Fix bogus tar-file padding logic for standby.signal.

robertmhaas · robertmhaas · commit 0278d3f79a30 · 2020-04-27T13:04:35.000-04:00
When pg_basebackup -R is used, we inject standby.signal into the tar file for the main tablespace. The proper thing to do is to pad each file injected into the tar file out to a 512-byte boundary by appending nulls, but here the file is of length 0 and we add 511 zero bytes. Since 0 is already a multiple of 512, we should not add any zero bytes. Do that instead. Patch by me, reviewed by Tom Lane. Discussion: http://postgr.es/m/CA+TgmobWbfReO9-XFk8urR1K4wTNwqoHx_v56t7=T8KaiEoKNw@mail.gmail.com
diff --git a/src/bin/pg_basebackup/pg_basebackup.c b/src/bin/pg_basebackup/pg_basebackup.c
@@ -1207,7 +1207,12 @@ ReceiveTarFile(PGconn *conn, PGresult *res, int rownum)
 							time(NULL));
 
 			writeTarData(&state, header, sizeof(header));
-			writeTarData(&state, zerobuf, 511);
+
+			/*
+			 * we don't need to pad out to a multiple of the tar block size
+			 * here, because the file is zero length, which is a multiple of
+			 * any block size.
+			 */
 		}
 	}
 

Original file line number	Diff line number	Diff line change
`@@ -1207,7 +1207,12 @@ ReceiveTarFile(PGconn conn, PGresult res, int rownum)`
`1207`	`1207`	`time(NULL));`
`1208`	`1208`
`1209`	`1209`	`writeTarData(&state, header, sizeof(header));`
`1210`		`- writeTarData(&state, zerobuf, 511);`
	`1210`	`+`
	`1211`	`+ /*`
	`1212`	`+ * we don't need to pad out to a multiple of the tar block size`
	`1213`	`+ * here, because the file is zero length, which is a multiple of`
	`1214`	`+ * any block size.`
	`1215`	`+ */`
`1211`	`1216`	`}`
`1212`	`1217`	`}`
`1213`	`1218`