Merge pull request #214 from dAdAbird/xlog_key_mgmt

Add key management for WAL

Make the *.map *.dat processing code aware of custom databases and
table spaces

Add XLog GUC and init the keyring based on that. Only FS for now

Make the internal/external key infrastructure work with custom
(not stored in the database) keyrings.

Check and create an internal key for XLog during the server start.
If the key is created (not the first start with the EncryptWAL), then
upload it into the cache. We can't read the key from files while
writing the XLog to the disk as it happens in the critical section and
no palloc is allowed.

Create a custom cache for the global catalog external key as we can't
use PG's hashmap during the (again, no pallocs in critical section).

During the server start, when pg_tde module is loading and it needs to
read *.map, *.dat file, InitFileAccess is yet to be called, hence Vfd
isn't ready to use. The same gonna happen during recovery. So use raw
pread/pwrite calls istead.

Makefile.in

@@ -40,6 +40,7 @@ src/keyring/keyring_curl.o \
 src/keyring/keyring_file.o \
 src/keyring/keyring_vault.o \
 src/keyring/keyring_api.o \
+src/catalog/tde_global_catalog.o \
 src/catalog/tde_keyring.o \
 src/catalog/tde_master_key.o \
 src/common/pg_tde_shmem.o \

meson.build

@@ -40,6 +40,7 @@ pg_tde_sources = files(
 
         'src/smgr/pg_tde_smgr.c',
 
+        'src/catalog/tde_global_catalog.c',
         'src/catalog/tde_keyring.c',
         'src/catalog/tde_master_key.c',
         'src/common/pg_tde_shmem.c',