Add support for querying client environement variables

At connection, a remote client sends all its environement to the
server, which then provides access to client env through
kak_client_env_VAR_NAME variables in the shell.

src/client.cc

@@ -14,10 +14,13 @@ namespace Kakoune
 
 Client::Client(std::unique_ptr<UserInterface>&& ui,
                std::unique_ptr<Window>&& window,
-               SelectionList selections, String name)
+               SelectionList selections,
+               EnvVarMap env_vars,
+               String name)
     : m_ui{std::move(ui)}, m_window{std::move(window)},
       m_input_handler{m_window->buffer(), std::move(selections),
-                      std::move(name)}
+                      std::move(name)},
+      m_env_vars(env_vars)
 {
     context().set_client(*this);
     context().set_window(*m_window);
@@ -151,4 +154,13 @@ void Client::check_buffer_fs_timestamp()
         reload_buffer(context(), filename);
 }
 
+const String& Client::get_env_var(const String& name) const
+{
+    auto it = m_env_vars.find(name);
+    static String empty{};
+    if (it == m_env_vars.end())
+        return empty;
+    return it->second;
+}
+
 }

src/client.hh

@@ -5,6 +5,7 @@
 #include "utils.hh"
 #include "display_buffer.hh"
 #include "input_handler.hh"
+#include "env_vars.hh"
 
 namespace Kakoune
 {
@@ -17,7 +18,9 @@ class Client : public SafeCountable
 public:
     Client(std::unique_ptr<UserInterface>&& ui,
            std::unique_ptr<Window>&& window,
-           SelectionList selections, String name);
+           SelectionList selections,
+           EnvVarMap env_vars,
+           String name);
     ~Client();
 
     // handle all the keys currently available in the user interface
@@ -37,12 +40,16 @@ public:
 
     void change_buffer(Buffer& buffer);
 
+    const String& get_env_var(const String& name) const;
+
 private:
     DisplayLine generate_mode_line() const;
 
     std::unique_ptr<UserInterface> m_ui;
     std::unique_ptr<Window> m_window;
 
+    EnvVarMap m_env_vars;
+
     InputHandler m_input_handler;
 
     DisplayLine m_status_line;

src/client_manager.cc

@@ -25,12 +25,14 @@ String ClientManager::generate_name() const
 }
 
 Client* ClientManager::create_client(std::unique_ptr<UserInterface>&& ui,
+                                     EnvVarMap env_vars,
                                      const String& init_commands)
 {
     Buffer& buffer = **BufferManager::instance().begin();
     WindowAndSelections ws = get_free_window(buffer);
     Client* client = new Client{std::move(ui), std::move(ws.window),
-                                std::move(ws.selections), generate_name()};
+                                std::move(ws.selections), std::move(env_vars),
+                                generate_name()};
     m_clients.emplace_back(client);
     try
     {

src/client_manager.hh

@@ -22,7 +22,7 @@ public:
     ~ClientManager();
 
     Client* create_client(std::unique_ptr<UserInterface>&& ui,
-                          const String& init_cmd);
+                          EnvVarMap env_vars, const String& init_cmd);
 
     bool   empty() const { return m_clients.empty(); }
     size_t count() const { return m_clients.size(); }

src/env_vars.cc

@@ -0,0 +1,20 @@
+#include "env_vars.hh"
+
+namespace Kakoune
+{
+
+EnvVarMap get_env_vars()
+{
+    EnvVarMap env_vars;
+    for (char** it = environ; *it; ++it)
+    {
+        const char* name = *it;
+        const char* value = name;
+        while (*value != 0 and *value != '=')
+            ++value;
+        env_vars[String{name, value}] = (*value == '=') ? value+1 : value;
+    }
+    return env_vars;
+}
+
+}

src/env_vars.hh

@@ -0,0 +1,18 @@
+#ifndef env_vars_hh_INCLUDED
+#define env_vars_hh_INCLUDED
+
+#include "string.hh"
+
+#include <unordered_map>
+
+namespace Kakoune
+{
+
+using EnvVarMap = std::unordered_map<String, String>;
+
+EnvVarMap get_env_vars();
+
+}
+
+#endif // env_vars_hh_INCLUDED
+

src/main.cc

@@ -101,6 +101,10 @@ void register_env_vars()
             "reg_.+",
             [](const String& name, const Context& context) -> String
             { return RegisterManager::instance()[name[4]].values(context)[0]; }
+        }, {
+            "client_env_.+",
+            [](const String& name, const Context& context) -> String
+            { return context.client().get_env_var(name.substr(11_byte)); }
         }, {
             "session",
             [](const String& name, const Context& context) -> String
@@ -189,7 +193,7 @@ void create_local_client(const String& init_command)
 
