Incorrect fsync handling in pg_basebackup's tar_finish

Hi all,

I was just looking at the code of pg_basebackup, and noticed that we
don't actually check if the two last empty blocks of any tar file
produced are correctly fsync'd or not:
@@ -957,7 +957,10 @@ tar_finish(void)

/* sync the empty blocks as well, since they're after the last file */
if (tar_data->sync)
- fsync(tar_data->fd);
+ {
+ if (fsync(tar_data->fd) != 0)
+ return false;
+ }

That looks incorrect to me, hence shouldn't something like the attached
be done? Magnus and others, any opinions?

Thanks,
--
Michael