src: allow per-Environment set of env vars

Abstract the `process.env` backing mechanism in C++ to allow
different kinds of backing stores for `process.env` for different
Environments.

PR-URL: #26544
Fixes: #24947
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

src/env-inl.h

@@ -447,6 +447,14 @@ inline uint64_t Environment::timer_base() const {
   return timer_base_;
 }
 
+inline std::shared_ptr<KVStore> Environment::envvars() {
+  return envvars_;
+}
+
+inline void Environment::set_envvars(std::shared_ptr<KVStore> envvars) {
+  envvars_ = envvars;
+}
+
 inline bool Environment::printed_error() const {
   return printed_error_;
 }

src/env.cc

@@ -178,6 +178,8 @@ Environment::Environment(IsolateData* isolate_data,
     set_as_callback_data_template(templ);
   }
 
+  set_envvars(per_process::real_environment);
+
   // We create new copies of the per-Environment option sets, so that it is
   // easier to modify them after Environment creation. The defaults are
   // part of the per-Isolate option set, for which in turn the defaults are
@@ -221,7 +223,7 @@ Environment::Environment(IsolateData* isolate_data,
   should_abort_on_uncaught_toggle_[0] = 1;
 
   std::string debug_cats;
-  credentials::SafeGetenv("NODE_DEBUG_NATIVE", &debug_cats);
+  credentials::SafeGetenv("NODE_DEBUG_NATIVE", &debug_cats, this);
   set_debug_categories(debug_cats, true);
 
   isolate()->GetHeapProfiler()->AddBuildEmbedderGraphCallback(

src/env.h

@@ -540,6 +540,23 @@ class AsyncRequest : public MemoryRetainer {
   std::atomic_bool stopped_ {true};
 };
 
+class KVStore {
+ public:
+  virtual v8::Local<v8::String> Get(v8::Isolate* isolate,
+                                    v8::Local<v8::String> key) const = 0;
+  virtual void Set(v8::Isolate* isolate,
+                   v8::Local<v8::String> key,
+                   v8::Local<v8::String> value) = 0;
+  virtual int32_t Query(v8::Isolate* isolate,
+                        v8::Local<v8::String> key) const = 0;
+  virtual void Delete(v8::Isolate* isolate, v8::Local<v8::String> key) = 0;
+  virtual v8::Local<v8::Array> Enumerate(v8::Isolate* isolate) const = 0;
+};
+
+namespace per_process {
+extern std::shared_ptr<KVStore> real_environment;
+}
+
 class AsyncHooks {
  public:
   // Reason for both UidFields and Fields are that one is stored as a double*
@@ -789,6 +806,8 @@ class Environment {
   inline ImmediateInfo* immediate_info();
   inline TickInfo* tick_info();
   inline uint64_t timer_base() const;
+  inline std::shared_ptr<KVStore> envvars();
+  inline void set_envvars(std::shared_ptr<KVStore> envvars);
 
   inline IsolateData* isolate_data() const;
 
@@ -1075,6 +1094,7 @@ class Environment {
   ImmediateInfo immediate_info_;
   TickInfo tick_info_;
   const uint64_t timer_base_;
+  std::shared_ptr<KVStore> envvars_;
   bool printed_error_ = false;
   bool emit_env_nonstring_warning_ = true;
   bool emit_err_name_warning_ = true;

src/node_credentials.cc

@@ -15,11 +15,14 @@ using v8::Array;
 using v8::Context;
 using v8::Function;
 using v8::FunctionCallbackInfo;
+using v8::HandleScope;
 using v8::Isolate;
 using v8::Local;
 using v8::MaybeLocal;
+using v8::NewStringType;
 using v8::Object;
 using v8::String;
+using v8::TryCatch;
 using v8::Uint32;
 using v8::Value;
 
@@ -30,13 +33,27 @@ bool linux_at_secure = false;
 namespace credentials {
 
 // Look up environment variable unless running as setuid root.
-bool SafeGetenv(const char* key, std::string* text) {
+bool SafeGetenv(const char* key, std::string* text, Environment* env) {
 #if !defined(__CloudABI__) && !defined(_WIN32)
   if (per_process::linux_at_secure || getuid() != geteuid() ||
       getgid() != getegid())
     goto fail;
 #endif
 
+  if (env != nullptr) {
+    HandleScope handle_scope(env->isolate());
+    TryCatch ignore_errors(env->isolate());
+    MaybeLocal<String> value = env->envvars()->Get(
+        env->isolate(),
+        String::NewFromUtf8(env->isolate(), key, NewStringType::kNormal)
+            .ToLocalChecked());
+    if (value.IsEmpty()) goto fail;
+    String::Utf8Value utf8_value(env->isolate(), value.ToLocalChecked());
+    if (*utf8_value == nullptr) goto fail;
+    *text = std::string(*utf8_value, utf8_value.length());
+    return true;
+  }
+
   {
     Mutex::ScopedLock lock(per_process::env_var_mutex);
     if (const char* value = getenv(key)) {
@@ -52,10 +69,11 @@ bool SafeGetenv(const char* key, std::string* text) {
 
 static void SafeGetenv(const FunctionCallbackInfo<Value>& args) {
   CHECK(args[0]->IsString());
-  Isolate* isolate = args.GetIsolate();
+  Environment* env = Environment::GetCurrent(args);
+  Isolate* isolate = env->isolate();
   Utf8Value strenvtag(isolate, args[0]);
   std::string text;
-  if (!SafeGetenv(*strenvtag, &text)) return;
+  if (!SafeGetenv(*strenvtag, &text, env)) return;
   Local<Value> result =
       ToV8Value(isolate->GetCurrentContext(), text).ToLocalChecked();
   args.GetReturnValue().Set(result);