Hi,
basebackup.c's code to read from files uses fread() and friends. This
is not great, because it's not documented to set errno. See commit
286af0ce12117bc673b97df6228d1a666594d247 and related discussion. It
seems like a better idea would be to use pg_pgread(), which not only
does set errno, but also lets us eliminate a bit of code that uses
fseek().
There are a couple of other things here that can also be improved. One
is that it seems like a good idea to set a wait event while doing I/O
here, as we do elsewhere. Another is that it seems like a good idea to
report short reads in a non-confusing, non-wrong sort of way. I here
adopted the convention previously mentioned in
http://postgr.es/m/20200128020303.GA1552@paquier.xyz
Patch, for v14, attached.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company