Don't crash when pg_xlog is empty and pg_basebackup -x is used

The backup will not work (without a logarchive, and that's the whole
point of -x) in this case, this patch just changes it to throw an
error instead of crashing when this happens.

Noticed and diagnosed by TAKATSUKA Haruka

diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c
index 12b5e24cac505016b4bfa059117b94a91f91d333..ba8d173357e036e9d9242a2a4a9d640c59780318 100644 (file)
--- a/src/backend/replication/basebackup.c
+++ b/src/backend/replication/basebackup.c
@@ -303,6 +303,14 @@ perform_base_backup(basebackup_options *opt, DIR *tblspcdir)
                }
                qsort(walFiles, nWalFiles, sizeof(char *), compareWalFileNames);
 
+               /*
+                * There must be at least one xlog file in the pg_xlog directory,
+                * since we are doing backup-including-xlog.
+                */
+               if (nWalFiles < 1)
+                       ereport(ERROR,
+                                       (errmsg("could not find any WAL files")));
+
                /*
                 * Sanity check: the first and last segment should cover startptr and
                 * endptr, with no gaps in between.