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, 73 insertions, 3 deletions

diff --git a/src/common/parse_manifest.c b/src/common/parse_manifest.c
index 92a97714f36..3f6d1dfd3de 100644
--- a/src/common/parse_manifest.c
+++ b/src/common/parse_manifest.c
@@ -25,6 +25,7 @@ typedef enum
 	JM_EXPECT_TOPLEVEL_END,
 	JM_EXPECT_TOPLEVEL_FIELD,
 	JM_EXPECT_VERSION_VALUE,
+	JM_EXPECT_SYSTEM_IDENTIFIER_VALUE,
 	JM_EXPECT_FILES_START,
 	JM_EXPECT_FILES_NEXT,
 	JM_EXPECT_THIS_FILE_FIELD,
@@ -85,6 +86,8 @@ typedef struct
 
 	/* Miscellaneous other stuff. */
 	bool		saw_version_field;
+	char	   *manifest_version;
+	char	   *manifest_system_identifier;
 	char	   *manifest_checksum;
 } JsonManifestParseState;
 
@@ -96,6 +99,8 @@ static JsonParseErrorType json_manifest_object_field_start(void *state, char *fn
 														   bool isnull);
 static JsonParseErrorType json_manifest_scalar(void *state, char *token,
 											   JsonTokenType tokentype);
+static void json_manifest_finalize_version(JsonManifestParseState *parse);
+static void json_manifest_finalize_system_identifier(JsonManifestParseState *parse);
 static void json_manifest_finalize_file(JsonManifestParseState *parse);
 static void json_manifest_finalize_wal_range(JsonManifestParseState *parse);
 static void verify_manifest_checksum(JsonManifestParseState *parse,
@@ -312,6 +317,13 @@ json_manifest_object_field_start(void *state, char *fname, bool isnull)
 				break;
 			}
 
+			/* Is this the system identifier? */
+			if (strcmp(fname, "System-Identifier") == 0)
+			{
+				parse->state = JM_EXPECT_SYSTEM_IDENTIFIER_VALUE;
+				break;
+			}
+
 			/* Is this the list of files? */
 			if (strcmp(fname, "Files") == 0)
 			{
@@ -404,9 +416,14 @@ json_manifest_scalar(void *state, char *token, JsonTokenType tokentype)
 	switch (parse->state)
 	{
 		case JM_EXPECT_VERSION_VALUE:
-			if (strcmp(token, "1") != 0)
-				json_manifest_parse_failure(parse->context,
-											"unexpected manifest version");
+			parse->manifest_version = token;
+			json_manifest_finalize_version(parse);
+			parse->state = JM_EXPECT_TOPLEVEL_FIELD;
+			break;
+
+		case JM_EXPECT_SYSTEM_IDENTIFIER_VALUE:
+			parse->manifest_system_identifier = token;
+			json_manifest_finalize_system_identifier(parse);
 			parse->state = JM_EXPECT_TOPLEVEL_FIELD;
 			break;
 
@@ -465,6 +482,59 @@ json_manifest_scalar(void *state, char *token, JsonTokenType tokentype)
 }
 
 /*
+ * Do additional parsing and sanity-checking of the manifest version, and invoke
+ * the callback so that the caller can gets that detail and take actions
+ * accordingly.  This happens for each manifest when the corresponding JSON
+ * object is completely parsed.
+ */
+static void
+json_manifest_finalize_version(JsonManifestParseState *parse)
+{
+	JsonManifestParseContext *context = parse->context;
+	int			version;
+	char	   *ep;
+
+	Assert(parse->saw_version_field);
+
+	/* Parse version. */
+	version = strtoi64(parse->manifest_version, &ep, 10);
+	if (*ep)
+		json_manifest_parse_failure(parse->context,
+									"manifest version not an integer");
+
+	if (version != 1 && version != 2)
+		json_manifest_parse_failure(parse->context,
+									"unexpected manifest version");
+
+	/* Invoke the callback for version */
+	context->version_cb(context, version);
+}
+
+/*
+ * Do additional parsing and sanity-checking of the system identifier, and
+ * invoke the callback so that the caller can gets that detail and take actions
+ * accordingly.
+ */
+static void
+json_manifest_finalize_system_identifier(JsonManifestParseState *parse)
+{
+	JsonManifestParseContext *context = parse->context;
+	uint64		system_identifier;
+	char	   *ep;
+
+	Assert(parse->manifest_system_identifier != NULL);
+
+	/* Parse system identifier. */
+	system_identifier = strtou64(parse->manifest_system_identifier, &ep, 10);
+	if (*ep)
+		json_manifest_parse_failure(parse->context,
+									"manifest system identifier not an integer");
+
+	/* Invoke the callback for system identifier */
+	context->system_identifier_cb(context, system_identifier);
+}
+
+/*
  * Do additional parsing and sanity-checking of the details gathered for one
  * file, and invoke the per-file callback so that the caller gets those
  * details. This happens for each file when the corresponding JSON object is