[RFC 04/15] linux-module: Do not use shell environment

[Anton Mikanovich <amikan@ilbers.de>]

To make package build process independent of the shell environment we
should remove KDIR and PN passing through export call.
KDIR can be prepared during package build. This also will allow not to
rely on previous builddeps install task.
To pass PN variable we can just migrate to template-based debian/rules
file.

Signed-off-by: Anton Mikanovich <amikan@ilbers.de>
---
 .../files/debian/{rules => rules.tmpl}        | 10 +++++++-
 meta/recipes-kernel/linux-module/module.inc   | 23 +++++++------------
 2 files changed, 17 insertions(+), 16 deletions(-)
 rename meta/recipes-kernel/linux-module/files/debian/{rules => rules.tmpl} (55%)

diff --git a/meta/recipes-kernel/linux-module/files/debian/rules b/meta/recipes-kernel/linux-module/files/debian/rules.tmpl
similarity index 55%
rename from meta/recipes-kernel/linux-module/files/debian/rules
rename to meta/recipes-kernel/linux-module/files/debian/rules.tmpl
index c476bf3..39abc52 100755
--- a/meta/recipes-kernel/linux-module/files/debian/rules
+++ b/meta/recipes-kernel/linux-module/files/debian/rules.tmpl
@@ -24,11 +24,19 @@ ifneq (,$(findstring 86,$(DEB_HOST_GNU_CPU)))
 export ARCH=x86
 endif
 
+# Custom kernels contain the build folder directly.
+KDIR := $(shell dpkg -L linux-headers-${KERNEL_NAME} | grep "/lib/modules/.*/build")
+ifeq ($(KDIR),)
+# Debian kernels install that folder indirectly via a dependency.
+KERNEL_DEP := $(shell dpkg-query -W -f '$${Depends}' linux-headers-${KERNEL_NAME} | sed 's/.*\(linux-headers-[[:graph:]]*\).*/\1/')
+KDIR := $(shell dpkg -L $(KERNEL_DEP) | grep "/lib/modules/.*/build")
+endif
+
 override_dh_auto_build:
 	$(MAKE) -C $(KDIR) M=$(PWD) modules
 
 override_dh_auto_install:
-	$(MAKE) -C $(KDIR) M=$(PWD) INSTALL_MOD_PATH=$(PWD)/debian/$(PN) modules_install
+	$(MAKE) -C $(KDIR) M=$(PWD) INSTALL_MOD_PATH=$(PWD)/debian/${PN} modules_install
 
 %:
 	CFLAGS= LDFLAGS= dh $@ --parallel
diff --git a/meta/recipes-kernel/linux-module/module.inc b/meta/recipes-kernel/linux-module/module.inc
index 0515621..5b08623 100644
--- a/meta/recipes-kernel/linux-module/module.inc
+++ b/meta/recipes-kernel/linux-module/module.inc
@@ -22,8 +22,9 @@ AUTOLOAD ?= ""
 inherit dpkg
 
 TEMPLATE_FILES = "debian/control.tmpl \
-                  debian/changelog.tmpl"
-TEMPLATE_VARS += "KERNEL_NAME"
+                  debian/changelog.tmpl \
+                  debian/rules.tmpl"
+TEMPLATE_VARS += "KERNEL_NAME PN"
 
 do_prepare_build() {
     cp -r ${WORKDIR}/debian ${S}/
@@ -31,18 +32,10 @@ do_prepare_build() {
     for module in "${AUTOLOAD}"; do
         echo "echo $module >> /etc/modules" >> ${S}/debian/postinst
     done
-}
 
-dpkg_runbuild_prepend() {
-    # Custom kernels contain the build folder directly.
-    export KDIR=$(dpkg -L --root=${BUILDCHROOT_DIR} linux-headers-${KERNEL_NAME} | \
-                  grep "/lib/modules/.*/build")
-    if [ -z "$KDIR" ]; then
-        # Debian kernels install that folder indirectly via a dependency.
-        KERNEL_DEP=$(dpkg-query -W -f '${Depends}' --admindir=${BUILDCHROOT_DIR}/var/lib/dpkg \
-                     linux-headers-${KERNEL_NAME} | sed 's/.*\(linux-headers-[[:graph:]]*\).*/\1/')
-        export KDIR=$(dpkg -L --root=${BUILDCHROOT_DIR} ${KERNEL_DEP} | \
-                      grep "/lib/modules/.*/build")
-    fi
-    export PN=${PN}
+    # remove templates from the source tree
+    find ${S}/debian -name *.tmpl | xargs rm -f
+
+    # restore execute permissions
+    chmod a+x ${S}/debian/rules
 }
-- 
2.25.1