Expose control file data via SQL accessible functions.

Add four new SQL accessible functions: pg_control_system(),
pg_control_checkpoint(), pg_control_recovery(), and pg_control_init()
which expose a subset of the control file data.

Along the way move the code to read and validate the control file to
src/common, where it can be shared by the new backend functions
and the original pg_controldata frontend program.

Patch by me, significant input, testing, and review by Michael Paquier.

4 files changed, 35 insertions, 1 deletions

diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index 2f57524fcb2..16cd304f1b7 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201603021
+#define CATALOG_VERSION_NO	201603051
 
 #endif
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index aec6c4ca904..cbbb8835c46 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -5225,6 +5225,19 @@ DESCR("row security for current context active on table by table name");
 DATA(insert OID = 3400 ( pg_config PGNSP PGUID 12 1 23 0 0 f f f f t t i r 0 0 2249 "" "{25,25}" "{o,o}" "{name,setting}" _null_ _null_ pg_config _null_ _null_ _null_ ));
 DESCR("pg_config binary as a function");
 
+/* pg_controldata related functions */
+DATA(insert OID = 3441 ( pg_control_system PGNSP PGUID 12 1 0 0 0 f f f f t f v s 0 0 2249 "" "{23,23,20,1184}" "{o,o,o,o}" "{pg_control_version,catalog_version_no,system_identifier,pg_control_last_modified}" _null_ _null_ pg_control_system _null_ _null_ _null_ ));
+DESCR("pg_controldata general state information as a function");
+
+DATA(insert OID = 3442 ( pg_control_checkpoint PGNSP PGUID 12 1 0 0 0 f f f f t f v s 0 0 2249 "" "{3220,3220,3220,25,23,23,16,25,26,28,28,28,26,28,28,26,28,28,1184}" "{o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{checkpoint_location,prior_location,redo_location,redo_wal_file,timeline_id,prev_timeline_id,full_page_writes,next_xid,next_oid,next_multixact_id,next_multi_offset,oldest_xid,oldest_xid_dbid,oldest_active_xid,oldest_multi_xid,oldest_multi_dbid,oldest_commit_ts_xid,newest_commit_ts_xid,checkpoint_time}" _null_ _null_ pg_control_checkpoint _null_ _null_ _null_ ));
+DESCR("pg_controldata checkpoint state information as a function");
+
+DATA(insert OID = 3443 ( pg_control_recovery PGNSP PGUID 12 1 0 0 0 f f f f t f v s 0 0 2249 "" "{3220,23,3220,3220,16}" "{o,o,o,o,o}" "{min_recovery_end_location,min_recovery_end_timeline,backup_start_location,backup_end_location,end_of_backup_record_required}" _null_ _null_ pg_control_recovery _null_ _null_ _null_ ));
+DESCR("pg_controldata recovery state information as a function");
+
+DATA(insert OID = 3444 ( pg_control_init PGNSP PGUID 12 1 0 0 0 f f f f t f v s 0 0 2249 "" "{23,23,23,23,23,23,23,23,23,16,16,16,23}" "{o,o,o,o,o,o,o,o,o,o,o,o,o}" "{max_data_alignment,database_block_size,blocks_per_segment,wal_block_size,bytes_per_wal_segment,max_identifier_length,max_index_columns,max_toast_chunk_size,large_object_chunk_size,bigint_timestamps,float4_pass_by_value,float8_pass_by_value,data_page_checksum_version}" _null_ _null_ pg_control_init _null_ _null_ _null_ ));
+DESCR("pg_controldata init state information as a function");
+
 /*
  * Symbolic values for provolatile column: these indicate whether the result
  * of a function is dependent *only* on the values of its explicit arguments,
diff --git a/src/include/common/controldata_utils.h b/src/include/common/controldata_utils.h
new file mode 100644
index 00000000000..1a097653dab
--- /dev/null
+++ b/src/include/common/controldata_utils.h
@@ -0,0 +1,15 @@
+/*
+ * controldata_utils.h
+ *		Common code for pg_controldata output
+ *
+ *	Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
+ *	Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *	src/include/common/controldata_utils.h
+ */
+#ifndef COMMON_CONTROLDATA_UTILS_H
+#define COMMON_CONTROLDATA_UTILS_H
+
+extern ControlFileData *get_controlfile(char *DataDir, const char *progname);
+
+#endif   /* COMMON_CONTROLDATA_UTILS_H */
diff --git a/src/include/utils/builtins.h b/src/include/utils/builtins.h
index 7ec93c95c7c..115f8afb45b 100644
--- a/src/include/utils/builtins.h
+++ b/src/include/utils/builtins.h
@@ -1151,6 +1151,12 @@ extern Datum show_all_file_settings(PG_FUNCTION_ARGS);
 /* pg_config.c */
 extern Datum pg_config(PG_FUNCTION_ARGS);
 
+/* pg_controldata.c */
+extern Datum pg_control_checkpoint(PG_FUNCTION_ARGS);
+extern Datum pg_control_system(PG_FUNCTION_ARGS);
+extern Datum pg_control_init(PG_FUNCTION_ARGS);
+extern Datum pg_control_recovery(PG_FUNCTION_ARGS);
+
 /* rls.c */
 extern Datum row_security_active(PG_FUNCTION_ARGS);
 extern Datum row_security_active_name(PG_FUNCTION_ARGS);