How to build Python-4-Android for the x86

Currently the Py4A project only compiles for the ARM architecture.

The following patch for the python-build sub-directory allows you to cross-compile Py4A for the x86 architecture. The patch consists in:

1. Adding a set of new files to support the x86 architecture (including creating a new libffi/linux-x86/ directory):
   
   libffi/linux-x86/ffi.h
   libffi/linux-x86/fficonfig.h
   setup-x86.cfg
2. changing the build.sh script to accept a new parameter - the Android ABI (for example 'armeabi' or 'x86') - so that the script can call
   
   ndk-build APP_ABI:=x86
   
   to trigger the cross-compilation for the x86 processor;
3. changing the build.py script to parametrize the GCC strip command and the selection of the setup.cfg configuration file based on the input ABI;
4. changing the libffi/Android.mk makefile to select the right set of source files based on the input ABI;
5. changing the libffi/include/ffi_real.h header file to redefine FFI_TYPE_LONGDOUBLE to 4;
6. changing the openssl/crypto/Android.mk and openssl/ssl/Android.mk makefiles to strip down the openssl library with only the bare minimum set that allows you to cross-compile the source code;
7. changing the  python/jni/modules.mk makefile to add the -fno-stack-protector compiler and linker option when building the _socket module and exclude the openssl module.

After applying the patch, to cross-compile Py4A for the x86 architecture you should run the following:

$ cd python-build

$ ./build.sh x86

Binaries for the x86 can be downloaded here:

• python_extras_r14.zip
• python-lib_r16.zip
• python_r16.zip
• python_scripts_r13.zip

--- orig/python/jni/modules.mk    2013-01-21 14:39:56.000000000 -0500
+++ python/jni/modules.mk    2013-01-29 14:58:52.922096000 -0500
@@ -58,7 +58,7 @@ $(call build-module,  syslog ,  Modules/
 $(call build-module,  audioop ,  Modules/audioop.c )
 $(call build-module,  imageop ,  Modules/imageop.c )
 $(call build-module,  _csv ,  Modules/_csv.c )
-$(call build-module,  _socket ,  Modules/socketmodule.c, libc, -lc, -nostdlib )
+$(call build-module,  _socket ,  Modules/socketmodule.c, libc, -lc -fno-stack-protector, -nostdlib -fno-stack-protector )
 $(call build-module,  _sha ,  Modules/shamodule.c )
 $(call build-module,  _md5 ,  Modules/md5module.c Modules/md5.c )
 $(call build-module,  _sha256 ,  Modules/sha256module.c )
@@ -125,6 +125,7 @@ include $(BUILD_SHARED_LIBRARY)
 
 #$(call build-module,  _ssl ,  Modules/_ssl.c, ssl crypto )
 
+ifneq ($(APP_ABI), x86)
 $(call import-module, openssl)
 LOCAL_PATH :=  $(PYTHON_SRC_PATH)
 LOCAL_C_INCLUDES += $(PYTHON_SRC_PATH) $(PYTHON_SRC_PATH)/Include $(OPENSSL)/include $(OPENSSL)
@@ -133,6 +134,7 @@ LOCAL_MODULE_FILENAME := _ssl
 LOCAL_SRC_FILES := Modules/_ssl.c
 LOCAL_SHARED_LIBRARIES := libpython2.6 libcrypto libssl
 include $(BUILD_SHARED_LIBRARY)
+endif
 
 
 $(call import-module, libffi)
--- orig/setup-x86.cfg    1969-12-31 19:00:00.000000000 -0500
+++ setup-x86.cfg    2013-01-28 16:09:49.004463929 -0500
@@ -0,0 +1,2 @@
+[bdist_egg]
+plat-name=linux-x86
--- orig/openssl/ssl/Android.mk    2013-01-21 14:42:17.000000000 -0500
+++ openssl/ssl/Android.mk    2013-01-28 16:33:35.563643087 -0500
@@ -7,6 +7,10 @@ local_c_includes := \
 
 include $(CLEAR_VARS)
 
+ifeq ($(APP_ABI), x86)
+LOCAL_SRC_FILES:= \
+    kssl.c
+else
 LOCAL_SRC_FILES:= \
     s2_meth.c \
     s2_srvr.c \
@@ -45,6 +49,7 @@ LOCAL_SRC_FILES:= \
     bio_ssl.c \
     ssl_err.c \
     kssl.c
+endif
 
 include $(LOCAL_PATH)/../android-config.mk
 
--- orig/openssl/crypto/Android.mk    2013-01-21 14:42:08.000000000 -0500
+++ openssl/crypto/Android.mk    2013-01-29 14:49:00.334324159 -0500
@@ -2,27 +2,17 @@ LOCAL_PATH:= $(call my-dir)
 include $(CLEAR_VARS)
 
