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

robertmhaas · robertmhaas · commit a08bfe742492 · 2020-04-27T14:00:36.000-04:00
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
@@ -1131,7 +1131,12 @@ ReceiveTarFile(PGconn *conn, PGresult *res, int rownum)
 									time(NULL));
 
 					WRITE_TAR_DATA(header, sizeof(header));
-					WRITE_TAR_DATA(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
`@@ -1131,7 +1131,12 @@ ReceiveTarFile(PGconn conn, PGresult res, int rownum)`
`1131`	`1131`	`time(NULL));`
`1132`	`1132`
`1133`	`1133`	`WRITE_TAR_DATA(header, sizeof(header));`
`1134`		`- WRITE_TAR_DATA(zerobuf, 511);`
	`1134`	`+`
	`1135`	`+ /*`
	`1136`	`+ * we don't need to pad out to a multiple of the tar block`
	`1137`	`+ * size here, because the file is zero length, which is a`
	`1138`	`+ * multiple of any block size.`
	`1139`	`+ */`
`1135`	`1140`	`}`
`1136`	`1141`	`}`
`1137`	`1142`