From 171cad2a98a909541da04112d1278194a9ff94be Mon Sep 17 00:00:00 2001
From: Shlomi Noach <shlomi-noach@github.com>
Date: Wed, 21 Dec 2016 09:23:00 +0200
Subject: [PATCH] sanity checks for resurrection

---
 go/cmd/gh-ost/main.go | 10 ++++++----
 go/logic/applier.go   | 13 +++++++++++++
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/go/cmd/gh-ost/main.go b/go/cmd/gh-ost/main.go
index c9109c7..b498e90 100644
--- a/go/cmd/gh-ost/main.go
+++ b/go/cmd/gh-ost/main.go
@@ -180,11 +180,13 @@ func main() {
 	if *cliMasterPassword != "" && migrationContext.AssumeMasterHostname == "" {
 		log.Fatalf("--master-password requires --assume-master-host")
 	}
-	if migrationContext.InitiallyDropGhostTable && migrationContext.Resurrect {
-		log.Fatalf("--initially-drop-ghost-table and --resurrect are mutually exclusive")
+	if migrationContext.Resurrect && migrationContext.InitiallyDropGhostTable {
+		migrationContext.InitiallyDropGhostTable = false
+		log.Warningf("--resurrect given, implicitly disabling --initially-drop-ghost-table")
 	}
-	if migrationContext.InitiallyDropOldTable && migrationContext.Resurrect {
-		log.Fatalf("--initially-drop-old-table and --resurrect are mutually exclusive")
+	if migrationContext.Resurrect && migrationContext.InitiallyDropOldTable {
+		migrationContext.InitiallyDropOldTable = false
+		log.Warningf("--resurrect given, implicitly disabling --initially-drop-old-table")
 	}
 
 	switch *cutOver {
diff --git a/go/logic/applier.go b/go/logic/applier.go
index 3dfce2b..0d322f6 100644
--- a/go/logic/applier.go
+++ b/go/logic/applier.go
@@ -128,6 +128,19 @@ func (this *Applier) tableExists(tableName string) (tableFound bool) {
 // ValidateOrDropExistingTables verifies ghost and changelog tables do not exist,
 // or attempts to drop them if instructed to.
 func (this *Applier) ValidateOrDropExistingTables() error {
+	if this.migrationContext.Resurrect {
+		ghostTableExists := this.tableExists(this.migrationContext.GetGhostTableName())
+		if !ghostTableExists {
+			return fmt.Errorf("--ressurect requested, but ghost table %s doesn't exist. Panicking.", this.migrationContext.GetGhostTableName())
+		}
+		changelogTableExists := this.tableExists(this.migrationContext.GetChangelogTableName())
+		if !changelogTableExists {
+			return fmt.Errorf("--ressurect requested, but changelog table %s doesn't exist. Panicking.", this.migrationContext.GetChangelogTableName())
+		}
+		return nil
+	}
+	// Normal mode (no resurrection)
+
 	if this.migrationContext.InitiallyDropGhostTable {
 		if err := this.DropGhostTable(); err != nil {
 			return err