postgresql_set - Fix GUC_LIST_QUOTE parameters

[RealGreenDragon]

SUMMARY

My PR fixes GUC_LIST_QUOTE parameters management in postgresql_set module.

GUC_LIST_QUOTE parameters are multi-value parameters (like GUC_LIST_INPUT parameters) whose elements are surrounded by double-quotes if not match ^[A-Za-z09_]+$ pattern.
Now such double-quotes are ignored by postgresql_set module and it causes an always-changed status in these cases. It is a very serious bug if the parameter is a postmaster, as unix_socket_directories (it became GUC_LIST_QUOTE in PostgreSQL 14).
The bug has not seen until now as GUC_LIST_QUOTE parameters are few and many of them have not valid values that contain special characters (as shared_preload_libraries parameter).

Examples:

#### PostgreSQL 13

pg13=# ALTER SYSTEM SET unix_socket_directories = '/var/run/postgresql';
ALTER SYSTEM

postgres@pg13:~$ grep unix_socket_directories postgresql.auto.conf 
unix_socket_directories = '/var/run/postgresql'

pg13=# ALTER SYSTEM SET unix_socket_directories = '/var/run/postgresql,/tmp'; --> NEVER DONE FROM PR #357 
ALTER SYSTEM

postgres@pg13:~$ grep unix_socket_directories postgresql.auto.conf 
unix_socket_directories = '/var/run/postgresql,/tmp' --> RIGHT BUT NOW NEVER OBTAINED (AS CONSIDERED MULTI_VALUE)

pg13=# ALTER SYSTEM SET unix_socket_directories = '/var/run/postgresql','/tmp';
ERROR:  SET unix_socket_directories takes only one argument

#### PostgreSQL 14

pg14=# ALTER SYSTEM SET unix_socket_directories = '/var/run/postgresql';
ALTER SYSTEM

postgres@pg14:~$ grep unix_socket_directories postgresql.auto.conf 
unix_socket_directories = '"/var/run/postgresql"'

pg13=# ALTER SYSTEM SET unix_socket_directories = '/var/run/postgresql,/tmp'; --> NEVER DONE FROM PR #357 
ALTER SYSTEM

postgres@pg13:~$ grep unix_socket_directories postgresql.auto.conf 
unix_socket_directories = '"/var/run/postgresql,/tmp"' --> WRONG (SO CORRECT BEHAVIOR)

pg14=# ALTER SYSTEM SET unix_socket_directories = '/var/run/postgresql','/tmp';
ALTER SYSTEM

postgres@pg14:~$ grep unix_socket_directories postgresql.auto.conf
unix_socket_directories = '"/var/run/postgresql", "/tmp"'

To solve the bug the only way is to hard-code GUC_LIST_QUOTE parameters list in the code (very short and static in the time) as there is no way to distinguish the case in with a parameter value need an unquote or not (specially with values composed by a single elements). The same approach is applied in pg_dump code (variable_is_guc_list_quote function).

Hard-code also the list of GUC_LIST_INPUT parameters is expensive and for now (I think) not necessary. However I added a check to not consider multi-value unix_socket_directories parameter until PostgreSQL 13, as only from PostgreSQL 14 GUC_LIST_INPUT and GUC_LIST_QUOTE options are added to that parameter.

In test added there is also a general idempotence check after a reboot (as unix_socket_directories parameter is postmaster).

ISSUE TYPE

• Bugfix Pull Request

COMPONENT NAME

postgresql_set

ADDITIONAL INFORMATION

@ PostgreSQL 14 -> Add GUC_LIST_INPUT and GUC_LIST_QUOTE to unix_socket_directories
postgres/postgres@a05dbf4

@ List of GUC params (PostgreSQL 15 only)
https://github.com/postgres/postgres/blob/5edf438eeb00271cca5d19d0ea10a2d6e8d018c4/src/backend/utils/misc/guc_tables.c

@ Fixed list of GUC_LIST_QUOTE params in each supported major version (variable_is_guc_list_quote function)
15 -> https://github.com/postgres/postgres/blob/8382864eb5c9f9ebe962ac20b3392be5ae304d23/src/bin/pg_dump/dumputils.c#L689
14 -> https://github.com/postgres/postgres/blob/b6cf730e80e8571066c0ce76e76ce99b9144c149/src/bin/pg_dump/dumputils.c#L849
13 -> https://github.com/postgres/postgres/blob/2faab87390b03929a8cbb5a9336a04faa45a27c5/src/bin/pg_dump/dumputils.c#L849
12 -> https://github.com/postgres/postgres/blob/117dd58fd9cd01e661a2c36977e16a2722306a6d/src/bin/pg_dump/dumputils.c#L849
11 -> https://github.com/postgres/postgres/blob/f96e531b1c079ae148b927a204845c7150a573f8/src/bin/pg_dump/dumputils.c#L849
10 -> https://github.com/postgres/postgres/blob/02991e79f8f58bc208f05dcc8af0c62dbe0a6ea4/src/bin/pg_dump/dumputils.c#L846
9.6 -> https://github.com/postgres/postgres/blob/a4116b8d5a4f68803452d8f1aa3f74f302049a90/src/bin/pg_dump/dumputils.c#L853
9.5 -> https://github.com/postgres/postgres/blob/202c587e2f28bc295f6935d044e20680b627e7a1/src/bin/pg_dump/dumputils.c#L1536
9.4 -> https://github.com/postgres/postgres/blob/30ffdd24d7222bc01183a56d536c236240674516/src/bin/pg_dump/dumputils.c#L1537

@ GUC_LIST_QUOTE element quote function (quote_identifier function - PostgreSQL 15 only)
https://github.com/postgres/postgres/blob/master/src/backend/utils/adt/ruleutils.c#L11930

@ GUC_LIST_INPUT/GUC_LIST_QUOTE elements split function (SplitGUCList function - PostgreSQL 15 only)
https://github.com/postgres/postgres/blob/6ee01e25b7f79bdf835d12927b306ad922c55fd3/src/backend/utils/adt/varlena.c#L3702

[RealGreenDragon]

Ready for review

[RealGreenDragon]

@hunleyd Change done, now ansible/third-party-check fails but I don't know why (seems it fails also for all other PRs)

[Andersson007]

@RealGreenDragon thanks for the contribution!
@hunleyd @jchancojr thanks for reviewing and merging!