Make most of functions const correct (#714)

* Make most of the functions const correct

Used clang-tidy and sonarlint to help find places where const could
pretty easily applied. Also lot of hand work.

This commit does not yet touch handlers and typedefs of those.

* Fix Arduino uno handler_who_is() has extra parenthesis

For some reason there is extra parenthesis. Remove it this is more
likely buildable.

* Bugfix/bacapp: Fix uninitilized array_index

We have changed bacapp_snprintf_value() to be const correct. After that
we got

```
/home/runner/work/bacnet-stack/bacnet-stack/src/bacnet/bacapp.c:3183:27: warning: 4th function call argument is an uninitialized value [core.CallAndMessage]
                ret_val = bacapp_snprintf_weeklyschedule(
                          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
```

So analyzer could now spot that we do not actually initilize array_index
at all. Fix this by setting array_index to zero. Note that I actually do
not know if zeroing is right thing to do here. I choose zero as if this
has worked before it is most likely that it will work with zero value.

* cmake: Add and ignore Wwrite-strings compiler option

Wwrite-strings helps find places where const correctness is broken.

Example it will warn about these

```C

void func1(char* str);

func("test") /* "test" is const so we should not pass it to func1().

char* func2()
{
  return "test"; /* func2() should return const char*.
}
```

We still need to ignore it as not all are fixed but let's add it already
so we remember that it should be opened at some point.

---------

Co-authored-by: Kari Argillander <kari.argillander@fidelix.com>

ports/xplained/bname.c

@@ -21,7 +21,7 @@
  * RETURN: true if valid
  * NOTES: none
  **************************************************************************/
-static bool bacnet_name_isvalid(uint8_t encoding, uint8_t length, char *str)
+static bool bacnet_name_isvalid(uint8_t encoding, uint8_t length, const char *str)
 {
     bool valid = false;
 
@@ -82,7 +82,7 @@ int bacnet_name_copy(uint16_t offset, uint8_t *dest, uint8_t dest_len)
 uint8_t bacnet_name_encode(uint8_t *buffer,
     uint8_t buffer_len,
     uint8_t encoding,
-    char *str,
+    const char *str,
     uint8_t str_len)
 {
     unsigned len = 0;
@@ -110,7 +110,7 @@ uint8_t bacnet_name_encode(uint8_t *buffer,
  * NOTES: none
  **************************************************************************/
 bool bacnet_name_save(
-    uint16_t offset, uint8_t encoding, char *str, uint8_t str_len)
+    uint16_t offset, uint8_t encoding, const char *str, uint8_t str_len)
 {
     uint8_t buffer[NVM_NAME_SIZE] = { 0 };
     uint8_t length = 0;
@@ -127,11 +127,11 @@ bool bacnet_name_save(
     return false;
 }
 
-bool bacnet_name_set(uint16_t offset, BACNET_CHARACTER_STRING *char_string)
+bool bacnet_name_set(uint16_t offset, const BACNET_CHARACTER_STRING *char_string)
 {
     uint8_t encoding = 0;
     uint8_t length = 0;
-    char *str = NULL;
+    const char *str = NULL;
 
     length = characterstring_length(char_string);
     encoding = characterstring_encoding(char_string);
@@ -142,7 +142,7 @@ bool bacnet_name_set(uint16_t offset, BACNET_CHARACTER_STRING *char_string)
 bool bacnet_name_write_unique(uint16_t offset,
     int object_type,
     uint32_t object_instance,
-    BACNET_CHARACTER_STRING *char_string,
+    const BACNET_CHARACTER_STRING *char_string,
     BACNET_ERROR_CLASS *error_class,
     BACNET_ERROR_CODE *error_code)
 {
@@ -192,7 +192,7 @@ bool bacnet_name_write_unique(uint16_t offset,
 
 /* no required minumum length or duplicate checking */
 bool bacnet_name_write(uint16_t offset,
-    BACNET_CHARACTER_STRING *char_string,
+    const BACNET_CHARACTER_STRING *char_string,
     BACNET_ERROR_CLASS *error_class,
     BACNET_ERROR_CODE *error_code)
 {
@@ -221,14 +221,16 @@ bool bacnet_name_write(uint16_t offset,
     return status;
 }
 
