libyang-legacy: split a v3 ABI compat package from libyang

Build a second package from the same libyang 3.13.6 tarball, so
consumers bound to the v3 ABI keep working once libyang moves to 5.x.
It ships only /usr/lib/libyang.so.3* and stages its headers, library
and .pc under /usr/lib/libyang-legacy to avoid colliding with libyang.

All in-tree consumers are switched to it here; the commits that follow
move libnetconf2, sysrepo and netopeer2 back to +libyang as their
upstream releases gain v5 support. frr stays on the legacy ABI.

Signed-off-by: Alexandru Ardelean <alex@shruggie.ro>

libs/libnetconf2/Makefile

@@ -25,14 +25,15 @@ include $(INCLUDE_DIR)/package.mk
 include $(INCLUDE_DIR)/cmake.mk
 
 CMAKE_OPTIONS += \
-	-DENABLE_PAM=OFF
+	-DENABLE_PAM=OFF \
+	-DCMAKE_PREFIX_PATH=$(STAGING_DIR)/usr/lib/libyang-legacy
 
 define Package/libnetconf2
   SECTION:=libs
   CATEGORY:=Libraries
   TITLE:=NETCONF library
   URL:=https://github.com/CESNET/libnetconf2
-  DEPENDS:= +libyang +libcurl +libssh +libopenssl +libpthread
+  DEPENDS:=+libyang-legacy +libcurl +libssh +libopenssl +libpthread
 endef
 
 define Package/libnetconf2/description

libs/libyang-legacy/Makefile

@@ -0,0 +1,71 @@
+#
+# Copyright (C) 2017 OpenWrt.org
+#
+# This is free software, licensed under the GNU General Public License v2.
+# See /LICENSE for more information.
+#
+
+include $(TOPDIR)/rules.mk
+
+PKG_NAME:=libyang-legacy
+PKG_VERSION:=3.13.6
+PKG_RELEASE:=1
+
+PKG_SOURCE:=libyang-$(PKG_VERSION).tar.gz
+PKG_SOURCE_URL:=https://codeload.github.com/CESNET/libyang/tar.gz/v$(PKG_VERSION)?
+PKG_HASH:=5cd5018f39c830f97d70616c003990287ce5e820ae2792763a49e2a1f63af8d6
+
+PKG_BUILD_DIR:=$(BUILD_DIR)/libyang-$(PKG_VERSION)
+
+PKG_MAINTAINER:=Alexandru Ardelean <ardeleanalex@gmail.com>
+PKG_LICENSE:=BSD-3-Clause
+PKG_LICENSE_FILES:=LICENSE
+PKG_CPE_ID:=cpe:/a:cesnet:libyang
+
+CMAKE_INSTALL:=1
+CMAKE_BINARY_SUBDIR:=build
+
+include $(INCLUDE_DIR)/package.mk
+include $(INCLUDE_DIR)/cmake.mk
+
+define Package/libyang-legacy
+  SECTION:=libs
+  CATEGORY:=Libraries
+  TITLE:=YANG data modeling language library (legacy v3 ABI)
+  URL:=https://github.com/CESNET/libyang
+  DEPENDS:=+libpcre2 +libpthread +libxxhash
+endef
+
+define Package/libyang-legacy/description
+  libyang-legacy ships the libyang 3.x runtime (libyang.so.3) for binaries
+  still linked against the legacy ABI. It is install-time co-installable
+  with libyang 5.x (libyang.so.5), whose SONAME differs.
+
+  Build-time consumers should point CMAKE_PREFIX_PATH (or PKG_CONFIG_PATH)
+  at $$$$(STAGING_DIR)/usr/lib/libyang-legacy so that the legacy headers,
+  library and pkg-config file are picked up in preference to libyang 5.x.
+endef
+
+# Staged under a self-contained /usr/lib/libyang-legacy prefix, with a
+# sysroot-relative .pc prefix so pkg-config does not double-prepend.
+define Build/InstallDev
+	$(INSTALL_DIR) $(1)/usr/lib/libyang-legacy/include
+	$(CP) $(PKG_INSTALL_DIR)/usr/include/libyang \
+		$(1)/usr/lib/libyang-legacy/include/
+	$(INSTALL_DIR) $(1)/usr/lib/libyang-legacy/lib
+	$(CP) $(PKG_INSTALL_DIR)/usr/lib/libyang.so* \
+		$(1)/usr/lib/libyang-legacy/lib/
+	$(INSTALL_DIR) $(1)/usr/lib/libyang-legacy/lib/pkgconfig
+	sed -e 's|^prefix=.*|prefix=/usr/lib/libyang-legacy|' \
+	    -e 's|^libdir=.*|libdir=$${prefix}/lib|' \
+	    -e 's|^includedir=.*|includedir=$${prefix}/include|' \
+		$(PKG_INSTALL_DIR)/usr/lib/pkgconfig/libyang.pc \
+		> $(1)/usr/lib/libyang-legacy/lib/pkgconfig/libyang.pc
+endef
+
+define Package/libyang-legacy/install
+	$(INSTALL_DIR) $(1)/usr/lib
+	$(CP) $(PKG_INSTALL_DIR)/usr/lib/libyang.so.3* $(1)/usr/lib/
+endef
+
+$(eval $(call BuildPackage,libyang-legacy))

