Read bspwm events from bspc process

dapper.cpp

@@ -1,17 +1,56 @@
+// Sockets code largely stolen from bspwm
+
 #include <cstdio>
 #include <iostream>
+#include <signal.h>
 #include <sys/socket.h>
 #include <sys/un.h>
+#include <sys/wait.h>
 #include <unistd.h>
 
 static const char *SOCKET_PATH = "/tmp/dapper.socket";
 
+static volatile bool running = false;
+
+#define MAX(A, B) ((A) > (B) ? (A) : (B))
+
 void err(std::string msg) {
   std::cerr << msg << std::endl;
   std::exit(1);
 }
 
+void sig_handler(int sig) {
+  if (sig == SIGINT || sig == SIGHUP || sig == SIGTERM) {
+    running = false;
+  }
+}
+
 int main() {
+  // Create fd for `bspc subscribe` process's stdout
+
+  int pipe_fds[2];
+  if (pipe(pipe_fds) == -1) {
+    err("Failed to create pipe");
+  }
+
+  int pipe_read = pipe_fds[0], pipe_write = pipe_fds[1];
+
+  int pid = fork();
+  if (pid == 0) {
+    dup2(pipe_write, STDOUT_FILENO);
+    const char *const args[] = {"bspc", "subscribe", "node", NULL};
+    execvp("bspc", (char *const *)args);
+  } else {
+    close(pipe_write);
+  }
+
+  signal(SIGINT, sig_handler);
+  signal(SIGHUP, sig_handler);
+  signal(SIGTERM, sig_handler);
+  signal(SIGPIPE, SIG_IGN);
+
+  // Create fd for dapper's communication socket
+
   struct sockaddr_un sock_address;
   sock_address.sun_family = AF_UNIX;
   std::snprintf(sock_address.sun_path, sizeof(sock_address.sun_path), "%s",
@@ -33,27 +72,44 @@ int main() {
     err("Couldn't listen to the socket");
   }
 
-  bool running = true;
-  int max_fd = sock_fd;
-  char msg[1024];
+  // Loop over input fds
+
+  running = true;
+  int max_fd = MAX(sock_fd, pipe_read);
+  const size_t BUF_SIZE = 1024;
+  char msg[BUF_SIZE];
 
   while (running) {
     fd_set descriptors;
     FD_ZERO(&descriptors);
     FD_SET(sock_fd, &descriptors);
+    FD_SET(pipe_read, &descriptors);
 
     if (select(max_fd + 1, &descriptors, NULL, NULL, NULL) > 0) {
+      if (FD_ISSET(pipe_read, &descriptors)) {
+        int n = read(pipe_read, msg, BUF_SIZE);
+        if (n > 0) {
+          std::string message(msg, n);
+
+          std::cout << message << std::endl;
+        }
+      }
+
       if (FD_ISSET(sock_fd, &descriptors)) {
         int cli_fd = accept(sock_fd, NULL, 0);
         if (cli_fd > 0) {
-          int n = recv(cli_fd, msg, sizeof(msg), 0);
+          int n = recv(cli_fd, msg, BUF_SIZE, 0);
           if (n > 0) {
-            msg[n] = '\0';
+            std::string message(msg, n);
 
-            std::cout << std::string(msg) << std::endl;
+            std::cout << message << std::endl;
           }
         }
       }
     }
   }
+
+  close(sock_fd);
+  unlink(SOCKET_PATH);
+  close(pipe_read);
 }

dapperc.cpp

@@ -1,4 +1,4 @@
-// Sockets code largely stolen from bspc
+// Sockets code largely stolen from bspwm
 
 #include <cstdio>
 #include <iostream>
@@ -46,22 +46,10 @@ int main(int argc, char *argv[]) {
   std::string arg_str = arg_buf.str();
   size_t msg_size = arg_str.size() * sizeof(arg_str[0]);
 
+  // Sent string is NOT null-terminated
   if (send(sock_fd, arg_str.c_str(), msg_size, 0) == -1) {
     err("Failed to send the data");
   }
 
-  // struct pollfd poll_fd = {sock_fd, POLLIN, 0};
-
-  // struct pollfd fds[] = {
-  //     {sock_fd, POLLIN, 0},
-  //     {STDOUT_FILENO, POLLHUP, 0},
-  // };
-
-  // while (poll(fds, 2, -1) > 0) {
-  //   if (fds[1].revents & (POLLERR | POLLHUP)) {
-  //     break;
-  //   }
-  // }
-
   close(sock_fd);
 }