build: make git sub-modules to fetch configurable

Currently the git protocol downloads all submodules of the target
repository. This can be unwieldy for repositories with a lot of submodules
where only a subset are required in the context of the OpenWrt build.

This change adds a PKG_SOURCE_SUBMODULES variable to configure this
behavior. It takes a space-separated list of submodule paths, or the word
"skip" to disable submodule downloads entirely. The default is to download
all submodules, i.e. preserving current behavior.

Signed-off-by: Karsten Sperling <ksperling@apple.com>

scripts/dl_github_archive.py

@@ -239,6 +239,7 @@ class DownloadGitHubTarball(object):
         self.version = args.version
         self.subdir = args.subdir
         self.source = args.source
+        self.submodules = args.submodules
         self.url = args.url
         self._init_owner_repo()
         self.xhash = args.hash
@@ -249,6 +250,8 @@ class DownloadGitHubTarball(object):
 
     def download(self):
         """Download and repack GitHub archive tarball."""
+        if self.submodules and self.submodules != ['skip']:
+            raise self._error('Fetching submodules is not yet supported')
         self._init_commit_ts()
         with Path(TMPDIR_DL, keep=True) as dir_dl:
             # fetch tarball from GitHub
@@ -262,7 +265,7 @@ class DownloadGitHubTarball(object):
                     dir0 = os.path.join(dir_untar.path, tarball_prefix)
                     dir1 = os.path.join(dir_untar.path, self.subdir)
                     # submodules check
-                    if self._has_submodule(dir0):
+                    if self.submodules != ['skip'] and self._has_submodule(dir0):
                         raise self._error('Fetching submodules is not yet supported')
                     # rename subdir
                     os.rename(dir0, dir1)
@@ -415,6 +418,7 @@ def main():
     parser.add_argument('--version', help='Source code version')
     parser.add_argument('--source', help='Source tarball filename')
     parser.add_argument('--hash', help='Source tarball\'s expected sha256sum')
+    parser.add_argument('--submodules', nargs='*', help='List of submodules, or "skip"')
     args = parser.parse_args()
     try:
         method = DownloadGitHubTarball(args)