[Pgpool-hackers] Reload does not help if password file changed

[Gurjeet Singh]

Hi,

    Maybe this is expected behaviour, but it definitely is not desirable. If
we add a new user:passwrod to the contents of pool_passwd file and send a
reload signal to pgpool, the child processes are still not able to honor the
new user and the trying to login using the new user causes error "MD5
authentication failed..."

    I have diagnosed it back to the fact that pgpool uses stdio.h interface
(FILE *) to access the pool_passwd file, and it reads the contents of the
file for every new login that requests MD5 authentication. The problem with
the stdio.h interface is that it caches the contents of the file and it does
not refresh the cache even when the contents of the file change on-disk, so
every time pgpool tries to read new user's password it does not see the new
entry and hence fails.

    To be able to connect as the new user we have to either restart pgpool
or wait for a new child to be forked which will see the new contents of the
file. All of these problems also apply to the case where we might alter the
password of an existing user and update the md5 password in pool_passwd
file.

    I have attached a minimal patch to address this issue. In the patch, we
save the file path that was initially used to open the pool_passwd and upon
every reload the child closes and reopens the file so that the stdio.h
interface does not show it cached data.

Regards,
-- 
Gurjeet Singh
EnterpriseDB Corporation
The Enterprise PostgreSQL Company
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://pgfoundry.org/pipermail/pgpool-hackers/attachments/20110926/df1d902f/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: pgpool_passwd_reload.patch
Type: text/x-diff
Size: 1587 bytes
Desc: not available
URL: <http://pgfoundry.org/pipermail/pgpool-hackers/attachments/20110926/df1d902f/attachment.bin>