Entering a blank password causes infinite loop

[egashira-yusuke]

pg_repack hangs when entering an empty or blank string at the password prompt of pg_repack.
It does not return until interrupt with Ctrl+C.
Also, during this, pg_repack is continuously trying to connect to the database.
This causes outputting a large amount of connection log if log_connections=on was specified in the database.
I found this problem in PostgreSQL 14.1 and pg_repack 1.4.7.

[Reproduce procedure]

1. Create a password authenticated user on the database.
2. Run pg_repack specifing 1.'s user. (Do not specify -w option)
3. When the password prompt appears, press Enter without entering anything or with entering only blank.

According to my research, this problem seems to start from #184.
In pgut_connect()'s connection loop, if PQconnectionNeedsPassword(conn) is true,
the password prompt is appeared by prompt_for_password() and it requires input of password.
prompt_for_password() remembers the password.
In pgut_connect(), the password obtained from prompt_for_password() is appended to the connection string as "password=%s" format.
Then, the connection string will end with "password=" because the entered password was empty string.
On the other hand, PostgreSQL Server seems to request the password again if the connection string ends with "password=".
Therefore, PQconnectionNeedsPassword(conn) is still true during reconnect loop of pgut_connect(), and it causes infinite loop.

[MichaelDBA]

Validated the hanging condition using v1.4.8 and PG version 14...

[andreasscherbaum]

Fixed in #354