Support configurable WAL segment size.

PostgreSQL 11 introduces configurable WAL segment sizes, from 1MB to 1GB.

There are two areas that needed to be updated to support this: building the archive-get queue and checking that WAL has been archived after a backup.  Both operations require the WAL segment size to properly build a list.

Checking the archive after a backup is still implemented in Perl and has an active database connection, so just get the WAL segment size from the database.

The archive-get command does not have a connection to the database, so get the WAL segment size from pg_control instead.  This requires a deeper inspection of pg_control than has been done in the past, so it seemed best to copy the relevant data structures from each version of PostgreSQL and build a generic interface layer to address them.  While this approach is a bit verbose, it has the advantage of being relatively simple, and can easily be updated for new versions of PostgreSQL.

Since the integration tests generate pg_control files for testing, teach Perl how to generate files with the correct offsets for both 32-bit and 64-bit architectures.

src/postgres/interface/v091.c

@@ -0,0 +1,81 @@
+/***********************************************************************************************************************************
+PostgreSQL 9.1 Interface
+***********************************************************************************************************************************/
+#include "common/debug.h"
+#include "common/log.h"
+#include "postgres/interface/v091.h"
+
+/***********************************************************************************************************************************
+Include PostgreSQL Types
+***********************************************************************************************************************************/
+#include "postgres/interface/v091.auto.c"
+
+/***********************************************************************************************************************************
+Is the control file for this version of PostgreSQL?
+***********************************************************************************************************************************/
+bool
+pgInterfaceIs091(const Buffer *controlFile)
+{
+    FUNCTION_TEST_BEGIN();
+        FUNCTION_TEST_PARAM(BUFFER, controlFile);
+
+        FUNCTION_TEST_ASSERT(controlFile != NULL);
+    FUNCTION_TEST_END();
+
+    ControlFileData *controlData = (ControlFileData *)bufPtr(controlFile);
+
+    FUNCTION_TEST_RESULT(
+        BOOL, controlData->pg_control_version == PG_CONTROL_VERSION && controlData->catalog_version_no == CATALOG_VERSION_NO);
+}
+
+/***********************************************************************************************************************************
+Get information from pg_control in a common format
+***********************************************************************************************************************************/
+PgControl
+pgInterfaceControl091(const Buffer *controlFile)
+{
+    FUNCTION_DEBUG_BEGIN(logLevelTrace);
+        FUNCTION_DEBUG_PARAM(BUFFER, controlFile);
+
+        FUNCTION_TEST_ASSERT(controlFile != NULL);
+        FUNCTION_TEST_ASSERT(pgInterfaceIs091(controlFile));
+    FUNCTION_DEBUG_END();
+
+    PgControl result = {0};
+    ControlFileData *controlData = (ControlFileData *)bufPtr(controlFile);
+
+    result.systemId = controlData->system_identifier;
+    result.controlVersion = controlData->pg_control_version;
+    result.catalogVersion = controlData->catalog_version_no;
+
+    result.pageSize = controlData->blcksz;
+    result.walSegmentSize = controlData->xlog_seg_size;
+
+    FUNCTION_DEBUG_RESULT(PG_CONTROL, result);
+}
+
+/***********************************************************************************************************************************
+Create pg_control for testing
+***********************************************************************************************************************************/
+#ifdef DEBUG
+
+void
+pgInterfaceControlTest091(PgControl pgControl, Buffer *buffer)
+{
+    FUNCTION_TEST_BEGIN();
+        FUNCTION_TEST_PARAM(PG_CONTROL, pgControl);
+    FUNCTION_TEST_END();
+
+    ControlFileData *controlData = (ControlFileData *)bufPtr(buffer);
+
+    controlData->system_identifier = pgControl.systemId;
+    controlData->pg_control_version = pgControl.controlVersion == 0 ? PG_CONTROL_VERSION : pgControl.controlVersion;
+    controlData->catalog_version_no = pgControl.catalogVersion == 0 ? CATALOG_VERSION_NO : pgControl.catalogVersion;
+
+    controlData->blcksz = pgControl.pageSize;
+    controlData->xlog_seg_size = pgControl.walSegmentSize;
+
+    FUNCTION_TEST_RESULT_VOID();
+}
+
+#endif