MCP FS access fine tuning, with examples

mcp.allowed.example

+# Example MCP allowed-config file.
+# Point -Delphel.mcp.allowed.configfile to this file.
+# You can set either allowed.configdir or allowed.config.
+#
+# allowed.configdir=/media/elphel/btrfs-data/lwir16-proc/NC/config
+# allowed.config=/media/elphel/btrfs-data/lwir16-proc/NC/config/MI184-v89-nc_site_30A-no_out.corr-xml

src/main/java/com/elphel/imagej/mcp/McpFsAccess.java

@@ -17,11 +17,12 @@ import com.elphel.imagej.cameras.EyesisCorrectionParameters.CorrectionParameters
 public class McpFsAccess {
 	private static final String PROP_ALLOWED_CONFIG = "elphel.mcp.allowed.config";
 	private static final String PROP_ALLOWED_CONFIG_DIR = "elphel.mcp.allowed.configdir";
+	private static final String PROP_ALLOWED_CONFIG_FILE = "elphel.mcp.allowed.configfile";
 	private static final String PROP_ALLOWED_EXTRA = "elphel.mcp.allowed.extra";
 	private static final String CONFIG_LIST_KEY = "CORRECTION_PARAMETERS.sourceSequencesList";
 
 	private static List<Path> cachedRoots = null;
-	private static String cachedConfig = null;
+	private static String cachedConfigKey = null;
 	private static long cachedConfigMtime = -1L;
 
 	private McpFsAccess() {
@@ -30,16 +31,41 @@ public class McpFsAccess {
 	public static synchronized List<Path> getAllowedRoots() {
 		String configPath = System.getProperty(PROP_ALLOWED_CONFIG);
 		String configDir = System.getProperty(PROP_ALLOWED_CONFIG_DIR);
-		long mtime = getMtime(configPath, configDir);
-		if (cachedRoots != null && configEquals(configPath, cachedConfig) && mtime == cachedConfigMtime) {
+		String configFile = System.getProperty(PROP_ALLOWED_CONFIG_FILE);
+		String[] resolved = resolveConfigFromFile(configPath, configDir, configFile);
+		configPath = resolved[0];
+		configDir = resolved[1];
+		String cacheKey = buildCacheKey(configPath, configDir, configFile);
+		long mtime = getMtime(configPath, configDir, configFile);
+		if (cachedRoots != null && configEquals(cacheKey, cachedConfigKey) && mtime == cachedConfigMtime) {
 			return cachedRoots;
 		}
 		cachedRoots = buildAllowedRoots(configPath, configDir);
-		cachedConfig = configPath;
+		cachedConfigKey = cacheKey;
 		cachedConfigMtime = mtime;
 		return cachedRoots;
 	}
 
+	public static boolean hasConfig() {
+		String configPath = System.getProperty(PROP_ALLOWED_CONFIG);
+		String configDir = System.getProperty(PROP_ALLOWED_CONFIG_DIR);
+		String configFile = System.getProperty(PROP_ALLOWED_CONFIG_FILE);
+		String[] resolved = resolveConfigFromFile(configPath, configDir, configFile);
+		configPath = resolved[0];
+		configDir = resolved[1];
+		return (configPath != null && !configPath.trim().isEmpty())
+				|| (configDir != null && !configDir.trim().isEmpty());
+	}
+
+	public static void ensureConfigured() {
+		if (!hasConfig()) {
+			throw new IllegalStateException(
+					"MCP enabled but no allowed config specified. Set -Delphel.mcp.allowed.configdir "
+							+ "or -Delphel.mcp.allowed.config, or provide -Delphel.mcp.allowed.configfile "
+							+ "pointing to a file with allowed.configdir.");
+		}
+	}
+
 	public static boolean isAllowed(Path path) {
 		if (path == null) {
 			return false;
@@ -200,16 +226,17 @@ public class McpFsAccess {
 		return -1L;
 	}
 
-	private static long getMtime(String configPath) {
-		if (configPath == null || configPath.trim().isEmpty()) {
-			return -1L;
-		}
+	private static long getMtime(String configPath, String configDir, String configFile) {
+		long max = getMtime(configPath, configDir);
+		if (configFile != null && !configFile.trim().isEmpty()) {
 			try {
-			return Files.getLastModifiedTime(Paths.get(configPath)).toMillis();
+				max = Math.max(max, Files.getLastModifiedTime(Paths.get(configFile)).toMillis());
 			} catch (IOException e) {
-			return -1L;
+				// ignore
 			}
 		}
+		return max;
+	}
 
 	private static boolean configEquals(String a, String b) {
 		if (a == null && b == null) {
@@ -220,4 +247,58 @@ public class McpFsAccess {
 		}
 		return a.equals(b);
 	}
+
+	private static String buildCacheKey(String configPath, String configDir, String configFile) {
+		StringBuilder sb = new StringBuilder();
+		if (configPath != null) {
+			sb.append(configPath);
+		}
+		sb.append("|");
+		if (configDir != null) {
+			sb.append(configDir);
+		}
+		sb.append("|");
+		if (configFile != null) {
+			sb.append(configFile);
+		}
+		return sb.toString();
+	}
+
+	private static String[] resolveConfigFromFile(String configPath, String configDir, String configFile) {
+		if ((configPath != null && !configPath.trim().isEmpty())
+				|| (configDir != null && !configDir.trim().isEmpty())) {
+			return new String[] { configPath, configDir };
+		}
+		if (configFile == null || configFile.trim().isEmpty()) {
+			return new String[] { configPath, configDir };
+		}
+		Path filePath = Paths.get(configFile).toAbsolutePath().normalize();
+		if (!Files.exists(filePath)) {
+			return new String[] { configPath, configDir };
+		}
+		try {
+			List<String> lines = Files.readAllLines(filePath);
+			for (String line : lines) {
+				String trimmed = line.trim();
+				if (trimmed.isEmpty() || trimmed.startsWith("#")) {
+					continue;
+				}
+				int eq = trimmed.indexOf('=');
+				if (eq > 0) {
+					String key = trimmed.substring(0, eq).trim();
+					String value = trimmed.substring(eq + 1).trim();
+					if (key.equals(PROP_ALLOWED_CONFIG)) {
+						configPath = value;
+					} else if (key.equals(PROP_ALLOWED_CONFIG_DIR) || key.equals("allowed.configdir")) {
+						configDir = value;
+					}
+				} else if (configDir == null || configDir.trim().isEmpty()) {
+					configDir = trimmed;
+				}
+			}
+		} catch (IOException e) {
+			return new String[] { configPath, configDir };
+		}
+		return new String[] { configPath, configDir };
+	}
 }

src/main/java/com/elphel/imagej/mcp/McpServer.java

@@ -30,6 +30,7 @@ public class McpServer {
         if (INSTANCE != null) {
             return INSTANCE;
         }
+        McpFsAccess.ensureConfigured();
         McpServer instance = new McpServer(owner, port);
         instance.start();
         INSTANCE = instance;