postgresql-exclusive_backup_start_time-patch.diff

diff -ru postgresql/doc/src/sgml/func.sgml postgresql-exclusive_backup_start_time-patch/doc/src/sgml/func.sgml
--- postgresql/doc/src/sgml/func.sgml	2012-01-26 23:01:31.956613398 +0100
+++ postgresql-exclusive_backup_start_time-patch/doc/src/sgml/func.sgml	2012-03-02 10:56:56.986487006 +0100
@@ -14371,6 +14371,9 @@
     <primary>pg_current_xlog_location</primary>
    </indexterm>
    <indexterm>
+    <primary>pg_exclusive_backup_start_time</primary>
+   </indexterm>
+   <indexterm>
     <primary>pg_start_backup</primary>
    </indexterm>
    <indexterm>
@@ -14424,6 +14427,14 @@
       </row>
       <row>
        <entry>
+        <literal><function>pg_exclusive_backup_start_time()</function></literal>
+        </entry>
+       <entry><type>timestamp with time zone</type></entry>
+       <entry>Get start time of an on-line exclusive backup in progress.
+       </entry>
+      </row>
+      <row>
+       <entry>
         <literal><function>pg_start_backup(<parameter>label</> <type>text</> <optional>, <parameter>fast</> <type>boolean</> </optional>)</function></literal>
         </entry>
        <entry><type>text</type></entry>
diff -ru postgresql/src/backend/access/transam/xlogfuncs.c postgresql-exclusive_backup_start_time-patch/src/backend/access/transam/xlogfuncs.c
--- postgresql/src/backend/access/transam/xlogfuncs.c	2012-03-02 15:21:42.278479256 +0100
+++ postgresql-exclusive_backup_start_time-patch/src/backend/access/transam/xlogfuncs.c	2012-03-02 15:17:50.390479369 +0100
@@ -28,6 +28,7 @@
 #include "utils/builtins.h"
 #include "utils/guc.h"
 #include "utils/timestamp.h"
+#include "storage/fd.h"
 
 /*
  * pg_start_backup: set up for taking an on-line backup dump
@@ -465,3 +466,71 @@
 {
 	PG_RETURN_BOOL(RecoveryInProgress());
 }
+
+
+/*
+ * Returns start time of an online exclusive backup.
+ *
+ * When there's no exclusive backup in progress, the function
+ * returns NULL.
+ */
+Datum
+pg_exclusive_backup_start_time(PG_FUNCTION_ARGS)
+{
+	TimestampTz                xtime;
+	FILE                        *lfp;
+	char            fline[MAXPGPATH];
+	char       backup_start_time[30];
+
+	/*
+	 * See if label file is present
+	 */
+	lfp = AllocateFile(BACKUP_LABEL_FILE, "r");
+	if (lfp == NULL)
+	{
+		if (errno != ENOENT)
+			ereport(ERROR,
+					(errcode_for_file_access(),
+					 errmsg("could not read file \"%s\": %m",
+							BACKUP_LABEL_FILE)));
+		PG_RETURN_NULL();
+	}
+
+        /*
+         * Parse the file to find the the START TIME line.
+         */
+	backup_start_time[0] = '\0';
+        while (fgets(fline, sizeof(fline), lfp) != NULL)
+        {
+		if (sscanf(fline, "START TIME: %25[^\n]\n", backup_start_time) == 1)
+			break;
+	}
+
+	/*
+	 * Close the backup label file.
+	 */
+	if (ferror(lfp) || FreeFile(lfp)) {
+		ereport(ERROR,
+				(errcode_for_file_access(),
+				 errmsg("could not read file \"%s\": %m",
+						BACKUP_LABEL_FILE)));
+	}
+
+	if (strlen(backup_start_time) == 0) {
+		ereport(ERROR,
+			(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+			 errmsg("invalid data in file \"%s\"", BACKUP_LABEL_FILE)));
+	}
+
+	/*
+	 * Convert the time string read from file to TimestampTz form.
+	 */
+	xtime = DatumGetTimestampTz(
+		DirectFunctionCall3(timestamptz_in, CStringGetDatum(backup_start_time),
+			ObjectIdGetDatum(InvalidOid),Int32GetDatum(-1))
+	);
+
+
+	PG_RETURN_TIMESTAMPTZ(xtime);
+}
+
diff -ru postgresql/src/include/access/xlog_internal.h postgresql-exclusive_backup_start_time-patch/src/include/access/xlog_internal.h
--- postgresql/src/include/access/xlog_internal.h	2012-01-26 23:01:32.332613398 +0100
+++ postgresql-exclusive_backup_start_time-patch/src/include/access/xlog_internal.h	2012-03-02 11:04:48.378486777 +0100
@@ -281,5 +281,6 @@
 extern Datum pg_xlog_replay_pause(PG_FUNCTION_ARGS);
 extern Datum pg_xlog_replay_resume(PG_FUNCTION_ARGS);
 extern Datum pg_is_xlog_replay_paused(PG_FUNCTION_ARGS);
+extern Datum pg_exclusive_backup_start_time(PG_FUNCTION_ARGS);
 
 #endif   /* XLOG_INTERNAL_H */
diff -ru postgresql/src/include/catalog/pg_proc.h postgresql-exclusive_backup_start_time-patch/src/include/catalog/pg_proc.h
--- postgresql/src/include/catalog/pg_proc.h	2012-01-26 23:01:32.340613398 +0100
+++ postgresql-exclusive_backup_start_time-patch/src/include/catalog/pg_proc.h	2012-03-02 11:02:45.346486836 +0100
@@ -2899,6 +2899,8 @@
 DESCR("prepare for taking an online backup");
 DATA(insert OID = 2173 ( pg_stop_backup			PGNSP PGUID 12 1 0 0 0 f f f t f v 0 0 25 "" _null_ _null_ _null_ _null_ pg_stop_backup _null_ _null_ _null_ ));
 DESCR("finish taking an online backup");
+DATA(insert OID = 3882 (  pg_exclusive_backup_start_time		PGNSP PGUID 12 1 0 0 0 f f f t f s 0 0 1184 "" _null_ _null_ _null_ _null_ pg_exclusive_backup_start_time _null_ _null_ _null_ ));
+DESCR("start time of an online backup");
 DATA(insert OID = 2848 ( pg_switch_xlog			PGNSP PGUID 12 1 0 0 0 f f f t f v 0 0 25 "" _null_ _null_ _null_ _null_ pg_switch_xlog _null_ _null_ _null_ ));
 DESCR("switch to new xlog file");
 DATA(insert OID = 3098 ( pg_create_restore_point	PGNSP PGUID 12 1 0 0 0 f f f t f v 1 0 25 "25" _null_ _null_ _null_ _null_ pg_create_restore_point _null_ _null_ _null_ ));