src: allow inspector to be run on ephemeral port

src/node_debug_options.cc

@@ -22,7 +22,8 @@ int parse_and_validate_port(const std::string& port) {
   char* endptr;
   errno = 0;
   const long result = strtol(port.c_str(), &endptr, 10);  // NOLINT(runtime/int)
-  if (errno != 0 || *endptr != '\0'|| result < 1024 || result > 65535) {
+  if (errno != 0 || *endptr != '\0' ||
+     (result != 0 && (result < 1024 || result > 65535))) {
     fprintf(stderr, "Debug port must be in range 1024 to 65535.\n");
     exit(12);
   }

test/parallel/test-inspector-ephemeral-port.js

@@ -0,0 +1,23 @@
+'use strict';
+const common = require('../common');
+common.skipIfInspectorDisabled();
+
+// Check that inspector can run on an ephemeral port.
+
+const assert = require('assert');
+const exec = require('child_process').exec;
+
+const printA = require.resolve('../fixtures/printA.js');
+const cmd = [
+  process.execPath,
+  '--inspect=0',
+  printA,
+].join(' ');
+
+exec(cmd, common.mustCall(function(err, _, stderr) {
+  assert.ifError(err);
+  const port1 = Number(stderr.match(/Debugger listening on port (\d+)/)[1]);
+  const port2 = Number(stderr.match(/chrome-devtools.*:(\d+)/)[1]);
+  assert.strictEqual(port1, port2);
+  assert(port1 > 0);
+}));