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/linux/arcnet.c

@@ -69,7 +69,7 @@ void arcnet_cleanup(void)
     return;
 }
 
-static int arcnet_bind(char *interface_name)
+static int arcnet_bind(const char *interface_name)
 {
     int sock_fd = -1; /* return value */
     struct ifreq ifr;

ports/linux/bacport.h

@@ -100,7 +100,7 @@ extern int bip_get_local_netmask(
 
 BACNET_STACK_EXPORT
 extern int bip_get_local_address_ioctl(
-    char *ifname,
+    const char *ifname,
     struct in_addr *addr,
     int request);
 

ports/linux/bip-init.c

@@ -178,7 +178,7 @@ void bip_get_broadcast_address(BACNET_ADDRESS *dest)
  *
  * @param addr - network IPv4 address
  */
-bool bip_set_addr(BACNET_IP_ADDRESS *addr)
+bool bip_set_addr(const BACNET_IP_ADDRESS *addr)
 {
     /* not something we do within this driver */
     (void)addr;
@@ -205,7 +205,7 @@ bool bip_get_addr(BACNET_IP_ADDRESS *addr)
  * @param addr - network IPv4 address
  * @return true if the address was set
  */
-bool bip_set_broadcast_addr(BACNET_IP_ADDRESS *addr)
+bool bip_set_broadcast_addr(const BACNET_IP_ADDRESS *addr)
 {
     /* not something we do within this driver */
     (void)addr;
@@ -273,7 +273,8 @@ uint8_t bip_get_subnet_prefix(void)
  * @return Upon successful completion, returns the number of bytes sent.
  *  Otherwise, -1 shall be returned and errno set to indicate the error.
  */
-int bip_send_mpdu(BACNET_IP_ADDRESS *dest, uint8_t *mtu, uint16_t mtu_len)
+int bip_send_mpdu(
+    const BACNET_IP_ADDRESS *dest, const uint8_t *mtu, uint16_t mtu_len)
 {
     struct sockaddr_in bip_dest = { 0 };
 
@@ -292,7 +293,7 @@ int bip_send_mpdu(BACNET_IP_ADDRESS *dest, uint8_t *mtu, uint16_t mtu_len)
     /* Send the packet */
     debug_print_ipv4(
         "Sending MPDU->", &bip_dest.sin_addr, bip_dest.sin_port, mtu_len);
-    return sendto(BIP_Socket, (char *)mtu, mtu_len, 0,
+    return sendto(BIP_Socket, (const char *)mtu, mtu_len, 0,
         (struct sockaddr *)&bip_dest, sizeof(struct sockaddr));
 }
 
@@ -465,7 +466,8 @@ bool bip_get_addr_by_name(const char *host_name, BACNET_IP_ADDRESS *addr)
  * @param request - the ioctl() request
  * @return 0 on success, else the error from the ioctl() call.
  */
-static int get_local_ifr_ioctl(char *ifname, struct ifreq *ifr, int request)
+static int get_local_ifr_ioctl(
+    const char *ifname, struct ifreq *ifr, int request)
 {
     int fd;
     int rv; /* return value */
@@ -491,7 +493,8 @@ static int get_local_ifr_ioctl(char *ifname, struct ifreq *ifr, int request)
  * @param request - the ioctl() request
  * @return 0 on success, else the error from the ioctl() call.
  */
-int bip_get_local_address_ioctl(char *ifname, struct in_addr *addr, int request)
+int bip_get_local_address_ioctl(
+    const char *ifname, struct in_addr *addr, int request)
 {
     struct ifreq ifr = { 0 };
     struct sockaddr_in *tcpip_address;
@@ -746,7 +749,7 @@ int bip_set_broadcast_binding(
  * @param ifname [in] The named interface to use for the network layer.
  *        Eg, for Linux, ifname is eth0, ath0, arc0, and others.
  */
-void bip_set_interface(char *ifname)
+void bip_set_interface(const char *ifname)
 {
     struct in_addr local_address;
     struct in_addr netmask;
@@ -804,7 +807,7 @@ void bip_set_interface(char *ifname)
     }
 }
 
