[refactor] reorganize platform and wire sources

apps/desktop/src/platform/linux/daemon_backend.cpp

@@ -0,0 +1,58 @@
+#include "platform/daemon_backend.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <signal.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <cstring>
+#include <iostream>
+
+namespace crossdesk::platform {
+
+bool PrepareDaemon() {
+  const bool from_terminal =
+      isatty(STDIN_FILENO) != 0 || isatty(STDOUT_FILENO) != 0;
+  pid_t process = fork();
+  if (process < 0) return false;
+  if (process > 0) _exit(0);
+  if (setsid() < 0) return false;
+
+  process = fork();
+  if (process < 0) return false;
+  if (process > 0) _exit(0);
+
+  umask(0);
+  if (chdir("/") != 0) {
+    std::cerr << "Failed to change daemon working directory to /: "
+              << std::strerror(errno) << std::endl;
+    return false;
+  }
+
+  const int null_fd = open("/dev/null", O_RDWR);
+  if (null_fd >= 0) {
+    dup2(null_fd, STDIN_FILENO);
+    if (!from_terminal) {
+      dup2(null_fd, STDOUT_FILENO);
+      dup2(null_fd, STDERR_FILENO);
+    }
+    if (null_fd > STDERR_FILENO) close(null_fd);
+  }
+
+  signal(SIGTERM, [](int) { g_daemon_stop_requested = 1; });
+  signal(SIGINT, [](int) { g_daemon_stop_requested = 1; });
+  signal(SIGPIPE, SIG_IGN);
+  return true;
+}
+
+std::string GetDaemonExecutablePath() {
+  char path[PATH_MAX] = {};
+  const ssize_t count = readlink("/proc/self/exe", path, sizeof(path) - 1);
+  return count > 0 ? std::string(path, static_cast<size_t>(count))
+                   : std::string();
+}
+
+}  // namespace crossdesk::platform