AP_Logger: fix timestamp on log files opened before GPS lock

libraries/AP_Logger/AP_Logger_File.cpp

@@ -883,6 +883,11 @@ uint16_t AP_Logger_File::start_new_log(void)
         write_fd_semaphore.give();
         return 0xFFFF;
     }
+
+    // remember if we had utc time when we opened the file
+    uint64_t utc_usec;
+    _need_rtc_update = !AP::rtc().get_utc_usec(utc_usec);
+
     EXPECT_DELAY_MS(3000);
 #if HAL_OS_POSIX_IO
     _write_fd = ::open(_write_filename, O_WRONLY|O_CREAT|O_TRUNC|O_CLOEXEC, 0666);
@@ -1058,7 +1063,24 @@ void AP_Logger_File::_io_timer(void)
         ::fsync(_write_fd);
         last_io_operation = "";
 #endif
+
+#if CONFIG_HAL_BOARD == HAL_BOARD_CHIBIOS
+        // ChibiOS does not update mtime on writes, so if we opened
+        // without knowing the time we should update it later
+        if (_need_rtc_update) {
+            uint64_t utc_usec;
+            if (AP::rtc().get_utc_usec(utc_usec)) {
+                struct utimbuf t {};
+                t.modtime = utc_usec / (1000UL * 1000UL);
+                t.actime = t.modtime;
+                // we ignore return on utime() as there is nothing useful we can do
+                (void)utime(_write_filename, &t);
+                _need_rtc_update = false;
+            }
+        }
+#endif
     }
+
     write_fd_semaphore.give();
     hal.util->perf_end(_perf_write);
 }

libraries/AP_Logger/AP_Logger_File.h

@@ -67,6 +67,7 @@ private:
     int _write_fd;
     char *_write_filename;
     uint32_t _last_write_ms;
+    bool _need_rtc_update;
     
     int _read_fd;
     uint16_t _read_fd_log_num;