-static int createSocket(struct sockaddr_in *sin)
+static int createSocket(const struct sockaddr_in *sin)
 {
     int status = 0; /* return from socket lib calls */
     int sockopt = 0;

ports/linux/bip6.c

@@ -188,7 +188,7 @@ void bip6_get_my_address(BACNET_ADDRESS *addr)
  *
  * @param addr - network IPv6 address
  */
-bool bip6_set_addr(BACNET_IP6_ADDRESS *addr)
+bool bip6_set_addr(const BACNET_IP6_ADDRESS *addr)
 {
     return bvlc6_address_copy(&BIP6_Addr, addr);
 }
@@ -208,7 +208,7 @@ bool bip6_get_addr(BACNET_IP6_ADDRESS *addr)
  *
  * @param addr - network IPv6 address
  */
-bool bip6_set_broadcast_addr(BACNET_IP6_ADDRESS *addr)
+bool bip6_set_broadcast_addr(const BACNET_IP6_ADDRESS *addr)
 {
     return bvlc6_address_copy(&BIP6_Broadcast_Addr, addr);
 }
@@ -234,7 +234,8 @@ bool bip6_get_broadcast_addr(BACNET_IP6_ADDRESS *addr)
  * @return Upon successful completion, returns the number of bytes sent.
  *  Otherwise, -1 shall be returned and errno set to indicate the error.
  */
-int bip6_send_mpdu(BACNET_IP6_ADDRESS *dest, uint8_t *mtu, uint16_t mtu_len)
+int bip6_send_mpdu(
+    const BACNET_IP6_ADDRESS *dest, const uint8_t *mtu, uint16_t mtu_len)
 {
     struct sockaddr_in6 bvlc_dest = { 0 };
     uint16_t addr16[8];
@@ -259,7 +260,7 @@ int bip6_send_mpdu(BACNET_IP6_ADDRESS *dest, uint8_t *mtu, uint16_t mtu_len)
     bvlc_dest.sin6_scope_id = BIP6_Socket_Scope_Id;
     debug_print_ipv6("Sending MPDU->", &bvlc_dest.sin6_addr);
     /* Send the packet */
-    return sendto(BIP6_Socket, (char *)mtu, mtu_len, 0,
+    return sendto(BIP6_Socket, (const char *)mtu, mtu_len, 0,
         (struct sockaddr *)&bvlc_dest, sizeof(bvlc_dest));
 }
 

ports/linux/dlmstp.c

@@ -398,16 +398,18 @@ uint16_t MSTP_Get_Send(struct mstp_port_struct_t *mstp_port, unsigned timeout)
  * @param nbytes - number of bytes of data to send
  */
 void MSTP_Send_Frame(
-    struct mstp_port_struct_t *mstp_port, uint8_t *buffer, uint16_t nbytes)
+    struct mstp_port_struct_t *mstp_port,
+    const uint8_t *buffer,
+    uint16_t nbytes)
 {
     RS485_Send_Frame(mstp_port, buffer, nbytes);
 }
 
 static bool dlmstp_compare_data_expecting_reply(
-    uint8_t *request_pdu,
+    const uint8_t *request_pdu,
     uint16_t request_pdu_len,
     uint8_t src_address,
-    uint8_t *reply_pdu,
+    const uint8_t *reply_pdu,
     uint16_t reply_pdu_len,
     uint8_t dest_address)
 {

ports/linux/dlmstp_linux.c

@@ -379,16 +379,18 @@ uint16_t MSTP_Get_Send(struct mstp_port_struct_t *mstp_port, unsigned timeout)
  * @param nbytes - number of bytes of data to send
  */
 void MSTP_Send_Frame(
-    struct mstp_port_struct_t *mstp_port, uint8_t *buffer, uint16_t nbytes)
+    struct mstp_port_struct_t *mstp_port,
+    const uint8_t *buffer,
+    uint16_t nbytes)
 {
     RS485_Send_Frame(mstp_port, buffer, nbytes);
 }
 
