src: protect global state with mutexes

Protect environment variables and inherently per-process state
(e.g. the process title) with mutexes, to better accomodate
Node’s usage in multi-threading environments.

Thanks to Stephen Belanger for reviewing this change in its original PR.

Refs: ayojs/ayo#82

src/node.cc

@@ -172,6 +172,10 @@ using v8::Value;
 
 using AsyncHooks = Environment::AsyncHooks;
 
+Mutex process_title_mutex;
+static Mutex process_mutex;
+static Mutex environ_mutex;
+
 static bool print_eval = false;
 static bool force_repl = false;
 static bool syntax_check_only = false;
@@ -699,9 +703,12 @@ bool SafeGetenv(const char* key, std::string* text) {
     goto fail;
 #endif
 
-  if (const char* value = getenv(key)) {
-    *text = value;
-    return true;
+  {
+    Mutex::ScopedLock lock(environ_mutex);
+    if (const char* value = getenv(key)) {
+      *text = value;
+      return true;
+    }
   }
 
 fail:
@@ -1359,6 +1366,7 @@ void AppendExceptionLine(Environment* env,
   if (!can_set_arrow || (mode == FATAL_ERROR && !err_obj->IsNativeError())) {
     if (env->printed_error())
       return;
+    Mutex::ScopedLock lock(process_mutex);
     env->set_printed_error(true);
 
     uv_tty_reset_mode();
@@ -2600,6 +2608,7 @@ static void GetLinkedBinding(const FunctionCallbackInfo<Value>& args) {
 
 static void ProcessTitleGetter(Local<Name> property,
                                const PropertyCallbackInfo<Value>& info) {
+  Mutex::ScopedLock lock(process_title_mutex);
   char buffer[512];
   uv_get_process_title(buffer, sizeof(buffer));
   info.GetReturnValue().Set(String::NewFromUtf8(info.GetIsolate(), buffer));
@@ -2610,7 +2619,7 @@ static void ProcessTitleSetter(Local<Name> property,
                                Local<Value> value,
                                const PropertyCallbackInfo<void>& info) {
   node::Utf8Value title(info.GetIsolate(), value);
-  // TODO(piscisaureus): protect with a lock
+  Mutex::ScopedLock lock(process_title_mutex);
   uv_set_process_title(*title);
 }
 
@@ -2621,6 +2630,7 @@ static void EnvGetter(Local<Name> property,
   if (property->IsSymbol()) {
     return info.GetReturnValue().SetUndefined();
   }
+  Mutex::ScopedLock lock(environ_mutex);
 #ifdef __POSIX__
   node::Utf8Value key(isolate, property);
   const char* val = getenv(*key);
@@ -2661,6 +2671,8 @@ static void EnvSetter(Local<Name> property,
           "DEP0104").IsNothing())
       return;
   }
+
+  Mutex::ScopedLock lock(environ_mutex);
 #ifdef __POSIX__
   node::Utf8Value key(info.GetIsolate(), property);
   node::Utf8Value val(info.GetIsolate(), value);
@@ -2681,6 +2693,7 @@ static void EnvSetter(Local<Name> property,
 
 static void EnvQuery(Local<Name> property,
                      const PropertyCallbackInfo<Integer>& info) {
+  Mutex::ScopedLock lock(environ_mutex);
   int32_t rc = -1;  // Not found unless proven otherwise.
   if (property->IsString()) {
 #ifdef __POSIX__
@@ -2710,6 +2723,7 @@ static void EnvQuery(Local<Name> property,
 
 static void EnvDeleter(Local<Name> property,
                        const PropertyCallbackInfo<Boolean>& info) {
+  Mutex::ScopedLock lock(environ_mutex);
   if (property->IsString()) {
 #ifdef __POSIX__
     node::Utf8Value key(info.GetIsolate(), property);
@@ -2735,6 +2749,7 @@ static void EnvEnumerator(const PropertyCallbackInfo<Array>& info) {
   Local<Value> argv[NODE_PUSH_VAL_TO_ARRAY_MAX];
   size_t idx = 0;
 
+  Mutex::ScopedLock lock(environ_mutex);
 #ifdef __POSIX__
   int size = 0;
   while (environ[size])
@@ -2850,6 +2865,7 @@ static Local<Object> GetFeatures(Environment* env) {
 
 static void DebugPortGetter(Local<Name> property,
                             const PropertyCallbackInfo<Value>& info) {
+  Mutex::ScopedLock lock(process_mutex);
   int port = debug_options.port();
 #if HAVE_INSPECTOR
   if (port == 0) {
@@ -2865,6 +2881,7 @@ static void DebugPortGetter(Local<Name> property,
 static void DebugPortSetter(Local<Name> property,
                             Local<Value> value,
                             const PropertyCallbackInfo<void>& info) {
+  Mutex::ScopedLock lock(process_mutex);
   debug_options.set_port(value->Int32Value());
 }
 

src/node_crypto.cc

@@ -721,6 +721,9 @@ void SecureContext::SetCert(const FunctionCallbackInfo<Value>& args) {
 
 static X509_STORE* NewRootCertStore() {
   static std::vector<X509*> root_certs_vector;
+  static Mutex root_certs_vector_mutex;
+  Mutex::ScopedLock lock(root_certs_vector_mutex);
+
   if (root_certs_vector.empty()) {
     for (size_t i = 0; i < arraysize(root_certs); i++) {
       BIO* bp = NodeBIO::NewFixed(root_certs[i], strlen(root_certs[i]));

src/node_internals.h

@@ -25,6 +25,7 @@
 #if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
 
 #include "node.h"
+#include "node_mutex.h"
 #include "node_persistent.h"
 #include "util-inl.h"
 #include "env-inl.h"
@@ -215,6 +216,9 @@ extern bool v8_initialized;
 // Used in node_config.cc.
 extern node::DebugOptions debug_options;
 
+// Used to protect the process title in multi-threading situations.
+extern Mutex process_title_mutex;
+
 // Forward declaration
 class Environment;
 

src/util.cc

@@ -114,6 +114,7 @@ std::string GetHumanReadableProcessName() {
 
 void GetHumanReadableProcessName(char (*name)[1024]) {
   char title[1024] = "Node.js";
+  Mutex::ScopedLock lock(process_title_mutex);
   uv_get_process_title(title, sizeof(title));
   snprintf(*name, sizeof(*name), "%s[%u]", title, uv_os_getpid());
 }