-void bacnet_name_init(uint16_t offset, char *default_string)
+void bacnet_name_init(uint16_t offset, const char *default_string)
 {
     (void)bacnet_name_save(
         offset, CHARACTER_UTF8, default_string, strlen(default_string));
 }
 
 void bacnet_name(
-    uint16_t offset, BACNET_CHARACTER_STRING *char_string, char *default_string)
+    uint16_t offset,
+    BACNET_CHARACTER_STRING *char_string,
+    const char *default_string)
 {
     uint8_t encoding = 0;
     uint8_t length = 0;

ports/xplained/bname.h

@@ -21,36 +21,36 @@ extern "C" {
         uint8_t dest_len);
     bool bacnet_name_set(
         uint16_t eeprom_offset,
-        BACNET_CHARACTER_STRING * char_string);
+        const BACNET_CHARACTER_STRING * char_string);
     void bacnet_name_init(
         uint16_t eeprom_offset,
-        char *default_string);
+        const char *default_string);
     uint8_t bacnet_name_encode(
         uint8_t *buffer,
         uint8_t buffer_len,
         uint8_t encoding,
-        char *str,
+        const char *str,
         uint8_t str_len);
     bool bacnet_name_save(
         uint16_t offset,
         uint8_t encoding,
-        char *str,
+        const char *str,
         uint8_t str_len);
     void bacnet_name(
         uint16_t eeprom_offset,
         BACNET_CHARACTER_STRING * char_string,
-        char *default_string);
+        const char *default_string);
     bool bacnet_name_write_unique(
         uint16_t offset,
         int object_type,
         uint32_t object_instance,
-        BACNET_CHARACTER_STRING * char_string,
+        const BACNET_CHARACTER_STRING * char_string,
         BACNET_ERROR_CLASS * error_class,
         BACNET_ERROR_CODE * error_code);
     /* no required minumum length or duplicate checking */
     bool bacnet_name_write(
         uint16_t offset,
-        BACNET_CHARACTER_STRING * char_string,
+        const BACNET_CHARACTER_STRING * char_string,
         BACNET_ERROR_CLASS * error_class,
         BACNET_ERROR_CODE * error_code);
 

ports/xplained/device.c

@@ -526,7 +526,7 @@ int Device_Object_List_Element_Encode(
     return apdu_len;
 }
 
-bool Device_Valid_Object_Name(BACNET_CHARACTER_STRING *object_name1,
+bool Device_Valid_Object_Name(const BACNET_CHARACTER_STRING *object_name1,
     BACNET_OBJECT_TYPE *object_type,
     uint32_t *object_instance)
 {

ports/xplained/netport.c

@@ -288,7 +288,7 @@ bool Network_Port_MAC_Address(
  * @return  true if object-name was set
  */
 bool Network_Port_MAC_Address_Set(
-    uint32_t object_instance, uint8_t *mac_src, uint8_t mac_len)
+    uint32_t object_instance, const uint8_t *mac_src, uint8_t mac_len)
 {
     if (mac_len == 1) {
         Object_List[0].MAC_Address[0] = mac_src[0];

ports/xplained/rs485.c

@@ -147,7 +147,7 @@ bool rs485_receive_error(void)
  * @param buffer - array of one or more bytes to transmit
  * @param nbytes - number of bytes to transmit
  */
-void rs485_bytes_send(uint8_t *buffer, uint16_t nbytes)
+void rs485_bytes_send(const uint8_t *buffer, uint16_t nbytes)
 {
     bool status = false;
     bool start_required = false;

ports/xplained/rs485.h

@@ -20,7 +20,7 @@ bool rs485_rts_enabled(void);
 bool rs485_byte_available(uint8_t *data_register);
 bool rs485_receive_error(void);
 
-void rs485_bytes_send(uint8_t *buffer, uint16_t nbytes);
+void rs485_bytes_send(const uint8_t *buffer, uint16_t nbytes);
 
 uint32_t rs485_baud_rate(void);
 bool rs485_baud_rate_set(uint32_t baud);