 static bool dlmstp_compare_data_expecting_reply(
-    uint8_t *request_pdu,
+    const uint8_t *request_pdu,
     uint16_t request_pdu_len,
     uint8_t src_address,
-    uint8_t *reply_pdu,
+    const uint8_t *reply_pdu,
     uint16_t reply_pdu_len,
     uint8_t dest_address)
 {

ports/linux/ethernet.c

@@ -64,7 +64,7 @@ int setNonblocking(
 #endif
 
 /* opens an 802.2 socket to receive and send packets */
-static int ethernet_bind(struct sockaddr *eth_addr, char *interface_name)
+static int ethernet_bind(struct sockaddr *eth_addr, const char *interface_name)
 {
     int sock_fd = -1; /* return value */
 #if 0
@@ -339,7 +339,7 @@ uint16_t ethernet_receive(BACNET_ADDRESS *src, /* source address */
     return pdu_len;
 }
 
-void ethernet_set_my_address(BACNET_ADDRESS *my_address)
+void ethernet_set_my_address(const BACNET_ADDRESS *my_address)
 {
     int i = 0;
 
@@ -387,7 +387,7 @@ void ethernet_get_broadcast_address(BACNET_ADDRESS *dest)
     return;
 }
 
-void ethernet_debug_address(const char *info, BACNET_ADDRESS *dest)
+void ethernet_debug_address(const char *info, const BACNET_ADDRESS *dest)
 {
     int i = 0; /* counter */
 

ports/linux/mstpsnap.c

@@ -84,7 +84,7 @@ uint16_t MSTP_Get_Send(
  */
 void MSTP_Send_Frame(
     struct mstp_port_struct_t *mstp_port,
-    uint8_t * buffer,
+    const uint8_t * buffer,
     uint16_t nbytes)
 {
     (void)mstp_port;
@@ -141,7 +141,7 @@ static int network_init(const char *name, int protocol)
 }
 
 static void snap_received_packet(
-    struct mstp_port_struct_t *mstp_port, int sockfd)
+    const struct mstp_port_struct_t *mstp_port, int sockfd)
 {
     uint16_t mtu_len = 0; /* number of octets of packet saved in file */
     unsigned i = 0; /* counter */

ports/linux/rs485.c

@@ -355,14 +355,14 @@ bool RS485_Set_Baud_Rate(uint32_t baud)
  *****************************************************************************/
 void RS485_Send_Frame(
     struct mstp_port_struct_t *mstp_port, /* port specific data */
-    uint8_t *buffer, /* frame to send (up to 501 bytes of data) */
+    const uint8_t *buffer, /* frame to send (up to 501 bytes of data) */
     uint16_t nbytes)
 { /* number of bytes of data (up to 501) */
     uint32_t turnaround_time = Tturnaround * 1000;
     uint32_t baud;
     ssize_t written = 0;
     int greska;
-    SHARED_MSTP_DATA *poSharedData = NULL;
+    const SHARED_MSTP_DATA *poSharedData = NULL;
 
     if (mstp_port) {
         poSharedData = (SHARED_MSTP_DATA *)mstp_port->UserData;

ports/linux/rs485.h

@@ -29,7 +29,7 @@ extern "C" {
     BACNET_STACK_EXPORT
     void RS485_Send_Frame(
         struct mstp_port_struct_t *mstp_port,  /* port specific data */
-        uint8_t * buffer,       /* frame to send (up to 501 bytes of data) */
+        const uint8_t * buffer, /* frame to send (up to 501 bytes of data) */
         uint16_t nbytes);       /* number of bytes of data (up to 501) */
 
     BACNET_STACK_EXPORT