Avoid runtime failure in CopyXLogRecordToWAL with sanitizers (cf. 46ab07f) (#554)

alexanderlaw · lubennikovaav · commit 2947fb798f79 · 2025-05-09T16:14:06.000+01:00
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
@@ -1348,7 +1348,8 @@ CopyXLogRecordToWAL(int write_len, bool isLogSwitch, XLogRecData *rdata,
 		}
 
 		Assert(CurrPos % XLOG_BLCKSZ >= SizeOfXLogShortPHD || rdata_len == 0);
-		memcpy(currpos, rdata_data, rdata_len);
+		if (rdata_len > 0)
+			memcpy(currpos, rdata_data, rdata_len);
 		currpos += rdata_len;
 		CurrPos += rdata_len;
 		freespace -= rdata_len;

Original file line number	Diff line number	Diff line change
`@@ -1348,7 +1348,8 @@ CopyXLogRecordToWAL(int write_len, bool isLogSwitch, XLogRecData *rdata,`
`1348`	`1348`	`}`
`1349`	`1349`
`1350`	`1350`	`Assert(CurrPos % XLOG_BLCKSZ >= SizeOfXLogShortPHD \|\| rdata_len == 0);`
`1351`		`- memcpy(currpos, rdata_data, rdata_len);`
	`1351`	`+ if (rdata_len > 0)`
	`1352`	`+ memcpy(currpos, rdata_data, rdata_len);`
`1352`	`1353`	`currpos += rdata_len;`
`1353`	`1354`	`CurrPos += rdata_len;`
`1354`	`1355`	`freespace -= rdata_len;`