Replace g_time3() with g_get_elapsed_ms()

The function as specified used gettimeofday() which is susceptible
to manual time changes, and is obsoleted in POSIX.1-2008. The
replacement uses clock_gettime(CLOCK_MONOTONIC, ) which is not
susceptible to manual time changes (at least on Linux) and cannot run
backwards.

Also, on systems with 32-bit integers, the value returned by this
function wraps around every 49.7 days. To cope with a wraparound in
a way compliant with the C standard, this value needs to return an
unsigned integer type rather than a signed integer type.

common/os_calls.c

@@ -3764,19 +3764,21 @@ g_check_user_in_group(const char *username, int gid, int *ok)
 #endif // HAVE_GETGROUPLIST
 
 /*****************************************************************************/
-/* returns time in milliseconds, uses gettimeofday
-   does not work in win32 */
-int
-g_time3(void)
+unsigned int
+g_get_elapsed_ms(void)
 {
-#if defined(_WIN32)
-    return 0;
-#else
-    struct timeval tp;
+    unsigned int result = 0;
+    struct timespec tp;
 
-    gettimeofday(&tp, 0);
-    return (tp.tv_sec * 1000) + (tp.tv_usec / 1000);
-#endif
+    if (clock_gettime(CLOCK_MONOTONIC, &tp) == 0)
+    {
+        result = (unsigned int)tp.tv_sec * 1000;
+        // POSIX 1003.1, 2004 that tv_nsec is a long (i.e. a signed type),
+        // but can only contain [0..999,999,999]
+        result += tp.tv_nsec / 1000000;
+    }
+
+    return result;
 }
 
 /******************************************************************************/

common/os_calls.h

@@ -393,7 +393,23 @@ int      g_getgroup_info(const char *groupname, int *gid);
  * Primary group of username is also checked
  */
 int      g_check_user_in_group(const char *username, int gid, int *ok);
-int      g_time3(void);
+
+/**
+ * Gets elapsed milliseconds since some arbitrary point in the past
+ *
+ * The returned value is unaffected by leap-seconds or time zone changes.
+ *
+ * @returns elaped ms since some arbirtary point
+ *
+ * The value wraps every so often (every 49.7 days on a 32-bit system),
+ * but as we are using unsigned arithmetic, the difference of any of these
+ * two values can be used to calculate elapsed time, whether-or-not a wrap
+ * occurs during the interval - provided of course the time being measured
+ * is less than the total wraparound interval.
+ */
+unsigned int
+g_get_elapsed_ms(void);
+
 int      g_save_to_bmp(const char *filename, char *data, int stride_bytes,
                        int width, int height, int depth, int bits_per_pixel);
 void    *g_shmat(int shmid);

common/trans.c

@@ -696,18 +696,18 @@ local_connect_shim(int fd, const char *server, const char *port)
 /**************************************************************************//**
  * Waits for an asynchronous connect to complete.
  * @param self - Transport object
- * @param start_time Start time of connect (from g_time3())
+ * @param start_time Start time of connect (from g_get_elapsed_ms())
  * @param timeout Total wait timeout
  * @return 0 - connect succeeded, 1 - Connect failed
  *
  * If the transport is set up for checking a termination object, this
  * on a regular basis.
  */
 static int
-poll_for_async_connect(struct trans *self, int start_time, int timeout)
+poll_for_async_connect(struct trans *self, unsigned int start_time, int timeout)
 {
     int rv = 1;
-    int ms_remaining = timeout - (g_time3() - start_time);
+    int ms_remaining = timeout - (g_get_elapsed_ms() - start_time);
 
     while (ms_remaining > 0)
     {
@@ -736,7 +736,7 @@ poll_for_async_connect(struct trans *self, int start_time, int timeout)
             break;
         }
 
-        ms_remaining = timeout - (g_time3() - start_time);
+        ms_remaining = timeout - (g_get_elapsed_ms() - start_time);
     }
     return rv;
 }
@@ -747,7 +747,7 @@ int
 trans_connect(struct trans *self, const char *server, const char *port,
               int timeout)
 {
-    int start_time = g_time3();
+    unsigned int start_time = g_get_elapsed_ms();
     int error;
     int ms_before_next_connect;
 
@@ -826,7 +826,7 @@ trans_connect(struct trans *self, const char *server, const char *port,
         }
 
         /* Have we reached the total timeout yet? */
-        int ms_left = timeout - (g_time3() - start_time);
+        int ms_left = timeout - (g_get_elapsed_ms() - start_time);
         if (ms_left <= 0)
         {
             error = 1;

sesman/chansrv/chansrv.c

@@ -132,7 +132,7 @@ add_timeout(int msoffset, void (*callback)(void *data), void *data)
     tui32 now;
 
