Refactor: pg_waldump: Move some declarations to new pg_waldump.h

This change prepares for a second source file in this directory to
support reading WAL from tar files. Common structures, declarations,
and functions are being exported through this include file so
they can be used in both files.

Author: amulsul

src/bin/pg_waldump/pg_waldump.c

@@ -29,6 +29,7 @@
 #include "common/logging.h"
 #include "common/relpath.h"
 #include "getopt_long.h"
+#include "pg_waldump.h"
 #include "rmgrdesc.h"
 #include "storage/bufpage.h"
 
@@ -39,19 +40,11 @@
 
 static const char *progname;
 
-static int	WalSegSz;
+int			WalSegSz = DEFAULT_XLOG_SEG_SIZE;
 static volatile sig_atomic_t time_to_stop = false;
 
 static const RelFileLocator emptyRelFileLocator = {0, 0, 0};
 
-typedef struct XLogDumpPrivate
-{
-	TimeLineID	timeline;
-	XLogRecPtr	startptr;
-	XLogRecPtr	endptr;
-	bool		endptr_reached;
-} XLogDumpPrivate;
-
 typedef struct XLogDumpConfig
 {
 	/* display options */

src/bin/pg_waldump/pg_waldump.h

@@ -0,0 +1,27 @@
+/*-------------------------------------------------------------------------
+ *
+ * pg_waldump.h - decode and display WAL
+ *
+ * Copyright (c) 2013-2025, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *		  src/bin/pg_waldump/pg_waldump.h
+ *-------------------------------------------------------------------------
+ */
+#ifndef PG_WALDUMP_H
+#define PG_WALDUMP_H
+
+#include "access/xlogdefs.h"
+
+extern int	WalSegSz;
+
+/* Contains the necessary information to drive WAL decoding */
+typedef struct XLogDumpPrivate
+{
+	TimeLineID	timeline;
+	XLogRecPtr	startptr;
+	XLogRecPtr	endptr;
+	bool		endptr_reached;
+} XLogDumpPrivate;
+
+#endif		/* end of PG_WALDUMP_H */