fix(exp_modem): DTE should own both command and data terminal

reworks to clear shared_ptr<> of both command and data terminals
and having DTE own it. When we swith to CMUX mode the ownership is transfered to CMux terminal

components/esp_modem/include/cxx_include/esp_modem_cmux.hpp

@@ -54,7 +54,7 @@ class CMuxInstance;
  */
 class CMux {
 public:
-    explicit CMux(std::unique_ptr<Terminal> t, std::unique_ptr<uint8_t[]> b, size_t buff_size):
+    explicit CMux(std::shared_ptr<Terminal> t, std::unique_ptr<uint8_t[]> b, size_t buff_size):
         term(std::move(t)), payload_start(nullptr), total_payload_size(0), buffer_size(buff_size), buffer(std::move(b))  {}
     ~CMux() = default;
 
@@ -69,7 +69,7 @@ public:
      * @return  nullptr on failure
      *          tuple of the original terminal and buffer on success
      */
-    std::tuple<std::unique_ptr<Terminal>, std::unique_ptr<uint8_t[]>, size_t> deinit_and_eject();
+    std::tuple<std::shared_ptr<Terminal>, std::unique_ptr<uint8_t[]>, size_t> deinit_and_eject();
 
     /**
      * @brief Sets read callback for the appropriate terminal
@@ -110,7 +110,7 @@ private:
     bool on_footer(CMuxFrame &frame);
 
     std::function<bool(uint8_t *data, size_t len)> read_cb[MAX_TERMINALS_NUM];  /*!< Function pointers to read callbacks */
-    std::unique_ptr<Terminal> term;                   /*!< The original terminal */
+    std::shared_ptr<Terminal> term;                   /*!< The original terminal */
     cmux_state state;                                 /*!< CMux protocol state */
 
     /**

components/esp_modem/include/cxx_include/esp_modem_dce.hpp

@@ -40,6 +40,7 @@ public:
     modem_mode get();
 
 private:
+    bool set_unsafe(DTE *dte, ModuleIf *module, Netif &netif, modem_mode m);
     modem_mode mode;
 
 };

components/esp_modem/include/cxx_include/esp_modem_dte.hpp

@@ -94,19 +94,26 @@ public:
      */
     command_result command(const std::string &command, got_line_cb got_line, uint32_t time_ms, char separator) override;
 
+protected:
+    /**
+     * @brief Allows for locking the DTE
+     */
+    void lock()     { internal_lock.lock();   }
+    void unlock()   { internal_lock.unlock(); }
+    friend class Scoped<DTE>;                               /*!< Declaring "Scoped<DTE> lock(dte)" locks this instance */
 private:
     static const size_t GOT_LINE = SignalGroup::bit0;       /*!< Bit indicating response available */
 
     [[nodiscard]] bool setup_cmux();                         /*!< Internal setup of CMUX mode */
     [[nodiscard]] bool exit_cmux();                          /*!< Exit of CMUX mode */
 
-    Lock lock{};                                            /*!< Locks DTE operations */
+    Lock internal_lock{};                                    /*!< Locks DTE operations */
     size_t buffer_size;                                      /*!< Size of available DTE buffer */
     size_t consumed;                                         /*!< Indication of already processed portion in DTE buffer */
     std::unique_ptr<uint8_t[]> buffer;                       /*!< DTE buffer */
-    std::unique_ptr<Terminal> term;                          /*!< Primary terminal for this DTE */
-    Terminal *command_term;                                  /*!< Reference to the terminal used for sending commands */
-    std::unique_ptr<Terminal> other_term;                    /*!< Secondary terminal for this DTE */
+    std::shared_ptr<CMux> cmux_term;                        /*!< Primary terminal for this DTE */
+    std::shared_ptr<Terminal> command_term;                 /*!< Reference to the terminal used for sending commands */
+    std::shared_ptr<Terminal> data_term;                    /*!< Secondary terminal for this DTE */
     modem_mode mode;                                         /*!< DTE operation mode */
     SignalGroup signal;                                     /*!< Event group used to signal request-response operations */
     std::function<bool(uint8_t *data, size_t len)> on_data;  /*!< on data callback for current terminal */