Add additional methods for DeviceInfo.

internal/platform/implementation/linux/device_info.cc

@@ -1,10 +1,13 @@
+#include <cstdlib>
 #include <cstring>
 #include <optional>
 #include <string>
 
 #include <pwd.h>
 #include <sys/types.h>
+
 #include <systemd/sd-bus.h>
+#include <systemd/sd-login.h>
 
 #include "internal/platform/implementation/device_info.h"
 #include "internal/platform/implementation/linux/device_info.h"
@@ -18,6 +21,10 @@ const char *HOSTNAME_DEST = "org.freedesktop.hostname1";
 const char *HOSTNAME_PATH = "/org/freedesktop/hostname1";
 const char *HOSTNAME_INTERFACE = "org.freedesktop.hostname1";
 
+const char *LOGIN_DEST = "org.freedesktop.login1";
+const char *LOGIN_PATH = "/org/freedesktop/login1/session/_";
+const char *LOGIN_INTERFACE = "org.freedesktop.login1.Session";
+
 std::optional<std::u16string> DeviceInfo::GetOsDeviceName() const {
   sd_bus *bus = nullptr;
   if (sd_bus_default_system(&bus) < 0) {
@@ -117,5 +124,88 @@ std::optional<std::string> DeviceInfo::GetProfileUserName() const {
   char *name = strtok(pwd->pw_gecos, ",");
   return std::string(name);
 }
+
+std::optional<std::filesystem::path> DeviceInfo::GetDownloadPath() const {
+  char *dir = getenv("XDG_DOWNLOAD_DIR");
+  if (dir == NULL) {
+    std::filesystem::path home_path(std::string(getenv("HOME")));
+    return home_path / "Desktop";
+  }
+  return std::filesystem::path(std::string(dir));
+}
+
+std::optional<std::filesystem::path> DeviceInfo::GetLocalAppDataPath() const {
+  char *dir = getenv("XDG_STATE_HOME");
+  if (dir == NULL) {
+    return std::filesystem::path("/tmp");
+  }
+  return std::filesystem::path(std::string(dir)) / "com.github.google.nearby";
+}
+
+std::optional<std::filesystem::path> DeviceInfo::GetTemporaryPath() const {
+  char *dir = getenv("XDG_CACHE_HOME");
+  if (dir == NULL) {
+    return std::filesystem::path("/tmp");
+  }
+  return std::filesystem::path(std::string(dir)) / "com.github.google.nearby";
+}
+
+std::optional<std::filesystem::path> DeviceInfo::GetLogPath() const {
+  char *dir = getenv("XDG_STATE_HOME");
+  if (dir == NULL) {
+    return std::filesystem::path("/tmp");
+  }
+  return std::filesystem::path(std::string(dir)) / "com.github.google.nearby" /
+         "logs";
+}
+
+std::optional<std::filesystem::path> DeviceInfo::GetCrashDumpPath() const {
+  char *dir = getenv("XDG_STATE_HOME");
+  if (dir == NULL) {
+    return std::filesystem::path("/tmp");
+  }
+  return std::filesystem::path(std::string(dir)) / "com.github.google.nearby" /
+         "crash";
+}
+
+bool DeviceInfo::IsScreenLocked() const {
+  char *session = nullptr;
+  if (sd_pid_get_session(getpid(), &session) < 0) {
+    NEARBY_LOGS(ERROR) << __func__
+                       << ": Error getting session for current user";
+    return false;
+  }
+
+  sd_bus *bus;
+  if (sd_bus_default_system(&bus) < 0) {
+    NEARBY_LOGS(ERROR) << __func__ << ": Error connecting to systemd bus.";
+    free(session);
+    return false;
+  }
+
+  std::string session_path(LOGIN_PATH);
+  session_path += session;
+
+  free(session);
+
+  sd_bus_error err = SD_BUS_ERROR_NULL;
+  bool locked;
+
+  if (sd_bus_get_property_trivial(bus, LOGIN_DEST, session_path.c_str(),
+                                  LOGIN_INTERFACE, "LockedHint", &err, 'b',
+                                  &locked) < 0) {
+
+    NEARBY_LOGS(ERROR)
+        << __func__
+        << ": Error getting LockedState from org.freedesktop.login1: "
+        << err.message;
+    locked = false;
+  }
+
+  sd_bus_error_free(&err);
+  sd_bus_unref(bus);
+
+  return locked;
+}
 } // namespace linux
 } // namespace nearby

internal/platform/implementation/linux/device_info.h

@@ -32,16 +32,20 @@ public:
 
   std::optional<std::filesystem::path> GetDownloadPath() const override;
   std::optional<std::filesystem::path> GetLocalAppDataPath() const override;
-  std::optional<std::filesystem::path> GetCommonAppDataPath() const override;
+  std::optional<std::filesystem::path> GetCommonAppDataPath() const override {
+    return std::nullopt;
+  };
   std::optional<std::filesystem::path> GetTemporaryPath() const override;
   std::optional<std::filesystem::path> GetLogPath() const override;
   std::optional<std::filesystem::path> GetCrashDumpPath() const override;
 
   bool IsScreenLocked() const override;
+  // TODO: Implement listening to logind for changes to LockedState.
   void RegisterScreenLockedListener(
       absl::string_view listener_name,
-      std::function<void(api::DeviceInfo::ScreenStatus)> callback) override;
-  void UnregisterScreenLockedListener(absl::string_view listener_name) override;
+      std::function<void(api::DeviceInfo::ScreenStatus)> callback) override{};
+  void
+  UnregisterScreenLockedListener(absl::string_view listener_name) override{};
 
   sd_bus *system_bus;
 };