Add macOS Apple Silicon (arm64) support#51
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macOS (especially Apple Silicon) enforces W^X on the __TEXT segment at the page-table level and caps mprotect by the segment's maxprot. Two issues previously prevented cpp-stub from patching its own text segment on an M-chip Mac: 1. mprotect cannot raise __TEXT to PROT_WRITE|PROT_EXEC. 2. Even with a writable alias obtained via mach_vm_remap, a plain store instruction that happens to sit on the same physical page as the destination deadlocks the current thread. Fixes: * src/stub.h: on __APPLE__, obtain a writable alias of the target page(s) via mach_vm_remap(VM_INHERIT_SHARE) + mach_vm_protect(RW) and route every write through libSystem's memcpy (invoked through a volatile function pointer) so the store opcodes live on libSystem's pages rather than our own __TEXT. The aarch64 REPLACE_FAR macro is specialized for Apple to build the trampoline in a local buffer and memcpy it across. All non-Apple branches keep the original logic. * tool/macos_enable_stub.sh: post-link helper that walks the Mach-O load commands, patches __TEXT's maxprot to rwx, and ad-hoc re-signs the binary with codesign. Required once per test executable (see issue coolxv#49). * test/Makefile.darwin.clang: new Darwin Makefile that drives clang++ and runs macos_enable_stub.sh automatically. * .github/workflows/make-test-multi-platform.yml: enable macOS-13 (Intel) and macOS-latest (Apple Silicon) jobs using the new Makefile, replacing the commented-out stubs. * README / README_zh: document the new macOS support. Verified on macOS 26.4 arm64 (M-chip): test_function, test_class_member_function, test_variadic_function all pass, and repeated set/reset cycles behave correctly. Refs: coolxv#49 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Downstream users no longer need to invoke tool/macos_enable_stub.sh themselves. The repo now ships: * CMakeLists.txt — INTERFACE target cpp-stub. When add_subdirectory'd, a cmake_language(DEFER) callback runs at end-of-config, finds every executable that links cpp-stub, and attaches the enable-stub post-build step automatically on Apple. A cpp_stub_enable(target) helper is exposed for the transitive-link corner case. * mk/cpp-stub.mk — Makefile fragment. Defines CPP_STUB_INCLUDE and a CPP_STUB_POSTLINK macro that expands to the enable-stub invocation on macOS and to ':' (no-op) elsewhere, so one rule works on every platform. * example/cmake_smoke/ — self-contained CMake project that just links cpp-stub and expects the patch+sign to happen with zero manual steps. Exercised by CI on both macos-13 and macos-latest. * test/Makefile.darwin.clang now dogfoods mk/cpp-stub.mk. * README.md / README_zh.md gain a 'macOS integration' section showing the zero-step CMake path, the one-line Make path, and a snippet for Xcode/Bazel/other build systems. * .github/workflows/make-test-multi-platform.yml gains a second step per macOS runner that configures and runs example/cmake_smoke, proving end-to-end that a downstream CMake project need do nothing beyond target_link_libraries(... cpp-stub). Verified locally on macOS 26.4 arm64: CMake smoke + Makefile-based tests all pass, and the existing test matrix (test_function, test_class_member_function, test_variadic_function) is unchanged. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Summary
Adds runtime support for cpp-stub on macOS, including Apple Silicon (M-chip).
Previously, calling
Stub::seton arm64 macOS failed withstub set memory protect to w+r+x faildbecause:mprotectby the Mach-O segment'smaxprot, and__TEXTdefaults tor-x.maxprotisn't enough — you cannot simultaneously hold write + execute on the same physical page via the original mapping.Refs #49.
Changes
src/stub.h: on__APPLE__, obtain a writable alias viamach_vm_remap(VM_INHERIT_SHARE)+mach_vm_protect(RW), and route every write through libSystem'smemcpy(called through avolatilefunction pointer) so the store opcodes are not co-located with the destination. The aarch64REPLACE_FARmacro is specialized for Apple to stage the trampoline in a stack buffer and memcpy it across. All non-Apple branches are unchanged.tool/macos_enable_stub.sh: post-link helper that walks the Mach-O load commands, patches__TEXT'smaxprottorwx, and ad-hoc re-signs withcodesign. Required once per macOS binary that uses cpp-stub.test/Makefile.darwin.clang: Darwin build recipe that filters Linux/Windows-only tests and automatically runs the enable-stub helper on each produced binary..github/workflows/make-test-multi-platform.yml: enablemacos-13(Intel) andmacos-latest(Apple Silicon) matrix entries using the new Makefile; drop the old commented-out macOS stubs.README/README_zh: document the new macOS support.Verification
Locally on macOS 26.4 arm64 (M-chip),
test_function,test_class_member_function, andtest_variadic_functionall pass viamake -f Makefile.darwin.clang. Repeated set/re-set/reset cycles behave correctly. CI will additionally validate onmacos-13(Intel) andmacos-latest(Apple Silicon).