rust-bin: use linker to set rpath

Patchelf should be reserved for when the ELF cannot be generated
correctly in the first place. This is not the case here because we have
control over the linker flags. The limitation is that -C link-args can
only be specified once, so consolidate the generation of link-args. Also
introduce some new intermediate variables in link-args generation for
customization.

Patchelf was running only in ${PKGD} because patching the ELF in ${D}
would cause objcopy to fail when splitting the debug sections. This is
not a problem when setting it correctly in the linker. The benefit is
that the rpath is correct in the sysroot as well.

This also switches the rpaths to be relative so that they work in both
the sysroot and the target in the same way.

Signed-off-by: Tyler Hall <tyler.hall@lexmark.com>
Signed-off-by: Steven Walter <swalter@lexmark.com>

classes/rust-bin.bbclass

@@ -1,6 +1,5 @@
 inherit rust
 
-DEPENDS_append = " patchelf-native"
 RDEPENDS_${PN} += "${RUSTLIB_DEP}"
 
 RUSTC_ARCHFLAGS += "-C opt-level=3 -g -L ${STAGING_DIR_HOST}/${rustlibdir} -C linker=${RUST_TARGET_CCLD}"
@@ -37,6 +36,44 @@ CRATE_TYPE ?= "dylib"
 BIN_SRC ?= "${S}/src/main.rs"
 LIB_SRC ?= "${S}/src/lib.rs"
 
+rustbindest ?= "${bindir}"
+rustlibdest ?= "${rustlibdir}"
+RUST_RPATH_ABS ?= "${rustlibdir}:${rustlib}"
+
+def relative_rpaths(paths, base):
+    relpaths = set()
+    for p in paths.split(':'):
+        if p == base:
+            relpaths.add('$ORIGIN')
+            continue
+        relpaths.add(os.path.join('$ORIGIN', os.path.relpath(p, base)))
+    return '-rpath=' + ':'.join(relpaths) if len(relpaths) else ''
+
+RUST_LIB_RPATH_FLAGS ?= "${@relative_rpaths(d.getVar('RUST_RPATH_ABS', True), d.getVar('rustlibdest', True))}"
+RUST_BIN_RPATH_FLAGS ?= "${@relative_rpaths(d.getVar('RUST_RPATH_ABS', True), d.getVar('rustbindest', True))}"
+
+def libfilename(d):
+    if d.getVar('CRATE_TYPE', True) == 'dylib':
+        return d.getVar('LIBNAME', True) + '.so'
+    else:
+        return d.getVar('LIBNAME', True) + '.rlib'
+
+def link_args(d, bin):
+    linkargs = []
+    if bin:
+        rpaths = d.getVar('RUST_BIN_RPATH_FLAGS', False)
+    else:
+        rpaths = d.getVar('RUST_LIB_RPATH_FLAGS', False)
+        if d.getVar('CRATE_TYPE', True) == 'dylib':
+            linkargs.append('-soname')
+            linkargs.append(libfilename(d))
+    if len(rpaths):
+        linkargs.append(rpaths)
+    if len(linkargs):
+        return ' '.join(['-Wl,' + arg for arg in linkargs])
+    else:
+        return ''
+
 get_overlap_externs () {
     externs=
     for dep in ${OVERLAP_DEPS}; do
@@ -62,17 +99,16 @@ oe_runrustc () {
 }
 
 oe_compile_rust_lib () {
-    [ "${CRATE_TYPE}" == "dylib" ] && suffix=so || suffix=rlib
     rm -rf ${LIBNAME}.{rlib,so}
     local -a link_args
-    if [ "${CRATE_TYPE}" == "dylib" ]; then
-        link_args[0]="-C"
-        link_args[1]="link-args=-Wl,-soname -Wl,${LIBNAME}.$suffix"
+    if [ -n '${@link_args(d, False)}' ]; then
+        link_args[0]='-C'
+        link_args[1]='link-args=${@link_args(d, False)}'
     fi
     oe_runrustc $(get_overlap_externs) \
         "${link_args[@]}" \
         ${LIB_SRC} \
-        -o ${LIBNAME}.$suffix \
+        -o ${@libfilename(d)} \
         --crate-name=${CRATE_NAME} --crate-type=${CRATE_TYPE} \
         "$@"
 }
@@ -80,20 +116,27 @@ oe_compile_rust_lib[vardeps] += "get_overlap_externs"
 
 oe_compile_rust_bin () {
     rm -rf ${BINNAME}
-    oe_runrustc $(get_overlap_externs) ${BIN_SRC} -o ${BINNAME} "$@"
+    local -a link_args
+    if [ -n '${@link_args(d, True)}' ]; then
+        link_args[0]='-C'
+        link_args[1]='link-args=${@link_args(d, True)}'
+    fi
+    oe_runrustc $(get_overlap_externs) \
+        "${link_args[@]}" \
+        ${BIN_SRC} -o ${BINNAME} "$@"
 }
 oe_compile_rust_bin[vardeps] += "get_overlap_externs"
 
 oe_install_rust_lib () {
     for lib in $(ls ${LIBNAME}.{so,rlib} 2>/dev/null); do
         echo Installing $lib
-        install -D -m 755 $lib ${D}/${rustlibdir}/$lib
+        install -D -m 755 $lib ${D}/${rustlibdest}/$lib
     done
 }
 
 oe_install_rust_bin () {
     echo Installing ${BINNAME}
-    install -D -m 755 ${BINNAME} ${D}/${bindir}/${BINNAME}
+    install -D -m 755 ${BINNAME} ${D}/${rustbindest}/${BINNAME}
 }
 
 do_rust_bin_fixups() {
@@ -101,13 +144,6 @@ do_rust_bin_fixups() {
         echo "Strip rust note: $f"
         ${OBJCOPY} -R .note.rustc $f $f
     done
-
-    for f in `find ${PKGD}`; do
-        file "$f" | grep -q ELF || continue
-        readelf -d "$f" | grep RUNPATH | grep -q rustlib || continue
-        echo "Set rpath:" "$f"
-        patchelf --set-rpath '$ORIGIN:'${rustlibdir}:${rustlib} "$f"
-    done
 }
 PACKAGE_PREPROCESS_FUNCS += "do_rust_bin_fixups"