pg_wal_blocks: Fix compilation with v11

The WAL segment size is something that can be customized at initialization
time in v11, and was previously decided at compilation time. This makes the
module able to work with a default segment size of 16MB. In order to
support more sizes, the segment size needs to be passed as an argument.

pg_wal_blocks/pg_wal_blocks.c

@@ -24,6 +24,7 @@ const char *progname;
 /* Global parameters */
 static bool verbose = false;
 static char *full_path = NULL;
+static uint32 WalSegSz = DEFAULT_XLOG_SEG_SIZE;	/* should be settable */
 /* Data regarding input WAL to parse */
 static XLogSegNo segno = 0;
@@ -94,7 +95,7 @@ XLogReadPageBlock(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 		(XLogReadBlockPrivate *) xlogreader->private_data;
 	uint32      targetPageOff;
-	targetPageOff = targetPagePtr % XLogSegSize;
+	targetPageOff = targetPagePtr % WalSegSz;
 	if (xlogreadfd < 0)
 	{
@@ -181,8 +182,8 @@ do_wal_parsing(void)
 	private.full_path = full_path;
 	/* Set the first record to look at */
-	XLogSegNoOffsetToRecPtr(segno, 0, first_record);
-	xlogreader = XLogReaderAllocate(XLogReadPageBlock, &private);
+	XLogSegNoOffsetToRecPtr(segno, 0, first_record, WalSegSz);
+	xlogreader = XLogReaderAllocate(WalSegSz, XLogReadPageBlock, &private);
 	first_record = XLogFindNextRecord(xlogreader, first_record);
 	/* Loop through all the records */
@@ -285,7 +286,7 @@ main(int argc, char **argv)
 		close(fd);
 		/* parse timeline and segment number from file name */
-		XLogFromFileName(fname, &timeline_id, &segno);
+		XLogFromFileName(fname, &timeline_id, &segno, WalSegSz);
 	}
 	if (full_path == NULL)