Add the system identifier to backup manifests.

Before this patch, if you took a full backup on server A and then
tried to use the backup manifest to take an incremental backup on
server B, it wouldn't know that the manifest was from a different
server and so the incremental backup operation could potentially
complete without error. When you later tried to run pg_combinebackup,
you'd find out that your incremental backup was and always had been
invalid. That's poor timing, because nobody likes finding out about
backup problems only at restore time.

With this patch, you'll get an error when trying to take the (invalid)
incremental backup, which seems a lot nicer.

Amul Sul, revised by me. Review by Michael Paquier.

Discussion: http://postgr.es/m/CA+TgmoYLZzbSAMM3cAjV4Y+iCRZn-bR9H2+Mdz7NdaJFU1Zb5w@mail.gmail.com

1 files changed, 40 insertions, 0 deletions

diff --git a/src/backend/backup/basebackup_incremental.c b/src/backend/backup/basebackup_incremental.c
index 2a522e4aea9..990b2872eaf 100644
--- a/src/backend/backup/basebackup_incremental.c
+++ b/src/backend/backup/basebackup_incremental.c
@@ -20,6 +20,7 @@
 #include "postgres.h"
 
 #include "access/timeline.h"
+#include "access/xlog.h"
 #include "backup/basebackup_incremental.h"
 #include "backup/walsummary.h"
 #include "common/blkreftable.h"
@@ -113,6 +114,10 @@ struct IncrementalBackupInfo
 	BlockRefTable *brtab;
 };
 
+static void manifest_process_version(JsonManifestParseContext *context,
+									 int manifest_version);
+static void manifest_process_system_identifier(JsonManifestParseContext *context,
+											   uint64 manifest_system_identifier);
 static void manifest_process_file(JsonManifestParseContext *context,
 								  char *pathname,
 								  size_t size,
@@ -199,6 +204,8 @@ FinalizeIncrementalManifest(IncrementalBackupInfo *ib)
 
 	/* Parse the manifest. */
 	context.private_data = ib;
+	context.version_cb = manifest_process_version;
+	context.system_identifier_cb = manifest_process_system_identifier;
 	context.per_file_cb = manifest_process_file;
 	context.per_wal_range_cb = manifest_process_wal_range;
 	context.error_cb = manifest_report_error;
@@ -928,6 +935,39 @@ hash_string_pointer(const char *s)
 }
 
 /*
+ * This callback to validate the manifest version for incremental backup.
+ */
+static void
+manifest_process_version(JsonManifestParseContext *context,
+						 int manifest_version)
+{
+	/* Incremental backups don't work with manifest version 1 */
+	if (manifest_version == 1)
+		context->error_cb(context,
+						  "backup manifest version 1 does not support incremental backup");
+}
+
+/*
+ * This callback to validate the manifest system identifier against the current
+ * database server.
+ */
+static void
+manifest_process_system_identifier(JsonManifestParseContext *context,
+								   uint64 manifest_system_identifier)
+{
+	uint64		system_identifier;
+
+	/* Get system identifier of current system */
+	system_identifier = GetSystemIdentifier();
+
+	if (manifest_system_identifier != system_identifier)
+		context->error_cb(context,
+						  "manifest system identifier is %llu, but database system identifier is %llu",
+						  (unsigned long long) manifest_system_identifier,
+						  (unsigned long long) system_identifier);
+}
+
+/*
  * This callback is invoked for each file mentioned in the backup manifest.
  *
  * We store the path to each file and the size of each file for sanity-checking