Fixes to linux TCP server example

examples/linux/platform.h

@@ -59,10 +59,11 @@ int server_fd = -1;
 int client_read_fd = -1;
 fd_set client_connections;
 
-void close_server_on_exit(int sig) {
+void close_tcp_server() {
-    UNUSED_PARAM(sig);
+    if (server_fd != -1) {
-    if (server_fd != -1)
         close(server_fd);
+        printf("Server closed\n");
+    }
 }
 
 
@@ -110,12 +111,6 @@ int create_tcp_server(const char* address, const char* port) {
         return errno;
     }
 
-    signal(SIGINT, close_server_on_exit);
-    signal(SIGTERM, close_server_on_exit);
-    signal(SIGQUIT, close_server_on_exit);
-    signal(SIGSTOP, close_server_on_exit);
-    signal(SIGHUP, close_server_on_exit);
-
     server_fd = fd;
     FD_ZERO(&client_connections);
 
@@ -163,17 +158,12 @@ void* server_poll(void) {
 
 void disconnect(void* conn) {
     int fd = *(int*) conn;
+    FD_CLR(fd, &client_connections);
     close(fd);
     printf("Closed connection %d\n", fd);
 }
 
 
-void close_server(void) {
-    close(server_fd);
-    printf("Server closed\n");
-}
-
-
 // Read/write/sleep platform functions
 
 int32_t read_fd_linux(uint8_t* buf, uint16_t count, int32_t timeout_ms, void* arg) {

examples/linux/server-tcp.c

@@ -25,10 +25,17 @@
 #define FILE_SIZE_MAX 32
 
 // A single nmbs_bitfield variable can keep 2000 coils
+bool terminate = false;
 nmbs_bitfield server_coils = {0};
 uint16_t server_registers[REGS_ADDR_MAX] = {0};
 uint16_t server_file[FILE_SIZE_MAX];
 
+
+void sighandler(int s) {
+    UNUSED_PARAM(s);
+    terminate = true;
+}
+
 nmbs_error handle_read_coils(uint16_t address, uint16_t quantity, nmbs_bitfield coils_out, uint8_t unit_id, void* arg) {
     UNUSED_PARAM(arg);
     UNUSED_PARAM(unit_id);
@@ -130,6 +137,11 @@ nmbs_error handle_write_file_record(uint16_t file_number, uint16_t record_number
 
 
 int main(int argc, char* argv[]) {
+    signal(SIGTERM, sighandler);
+    signal(SIGSTOP, sighandler);
+    signal(SIGINT, sighandler);
+    signal(SIGQUIT, sighandler);
+
     if (argc < 3) {
         fprintf(stderr, "Usage: server-tcp [address] [port]\n");
         return 1;
@@ -170,14 +182,13 @@ int main(int argc, char* argv[]) {
     printf("Modbus TCP server started\n");
 
     // Our server supports requests from more than one client
-    while (true) {
+    while (!terminate) {
         // Our server_poll() function will return the next client TCP connection to read from
         void* conn = server_poll();
-        if (!conn)
+        if (conn) {
-            break;
+            // Set the next connection handler used by the read/write platform functions
-
+            nmbs_set_platform_arg(&nmbs, conn);
-        // Set the next connection handler used by the read/write platform functions
+        }
-        nmbs_set_platform_arg(&nmbs, conn);
 
         err = nmbs_server_poll(&nmbs);
         if (err != NMBS_ERROR_NONE) {
@@ -187,7 +198,7 @@ int main(int argc, char* argv[]) {
     }
 
     // Close the TCP server
-    close_server();
+    close_tcp_server();
 
     // No need to destroy the nmbs instance, bye bye
     return 0;