 LOCAL_CFLAGS += -DOPENSSL_BN_ASM_MONT -DAES_ASM -DSHA1_ASM -DSHA256_ASM -DSHA512_ASM -DOPENSSL_NO_STATIC_ENGINE
+ifneq ($(APP_ABI), x86)
 LOCAL_SRC_FILES:= 0.9.9-dev/bn/armv4-mont.s \
                   0.9.9-dev/aes/aes-armv4.s \
                   0.9.9-dev/sha/sha1-armv4-large.s \
                   0.9.9-dev/sha/sha256-armv4.s \
                   0.9.9-dev/sha/sha512-armv4.s
-
 LOCAL_SRC_FILES+= \
-    cryptlib.c \
-    mem.c \
-    mem_clr.c \
     mem_dbg.c \
-    cversion.c \
     dyn_lck.c \
     ex_data.c \
-    tmdiff.c \
     cpt_err.c \
-    ebcdic.c \
-    uid.c \
-    o_time.c \
-    o_str.c \
-    o_dir.c \
     aes/aes_misc.c \
     aes/aes_ecb.c \
     aes/aes_cbc.c \
@@ -474,6 +464,19 @@ LOCAL_SRC_FILES+= \
     ripemd/rmd_dgst.c \
     ripemd/rmd_one.c \
     evp/m_ripemd.c
+endif
+
+LOCAL_SRC_FILES+= \
+    cryptlib.c \
+    mem.c \
+    mem_clr.c \
+    cversion.c \
+    tmdiff.c \
+    ebcdic.c \
+    uid.c \
+    o_time.c \
+    o_str.c \
+    o_dir.c
 
 LOCAL_CFLAGS += -DNO_WINDOWS_BRAINDEATH
 
--- orig/build.py    2013-01-21 14:44:17.000000000 -0500
+++ build.py    2013-01-28 16:19:35.088015089 -0500
@@ -82,6 +82,10 @@ def rm(path):
 
 
 def strip(path):
+  if len(sys.argv) > 1:
+    if sys.argv[1] == "x86":
+      run('i686-linux-android-strip %s' % path)
+    else:
   run('arm-linux-androideabi-strip %s' % path)
 
 
@@ -153,6 +157,12 @@ map(rm, find('output.temp/usr/lib/python
 map(rm, find('output.temp', 'python$', exclude=['setuptools', 'distutils'])[0])
 run("mkdir python", cwd="output.temp/usr")
 run("cp -r %s/python-libs/py4a python" % pwd, cwd="output.temp/usr")
+if len(sys.argv) > 1:
+    if sys.argv[1] == "x86":
+        run("cp %s/setup-x86.cfg ." % pwd, cwd="output.temp/usr")
+    else:
+        run("cp %s/setup.cfg ." % pwd, cwd="output.temp/usr")
+else:
 run("cp %s/setup.cfg ." % pwd, cwd="output.temp/usr")
 run("cp %s/prepare_setuptools.sh setup.sh" % pwd, cwd="output.temp/usr")
 run("cp %s/standalone_python.sh python.sh" % pwd, cwd="output.temp/usr")
--- orig/libffi/include/ffi_real.h    2013-01-21 14:42:35.000000000 -0500
+++ libffi/include/ffi_real.h    2013-01-29 10:27:30.664550823 -0500
@@ -371,8 +371,12 @@ void ffi_call(ffi_cif *cif,
 #if CONF_HAVE_LONG_DOUBLE       // android changed
 #define FFI_TYPE_LONGDOUBLE 4
 #else
+#ifdef x86
+#define FFI_TYPE_LONGDOUBLE 4
+#else
 #define FFI_TYPE_LONGDOUBLE FFI_TYPE_DOUBLE
 #endif
+#endif
 #define FFI_TYPE_UINT8      5  
 #define FFI_TYPE_SINT8      6
 #define FFI_TYPE_UINT16     7
--- orig/libffi/Android.mk    2013-01-21 14:42:42.000000000 -0500
+++ libffi/Android.mk    2013-01-28 17:00:21.190897854 -0500
@@ -21,6 +21,17 @@ include $(CLEAR_VARS)
 
