code addition

Makefile

@@ -0,0 +1,2 @@
+all:
+	g++ main.cpp -lasound -g -o TabletPcControl-server

main.cpp

@@ -1,14 +1,20 @@
+#include "secret.h"
+#include <alsa/asoundlib.h>
 #include <arpa/inet.h>
 #include <array>
+#include <cerrno>
 #include <codecvt>
 #include <csignal>
+#include <cstdint>
 #include <cstdio>
+#include <cstdlib>
 #include <fcntl.h>
 #include <fstream>
 #include <iostream>
 #include <memory>
 #include <netdb.h>
 #include <netinet/in.h>
+#include <sched.h>
 #include <stdexcept>
 #include <stdio.h>
 #include <stdlib.h>
@@ -23,36 +29,58 @@
 
 #define PORT 54321
 
-std::string exec(std::string cmd) {
-  std::array<char, 128> buffer;
-  std::string result;
-  std::unique_ptr<FILE, void (*)(FILE *)> pipe(popen(cmd.c_str(), "r"),
-                                               [](FILE *f) -> void {
-                                                 // wrapper to ignore the return
-                                                 // value from pclose() is
-                                                 // needed with newer versions
-                                                 // of gnu g++
-                                                 std::ignore = pclose(f);
-                                               });
-  if (!pipe) {
-    throw std::runtime_error("popen() failed!");
-  }
-  while (fgets(buffer.data(), static_cast<int>(buffer.size()), pipe.get()) !=
-         nullptr) {
-    result += buffer.data();
-  }
-  return result;
-}
-
 int serverSocket;
 
 void safe_exit(int code) {
 
   std::clog << "Exiting\n";
+
   close(serverSocket);
   exit(code);
 }
 
+int get_volume(const char *selem_name) {
+  long min, max, volume;
+  snd_mixer_t *handle;
+  snd_mixer_selem_id_t *sid;
+
+  // Open mixer
+  snd_mixer_open(&handle, 0);
+  snd_mixer_attach(handle,
+                   "default"); // Use "default" for the default sound card
+  snd_mixer_selem_register(handle, NULL, NULL);
+  snd_mixer_load(handle);
+
+  // Allocate and set mixer element ID
+  snd_mixer_selem_id_alloca(&sid);
+  snd_mixer_selem_id_set_name(sid, selem_name);
+
+  // Find the mixer element
+  snd_mixer_elem_t *elem = snd_mixer_find_selem(handle, sid);
+
+  int volume_percent;
+  if (elem) {
+    // Get the playback volume range
+    snd_mixer_selem_get_playback_volume_range(elem, &min, &max);
+
+    // Get the current playback volume for front left channel
+    snd_mixer_selem_get_playback_volume(elem, SND_MIXER_SCHN_FRONT_LEFT,
+                                        &volume);
+
+    // Calculate the volume percentage
+    volume_percent = (volume - min) * 100 / (max - min);
+
+  } else {
+    std::cerr << "Mixer element not found\n";
+    snd_mixer_close(handle);
+    safe_exit(ENODEV);
+  }
+
+  // Clean up
+  snd_mixer_close(handle);
+  return volume_percent;
+}
+
 int main(int argc, char *argv[]) {
 
   // signal handlers
@@ -83,22 +111,60 @@ int main(int argc, char *argv[]) {
   // listening to the assigned socket
   listen(serverSocket, 5);
 
+accept_new_connection:
   // accepting connection request
   int clientSocket = accept(serverSocket, nullptr, nullptr);
 
-  // recieving data
-  char buffer[1024] = {0};
-  {
-    int RecvRetVal = recv(clientSocket, buffer, sizeof(buffer), 0);
-    if (RecvRetVal > sizeof(buffer) || RecvRetVal < 0) {
-      std::cerr << "recv() returned an error code\n";
-      return RecvRetVal;
-    }
-  }
-  std::cout << "Message from client: " << buffer << std::endl;
+  pid_t pid;
+  pid = fork();
 
-  // closing the socket.
-  close(serverSocket);
+  if (pid == -1) {
+    std::cerr << "Fork failed";
+    safe_exit(-1);
+
+  } else if (pid == 0) {
+    // child process
+    signal(SIGUSR1, exit);
+    char bufferSend[1024];
+    int volume_percent = INTMAX_MIN;
+    int volume_percent_old;
+    while (1) {
+      volume_percent_old = volume_percent;
+      volume_percent = get_volume("Master");
+      if (volume_percent != volume_percent_old) {
+      }
+      usleep(100000);
+      sprintf(bufferSend, "Volume: %d%%\n", get_volume("Master"));
+      if (send(clientSocket, bufferSend, strlen(bufferSend), 0) == -1) {
+        std::cerr << "send() returned an error code\n";
+        safe_exit(-1);
+      }
+      sleep(1);
+    }
+
+  } else {
+    // parent process
+    char bufferRecv[1024];
+    // recieving data
+    while (1) {
+      memset(&bufferRecv, 0, sizeof(bufferRecv));
+      int RecvRetVal = recv(clientSocket, bufferRecv, sizeof(bufferRecv), 0);
+      if (RecvRetVal > sizeof(bufferRecv) || RecvRetVal < 0) {
+        std::cerr << "recv() returned an error code\n";
+        safe_exit(RecvRetVal);
+      } else if (RecvRetVal == 0) {
+        // detect if client disconected
+        kill(pid, SIGUSR1);
+        close(clientSocket);
+        goto accept_new_connection;
+      }
+
+      std::cout << "Message from client: " << bufferRecv << std::endl;
+    }
+
+    // closing the socket.
+    close(serverSocket);
+  }
 
   return 0;
 }