Fix libpython3.12 dlopen crash on Android: set SONAME at link time, drop patchelf (#7)

* revert patchelf changes

* fix(android-3.12): set libpython SONAME at link time

CPython 3.12's Makefile rule for libpython only passes -Wl,-soname
when INSTSONAME != LDLIBRARY. On Android both equal libpython3.X.so,
so the else branch runs and the shipped libpython carries no
DT_SONAME.

Author: ndonkoHenri

.github/workflows/build-python-version.yml

@@ -83,11 +83,6 @@ jobs:
         with:
           python-version: ${{ env.PYTHON_VERSION }}
       - run: python --version
-      - name: Install build deps
-        # patchelf is used by android/build.sh (3.12 path) to set SONAME
-        # on libpython3.X.so, which CPython's Makefile rule otherwise
-        # skips when LDLIBRARY==INSTSONAME (the Android case).
-        run: sudo apt-get update && sudo apt-get install -y patchelf
       - working-directory: android
         shell: bash
         run: |

android/build.sh

@@ -51,7 +51,11 @@ if [ $version_int -le 312 ]; then
     patches+=" soname"
 fi
 if [ $version_int -eq 312 ]; then
-    patches+=" bldlibrary grp"
+    # soname_linktime: makes CPython's Makefile rule emit -Wl,-soname even
+    # when INSTSONAME == LDLIBRARY (the Android case), so the shipped
+    # libpython3.X.so carries DT_SONAME. 3.13+ already gets this from its official
+    # Android tooling; this 3.12-only patch matches that behavior at link time.
+    patches+=" soname_linktime bldlibrary grp"
 fi
 for name in $patches; do
     patch_file="$script_dir/patches/$name.patch"
@@ -140,24 +144,6 @@ if [ $version_int -le 312 ]; then
     make -j $CPU_COUNT
     make install prefix=$PREFIX
 
-    # CPython's Makefile rule for libpython skips `-Wl,-soname` when
-    # INSTSONAME == LDLIBRARY, which is the case on Android (both are
-    # `libpython3.X.so`). The shipped libpython3.X.so therefore has no
-    # DT_SONAME, so consumer wheels record whichever name the linker
-    # was asked for in DT_NEEDED — e.g. a `-lpython3` resolved via a
-    # `libpython3.so` shim writes `libpython3.so` instead of the right
-    # `libpython3.X.so`. Patching the SONAME in here makes consumer
-    # DT_NEEDED entries correct regardless of how the link was reached.
-    # 3.13+ uses CPython's official Android tooling, which sets SONAME
-    # natively, so this branch only needs the post-install fix.
-    if command -v patchelf >/dev/null 2>&1; then
-        patchelf --set-soname "libpython$version_short.so" \
-            "$PREFIX/lib/libpython$version_short.so"
-    else
-        echo "WARNING: patchelf not installed; libpython$version_short.so will lack SONAME." >&2
-        echo "         Consumer wheels may end up with the wrong DT_NEEDED entry." >&2
-    fi
-
     echo ">>> Replacing host platform"
     sed -i -e "s/_PYTHON_HOST_PLATFORM=.*/_PYTHON_HOST_PLATFORM=android-$api_level-$abi/" $PREFIX/lib/python$version_short/config-$version_short/Makefile
 else

android/patches/soname_linktime.patch

@@ -0,0 +1,25 @@
+CPython 3.12's libpython link rule only passes -Wl,-soname when
+INSTSONAME != LDLIBRARY. On Android both equal "libpython3.X.so", so
+the else branch runs and the shipped libpython has no DT_SONAME.
+Consumer wheels' DT_NEEDED then records whatever name the linker saw
+(e.g. "libpython3.so" via a shim), and the device fails to dlopen at
+runtime.
+
+Adding -Wl,-h$(INSTSONAME) to the else branch makes ld stamp the
+SONAME during the actual link — same shape of fix as CPython 3.13's
+official Android tooling. Avoids needing a post-process patchelf step
+(which on NDK r27d interacts badly with llvm-strip and produces a
+PT_LOAD whose p_offset and p_vaddr violate the ELF spec's
+`p_offset ≡ p_vaddr (mod p_align)` requirement, breaking dlopen on
+strict bionic and crashing Py_Initialize on permissive bionic).
+
+--- a/Makefile.pre.in
++++ b/Makefile.pre.in
+@@ -819,5 +819,5 @@ libpython$(LDVERSION).so: $(LIBRARY_OBJS) $(DTRACE_OBJS)
+ 		$(BLDSHARED) -Wl,-h$(INSTSONAME) -o $(INSTSONAME) $(LIBRARY_OBJS) $(MODLIBS) $(SHLIBS) $(LIBC) $(LIBM); \
+ 		$(LN) -f $(INSTSONAME) $@; \
+ 	else \
+-		$(BLDSHARED) -o $@ $(LIBRARY_OBJS) $(MODLIBS) $(SHLIBS) $(LIBC) $(LIBM); \
++		$(BLDSHARED) -Wl,-h$(INSTSONAME) -o $@ $(LIBRARY_OBJS) $(MODLIBS) $(SHLIBS) $(LIBC) $(LIBM); \
+ 	fi
+