From de6258290571377ba1e2c6a934ff9cb15d51df0a Mon Sep 17 00:00:00 2001
From: Tomasz Gajewski <tomga@wp.pl>
Date: Fri, 19 Feb 2021 23:51:04 +0100
Subject: [PATCH] prepare_port: simple cache for downloads

Fixes #4028
---
 tool/ports/mk/install.mk             | 13 ++++++++++++-
 tool/ports/mk/prepare_single_port.mk |  1 +
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/tool/ports/mk/install.mk b/tool/ports/mk/install.mk
index 6fe5271abf..c4501ce6ab 100644
--- a/tool/ports/mk/install.mk
+++ b/tool/ports/mk/install.mk
@@ -188,16 +188,24 @@ _svn_dir = $(call _assert,$(DIR($1)),Missing declaration of DIR($*))
 
 _file_name = $(call _prefer,$(NAME($1)),$(notdir $(URL($1))))
 
+#
 # Some downloads are available via HTTPS only, but wget < 3.14 does not support
 # server-name identification, which is used by some sites. So, we disable
 # certificate checking in wget and check the validity of the download via SIG
 # or SHA.
+#
+# Successful and integrity-checked downloads are cached at the
+# GENODE_CONTRIB_CACHE directory. The combination of 'cp' and 'mv' when
+# populating the cache prevents corrupted files in the cache when the disk is
+# full.
+#
 
 %.file:
 	$(VERBOSE)test -n "$(URL($*))" ||\
 		($(ECHO) "Error: Undefined URL for $(call _file_name,$*)"; false);
 	$(VERBOSE)mkdir -p $(dir $(call _file_name,$*))
-	$(VERBOSE)name=$(call _file_name,$*);\
+	$(VERBOSE)name=$(call _file_name,$*); cached_name=$(GENODE_CONTRIB_CACHE)/$(SHA($*))_$$name; \
+		(test -f $$name || ! test -f $$cached_name || cp $$cached_name $$name); \
 		(test -f $$name || $(MSG_DOWNLOAD)$(URL($*))); \
 		(test -f $$name || wget --quiet --no-check-certificate $(URL($*)) -O $$name) || \
 			($(ECHO) Error: Download for $* failed; false)
@@ -205,6 +213,9 @@ _file_name = $(call _prefer,$(NAME($1)),$(notdir $(URL($1))))
 		($(ECHO) "$(SHA($*))  $(call _file_name,$*)" |\
 		sha256sum -c > /dev/null 2> /dev/null) || \
 			($(ECHO) Error: Hash sum check for $* failed; false)
+	$(VERBOSE)name=$(call _file_name,$*); cached_name=$(GENODE_CONTRIB_CACHE)/$(SHA($*))_$$name; \
+		mkdir -p $(GENODE_CONTRIB_CACHE); \
+		(test -f $$cached_name || (cp $$name $$cached_name.tmp && mv $$cached_name.tmp $$cached_name))
 
 
 ##
diff --git a/tool/ports/mk/prepare_single_port.mk b/tool/ports/mk/prepare_single_port.mk
index fe903ff981..a4c3f46754 100755
--- a/tool/ports/mk/prepare_single_port.mk
+++ b/tool/ports/mk/prepare_single_port.mk
@@ -9,6 +9,7 @@
 # 'create_builddir' tool within the Genode source tree
 #
 export GENODE_DIR := $(realpath $(dir $(MAKEFILE_LIST))/../../..)
+export GENODE_CONTRIB_CACHE ?= $(GENODE_DIR)/contrib/cache
 
 include $(GENODE_DIR)/tool/ports/mk/front_end.inc
 include $(GENODE_DIR)/tool/ports/mk/check_port_arg.inc