INIT

build/env.js

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+import process from 'node:process';
+
+/* global "" */
+
+const expected = new Set([
+	'SOCKET_PATH',
+	'HOST',
+	'PORT',
+	'ORIGIN',
+	'XFF_DEPTH',
+	'ADDRESS_HEADER',
+	'PROTOCOL_HEADER',
+	'HOST_HEADER',
+	'PORT_HEADER',
+	'BODY_SIZE_LIMIT',
+	'SHUTDOWN_TIMEOUT',
+	'IDLE_TIMEOUT',
+	'KEEP_ALIVE_TIMEOUT',
+	'HEADERS_TIMEOUT'
+]);
+
+const expected_unprefixed = new Set(['LISTEN_PID', 'LISTEN_FDS']);
+
+if ("") {
+	for (const name in process.env) {
+		if (name.startsWith("")) {
+			const unprefixed = name.slice("".length);
+			if (!expected.has(unprefixed)) {
+				throw new Error(
+					`You should change envPrefix (${""}) to avoid conflicts with existing environment variables — unexpectedly saw ${name}`
+				);
+			}
+		}
+	}
+}
+
+/**
+ * @param {string} name
+ * @param {any} fallback
+ */
+function env(name, fallback) {
+	const prefix = expected_unprefixed.has(name) ? '' : "";
+	const prefixed = prefix + name;
+	return prefixed in process.env ? process.env[prefixed] : fallback;
+}
+
+const integer_regexp = /^\d+$/;
+
+/**
+ * Throw a consistently-structured parsing error for environment variables.
+ * @param {string} name
+ * @param {any} value
+ * @param {string} description
+ * @returns {never}
+ */
+function parsing_error(name, value, description) {
+	throw new Error(
+		`Invalid value for environment variable ${name}: ${JSON.stringify(value)} (${description})`
+	);
+}
+
+/**
+ * Check the environment for a timeout value (non-negative integer) in seconds.
+ * @param {string} name
+ * @param {number} [fallback]
+ * @returns {number | undefined}
+ */
+function timeout_env(name, fallback) {
+	const raw = env(name, fallback);
+	if (!raw) {
+		return fallback;
+	}
+
+	if (!integer_regexp.test(raw)) {
+		parsing_error(name, raw, 'should be a non-negative integer');
+	}
+
+	const parsed = Number.parseInt(raw, 10);
+
+	// We don't technically need to check `Number.isNaN` because the value already passed the regexp test.
+	// However, just in case there's some new codepath introduced somewhere down the line, it's probably good
+	// to stick this in here.
+	if (Number.isNaN(parsed)) {
+		parsing_error(name, raw, 'should be a non-negative integer');
+	}
+
+	if (parsed < 0) {
+		parsing_error(name, raw, 'should be a non-negative integer');
+	}
+
+	return parsed;
+}
+
+export { env, timeout_env };