extension: Add support for building from source

So we can support environments for which wheels cannot be uploaded to
PyPI, such as Termux on Android.

Author: oleavr

setup.py

@@ -1,4 +1,5 @@
 import os
+import platform
 import shutil
 
 from setuptools import setup
@@ -22,6 +23,65 @@ def build_extension(self, ext):
         shutil.copyfile(frida_extension, target)
 
 
+class FridaMissingDevkitBuildExt(build_ext):
+    def build_extension(self, ext):
+        raise RuntimeError(
+            "Need frida-core devkit to build from source.\n"
+            "Download one from https://github.com/frida/frida/releases, "
+            "extract it to a directory,\n"
+            "and then add an environment variable named FRIDA_CORE_DEVKIT "
+            "pointing at the directory."
+        )
+
+
+include_dirs = []
+library_dirs = []
+libraries = []
+extra_link_args = []
+
+cmdclass = {}
+if frida_extension is not None:
+    cmdclass["build_ext"] = FridaPrebuiltExt
+else:
+    devkit_dir = os.environ.get("FRIDA_CORE_DEVKIT", None)
+    if devkit_dir is not None:
+        include_dirs += [devkit_dir]
+        library_dirs += [devkit_dir]
+        libraries += ["frida-core"]
+
+        system = platform.system()
+        if system == "Windows":
+            pass
+        elif system == "Darwin":
+            extra_link_args += [
+                "-Wl,-exported_symbol,_PyInit__frida",
+                "-Wl,-dead_strip",
+            ]
+        else:
+            version_script = os.path.join(package_dir, "src", "_frida.version")
+            if not os.path.exists(version_script):
+                with open(version_script, "w", encoding="utf-8") as f:
+                    f.write(
+                        "\n".join(
+                            [
+                                "{",
+                                "  global:",
+                                "    PyInit__frida;",
+                                "",
+                                "  local:",
+                                "    *;",
+                                "};",
+                            ]
+                        )
+                    )
+            extra_link_args += [
+                f"-Wl,--version-script,{version_script}",
+                "-Wl,--gc-sections",
+            ]
+    else:
+        cmdclass["build_ext"] = FridaMissingDevkitBuildExt
+
+
 if __name__ == "__main__":
     setup(
         name="frida",
@@ -60,7 +120,17 @@ def build_extension(self, ext):
         ],
         packages=["frida", "_frida"],
         package_data={"frida": ["py.typed"], "_frida": ["py.typed", "__init__.pyi"]},
-        ext_modules=[Extension("_frida", [], py_limited_api=True)],
-        cmdclass={"build_ext": FridaPrebuiltExt},
+        ext_modules=[
+            Extension(
+                name="_frida",
+                sources=["src/_frida.c"],
+                include_dirs=include_dirs,
+                library_dirs=library_dirs,
+                libraries=libraries,
+                extra_link_args=extra_link_args,
+                py_limited_api=True,
+            )
+        ],
+        cmdclass=cmdclass,
         zip_safe=False,
     )

src/_frida.c

@@ -6,7 +6,7 @@
 
 #include <frida-core.h>
 #include <string.h>
-#ifdef G_OS_UNIX
+#if defined (G_OS_UNIX) && !defined (G_TYPE_UNIX_SOCKET_ADDRESS_TYPE)
 # include <gio/gunixsocketaddress.h>
 #endif