From 0a9b12b8c5d7e8f4a4746543e714fb44d6e82ddf Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Wed, 29 Nov 2017 19:15:40 +0100
Subject: Display warning for clueless ROM developers

---
 Android.mk       | 14 ++++++++++++++
 version-check.sh |  6 ++++++
 2 files changed, 20 insertions(+)
 create mode 100755 version-check.sh

diff --git a/Android.mk b/Android.mk
index 953bece..d3ad721 100644
--- a/Android.mk
+++ b/Android.mk
@@ -4,10 +4,24 @@ fetch:
 	cd $(WIREGUARD_PATH) && ./fetch.sh
 
 TARGET_KERNEL_BINARIES: patch-wireguard
+ifeq ($(shell $(WIREGUARD_PATH)/version-check.sh "$(TARGET_KERNEL_SOURCE)" && echo compatible),compatible)
 patch-wireguard: fetch
 	ln -vsfT "$$(realpath --relative-to="$(TARGET_KERNEL_SOURCE)/net)" "$(WIREGUARD_PATH)/wireguard/src" || readlink -f "$(WIREGUARD_PATH)/wireguard/src")" "$(TARGET_KERNEL_SOURCE)/net/wireguard"
 	grep -q wireguard "$(TARGET_KERNEL_SOURCE)/net/Makefile" || sed -i "/^obj-\\\$$(CONFIG_NETFILTER).*+=/a obj-\$$(CONFIG_WIREGUARD) += wireguard/" "$(TARGET_KERNEL_SOURCE)/net/Makefile"
 	grep -q wireguard "$(TARGET_KERNEL_SOURCE)/net/Kconfig" || sed -i "/^if INET\$$/a source \"net/wireguard/Kconfig\"" "$(TARGET_KERNEL_SOURCE)/net/Kconfig"
+else
+patch-wireguard:
+	@echo -e "\e[1;37;41m=================================================\e[0m" >&2
+	@echo -e "\e[1;37;41m+            WARNING WARNING WARNING            +\e[0m" >&2
+	@echo -e "\e[1;37;41m+                                               +\e[0m" >&2
+	@echo -e "\e[1;37;41m+ You are trying to build WireGuard into a      +\e[0m" >&2
+	@echo -e "\e[1;37;41m+ kernel that is too old to run it. Please use  +\e[0m" >&2
+	@echo -e "\e[1;37;41m+ kernel >=3.10. This build will NOT have       +\e[0m" >&2
+	@echo -e "\e[1;37;41m+ WireGuard. You likely added this to your      +\e[0m" >&2
+	@echo -e "\e[1;37;41m+ local_manifest.xml without understanding this +\e[0m" >&2
+	@echo -e "\e[1;37;41m+ requirement. Sorry for the inconvenience.     +\e[0m" >&2
+	@echo -e "\e[1;37;41m=================================================\e[0m" >&2
+endif
 
 .PHONY: patch-wireguard fetch
 
diff --git a/version-check.sh b/version-check.sh
new file mode 100755
index 0000000..a85f023
--- /dev/null
+++ b/version-check.sh
@@ -0,0 +1,6 @@
+#!/bin/bash
+set -e
+[[ -n $1 && -f $1/Makefile ]]
+[[ $(< "$1/Makefile") =~ VERSION[[:space:]]*=[[:space:]]*([0-9]+).*PATCHLEVEL[[:space:]]*=[[:space:]]*([0-9]+).*SUBLEVEL[[:space:]]*=[[:space:]]*([0-9]+) ]]
+LINUX_VERSION_CODE=$(( (${BASH_REMATCH[1]} << 16) | (${BASH_REMATCH[2]} << 8) | ${BASH_REMATCH[3]} ))
+(( LINUX_VERSION_CODE >= ((3 << 16) | (10 << 8) | 0) ))
-- 
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