[Buildroot] [PATCH 1/3] Makefile: don't hang the build if there are no file lists

[Thomas De Schampheleire <patrickdepinguin@gmail.com>]

From: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

In very limited configurations, it is possible to have a case where no
.files-list-staging.txt files are created. In this case:

	cat $(sort $(wildcard $(BUILD_DIR)/*/.files-list-staging.txt)) > \
		$(BUILD_DIR)/packages-file-list-staging.txt

becomes:

	cat > \
		$(BUILD_DIR)/packages-file-list-staging.txt

which of course makes the build hang.. forever.

So we fix this by checking the list is not empty. To keep the code
readable, we introduce an intermediate variable to store the list of
these files.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>
---
 Makefile | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/Makefile b/Makefile
index 5455e6662e..29d30a4f70 100644
--- a/Makefile
+++ b/Makefile
@@ -728,6 +728,10 @@ $(TARGETS_ROOTFS): target-finalize
 # Avoid the rootfs name leaking down the dependency chain
 target-finalize: ROOTFS=
 
+TARGET_DIR_FILES_LISTS = $(sort $(wildcard $(BUILD_DIR)/*/.files-list.txt))
+HOST_DIR_FILES_LISTS = $(sort $(wildcard $(BUILD_DIR)/*/.files-list-host.txt))
+STAGING_DIR_FILES_LISTS = $(sort $(wildcard $(BUILD_DIR)/*/.files-list-staging.txt))
+
 .PHONY: host-finalize
 host-finalize: $(PACKAGES) $(HOST_DIR) $(HOST_DIR_SYMLINK)
 	@$(call MESSAGE,"Finalizing host directory")
@@ -808,12 +812,12 @@ endif # merged /usr
 
 	touch $(TARGET_DIR)/usr
 
-	cat $(sort $(wildcard $(BUILD_DIR)/*/.files-list.txt)) > \
-		$(BUILD_DIR)/packages-file-list.txt
-	cat $(sort $(wildcard $(BUILD_DIR)/*/.files-list-host.txt)) > \
-		$(BUILD_DIR)/packages-file-list-host.txt
-	cat $(sort $(wildcard $(BUILD_DIR)/*/.files-list-staging.txt)) > \
-		$(BUILD_DIR)/packages-file-list-staging.txt
+	$(if $(TARGET_DIR_FILES_LISTS), \
+		cat $(TARGET_DIR_FILES_LISTS) > $(BUILD_DIR)/packages-file-list.txt)
+	$(if $(HOST_DIR_FILES_LISTS), \
+		cat $(HOST_DIR_FILES_LISTS) > $(BUILD_DIR)/packages-file-list-host.txt)
+	$(if $(STAGING_DIR_FILES_LISTS), \
+		cat $(STAGING_DIR_FILES_LISTS) > $(BUILD_DIR)/packages-file-list-staging.txt)
 
 .PHONY: target-post-image
 target-post-image: $(TARGETS_ROOTFS) target-finalize staging-finalize
-- 
2.24.1