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

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
index faa69d14cebfabe371e16abb49d3ab6376ce576b..c1d3d8624bf324da367405fa5a03e5b7d4a4ccf8 100644 (file)
--- 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.
+                        */
                }
        }