Fix dynlib loading

Author: zanieb

cpython-unix/build-cpython.sh

@@ -616,21 +616,41 @@ if [ "${PYBUILD_SHARED}" = "1" ]; then
         LIBPYTHON_SHARED_LIBRARY_BASENAME=libpython${PYTHON_MAJMIN_VERSION}${PYTHON_BINARY_SUFFIX}.so.1.0
         LIBPYTHON_SHARED_LIBRARY=${ROOT}/out/python/install/lib/${LIBPYTHON_SHARED_LIBRARY_BASENAME}
 
-        # If we simply set DT_RUNPATH via --set-rpath, LD_LIBRARY_PATH would be used before
-        # DT_RUNPATH, which could result in confusion at run-time. But if DT_NEEDED
-        # contains a slash, the explicit path is used.
-        patchelf --replace-needed ${LIBPYTHON_SHARED_LIBRARY_BASENAME} "\$ORIGIN/../lib/${LIBPYTHON_SHARED_LIBRARY_BASENAME}" \
-            ${ROOT}/out/python/install/bin/python${PYTHON_MAJMIN_VERSION}
-
-        # libpython3.so isn't present in debug builds.
-        if [ -z "${CPYTHON_DEBUG}" ]; then
-            patchelf --replace-needed ${LIBPYTHON_SHARED_LIBRARY_BASENAME} "\$ORIGIN/../lib/${LIBPYTHON_SHARED_LIBRARY_BASENAME}" \
-                ${ROOT}/out/python/install/lib/libpython3.so
-        fi
-
-        if [ -n "${PYTHON_BINARY_SUFFIX}" ]; then
+        if [ "${CC}" == "musl-clang" ]; then
+            # musl does not support $ORIGIN in DT_NEEDED, so we use RPATH instead. This could be
+            # problematic, i.e., we could load the shared library from the wrong location — but
+            # there's not a clear alternative at this time. The longterm solution is likely to
+            # statically link to libpython instead.
+            patchelf --set-rpath "\$ORIGIN/../lib" \
+                ${ROOT}/out/python/install/bin/python${PYTHON_MAJMIN_VERSION}
+
+            # libpython3.so isn't present in debug builds.
+            if [ -z "${CPYTHON_DEBUG}" ]; then
+                patchelf --set-rpath "\$ORIGIN/../lib" \
+                    ${ROOT}/out/python/install/lib/libpython3.so
+            fi
+
+            if [ -n "${PYTHON_BINARY_SUFFIX}" ]; then
+                patchelf --set-rpath "\$ORIGIN/../lib" \
+                    ${ROOT}/out/python/install/bin/python${PYTHON_MAJMIN_VERSION}${PYTHON_BINARY_SUFFIX}
+            fi
+        else
+            # If we simply set DT_RUNPATH via --set-rpath, LD_LIBRARY_PATH would be used before
+            # DT_RUNPATH, which could result in confusion at run-time. But if DT_NEEDED contains a
+            # slash, the explicit path is used.
             patchelf --replace-needed ${LIBPYTHON_SHARED_LIBRARY_BASENAME} "\$ORIGIN/../lib/${LIBPYTHON_SHARED_LIBRARY_BASENAME}" \
-                ${ROOT}/out/python/install/bin/python${PYTHON_MAJMIN_VERSION}${PYTHON_BINARY_SUFFIX}
+                ${ROOT}/out/python/install/bin/python${PYTHON_MAJMIN_VERSION}
+
+            # libpython3.so isn't present in debug builds.
+            if [ -z "${CPYTHON_DEBUG}" ]; then
+                patchelf --replace-needed ${LIBPYTHON_SHARED_LIBRARY_BASENAME} "\$ORIGIN/../lib/${LIBPYTHON_SHARED_LIBRARY_BASENAME}" \
+                    ${ROOT}/out/python/install/lib/libpython3.so
+            fi
+
+            if [ -n "${PYTHON_BINARY_SUFFIX}" ]; then
+                patchelf --replace-needed ${LIBPYTHON_SHARED_LIBRARY_BASENAME} "\$ORIGIN/../lib/${LIBPYTHON_SHARED_LIBRARY_BASENAME}" \
+                    ${ROOT}/out/python/install/bin/python${PYTHON_MAJMIN_VERSION}${PYTHON_BINARY_SUFFIX}
+            fi
         fi
     fi
 fi