 LOCAL_MODULE := ffi
 LOCAL_MODULE_FILENAME :=
+ifeq ($(APP_ABI), x86)
+    LOCAL_SRC_FILES := src/x86/sysv.S \
+    src/x86/ffi.c \
+    src/debug.c \
+    src/java_raw_api.c \
+    src/prep_cif.c \
+    src/raw_api.c \
+    src/types.c
+
+    LOCAL_C_INCLUDES := $(LOCAL_PATH)/include $(LOCAL_PATH)/linux-x86
+else
 LOCAL_SRC_FILES := src/arm/sysv.S \
     src/arm/ffi.c \
     src/debug.c \
@@ -30,6 +41,7 @@ LOCAL_SRC_FILES := src/arm/sysv.S \
     src/types.c
 
 LOCAL_C_INCLUDES := $(LOCAL_PATH)/include $(LOCAL_PATH)/linux-arm
+endif
 LOCAL_EXPORT_C_INCLUDES := $(LOCAL_C_INCLUDES)
 
 $(call __ndk_info, Building libffi)
--- orig/libffi/linux-x86/ffi.h    1969-12-31 19:00:00.000000000 -0500
+++ libffi/linux-x86/ffi.h    2013-01-28 16:24:28.975890002 -0500
@@ -0,0 +1,10 @@
+/*
+ * Copyright 2008 The Android Open Source Project
+ */
+#ifndef LIBFFI_H
+
+#define x86
+#include "../src/x86/ffitarget.h"
+#include "../include/ffi_real.h"
+
+#endif
--- orig/libffi/linux-x86/fficonfig.h    1969-12-31 19:00:00.000000000 -0500
+++ libffi/linux-x86/fficonfig.h    2013-01-28 16:23:04.047926730 -0500
@@ -0,0 +1,160 @@
+/* fficonfig.h.in.  Generated from configure.ac by autoheader.  */
+
+/* Define to one of `_getb67', `GETB67', `getb67' for Cray-2 and Cray-YMP
+   systems. This function is required for `alloca.c' support on those systems.
+   */
+#undef CRAY_STACKSEG_END
+
+/* Define to 1 if using `alloca.c'. */
+#undef C_ALLOCA
+
+/* Define to the flags needed for the .section .eh_frame directive. */
+#define EH_FRAME_FLAGS "aw"
+
+/* Define this if you want extra debugging. */
+#undef FFI_DEBUG
+
+/* Define this is you do not want support for the raw API. */
+#undef FFI_NO_RAW_API
+
+/* Define this is you do not want support for aggregate types. */
+#undef FFI_NO_STRUCTS
+
+/* Define to 1 if you have `alloca', as a function or macro. */
+#define HAVE_ALLOCA 1
+
+/* Define to 1 if you have <alloca.h> and it should be used (not on Ultrix).
+   */
+#define HAVE_ALLOCA_H 1
+
+/* Define if your assembler supports .cfi_* directives. */
+#undef HAVE_AS_CFI_PSEUDO_OP
+
+/* Define if your assembler supports .register. */
+#undef HAVE_AS_REGISTER_PSEUDO_OP
+
+/* Define if your assembler and linker support unaligned PC relative relocs.
+   */
+#undef HAVE_AS_SPARC_UA_PCREL
+
+/* Define to 1 if you have the <dlfcn.h> header file. */
+#define HAVE_DLFCN_H 1
+
+/* Define if __attribute__((visibility("hidden"))) is supported. */
+#undef HAVE_HIDDEN_VISIBILITY_ATTRIBUTE
+
+/* Define to 1 if you have the <inttypes.h> header file. */
+#define HAVE_INTTYPES_H 1
+
+/* Define if you have the long double type and it is bigger than a double */
+#undef HAVE_LONG_DOUBLE
+
+/* Define to 1 if you have the `memcpy' function. */
+#define HAVE_MEMCPY 1
+
+/* Define to 1 if you have the <memory.h> header file. */
+#define HAVE_MEMORY_H 1
+
+/* Define to 1 if you have the `mmap' function. */
+#define HAVE_MMAP 1
+
+/* Define if mmap with MAP_ANON(YMOUS) works. */
+#define HAVE_MMAP_ANON 1
+
+/* Define if mmap of /dev/zero works. */
+#define HAVE_MMAP_DEV_ZERO 1
+
+/* Define if read-only mmap of a plain file works. */
+#define HAVE_MMAP_FILE 1
+
+/* Define if .eh_frame sections should be read-only. */
+#undef HAVE_RO_EH_FRAME
+
+/* Define to 1 if you have the <stdint.h> header file. */
+#define HAVE_STDINT_H 1
+
+/* Define to 1 if you have the <stdlib.h> header file. */
+#define HAVE_STDLIB_H 1
+
+/* Define to 1 if you have the <strings.h> header file. */
+#undef HAVE_STRINGS_H
+
+/* Define to 1 if you have the <string.h> header file. */
+#define HAVE_STRING_H 1
+
+/* Define to 1 if you have the <sys/mman.h> header file. */
+#define HAVE_SYS_MMAN_H 1
+
+/* Define to 1 if you have the <sys/stat.h> header file. */
+#define HAVE_SYS_STAT_H 1
+
+/* Define to 1 if you have the <sys/types.h> header file. */
+#define HAVE_SYS_TYPES_H 1
+
+/* Define to 1 if you have the <unistd.h> header file. */
+#define HAVE_UNISTD_H 1
+
+/* Define to 1 if your C compiler doesn't accept -c and -o together. */
+#undef NO_MINUS_C_MINUS_O
+
+/* Name of package */
+#define PACKAGE "libffi"
+
+/* Define to the address where bug reports for this package should be sent. */
+#undef PACKAGE_BUGREPORT
+
+/* Define to the full name of this package. */
+#undef PACKAGE_NAME
+
+/* Define to the full name and version of this package. */
+#undef PACKAGE_STRING
+
+/* Define to the one symbol short name of this package. */
+#undef PACKAGE_TARNAME
+
+/* Define to the version of this package. */
+#undef PACKAGE_VERSION
+
+/* The size of `double', as computed by sizeof. */
+#define SIZEOF_DOUBLE 8
+
+/* The size of `long double', as computed by sizeof. */
+#undef SIZEOF_LONG_DOUBLE
+
+/* If using the C implementation of alloca, define if you know the
+   direction of stack growth for your system; otherwise it will be
+   automatically deduced at runtime.
+    STACK_DIRECTION > 0 => grows toward higher addresses
+    STACK_DIRECTION < 0 => grows toward lower addresses
+    STACK_DIRECTION = 0 => direction of growth unknown */
+#undef STACK_DIRECTION
+
+/* Define to 1 if you have the ANSI C header files. */
+#define STDC_HEADERS 1
+
+/* Define this if you are using Purify and want to suppress spurious messages.
+   */
+#undef USING_PURIFY
+
+/* Version number of package */
+#undef VERSION
+
+/* Define to 1 if your processor stores words with the most significant byte
+   first (like Motorola and SPARC, unlike Intel and VAX). */
+#undef WORDS_BIGENDIAN
+
+
+#ifdef HAVE_HIDDEN_VISIBILITY_ATTRIBUTE
+#ifdef LIBFFI_ASM
+#define FFI_HIDDEN(name) .hidden name
+#else
+#define FFI_HIDDEN __attribute__ ((visibility ("hidden")))
+#endif
+#else
+#ifdef LIBFFI_ASM
+#define FFI_HIDDEN(name)
+#else
+#define FFI_HIDDEN
+#endif
+#endif
+

