Fix potential buffer overflows when calling sprintf

1. Replace sprintf with snprintf, which is safer
2. An unsigned int or unsigned long int requires 11 bytes to print
   (including the null terminator)
3. Use PRIu16 macro to print uint16_t
4. Format string "#%2d %2d:%02d:%02d.%02d\n" in
   StopWatch::stopLapBtnEventHandler() requires at least 17 bytes.
   The 16-byte buffer would clearly be overrun if sprintf were used.

src/components/datetime/DateTimeController.cpp

@@ -140,9 +140,9 @@ std::string DateTime::FormattedTime() {
       hour12 = (hour == 12) ? 12 : hour - 12;
       amPmStr = "PM";
     }
-    sprintf(buff, "%i:%02i %s", hour12, minute, amPmStr);
+    snprintf(buff, sizeof(buff), "%i:%02i %s", hour12, minute, amPmStr);
   } else {
-    sprintf(buff, "%02i:%02i", hour, minute);
+    snprintf(buff, sizeof(buff), "%02i:%02i", hour, minute);
   }
   return std::string(buff);
 }

src/displayapp/screens/StopWatch.cpp

@@ -198,11 +198,11 @@ void StopWatch::stopLapBtnEventHandler() {
         continue;
       }
       TimeSeparated_t times = convertTicksToTimeSegments(laps[i]);
-      char buffer[16];
+      char buffer[17];
       if (times.hours == 0) {
-        sprintf(buffer, "#%2d   %2d:%02d.%02d\n", i + 1, times.mins, times.secs, times.hundredths);
+        snprintf(buffer, sizeof(buffer), "#%2d   %2d:%02d.%02d\n", i + 1, times.mins, times.secs, times.hundredths);
       } else {
-        sprintf(buffer, "#%2d %2d:%02d:%02d.%02d\n", i + 1, times.hours, times.mins, times.secs, times.hundredths);
+        snprintf(buffer, sizeof(buffer), "#%2d %2d:%02d:%02d.%02d\n", i + 1, times.hours, times.mins, times.secs, times.hundredths);
       }
       lv_label_ins_text(lapText, LV_LABEL_POS_LAST, buffer);
     }

src/displayapp/screens/SystemInfo.cpp

@@ -236,9 +236,9 @@ std::unique_ptr<Screen> SystemInfo::CreateScreen4() {
   auto nb = uxTaskGetSystemState(tasksStatus, maxTaskCount, nullptr);
   std::sort(tasksStatus, tasksStatus + nb, sortById);
   for (uint8_t i = 0; i < nb && i < maxTaskCount; i++) {
-    char buffer[7] = {0};
+    char buffer[11] = {0};
 
-    sprintf(buffer, "%lu", tasksStatus[i].xTaskNumber);
+    snprintf(buffer, sizeof(buffer), "%lu", tasksStatus[i].xTaskNumber);
     lv_table_set_cell_value(infoTask, i + 1, 0, buffer);
     switch (tasksStatus[i].eCurrentState) {
       case eReady:
@@ -262,9 +262,9 @@ std::unique_ptr<Screen> SystemInfo::CreateScreen4() {
     lv_table_set_cell_value(infoTask, i + 1, 1, buffer);
     lv_table_set_cell_value(infoTask, i + 1, 2, tasksStatus[i].pcTaskName);
     if (tasksStatus[i].usStackHighWaterMark < 20) {
-      sprintf(buffer, "%d low", tasksStatus[i].usStackHighWaterMark);
+      snprintf(buffer, sizeof(buffer), "%" PRIu16 " low", tasksStatus[i].usStackHighWaterMark);
     } else {
-      sprintf(buffer, "%d", tasksStatus[i].usStackHighWaterMark);
+      snprintf(buffer, sizeof(buffer), "%" PRIu16, tasksStatus[i].usStackHighWaterMark);
     }
     lv_table_set_cell_value(infoTask, i + 1, 3, buffer);
   }

src/displayapp/screens/Twos.cpp

@@ -242,7 +242,7 @@ void Twos::updateGridDisplay() {
     const unsigned int col = i % nCols;
     if (grid[row][col].value > 0) {
       char buffer[7];
-      sprintf(buffer, "%d", grid[row][col].value);
+      snprintf(buffer, sizeof(buffer), "%u", grid[row][col].value);
       lv_table_set_cell_value(gridDisplay, row, col, buffer);
     } else {
       lv_table_set_cell_value(gridDisplay, row, col, "");

src/displayapp/screens/settings/SettingDisplay.cpp

@@ -46,7 +46,7 @@ SettingDisplay::SettingDisplay(Pinetime::Applications::DisplayApp* app, Pinetime
   char buffer[12];
   for (unsigned int i = 0; i < options.size(); i++) {
     cbOption[i] = lv_checkbox_create(container1, nullptr);
-    sprintf(buffer, "%2ds", options[i] / 1000);
+    snprintf(buffer, sizeof(buffer), "%2" PRIu16 "s", options[i] / 1000);
     lv_checkbox_set_text(cbOption[i], buffer);
     cbOption[i]->user_data = this;
     lv_obj_set_event_cb(cbOption[i], event_handler);