From 1c1812df057f6fa58c7c73f2a3409c81093d0d85 Mon Sep 17 00:00:00 2001
From: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date: Mon, 22 Mar 2021 11:39:29 +0200
Subject: [PATCH] Fix decoding WAL segment header

---
 src/waldecoder.rs | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/waldecoder.rs b/src/waldecoder.rs
index fb6c8e8cf1..05ff4ba9eb 100644
--- a/src/waldecoder.rs
+++ b/src/waldecoder.rs
@@ -8,6 +8,8 @@ use bytes::{Buf, BufMut, Bytes, BytesMut};
 
 use std::cmp::min;
 
+use log::*;
+
 const XLOG_BLCKSZ: u32 = 8192;
 
 // FIXME: this is configurable in PostgreSQL, 16 MB is the default
@@ -17,6 +19,7 @@ const WAL_SEGMENT_SIZE: u64 = 16*1024*1024;
 // From PostgreSQL headers
 
 #[repr(C)]
+#[derive(Debug)]
 struct XLogPageHeaderData
 {
     xlp_magic: u16,		/* magic value for correctness checks */
@@ -31,6 +34,7 @@ struct XLogPageHeaderData
 const SizeOfXLogShortPHD: usize = 2+2+4+8+4 + 4;
 
 #[repr(C)]
+#[derive(Debug)]
 struct XLogLongPageHeaderData
 {
     std: XLogPageHeaderData,	/* standard header fields */
@@ -209,9 +213,9 @@ impl WalStreamDecoder {
 
         let hdr : XLogLongPageHeaderData = XLogLongPageHeaderData {
             std: self.decode_XLogPageHeaderData(),
-            xlp_sysid: self.recordbuf.get_u64_le(),
-            xlp_seg_size: self.recordbuf.get_u32_le(),
-            xlp_xlog_blcksz: self.recordbuf.get_u32_le(),
+            xlp_sysid: self.inputbuf.get_u64_le(),
+            xlp_seg_size: self.inputbuf.get_u32_le(),
+            xlp_xlog_blcksz: self.inputbuf.get_u32_le(),
         };
 
         return hdr;
@@ -289,6 +293,8 @@ pub struct DecodedWALRecord {
 //
 pub fn decode_wal_record(lsn: u64, rec: Bytes) -> DecodedWALRecord {
 
+    trace!("decoding record at {:08X}/{:08X} ({} bytes)", lsn >> 32, lsn & 0xffff_ffff, rec.remaining());
+
     let mut buf = rec.clone();
 
     // FIXME: assume little-endian here