On my Linux Mint 19.1:
```bash
$ umask
0022
```

After the first run of `bitcoin-qt -sysperm=false` the `0700` permissions are expected for both the datadir (`~/.bitcoin`) and the walletdir (`~/.bitcoin/wallets`).

Actually, the directories are created with such access permissions:
```bash
$ stat ~/.bitcoin | grep Uid
Access: (0755/drwxr-xr-x)  Uid: ( 1000/ hebasto)   Gid: ( 1000/ hebasto)
$ stat ~/.bitcoin/wallets | grep Uid
Access: (0755/drwxr-xr-x)  Uid: ( 1000/ hebasto)   Gid: ( 1000/ hebasto)
```

Refs:
- #4286
- #13371
- #13389

NOTE: reading through the initial PR #4286 makes me think it was controversial. Is it a better and simpler way to just get rid of `-sysperm` option? I believe a user who needs this option can easily run `chown` command.
{
    static Mutex g_shutdown_mutex;
    TRY_LOCK(g_shutdown_mutex, lock_shutdown);
    if (!lock_shutdown) return;
    LogPrintf("%s: In progress...\n", __func__);
    Assert(node.args);
    
    
    
    
    util::ThreadRename("shutoff");
    if (node.mempool) node.mempool->AddTransactionsUpdated(1);
    StopHTTPRPC();
    StopREST();
    StopRPC();
    StopHTTPServer();
    for (const auto& client : node.chain_clients) {
        client->flush();
    }
    StopMapPort();
    
    
    if (node.peerman) UnregisterValidationInterface(node.peerman.get());