Fixed coverity warnings for class ATHandler and removed unnecessary assert from state machine.

Author: Teppo Järvelin

features/cellular/easy_cellular/CellularConnectionFSM.cpp

@@ -120,7 +120,6 @@ nsapi_error_t CellularConnectionFSM::init()
 
 bool CellularConnectionFSM::power_on()
 {
-    MBED_ASSERT(1);
     nsapi_error_t err = _power->on();
     if (err != NSAPI_ERROR_OK && err != NSAPI_ERROR_UNSUPPORTED) {
         tr_warn("Cellular start failed. Power off/on.");

features/cellular/framework/AT/ATHandler.cpp

@@ -88,17 +88,18 @@ ATHandler::ATHandler(FileHandle *fh, EventQueue &queue, int timeout, const char
     clear_error();
 
     if (output_delimiter) {
-        _output_delimiter_length = strlen(output_delimiter);
-        _output_delimiter = new char[_output_delimiter_length];
-        for (unsigned i=0; i<_output_delimiter_length; i++) {
-            _output_delimiter[i] = output_delimiter[i];
+        _output_delimiter = new char[strlen(output_delimiter) + 1];
+        if (!_output_delimiter) {
+            MBED_ASSERT(0);
+        } else {
+            memcpy(_output_delimiter, output_delimiter, strlen(output_delimiter) + 1);
         }
     } else {
-        _output_delimiter = NULL;
-        _output_delimiter_length = 0;
+         _output_delimiter = NULL;
     }
 
     reset_buffer();
+    memset(_recv_buff, 0, sizeof(_recv_buff));
     memset(_info_resp_prefix, 0, sizeof(_info_resp_prefix));
 
     _current_scope = NotSet;
@@ -481,7 +482,9 @@ ssize_t ATHandler::read_string(char *buf, size_t size, bool read_even_stop_tag)
             break;
         } else if (c == '\"') {
             match_pos = 0;
-            len--;
+            if (len > 0) {
+                len--;
+            }
             continue;
         } else if (_stop_tag->len && c == _stop_tag->tag[match_pos]) {
             match_pos++;
@@ -694,11 +697,9 @@ void ATHandler::set_3gpp_error(int err, DeviceErrorType error_type)
 
 void ATHandler::at_error(bool error_code_expected, DeviceErrorType error_type)
 {
-    int32_t err = -1;
-
     if (error_code_expected && (error_type == DeviceErrorTypeErrorCMS || error_type == DeviceErrorTypeErrorCME)) {
         set_scope(InfoType);
-        err = read_int();
+        int32_t err = read_int();
 
         if (err != -1) {
             set_3gpp_error(err, error_type);
@@ -1052,7 +1053,7 @@ void ATHandler::cmd_stop()
         return;
     }
      // Finish with CR
-    (void)write(_output_delimiter, _output_delimiter_length);
+    (void)write(_output_delimiter, strlen(_output_delimiter));
 }
 
 size_t ATHandler::write_bytes(const uint8_t *data, size_t len)

features/cellular/framework/AT/ATHandler.h

@@ -193,15 +193,13 @@ class ATHandler
     device_err_t  _last_at_err;
     uint16_t _oob_string_max_length;
     char *_output_delimiter;
-    uint8_t _output_delimiter_length;
 
     struct oob_t {
         const char *prefix;
         mbed::Callback<void()> cb;
         oob_t *next;
     };
     oob_t *_oobs;
-    bool _response_terminated;
     uint32_t _at_timeout;
     uint32_t _previous_at_timeout;