     LOG_DEVEL(LOG_LEVEL_DEBUG, "add_timeout:");
-    now = g_time3();
+    now = g_get_elapsed_ms();
     tobj = g_new0(struct timeout_obj, 1);
     tobj->mstime = now + msoffset;
     tobj->callback = callback;
@@ -167,7 +167,7 @@ get_timeout(int *timeout)
     tobj = g_timeout_head;
     if (tobj != 0)
     {
-        now = g_time3();
+        now = g_get_elapsed_ms();
         while (tobj != 0)
         {
             LOG_DEVEL(LOG_LEVEL_DEBUG, "  now %u tobj->mstime %u", now, tobj->mstime);
@@ -215,7 +215,7 @@ check_timeout(void)
         while (tobj != 0)
         {
             count++;
-            now = g_time3();
+            now = g_get_elapsed_ms();
             if (now >= tobj->mstime)
             {
                 tobj->callback(tobj->data);

sesman/chansrv/sound.c

@@ -71,7 +71,7 @@ static struct trans *g_audio_c_trans_out = 0; /* connection */
 static struct trans *g_audio_l_trans_in = 0;  /* listener */
 static struct trans *g_audio_c_trans_in = 0;  /* connection */
 
-static int    g_training_sent_time = 0;
+static unsigned int g_training_sent_time = 0;
 static int    g_cBlockNo = 0;
 static int    g_bytes_in_stream = 0;
 struct fifo  *g_in_fifo;
@@ -86,7 +86,7 @@ static struct stream *g_stream_incoming_packet = NULL;
 #define MAX_BBUF_SIZE (1024 * 16)
 static char g_buffer[MAX_BBUF_SIZE];
 static int g_buf_index = 0;
-static int g_sent_time[256];
+static unsigned int g_sent_time[256];
 
 static int g_bbuf_size = 1024 * 8; /* may change later */
 
@@ -341,15 +341,15 @@ sound_send_training(void)
 {
     struct stream *s;
     int bytes;
-    int time;
+    unsigned int time;
     char *size_ptr;
 
     make_stream(s);
     init_stream(s, 8182);
     out_uint16_le(s, SNDC_TRAINING);
     size_ptr = s->p;
     out_uint16_le(s, 0); /* size, set later */
-    time = g_time3();
+    time = g_get_elapsed_ms();
     g_training_sent_time = time;
     out_uint16_le(s, time);
     out_uint16_le(s, 1024);
@@ -885,7 +885,7 @@ sound_send_wave_data_chunk(char *data, int data_bytes)
 {
     struct stream *s;
     int bytes;
-    int time;
+    unsigned int time;
     int format_index;
     char *size_ptr;
 
@@ -912,7 +912,7 @@ sound_send_wave_data_chunk(char *data, int data_bytes)
     out_uint16_le(s, SNDC_WAVE);
     size_ptr = s->p;
     out_uint16_le(s, 0); /* size, set later */
-    time = g_time3();
+    time = g_get_elapsed_ms();
     out_uint16_le(s, time);
     out_uint16_le(s, format_index); /* wFormatNo */
     g_cBlockNo++;
@@ -1040,7 +1040,7 @@ sound_process_training(struct stream *s, int size)
 {
     int time_diff;
 
-    time_diff = g_time3() - g_training_sent_time;
+    time_diff = g_get_elapsed_ms() - g_training_sent_time;
     LOG(LOG_LEVEL_INFO, "sound_process_training: round trip time %u", time_diff);
     return 0;
 }
@@ -1052,12 +1052,12 @@ sound_process_wave_confirm(struct stream *s, int size)
 {
     int wTimeStamp;
     int cConfirmedBlockNo;
-    int time;
+    unsigned int time;
     int time_diff;
     int index;
     int acc;
 
-    time = g_time3();
+    time = g_get_elapsed_ms();
     in_uint16_le(s, wTimeStamp);
     in_uint8(s, cConfirmedBlockNo);
     time_diff = time - g_sent_time[cConfirmedBlockNo & 0xff];
@@ -1095,13 +1095,13 @@ static int
 process_pcm_message(int id, int size, struct stream *s)
 {
     static int sending_silence = 0;
-    static int silence_start_time = 0;
+    static unsigned int silence_start_time = 0;
     switch (id)
     {
         case 0:
             if ((g_client_does_fdk_aac || g_client_does_mp3lame) && sending_silence)
             {
-                if ((g_time3() - silence_start_time) < (int)g_cfg->msec_do_not_send)
+                if ((g_get_elapsed_ms() - silence_start_time) < g_cfg->msec_do_not_send)
                 {
                     /* do not send data within msec_do_not_send msec after SNDC_CLOSE is sent, to avoid stutter. setting from sesman.ini */
                     return 0;
@@ -1119,7 +1119,7 @@ process_pcm_message(int id, int size, struct stream *s)
                 if (buf != NULL)
                 {
                     int i;
-                    silence_start_time = g_time3();
+                    silence_start_time = g_get_elapsed_ms();
                     sending_silence = 1;
                     for (i = 0; i < send_silence_times; i++)
                     {

sesman/chansrv/xcommon.c

@@ -85,15 +85,6 @@ xcommon_fatal_handler(Display *dis)
     return 0;
 }
 
-/*****************************************************************************/
-/* returns time in milliseconds since a point in the past
-   this is a time value similar to what the xserver uses */
-int
-xcommon_get_local_time(void)
-{
-    return g_time3();
-}
-
 /******************************************************************************/
 /* this should be called first */
 int

sesman/chansrv/xcommon.h

@@ -28,8 +28,6 @@
 
 typedef void (*x_server_fatal_cb_type)(void);
 
