qubes-libvchan-xen: link against non-versionned xen libraries

Previous workaround to the xen upgrade race condition actually caused
xen to be uninstalled on most systems, breaking the template. This is
thus another approach at fixing the race condition by linking against
non-versionned xen libraries. Thus, a minor version upgrade of xen will
not cause libxenvchan.so to lose xen libraries.

The linking process is changed by adding a step before linking where ld
is linked against libraries where DT_SONAME has been patched with
patchelf. This is not an elegant solution, but it does work. Ideally, we
would find a way for seamless upgrading of xen while the proxy is up.

qubes-libvchan-xen/APKBUILD

@@ -2,17 +2,30 @@
 # Maintainer: Antoine Martin (ayakael) <dev@ayakael.net>
 pkgname=qubes-libvchan-xen
 pkgver=4.2.7
-pkgrel=0
+pkgrel=1
 _gittag=v$pkgver
 pkgdesc="The Qubes core libraries for installation inside a Qubes Dom0 and VM."
 arch="x86_64"
 url="https://github.com/QubesOS/qubes-core-vchan-xen"
 license='GPL'
-makedepends="xen-dev coreutils"
+depends="xen xen-dev"
+makedepends="xen-dev coreutils patchelf"
 builddir="$srcdir"/qubes-core-vchan-xen-$pkgver
 subpackages="$pkgname-dev"
 
-source="$pkgname-$_gittag.tar.gz::https://github.com/QubesOS/qubes-core-vchan-xen/archive/refs/tags/$_gittag.tar.gz"
+source="
+	$pkgname-$_gittag.tar.gz::https://github.com/QubesOS/qubes-core-vchan-xen/archive/refs/tags/$_gittag.tar.gz
+	link-against-patched-libs.patch
+	"
+
+prepare() {
+	default_prepare
+	cd "$builddir"/vchan
+	for i in libxenvchan.so libxenctrl.so; do
+		cp /usr/lib/$i ./
+		patchelf --set-soname $i $i
+	done
+}
 
 build() {
 	cd "$builddir"/vchan
@@ -25,4 +38,5 @@ package() {
 
 sha512sums="
 e6d85407e40ca12df5042ed2ed98d77b6e7b88360e4d6369c3c781c06654246ea81ceabfeae5a506537259fcca3db46f1fc0f1ded5e04e38035601e060fe24ed  qubes-libvchan-xen-v4.2.7.tar.gz
+db33b54121b172dfdbfddb620d56998f1be893608c23b5fbdfe373005650ab012c0462a4a01d8da12611c22c0bb9877c7b42f0bf58871dfc4474386c44ab2249  link-against-patched-libs.patch
 "

qubes-libvchan-xen/link-against-patched-libs.patch

@@ -0,0 +1,13 @@
+diff --git a/vchan/Makefile.linux.orig b/vchan/Makefile.linux
+index 587cb34..cccb5de 100644
+--- a/vchan/Makefile.linux.orig
++++ b/vchan/Makefile.linux
+@@ -34,7 +34,7 @@ CFLAGS += $(shell if printf '%s\n' '4.18.0' '$(XENCTRL_VERSION)' | \
+ SO_VER = 1
+ 
+ libvchan-xen.so.$(SO_VER): init.o io.o
+-	$(CC) $(LDFLAGS) -Wl,-soname,$@ -shared -o $@ $^ -lxenvchan -lxenctrl -lxenstore
++	$(CC) $(LDFLAGS) -Wl,-soname,$@ -shared -o $@ $^ ./libxenvchan.so ./libxenctrl.so -lxenstore
+ 
+ libvchan-xen.so: libvchan-xen.so.$(SO_VER)
+ 	ln -sf $< $@