Merge pull request #24992 from gnossen/fix_grpc_tools_so_mac_symbols
Fix visibility of libprotobuf symbols in protoc_compiler.so on Mac
diff --git a/tools/distrib/python/grpcio_tools/setup.py b/tools/distrib/python/grpcio_tools/setup.py
index 164088b..a316038 100644
--- a/tools/distrib/python/grpcio_tools/setup.py
+++ b/tools/distrib/python/grpcio_tools/setup.py
@@ -44,6 +44,12 @@
import protoc_lib_deps
import grpc_version
+_EXT_INIT_SYMBOL = None
+if sys.version_info[0] == 2:
+ _EXT_INIT_SYMBOL = "init_protoc_compiler"
+else:
+ _EXT_INIT_SYMBOL = "PyInit__protoc_compiler"
+
_parallel_compile_patch.monkeypatch_compile_maybe()
CLASSIFIERS = [
@@ -118,6 +124,28 @@
EXTRA_ENV_COMPILE_ARGS += ' -fno-wrapv -frtti'
if EXTRA_ENV_LINK_ARGS is None:
EXTRA_ENV_LINK_ARGS = ''
+ # NOTE(rbellevi): Clang on Mac OS will make all static symbols (both
+ # variables and objects) global weak symbols. When a process loads the
+ # protobuf wheel's shared object library before loading *this* C extension,
+ # the runtime linker will prefer the protobuf module's version of symbols.
+ # This results in the process using a mixture of symbols from the protobuf
+ # wheel and this wheel, which may be using different versions of
+ # libprotobuf. In the case that they *are* using different versions of
+ # libprotobuf *and* there has been a change in data layout (or in other
+ # invariants) segfaults, data corruption, or "bad things" may happen.
+ #
+ # This flag ensures that on Mac, the only global symbol is the one loaded by
+ # the Python interpreter. The problematic global weak symbols become local
+ # weak symbols. This is not required on Linux since the compiler does not
+ # produce global weak symbols. This is not required on Windows as our ".pyd"
+ # file does not contain any symbols.
+ #
+ # Finally, the leading underscore here is part of the Mach-O ABI. Unlike
+ # more modern ABIs (ELF et al.), Mach-O prepends an underscore to the names
+ # of C functions.
+ if "darwin" in sys.platform:
+ EXTRA_ENV_LINK_ARGS += ' -Wl,-exported_symbol,_{}'.format(
+ _EXT_INIT_SYMBOL)
if "linux" in sys.platform or "darwin" in sys.platform:
EXTRA_ENV_LINK_ARGS += ' -lpthread'
if check_linker_need_libatomic():
