src: add process.binding('config')

doc/api/process.md

@@ -489,6 +489,10 @@ An example of the possible output looks like:
 }
 ```
 
+*Note: the `process.config` property is **not** read-only and there are existing
+modules in the ecosystem that are known to extend, modify, or entirely replace
+the value of `process.config`.*
+
 ## process.connected
 
 * {Boolean} Set to false after `process.disconnect()` is called

node.gyp

@@ -130,6 +130,7 @@
         'src/js_stream.cc',
         'src/node.cc',
         'src/node_buffer.cc',
+        'src/node_config.cc',
         'src/node_constants.cc',
         'src/node_contextify.cc',
         'src/node_file.cc',

src/node_config.cc

@@ -0,0 +1,48 @@
+#include "node.h"
+#include "node_i18n.h"
+#include "env.h"
+#include "env-inl.h"
+#include "util.h"
+#include "util-inl.h"
+
+
+namespace node {
+
+using v8::Context;
+using v8::Local;
+using v8::Object;
+using v8::Value;
+using v8::ReadOnly;
+
+// The config binding is used to provide an internal view of compile or runtime
+// config options that are required internally by lib/*.js code. This is an
+// alternative to dropping additional properties onto the process object as
+// has been the practice previously in node.cc.
+
+#define READONLY_BOOLEAN_PROPERTY(str)                                        \
+  do {                                                                        \
+    target->DefineOwnProperty(env->context(),                                 \
+                              OneByteString(env->isolate(), str),             \
+                              True(env->isolate()), ReadOnly).FromJust();     \
+  } while (0)
+
+void InitConfig(Local<Object> target,
+                Local<Value> unused,
+                Local<Context> context) {
+  Environment* env = Environment::GetCurrent(context);
+
+#ifdef NODE_HAVE_I18N_SUPPORT
+  READONLY_BOOLEAN_PROPERTY("hasIntl");
+
+#ifdef NODE_HAVE_SMALL_ICU
+  READONLY_BOOLEAN_PROPERTY("hasSmallICU");
+#endif  // NODE_HAVE_SMALL_ICU
+
+  if (flag_icu_data_dir)
+    READONLY_BOOLEAN_PROPERTY("usingICUDataDir");
+#endif  // NODE_HAVE_I18N_SUPPORT
+}
+
+}  // namespace node
+
+NODE_MODULE_CONTEXT_AWARE_BUILTIN(config, node::InitConfig)

src/node_i18n.cc

@@ -42,10 +42,14 @@ extern "C" const char U_DATA_API SMALL_ICUDATA_ENTRY_POINT[];
 #endif
 
 namespace node {
+
+bool flag_icu_data_dir = false;
+
 namespace i18n {
 
 bool InitializeICUDirectory(const char* icu_data_path) {
   if (icu_data_path != nullptr) {
+    flag_icu_data_dir = true;
     u_setDataDirectory(icu_data_path);
     return true;  // no error
   } else {

src/node_i18n.h

@@ -6,6 +6,9 @@
 #if defined(NODE_HAVE_I18N_SUPPORT)
 
 namespace node {
+
+extern bool flag_icu_data_dir;
+
 namespace i18n {
 
 bool InitializeICUDirectory(const char* icu_data_path);