libs/libyang-legacy/test.sh

@@ -0,0 +1,15 @@
+#!/bin/sh
+
+case "$1" in
+	libyang-legacy)
+		# Runtime-only; the unversioned symlink belongs to libyang 5.x.
+		[ -e /usr/lib/libyang.so.3 ] || {
+			echo "libyang.so.3 not found" >&2
+			exit 1
+		}
+		;;
+	*)
+		echo "Unsupported test target: $1" >&2
+		exit 1
+		;;
+esac

net/frr/Makefile

@@ -74,13 +74,14 @@ define Package/frr/Default
   CATEGORY:=Network
   SUBMENU:=Routing and Redirection
   URL:=https://www.frrouting.org/
-  DEPENDS:=frr
+  # Spelled out: apk's soname resolution would pick libyang 5.x.
+  DEPENDS:=frr +libyang-legacy
 endef
 
 define Package/frr
   $(call Package/frr/Default)
   DEPENDS:=+librt +libatomic +libcap +libncurses +libjson-c +libreadline \
-    +libyang +libprotobuf-c +FRR_OPENSSL:libopenssl +FRR_SNMP:libnetsnmp +more
+    +libyang-legacy +libprotobuf-c +FRR_OPENSSL:libopenssl +FRR_SNMP:libnetsnmp +more
   TITLE:=The FRRouting (FRR) Software Routing Suite
   MENU:=1
 endef
@@ -153,7 +154,16 @@ define Package/frr/conffiles
 /etc/frr/vtysh.conf
 endef
 
-TARGET_LDFLAGS += -Wl,--gc-sections,--as-needed -latomic
+# frr needs the v3 ABI; its configure looks libyang up three ways
+# (PKG_CHECK_MODULES, pkg-config --modversion, AC_CHECK_LIB), so all of
+# LDFLAGS, LIBYANG_* and PKG_CONFIG_PATH point at the legacy prefix.
+TARGET_LDFLAGS += -Wl,--gc-sections,--as-needed -latomic \
+	-L$(STAGING_DIR)/usr/lib/libyang-legacy/lib
+
+CONFIGURE_VARS += \
+	LIBYANG_CFLAGS="-I$(STAGING_DIR)/usr/lib/libyang-legacy/include" \
+	LIBYANG_LIBS="-L$(STAGING_DIR)/usr/lib/libyang-legacy/lib -lyang" \
+	PKG_CONFIG_PATH="$(STAGING_DIR)/usr/lib/libyang-legacy/lib/pkgconfig:$$$$PKG_CONFIG_PATH"
 
 define Host/Configure
 	$(Host/Configure/Default)

net/netopeer2/Makefile

@@ -29,7 +29,7 @@ define Package/netopeer2-server
   CATEGORY:=Utilities
   TITLE:=NETCONF server
   URL:=https://github.com/CESNET/Netopeer2
-  DEPENDS:=+libcurl +libpthread +libyang +libnetconf2 +libsysrepo +sysrepocfg +sysrepoctl +sysrepo
+  DEPENDS:=+libcurl +libpthread +libyang-legacy +libnetconf2 +libsysrepo +sysrepocfg +sysrepoctl +sysrepo
   MENU:=1
 endef
 
@@ -38,7 +38,7 @@ define Package/netopeer2-cli
   CATEGORY:=Utilities
   TITLE:=Netopeer2 cli tool
   URL:=https://github.com/CESNET/Netopeer2
-  DEPENDS:=+libpthread +libyang +libnetconf2 +libopenssl
+  DEPENDS:=+libpthread +libyang-legacy +libnetconf2 +libopenssl
 endef
 
 define Package/netopeer2/description
@@ -51,7 +51,8 @@ endef
 CMAKE_OPTIONS += \
 	-DCMAKE_INSTALL_PREFIX:PATH=/usr \
 	-DCMAKE_BUILD_TYPE:STRING=Release \
-	-DSYSREPO_SETUP:BOOL=OFF
+	-DSYSREPO_SETUP:BOOL=OFF \
+	-DCMAKE_PREFIX_PATH=$(STAGING_DIR)/usr/lib/libyang-legacy
 
 define Package/netopeer2-server/install
 	$(INSTALL_DIR) $(1)/usr/bin

net/sysrepo/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=sysrepo
 PKG_VERSION:=3.7.11
-PKG_RELEASE:=3
+PKG_RELEASE:=4
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=https://codeload.github.com/sysrepo/sysrepo/tar.gz/v$(PKG_VERSION)?
@@ -29,7 +29,7 @@ define Package/libsysrepo
   CATEGORY:=Libraries
   TITLE:=YANG-based data store library
   URL:=https://www.sysrepo.org/
-  DEPENDS:=+libyang $(ATOMIC64_DEPENDS) +libprotobuf-c +libev +librt +libpthread
+  DEPENDS:=+libyang-legacy $(ATOMIC64_DEPENDS) +libprotobuf-c +libev +librt +libpthread
 endef
 
 define Package/sysrepo
@@ -71,7 +71,8 @@ CMAKE_OPTIONS += \
 	-DCMAKE_BUILD_TYPE="Package" \
 	-DREPOSITORY_LOC:PATH=/etc/sysrepo \
 	-DCALL_TARGET_BINS_DIRECTLY=OFF \
-	-DGEN_LANGUAGE_BINDINGS:BOOL=TRUE
+	-DGEN_LANGUAGE_BINDINGS:BOOL=TRUE \
+	-DCMAKE_PREFIX_PATH=$(STAGING_DIR)/usr/lib/libyang-legacy
 
 define Package/libsysrepo/install
 	$(INSTALL_DIR) $(1)/usr/lib