src: allows escaping NODE_OPTIONS with backslashes

The characters specified within NODE_OPTIONS can now be escaped, which
is handy especially in conjunction with `--require` (where the file path
might happen to contain spaces that shouldn't cause the option to be
split into two).

Fixes: nodejs#12971

doc/api/cli.md

@@ -774,6 +774,10 @@ if they had been specified on the command line before the actual command line
 (so they can be overridden). Node.js will exit with an error if an option
 that is not allowed in the environment is used, such as `-p` or a script file.
 
+In case an option happens to contain a space or a backslash (for example within
+the path passed to `--require`), they must be escaped using an additional
+backslash.
+
 Node.js options that are allowed are:
 - `--diagnostic-report-directory`
 - `--diagnostic-report-filename`

src/node.cc

@@ -671,11 +671,40 @@ int InitializeNodeWithArgs(std::vector<std::string>* argv,
 
 #if !defined(NODE_WITHOUT_NODE_OPTIONS)
   std::string node_options;
+
   if (credentials::SafeGetenv("NODE_OPTIONS", &node_options)) {
-    // [0] is expected to be the program name, fill it in from the real argv
-    // and use 'x' as a placeholder while parsing.
-    std::vector<std::string> env_argv = SplitString("x " + node_options, ' ');
-    env_argv[0] = argv->at(0);
+    std::vector<std::string> env_argv;
+    // [0] is expected to be the program name, fill it in from the real argv.
+    env_argv.push_back(argv->at(0));
+
+    bool will_start_new_arg = true;
+    for (std::string::size_type index = 0;
+         index < node_options.size();
+         ++index) {
+      char c = node_options.at(index);
+
+      // Backslashes escape the following character
+      if (c == '\\') {
+        if (index + 1 == node_options.size()) {
+          fprintf(stderr,
+                  "%s: invalid escaping for NODE_OPTIONS\n",
+                  argv->at(0).c_str());
+          exit(9);
+        } else {
+          c = node_options.at(++index);
+        }
+      } else if (c == ' ') {
+        will_start_new_arg = true;
+        continue;
+      }
+
+      if (will_start_new_arg) {
+        env_argv.push_back(std::string(1, c));
+        will_start_new_arg = false;
+      } else {
+        env_argv.back() += c;
+      }
+    }
 
     const int exit_code = ProcessGlobalArgs(&env_argv, nullptr, errors, true);
     if (exit_code != 0) return exit_code;

test/fixtures/print A.js

@@ -0,0 +1 @@
+console.log('A');

test/parallel/test-cli-node-options.js

@@ -12,7 +12,11 @@ const tmpdir = require('../common/tmpdir');
 tmpdir.refresh();
 
 const printA = require.resolve('../fixtures/printA.js');
+const printSpaceA = require.resolve('../fixtures/print A.js');
+
 expect(`-r ${printA}`, 'A\nB\n');
+expect(`-r ${printA.replace(/[a-z]/gi, '\\$&')}`, 'A\nB\n');
+expect(`-r ${printSpaceA.replace(/[\\ ]/g, '\\$&')}`, 'A\nB\n');
 expect(`-r ${printA} -r ${printA}`, 'A\nB\n');
 expect(`   -r ${printA}    -r ${printA}`, 'A\nB\n');
 expect(`   --require ${printA}    --require ${printA}`, 'A\nB\n');