Preload DWM plugins (dialer, calllog, xdrawer) with resident X11/Pango state and FIFO IPC

src/dwm-plugins/dwm_plugin_runner.c

@@ -1,5 +1,7 @@
 #include <dirent.h>
 #include <dlfcn.h>
+#include <fcntl.h>
+#include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -8,6 +10,45 @@
 
 #include "../sxmo-dwm/dwm_plugin.h"
 
+static int try_send_plugin_fifo(const char *plugin_name, int sub_argc, char **sub_argv) {
+  if (sub_argc >= 2 && sub_argv[1] && strcmp(sub_argv[1], "--preload") == 0) {
+    return 0;
+  }
+  char pid_path[128];
+  snprintf(pid_path, sizeof(pid_path), "/tmp/dwm_plugin_%s.pid", plugin_name);
+  FILE *pf = fopen(pid_path, "r");
+  if (!pf) {
+    return 0;
+  }
+  int pid = 0;
+  int ok = (fscanf(pf, "%d", &pid) == 1 && pid > 1 && kill((pid_t)pid, 0) == 0);
+  fclose(pf);
+  if (!ok) {
+    return 0;
+  }
+
+  char fifo_path[128];
+  snprintf(fifo_path, sizeof(fifo_path), "/tmp/dwm_plugin_%s.fifo", plugin_name);
+  int fd = open(fifo_path, O_WRONLY | O_NONBLOCK | O_CLOEXEC);
+  if (fd < 0) {
+    return 0;
+  }
+
+  char cmd[256];
+  int len = 0;
+  if (strcmp(plugin_name, "xdrawer") == 0) {
+    len = snprintf(cmd, sizeof(cmd), "TOGGLE\n");
+  } else if (sub_argc >= 2 && sub_argv[1] && sub_argv[1][0]) {
+    len = snprintf(cmd, sizeof(cmd), "OPEN %s\n", sub_argv[1]);
+  } else {
+    len = snprintf(cmd, sizeof(cmd), "OPEN\n");
+  }
+
+  ssize_t wr = (len > 0 && len < (int)sizeof(cmd)) ? write(fd, cmd, (size_t)len) : -1;
+  close(fd);
+  return wr > 0 ? 1 : 0;
+}
+
 static const char *const kPluginDirs[] = {
   "/home/user/.local/lib/dwm/plugins",
   "/usr/lib/dwm/plugins",
@@ -79,6 +120,10 @@ int main(int argc, char **argv) {
     sub_argv = argv + 1;
   }
 
+  if (try_send_plugin_fifo(plugin_name, sub_argc, sub_argv)) {
+    return 0;
+  }
+
   const char *env_dir = getenv("DWM_PLUGIN_PATH");
   char path[512];
   void *handle = NULL;