cli: accept /dev/stdin as input file on Linux

lib/module.js

@@ -195,6 +195,8 @@ Module._findPath = function(request, paths, isMain) {
         if (exts === undefined)
           exts = Object.keys(Module._extensions);
         filename = tryPackage(basePath, exts, isMain);
+      } else if (rc === 2) {
+        filename = basePath;
       }
 
       if (!filename) {

src/node_file.cc

@@ -546,7 +546,8 @@ static void InternalModuleReadFile(const FunctionCallbackInfo<Value>& args) {
 }
 
 // Used to speed up module loading.  Returns 0 if the path refers to
-// a file, 1 when it's a directory or < 0 on error (usually -ENOENT.)
+// a file, 1 when it's a directory, 2 when it's anything else, or < 0 on
+// error (usually -ENOENT.)
 // The speedup comes from not creating thousands of Stat and Error objects.
 static void InternalModuleStat(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
@@ -558,7 +559,14 @@ static void InternalModuleStat(const FunctionCallbackInfo<Value>& args) {
   int rc = uv_fs_stat(env->event_loop(), &req, *path, nullptr);
   if (rc == 0) {
     const uv_stat_t* const s = static_cast<const uv_stat_t*>(req.ptr);
-    rc = !!(s->st_mode & S_IFDIR);
+
+    if (s->st_mode & S_IFREG) {
+      rc = 0;
+    } else if (s->st_mode & S_IFDIR) {
+      rc = 1;
+    } else {
+      rc = 2;
+    }
   }
   uv_fs_req_cleanup(&req);
 

test/parallel/test-cli-arg-devstdin-posix.js

@@ -0,0 +1,23 @@
+'use strict';
+const common = require('../common');
+
+if (common.isWindows) {
+  common.skip('This test does not apply to Windows.');
+  return;
+}
+
+const assert = require('assert');
+
+const expected = '--option-to-be-seen-on-child';
+
+const { spawn } = require('child_process');
+const child = spawn(process.execPath, ['/dev/stdin', expected], { stdio: 'pipe' });
+
+child.stdin.end('console.log(process.argv[2])');
+
+let actual = '';
+child.stdout.setEncoding('utf8');
+child.stdout.on('data', (chunk) => actual += chunk);
+child.stdout.on('end', common.mustCall(() => {
+  assert.strictEqual(actual.trim(), expected);
+}));