add 'mtime' option

gallery_dl/downloader/http.py

@@ -25,6 +25,7 @@ class HttpDownloader(DownloaderBase):
         self.retries = self.config("retries", extractor._retries)
         self.timeout = self.config("timeout", extractor._timeout)
         self.verify = self.config("verify", extractor._verify)
+        self.mtime = self.config("mtime", True)
         self.rate = self.config("rate")
         self.downloading = False
         self.chunk_size = 16384
@@ -151,9 +152,10 @@ class HttpDownloader(DownloaderBase):
         self.downloading = False
         if adj_ext:
             pathfmt.set_extension(adj_ext)
-        filetime = response.headers.get("Last-Modified")
-        if filetime:
-            pathfmt.keywords["_filetime"] = filetime
+        if self.mtime:
+            filetime = response.headers.get("Last-Modified")
+            if filetime:
+                pathfmt.keywords["_filetime"] = filetime
         return True
 
     def receive(self, response, file):

gallery_dl/downloader/ytdl.py

@@ -27,6 +27,7 @@ class YoutubeDLDownloader(DownloaderBase):
             "socket_timeout": self.config("timeout", extractor._timeout),
             "nocheckcertificate": not self.config("verify", extractor._verify),
             "nopart": not self.part,
+            "updatetime": self.config("mtime", True),
         }
         options.update(self.config("raw-options") or {})
 

gallery_dl/option.py

@@ -182,6 +182,12 @@ def build_parser():
         dest="part", nargs=0, action=ConfigConstAction, const=False,
         help="Do not use .part files",
     )
+    downloader.add_argument(
+        "--no-mtime",
+        dest="mtime", nargs=0, action=ConfigConstAction, const=False,
+        help=("Do not set file modification times according to "
+              "Last-Modified HTTP response headers")
+    )
     downloader.add_argument(
         "--no-check-certificate",
         dest="verify", nargs=0, action=ConfigConstAction, const=False,