Merge #14057: [Logging] Only log "Using config file PATH_TO_bitcoin.conf" message on startup if conf file exists

946107a Only log "Using PATH_TO_bitcoin.conf" message on startup if conf file exists. (Alexander Leishman)

Pull request description:

  Currently we log a message indicating that a bitcoin.conf file is being used even if one does not exist. This PR changes the logic to:

  **If config file does not exist and no -conf flag passed, log:**
  `Config file: FILE_PATH (not found, skipping)`. Where `FILE_PATH` is the default or the path passed in with the `-conf` flag.

  **If config file does not exist and -conf flag passed with incorrect path, log warning:**
  `Warning: The specified config file FILE_PATH does not exist`

  **If config file exists, log**:
  `Config file: FILE_PATH`

  Note: This is a (modified) subset of changes introduced in bitcoin/bitcoin#13761 which creates a default example config file. I think it makes sense to extract this small bit out into a separate PR.

Tree-SHA512: be0f0ae6a0c9041e2d6acb54d2563bbcc79786fb2f8bf9a963fe01bc54cd4e388b89079fde1eb79f7f17099776428e5e984bf7107590a3d1ecfc0562dbc6e3f5

Author: laanwj

src/init.cpp

@@ -1245,7 +1245,19 @@ bool AppInitMain()
         LogPrintf("Startup time: %s\n", FormatISO8601DateTime(GetTime()));
     LogPrintf("Default data directory %s\n", GetDefaultDataDir().string());
     LogPrintf("Using data directory %s\n", GetDataDir().string());
-    LogPrintf("Using config file %s\n", GetConfigFile(gArgs.GetArg("-conf", BITCOIN_CONF_FILENAME)).string());
+
+    // Only log conf file usage message if conf file actually exists.
+    fs::path config_file_path = GetConfigFile(gArgs.GetArg("-conf", BITCOIN_CONF_FILENAME));
+    if (fs::exists(config_file_path)) {
+        LogPrintf("Config file: %s\n", config_file_path.string());
+    } else if (gArgs.IsArgSet("-conf")) {
+        // Warn if no conf file exists at path provided by user
+        InitWarning(strprintf(_("The specified config file %s does not exist\n"), config_file_path.string()));
+    } else {
+        // Not categorizing as "Warning" because it's the default behavior
+        LogPrintf("Config file: %s (not found, skipping)\n", config_file_path.string());
+    }
+
     LogPrintf("Using at most %i automatic connections (%i file descriptors available)\n", nMaxConnections, nFD);
 
     // Warn about relative -datadir path.