-int
-xcommon_get_local_time(void);
 int
 xcommon_init(void);
 int

xrdp/xrdp.h

@@ -489,8 +489,8 @@ struct display_control_monitor_layout_data
 {
     struct display_size_description description;
     enum display_resize_state state;
-    int last_state_update_timestamp;
-    int start_time;
+    unsigned int last_state_update_timestamp;
+    unsigned int start_time;
     /// This flag is set if the state machine needs to
     /// shutdown/startup EGFX
     int using_egfx;

xrdp/xrdp_mm.c

@@ -1280,9 +1280,9 @@ advance_resize_state_machine(struct xrdp_mm *mm,
               description->description.session_height,
               XRDP_DISPLAY_RESIZE_STATE_TO_STR(description->state),
               XRDP_DISPLAY_RESIZE_STATE_TO_STR(new_state),
-              g_time3() - description->last_state_update_timestamp);
+              g_get_elapsed_ms() - description->last_state_update_timestamp);
     description->state = new_state;
-    description->last_state_update_timestamp = g_time3();
+    description->last_state_update_timestamp = g_get_elapsed_ms();
     g_set_wait_obj(mm->resize_ready);
     return 0;
 }
@@ -1829,7 +1829,7 @@ process_display_control_monitor_layout_data(struct xrdp_wm *wm)
             // ever is, advance the state machine!
             if (chan->drdynvcs[mm->egfx->channel_id].status
                     == XRDP_DRDYNVC_STATUS_CLOSED
-                    || (g_time3() - description->last_state_update_timestamp) > 100)
+                    || (g_get_elapsed_ms() - description->last_state_update_timestamp) > 100)
             {
                 advance_resize_state_machine(mm, WMRZ_EGFX_CONN_CLOSED);
                 break;
@@ -2045,7 +2045,7 @@ dynamic_monitor_process_queue(struct xrdp_mm *self)
                                 g_malloc(LAYOUT_DATA_SIZE, 1);
             g_memcpy(&(self->resize_data->description), queue_head,
                      sizeof(struct display_size_description));
-            const int time = g_time3();
+            const unsigned int time = g_get_elapsed_ms();
             self->resize_data->start_time = time;
             self->resize_data->last_state_update_timestamp = time;
             self->resize_data->using_egfx = (self->egfx != NULL);
@@ -2075,7 +2075,7 @@ dynamic_monitor_process_queue(struct xrdp_mm *self)
             " completed resize (w: %d x h: %d). It took %d milliseconds.",
             self->resize_data->description.session_width,
             self->resize_data->description.session_height,
-            g_time3() - self->resize_data->start_time);
+            g_get_elapsed_ms() - self->resize_data->start_time);
         g_set_wait_obj(self->resize_ready);
     }
     else if (self->resize_data->state == WMRZ_ERROR)
@@ -3532,9 +3532,10 @@ xrdp_mm_get_wait_objs(struct xrdp_mm *self,
     {
         if (xrdp_region_not_empty(self->wm->screen_dirty_region))
         {
-            int now = g_time3();
-            int next_screen_draw_time = self->wm->last_screen_draw_time +
-                                        MIN_MS_BETWEEN_FRAMES;
+            unsigned int now = g_get_elapsed_ms();
+            unsigned int next_screen_draw_time =
+                self->wm->last_screen_draw_time +
+                MIN_MS_BETWEEN_FRAMES;
             int diff = next_screen_draw_time - now;
             int ltimeout = *timeout;
             diff = MAX(diff, MIN_MS_TO_WAIT_FOR_MORE_UPDATES);
@@ -3924,7 +3925,7 @@ xrdp_mm_check_wait_objs(struct xrdp_mm *self)
     {
         if (xrdp_region_not_empty(self->wm->screen_dirty_region))
         {
-            int now = g_time3();
+            unsigned int now = g_get_elapsed_ms();
             int diff = now - self->wm->last_screen_draw_time;
             LOG_DEVEL(LOG_LEVEL_TRACE, "xrdp_mm_check_wait_objs: not empty diff %d", diff);
             if ((diff < 0) || (diff >= 40))

xrdp/xrdp_types.h

@@ -589,7 +589,7 @@ struct xrdp_wm
     struct xrdp_tconfig_gfx *gfx_config;
 
     struct xrdp_region *screen_dirty_region;
-    int last_screen_draw_time;
+    unsigned int last_screen_draw_time;
 };
 
 /* rdp process */