Fix: CDRIVER-4050: Set the correct uploadDate on GridFS files

Previously used the time from bson_get_monotonic_time(), which is
incorrect on most systems, as it is usually realtive to the system
uptime and is stored as microseconds, whereas uploadDate should be
stored as number of milliseconds since the Unix Epoch.

Author: vector-of-bool

src/libbson/src/bson/bson-clock.c

@@ -98,6 +98,29 @@ bson_gettimeofday (struct timeval *tv) /* OUT */
 }
 
 
+/*
+ *--------------------------------------------------------------------------
+ *
+ * bson_get_real_time_ms --
+ *
+ * Returns:
+ *       The current number of milliseconds that have elapsed since the
+ *       Unix Epoch.
+ *
+ * Side effects:
+ *       None.
+ *
+ *--------------------------------------------------------------------------
+ */
+int64_t
+bson_get_real_time_ms (void)
+{
+   struct timeval tv;
+   const bool ok = bson_gettimeofday (&tv);
+   return tv.tv_sec * 1000 + tv.tv_usec / 1000;
+}
+
+
 /*
  *--------------------------------------------------------------------------
  *

src/libbson/src/bson/bson-clock.h

@@ -33,6 +33,8 @@ BSON_EXPORT (int64_t)
 bson_get_monotonic_time (void);
 BSON_EXPORT (int)
 bson_gettimeofday (struct timeval *tv);
+BSON_EXPORT (int64_t)
+bson_get_real_time_ms (void);
 
 
 BSON_END_DECLS

src/libmongoc/src/mongoc/mongoc-gridfs-bucket-file.c

@@ -491,7 +491,7 @@ _mongoc_gridfs_bucket_file_save (mongoc_gridfs_bucket_file_t *file)
    BSON_APPEND_VALUE (&new_doc, "_id", file->file_id);
    BSON_APPEND_INT64 (&new_doc, "length", file->length);
    BSON_APPEND_INT32 (&new_doc, "chunkSize", file->chunk_size);
-   BSON_APPEND_DATE_TIME (&new_doc, "uploadDate", bson_get_monotonic_time ());
+   BSON_APPEND_DATE_TIME (&new_doc, "uploadDate", bson_get_real_time_ms ());
    BSON_APPEND_UTF8 (&new_doc, "filename", file->filename);
    if (file->metadata) {
       BSON_APPEND_DOCUMENT (&new_doc, "metadata", file->metadata);

src/libmongoc/src/mongoc/mongoc-gridfs-file.c

@@ -337,7 +337,7 @@ _mongoc_gridfs_file_new (mongoc_gridfs_t *gridfs, mongoc_gridfs_file_opt_t *opt)
    file->files_id.value_type = BSON_TYPE_OID;
    bson_oid_init (&file->files_id.value.v_oid, NULL);
 
-   file->upload_date = ((int64_t) time (NULL)) * 1000;
+   file->upload_date = bson_get_real_time_ms ();
 
    if (opt->md5) {
       file->md5 = bson_strdup (opt->md5);