     UserInterface* ui = new LocalNCursesUI{};
     static Client* client = ClientManager::instance().create_client(
-        std::unique_ptr<UserInterface>{ui}, init_command);
+        std::unique_ptr<UserInterface>{ui}, get_env_vars(), init_command);
     signal(SIGHUP, [](int) {
         if (client)
             ClientManager::instance().remove_client(*client);
@@ -221,6 +225,7 @@ int run_client(const String& session, const String& init_command)
         EventManager event_manager;
         auto client = connect_to(session,
                                  std::unique_ptr<UserInterface>{new NCursesUI{}},
+                                 get_env_vars(),
                                  init_command);
         while (true)
             event_manager.handle_next_events();

src/remote.cc

@@ -74,6 +74,17 @@ public:
         write(memoryview<T>(vec));
     }
 
+    template<typename Key, typename Val>
+    void write(const std::unordered_map<Key, Val>& map)
+    {
+        write<uint32_t>(map.size());
+        for (auto& val : map)
+        {
+            write(val.first);
+            write(val.second);
+        }
+    }
+
     void write(Color color)
     {
         write(color.color);
@@ -210,6 +221,20 @@ DisplayBuffer read<DisplayBuffer>(int socket)
     return db;
 }
 
+template<typename Key, typename Val>
+std::unordered_map<Key, Val> read_map(int socket)
+{
+    uint32_t size = read<uint32_t>(socket);
+    std::unordered_map<Key, Val> res;
+    while (size--)
+    {
+        auto key = read<Key>(socket);
+        auto val = read<Val>(socket);
+        res.insert({std::move(key), std::move(val)});
+    }
+    return res;
+}
+
 class RemoteUI : public UserInterface
 {
 public:
@@ -368,12 +393,15 @@ void RemoteUI::set_input_callback(InputCallback callback)
 }
 
 RemoteClient::RemoteClient(int socket, std::unique_ptr<UserInterface>&& ui,
+                           const EnvVarMap& env_vars,
                            const String& init_command)
     : m_ui(std::move(ui)), m_dimensions(m_ui->dimensions()),
       m_socket_watcher{socket, [this](FDWatcher&){ process_next_message(); }}
 {
     Message msg(socket);
     msg.write(init_command.c_str(), (int)init_command.length()+1);
+    msg.write(env_vars);
+
     Key key{ resize_modifier, Codepoint(((int)m_dimensions.line << 16) |
                                         (int)m_dimensions.column) };
     msg.write(key);
@@ -446,6 +474,7 @@ void RemoteClient::write_next_key()
 
 std::unique_ptr<RemoteClient> connect_to(const String& session,
                                          std::unique_ptr<UserInterface>&& ui,
+                                         const EnvVarMap& env_vars,
                                          const String& init_command)
 {
     auto filename = "/tmp/kak-" + session;
@@ -459,6 +488,7 @@ std::unique_ptr<RemoteClient> connect_to(const String& session,
         throw connection_failed(filename);
 
     return std::unique_ptr<RemoteClient>{new RemoteClient{sock, std::move(ui),
+                                                          env_vars,
                                                           init_command}};
 }
 
@@ -525,8 +555,10 @@ private:
             }
             if (c == 0) // end of initial command stream, go to interactive ui
             {
+                EnvVarMap env_vars = read_map<String, String>(socket);
                 std::unique_ptr<UserInterface> ui{new RemoteUI{socket}};
                 ClientManager::instance().create_client(std::move(ui),
+                                                        std::move(env_vars),
                                                         m_buffer);
                 Server::instance().remove_accepter(this);
                 return;

src/remote.hh

@@ -4,6 +4,7 @@
 #include "display_buffer.hh"
 #include "event_manager.hh"
 #include "user_interface.hh"
+#include "env_vars.hh"
 
 namespace Kakoune
 {
@@ -23,7 +24,7 @@ class RemoteClient
 {
 public:
     RemoteClient(int socket, std::unique_ptr<UserInterface>&& ui,
-                 const String& init_command);
+                 const EnvVarMap& env_vars, const String& init_command);
 
 private:
     void process_next_message();
@@ -35,6 +36,7 @@ private:
 };
 std::unique_ptr<RemoteClient> connect_to(const String& session,
                                          std::unique_ptr<UserInterface>&& ui,
+                                         const EnvVarMap& env_vars,
                                          const String& init_command);
 
 void send_command(const String& session, const String& command);

src/shell_manager.hh

@@ -3,15 +3,13 @@
 
 #include "string.hh"
 #include "utils.hh"
-
+#include "env_vars.hh"
-#include <unordered_map>
 
 namespace Kakoune
 {
 
 class Context;
 using EnvVarRetriever = std::function<String (const String& name, const Context&)>;
-using EnvVarMap = std::unordered_map<String, String>;
 
 class ShellManager : public Singleton<ShellManager>
 {