rdbExitReportCorruptRDB("Duplicate keys detected");
+            }
         }
 
         /* All pairs should be read by now */
@@ -1164,11 +1176,11 @@ robj *rdbLoadObject(int rdbtype, rio *rdb) {
                     hashTypeConvert(o, REDIS_ENCODING_HT);
                 break;
             default:
-                redisPanic("Unknown encoding");
+                rdbExitReportCorruptRDB("Unknown encoding");
                 break;
         }
     } else {
-        redisPanic("Unknown object type");
+        rdbExitReportCorruptRDB("Unknown object type");
     }
     return o;
 }