1 files changed, 121 insertions, 0 deletions
diff --git a/ext/node/polyfills/internal/util/debuglog.ts b/ext/node/polyfills/internal/util/debuglog.ts
new file mode 100644
index 000000000..498facbd1
--- /dev/null
+++ b/ext/node/polyfills/internal/util/debuglog.ts
@@ -0,0 +1,121 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+// Copyright Joyent and Node contributors. All rights reserved. MIT license.
+import { inspect } from "internal:deno_node/polyfills/internal/util/inspect.mjs";
+
+// `debugImpls` and `testEnabled` are deliberately not initialized so any call
+// to `debuglog()` before `initializeDebugEnv()` is called will throw.
+let debugImpls: Record<string, (...args: unknown[]) => void>;
+let testEnabled: (str: string) => boolean;
+
+// `debugEnv` is initial value of process.env.NODE_DEBUG
+function initializeDebugEnv(debugEnv: string) {
+  debugImpls = Object.create(null);
+  if (debugEnv) {
+    // This is run before any user code, it's OK not to use primordials.
+    debugEnv = debugEnv.replace(/[|\\{}()[\]^$+?.]/g, "\\$&")
+      .replaceAll("*", ".*")
+      .replaceAll(",", "$|^");
+    const debugEnvRegex = new RegExp(`^${debugEnv}$`, "i");
+    testEnabled = (str) => debugEnvRegex.exec(str) !== null;
+  } else {
+    testEnabled = () => false;
+  }
+}
+
+// Emits warning when user sets
+// NODE_DEBUG=http or NODE_DEBUG=http2.
+function emitWarningIfNeeded(set: string) {
+  if ("HTTP" === set || "HTTP2" === set) {
+    console.warn(
+      "Setting the NODE_DEBUG environment variable " +
+        "to '" + set.toLowerCase() + "' can expose sensitive " +
+        "data (such as passwords, tokens and authentication headers) " +
+        "in the resulting log.",
+    );
+  }
+}
+
+const noop = () => {};
+
+function debuglogImpl(
+  enabled: boolean,
+  set: string,
+): (...args: unknown[]) => void {
+  if (debugImpls[set] === undefined) {
+    if (enabled) {
+      emitWarningIfNeeded(set);
+      debugImpls[set] = function debug(...args: unknown[]) {
+        const msg = args.map((arg) => inspect(arg)).join(" ");
+        console.error("%s %s: %s", set, String(Deno.pid), msg);
+      };
+    } else {
+      debugImpls[set] = noop;
+    }
+  }
+
+  return debugImpls[set];
+}
+
+// debuglogImpl depends on process.pid and process.env.NODE_DEBUG,
+// so it needs to be called lazily in top scopes of internal modules
+// that may be loaded before these run time states are allowed to
+// be accessed.
+export function debuglog(
+  set: string,
+  cb?: (debug: (...args: unknown[]) => void) => void,
+) {
+  function init() {
+    set = set.toUpperCase();
+    enabled = testEnabled(set);
+  }
+
+  let debug = (...args: unknown[]): void => {
+    init();
+    // Only invokes debuglogImpl() when the debug function is
+    // called for the first time.
+    debug = debuglogImpl(enabled, set);
+
+    if (typeof cb === "function") {
+      cb(debug);
+    }
+
+    return debug(...args);
+  };
+
+  let enabled: boolean;
+  let test = () => {
+    init();
+    test = () => enabled;
+    return enabled;
+  };
+
+  const logger = (...args: unknown[]) => debug(...args);
+
+  Object.defineProperty(logger, "enabled", {
+    get() {
+      return test();
+    },
+    configurable: true,
+    enumerable: true,
+  });
+
+  return logger;
+}
+
+let debugEnv;
+/* TODO(kt3k): enable initializing debugEnv.
+It's not possible to access env var when snapshotting.
+
+try {
+  debugEnv = Deno.env.get("NODE_DEBUG") ?? "";
+} catch (error) {
+  if (error instanceof Deno.errors.PermissionDenied) {
+    debugEnv = "";
+  } else {
+    throw error;
+  }
+}
+*/
+initializeDebugEnv(debugEnv);
+
+export default { debuglog };