From 2bf569c6e4fa936b4d809b0517647db58b240cb8 Mon Sep 17 00:00:00 2001
From: Frank Hunleth <fhunleth@troodon-software.com>
Date: Tue, 21 Jun 2016 13:08:17 -0400
Subject: [PATCH] toolchain: allow crosstool-ng musl toolchains

Currently, if using a crosstool-ng-generated external musl toolchain,
Buildroot exits with "Incorrect selection of the C library".

The musl.codu.org cross-compilers put their libraries in <sysroot>/lib
while crosstool-ng uses <sysroot>/usr/lib. This change checks that
location for libc.so and updates the ld-musl-$ARCH.so.1 symlink.

Signed-off-by: Frank Hunleth <fhunleth@troodon-software.com>
---
 toolchain/helpers.mk                                   |  2 +-
 toolchain/toolchain-external/pkg-toolchain-external.mk |  6 +++++-
 toolchain/toolchain/toolchain.mk                       | 14 ++++++++------
 3 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/toolchain/helpers.mk b/toolchain/helpers.mk
index 72e7292..42b69ee 100644
--- a/toolchain/helpers.mk
+++ b/toolchain/helpers.mk
@@ -209,7 +209,7 @@ check_glibc = \
 # $1: sysroot directory
 check_musl = \
 	SYSROOT_DIR="$(strip $1)"; \
-	if test ! -f $${SYSROOT_DIR}/lib/libc.so -o -e $${SYSROOT_DIR}/lib/libm.so ; then \
+	if test ! \( -f $${SYSROOT_DIR}/lib/libc.so -o -f $${SYSROOT_DIR}/usr/lib/libc.so \) -o -e $${SYSROOT_DIR}/lib/libm.so ; then \
 		echo "Incorrect selection of the C library" ; \
 		exit -1; \
 	fi
diff --git a/toolchain/toolchain-external/pkg-toolchain-external.mk b/toolchain/toolchain-external/pkg-toolchain-external.mk
index 11a1bf5..ce37173 100644
--- a/toolchain/toolchain-external/pkg-toolchain-external.mk
+++ b/toolchain/toolchain-external/pkg-toolchain-external.mk
@@ -488,7 +488,11 @@ else
 MUSL_ARCH = $(ARCH)
 endif
 define TOOLCHAIN_EXTERNAL_MUSL_LD_LINK
-	ln -sf libc.so $(TARGET_DIR)/lib/ld-musl-$(MUSL_ARCH).so.1
+	if [ -e $(STAGING_DIR)/usr/lib/libc.so ]; then \
+	    ln -sf ../usr/lib/libc.so $(TARGET_DIR)/lib/ld-musl-$(MUSL_ARCH).so.1 ; \
+	else \
+	    ln -sf libc.so $(TARGET_DIR)/lib/ld-musl-$(MUSL_ARCH).so.1 ; \
+	fi
 endef
 endif
 
diff --git a/toolchain/toolchain/toolchain.mk b/toolchain/toolchain/toolchain.mk
index b16db01..258068d 100644
--- a/toolchain/toolchain/toolchain.mk
+++ b/toolchain/toolchain/toolchain.mk
@@ -24,12 +24,14 @@ TOOLCHAIN_ADD_TOOLCHAIN_DEPENDENCY = NO
 # [1] http://www.openwall.com/lists/musl/2015/10/08/2
 ifeq ($(BR2_TOOLCHAIN_USES_MUSL),y)
 define TOOLCHAIN_MUSL_KERNEL_HEADERS_COMPATIBILITY_HACK
-	$(SED) 's/^#if defined(__GLIBC__)$$/#if 1/' \
-		$(STAGING_DIR)/usr/include/linux/libc-compat.h
-	$(SED) '1s/^/#define __USE_MISC\n/' \
-		$(STAGING_DIR)/usr/include/linux/libc-compat.h
-	$(SED) '1s/^/#define __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO 0\n/' \
-		$(STAGING_DIR)/usr/include/linux/libc-compat.h
+	if [ -e $(STAGING_DIR)/usr/include/linux/libc-compat.h ]; then \
+		$(SED) 's/^#if defined(__GLIBC__)$$/#if 1/' \
+			$(STAGING_DIR)/usr/include/linux/libc-compat.h; \
+		$(SED) '1s/^/#define __USE_MISC\n/' \
+			$(STAGING_DIR)/usr/include/linux/libc-compat.h; \
+		$(SED) '1s/^/#define __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO 0\n/' \
+			$(STAGING_DIR)/usr/include/linux/libc-compat.h; \
+	fi
 endef
 TOOLCHAIN_POST_INSTALL_STAGING_HOOKS += TOOLCHAIN_MUSL_KERNEL_HEADERS_COMPATIBILITY_HACK
 TOOLCHAIN_INSTALL_STAGING = YES
-- 
2.7.4