--- build.sh (orig/build.sh)
+++ build.sh (build.sh)
@@ -5,6 +5,7 @@
 set -ex
 CWD=$(pwd)
 DEBUG=no
+android_abi="$1"

 RELEASE_VERSION=$(cat LATEST_VERSION)
 echo "Building Python VM For Android Release ${RELEASE_VERSION}"
@@ -78,12 +79,12 @@
 ${CWD}/host/pgen ${CWD}/python-src/Grammar/Grammar \
  ${CWD}/python-src/Include/graminit.h \
  ${CWD}/python-src/Python/graminit.c
-ndk-build
+ndk-build APP_ABI:=$android_abi

 # copy out all the needed files
-mv obj/local/armeabi/python ${OUT}/usr/bin
-mv obj/local/armeabi/lib*.so ${OUT}/usr/lib
-mv obj/local/armeabi/*.so ${OUT}/usr/lib/python2.6/lib-dynload
+mv obj/local/$android_abi/python ${OUT}/usr/bin
+mv obj/local/$android_abi/lib*.so ${OUT}/usr/lib
+mv obj/local/$android_abi/*.so ${OUT}/usr/lib/python2.6/lib-dynload
 popd

 pushd ${CWD}/python-libs
@@ -91,7 +92,7 @@
 popd

 ${CWD}/host/bin/python ${OUT}/usr/lib/python2.6/compileall.py ${OUT}/usr/lib/python2.6
-${CWD}/host/bin/python build.py
+${CWD}/host/bin/python build.py $android_abi

 if [ "$DEBUG" != "yes" ]; then
     rm -rf output*