From 84bcd3aa24eabed2a5295dc3450e6f45aa79049c Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Tue, 10 Apr 2012 15:47:10 +0200
Subject: [PATCH] It is now possible to enable/disable RDB checksum computation
 from redis.conf or via CONFIG SET/GET. Also CONFIG SET support added for
 rdbcompression as well.

---
 redis.conf   |  9 +++++++++
 src/config.c | 15 +++++++++++++++
 src/rdb.c    | 15 ++++++++++-----
 src/redis.c  |  1 +
 src/redis.h  |  1 +
 5 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/redis.conf b/redis.conf
index 1b79e09e..d7d29303 100644
--- a/redis.conf
+++ b/redis.conf
@@ -114,6 +114,15 @@ stop-writes-on-bgsave-error yes
 # the dataset will likely be bigger if you have compressible values or keys.
 rdbcompression yes
 
+# Since verison 5 of RDB a CRC64 checksum is placed at the end of the file.
+# This makes the format more resistant to corruption but there is a performance
+# hit to pay (around 10%) when saving and loading RDB files, so you can disable it
+# for maximum performances.
+#
+# RDB files created with checksum disabled have a checksum of zero that will
+# tell the loading code to skip the check.
+rdbchecksum yes
+
 # The filename where to dump the DB
 dbfilename dump.rdb
 
diff --git a/src/config.c b/src/config.c
index 8dffe288..9899dfbc 100644
--- a/src/config.c
+++ b/src/config.c
@@ -210,6 +210,10 @@ void loadServerConfigFromString(char *config) {
             if ((server.rdb_compression = yesnotoi(argv[1])) == -1) {
                 err = "argument must be 'yes' or 'no'"; goto loaderr;
             }
+        } else if (!strcasecmp(argv[0],"rdbchecksum") && argc == 2) {
+            if ((server.rdb_checksum = yesnotoi(argv[1])) == -1) {
+                err = "argument must be 'yes' or 'no'"; goto loaderr;
+            }
         } else if (!strcasecmp(argv[0],"activerehashing") && argc == 2) {
             if ((server.activerehashing = yesnotoi(argv[1])) == -1) {
                 err = "argument must be 'yes' or 'no'"; goto loaderr;
@@ -633,6 +637,16 @@ void configSetCommand(redisClient *c) {
             enableWatchdog(ll);
         else
             disableWatchdog();
+    } else if (!strcasecmp(c->argv[2]->ptr,"rdbcompression")) {
+        int yn = yesnotoi(o->ptr);
+
+        if (yn == -1) goto badfmt;
+        server.rdb_compression = yn;
+    } else if (!strcasecmp(c->argv[2]->ptr,"rdbchecksum")) {
+        int yn = yesnotoi(o->ptr);
+
+        if (yn == -1) goto badfmt;
+        server.rdb_checksum = yn;
     } else {
         addReplyErrorFormat(c,"Unsupported CONFIG parameter: %s",
             (char*)c->argv[2]->ptr);
@@ -734,6 +748,7 @@ void configGetCommand(redisClient *c) {
             server.stop_writes_on_bgsave_err);
     config_get_bool_field("daemonize", server.daemonize);
     config_get_bool_field("rdbcompression", server.rdb_compression);
+    config_get_bool_field("rdbchecksum", server.rdb_checksum);
     config_get_bool_field("activerehashing", server.activerehashing);
 
     /* Everything we can't handle with macros follows. */
diff --git a/src/rdb.c b/src/rdb.c
index 1815dc24..8ffd2c28 100644
--- a/src/rdb.c
+++ b/src/rdb.c
@@ -614,7 +614,8 @@ int rdbSave(char *filename) {
     }
 
     rioInitWithFile(&rdb,fp);
-    rdb.update_cksum = rioGenericUpdateChecksum;
+    if (server.rdb_checksum)
+        rdb.update_cksum = rioGenericUpdateChecksum;
     snprintf(magic,sizeof(magic),"REDIS%04d",REDIS_RDB_VERSION);
     if (rdbWriteRaw(&rdb,magic,9) == -1) goto werr;
 
@@ -649,7 +650,8 @@ int rdbSave(char *filename) {
     /* EOF opcode */
     if (rdbSaveType(&rdb,REDIS_RDB_OPCODE_EOF) == -1) goto werr;
 
-    /* CRC64 checksum */
+    /* CRC64 checksum. It will be zero if checksum computation is disabled, the
+     * loading code skips the check in this case. */
     cksum = rdb.cksum;
     memrev64ifbe(&cksum);
     rioWrite(&rdb,&cksum,8);
@@ -1026,7 +1028,8 @@ int rdbLoad(char *filename) {
         return REDIS_ERR;
     }
     rioInitWithFile(&rdb,fp);
-    rdb.update_cksum = rioGenericUpdateChecksum;
+    if (server.rdb_checksum)
+        rdb.update_cksum = rioGenericUpdateChecksum;
     if (rioRead(&rdb,buf,9) == 0) goto eoferr;
     buf[9] = '\0';
     if (memcmp(buf,"REDIS",5) != 0) {
@@ -1108,12 +1111,14 @@ int rdbLoad(char *filename) {
         decrRefCount(key);
     }
     /* Verify the checksum if RDB version is >= 5 */
-    if (rdbver >= 5) {
+    if (rdbver >= 5 && server.rdb_checksum) {
         uint64_t cksum, expected = rdb.cksum;
 
         if (rioRead(&rdb,&cksum,8) == 0) goto eoferr;
         memrev64ifbe(&cksum);
-        if (cksum != expected) {
+        if (cksum == 0) {
+            redisLog(REDIS_WARNING,"RDB file was saved with checksum disabled: no check performed.");
+        } else if (cksum != expected) {
             redisLog(REDIS_WARNING,"Wrong RDB checksum. Aborting now.");
             exit(1);
         }
diff --git a/src/redis.c b/src/redis.c
index 84221add..ea5525dc 100644
--- a/src/redis.c
+++ b/src/redis.c
@@ -1061,6 +1061,7 @@ void initServerConfig() {
     server.aof_filename = zstrdup("appendonly.aof");
     server.requirepass = NULL;
     server.rdb_compression = 1;
+    server.rdb_checksum = 1;
     server.activerehashing = 1;
     server.maxclients = REDIS_MAX_CLIENTS;
     server.bpop_blocked_clients = 0;
diff --git a/src/redis.h b/src/redis.h
index 52d39bc7..42a9b581 100644
--- a/src/redis.h
+++ b/src/redis.h
@@ -646,6 +646,7 @@ struct redisServer {
     int saveparamslen;              /* Number of saving points */
     char *rdb_filename;             /* Name of RDB file */
     int rdb_compression;            /* Use compression in RDB? */
+    int rdb_checksum;               /* Use RDB checksum? */
     time_t lastsave;                /* Unix time of last save succeeede */
     int lastbgsave_status;          /* REDIS_OK or REDIS_ERR */
     int stop_writes_on_bgsave_err;  /* Don't allow writes if can't BGSAVE */