core/pkg-infra: download git submodules if the package wants them

Add a new package variable that packages can set to specify that they
need git submodules.

Only accept this option if the download method is git, as we can not get
submodules via an http download (via wget).

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Aleksandar Simeonov <aleksandar@barix.com>
Tested-by: Matt Weber <matt@thewebers.ws>
Reviewed-by: Matt Weber <matt@thewebers.ws>
Tested-By: Nicolas Cavallari <nicolas.cavallari@green-communications.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/pkg-download.mk

@@ -76,6 +76,7 @@ export BR_NO_CHECK_HASH_FOR =
 define DOWNLOAD_GIT
 	$(EXTRA_ENV) $(DL_WRAPPER) -b git \
 		-o $(DL_DIR)/$($(PKG)_SOURCE) \
+		$(if $($(PKG)_GIT_SUBMODULES),-r) \
 		$(QUIET) \
 		-- \
 		$($(PKG)_SITE) \

package/pkg-generic.mk

@@ -468,6 +468,14 @@ ifndef $(2)_SITE_METHOD
  endif
 endif
 
+# Do not accept to download git submodule if not using the git method
+ifneq ($$($(2)_GIT_SUBMODULES),)
+ ifneq ($$($(2)_SITE_METHOD),git)
+  $$(error $(2) declares having git sub-modules, but does not use the \
+	   'git' method (uses '$$($(2)_SITE_METHOD)' instead))
+ endif
+endif
+
 ifeq ($$($(2)_SITE_METHOD),local)
 ifeq ($$($(2)_OVERRIDE_SRCDIR),)
 $(2)_OVERRIDE_SRCDIR = $$($(2)_SITE)

support/download/dl-wrapper

@@ -21,15 +21,16 @@ set -e
 
 main() {
     local OPT OPTARG
-    local backend output hfile quiet
+    local backend output hfile recurse quiet
 
     # Parse our options; anything after '--' is for the backend
-    while getopts :hb:o:H:q OPT; do
+    while getopts :hb:o:H:rq OPT; do
         case "${OPT}" in
         h)  help; exit 0;;
         b)  backend="${OPTARG}";;
         o)  output="${OPTARG}";;
         H)  hfile="${OPTARG}";;
+        r)  recurse="-r";;
         q)  quiet="-q";;
         :)  error "option '%s' expects a mandatory argument\n" "${OPTARG}";;
         \?) error "unknown option '%s'\n" "${OPTARG}";;
@@ -82,7 +83,7 @@ main() {
     # If the backend fails, we can just remove the temporary directory to
     # remove all the cruft it may have left behind. Then we just exit in
     # error too.
-    if ! "${OLDPWD}/support/download/${backend}" ${quiet} "${tmpf}" "${@}"; then
+    if ! "${OLDPWD}/support/download/${backend}" ${quiet} ${recurse} "${tmpf}" "${@}"; then
         rm -rf "${tmpd}"
         exit 1
     fi