连接V8静态库的Android :找不到符号，但它们在那里

Question

我一直在为这件事拔头发。我正在开发Ubuntu12.04 64位.我创建了一个内置V8的本地安卓应用程序，但是在重新启动我的计算机之后，它就不再与V8连接了！我尝试过重新安装ndk并重新编译V8，但是没有结果。看来链接器确实包含静态库，但没有在其中找到符号。我用nm检查了一下，符号似乎就在那里。

当我运行ndk_build时，我得到以下输出：

$ ndk-build V=1
rm -f ./libs/armeabi/lib*.so ./libs/armeabi-v7a/lib*.so ./libs/armeabi-v7a-hard/lib*.so ./libs/mips/lib*.so ./libs/x86/lib*.so
rm -f ./libs/armeabi/gdbserver ./libs/armeabi-v7a/gdbserver ./libs/armeabi-v7a-hard/gdbserver ./libs/mips/gdbserver ./libs/x86/gdbserver
rm -f ./libs/armeabi/gdb.setup ./libs/armeabi-v7a/gdb.setup ./libs/armeabi-v7a-hard/gdb.setup ./libs/mips/gdb.setup ./libs/x86/gdb.setup
[armeabi] Compile++ thumb: native-activity <= main.cpp
/home/schooten/bin/packages/android-ndk-r9d/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86_64/bin/arm-linux-androideabi-g++ -MMD -MP -MF ./obj/local/armeabi/objs/native-activity/main.o.d -fpic -ffunction-sections -funwind-tables -fstack-protector -no-canonical-prefixes -march=armv5te -mtune=xscale -msoft-float -fno-exceptions -fno-rtti -mthumb -Os -g -DNDEBUG -fomit-frame-pointer -fno-strict-aliasing -finline-limit=64 -Ijni/include -I/home/schooten/bin/packages/android-ndk-r9d/sources/android/native_app_glue -I/home/schooten/bin/packages/android-ndk-r9d/sources/cxx-stl/system/include -Ijni -DANDROID  -Wa,--noexecstack -Wformat -Werror=format-security      -I/home/schooten/bin/packages/android-ndk-r9d/platforms/android-9/arch-arm/usr/include -c  jni/main.cpp -o ./obj/local/armeabi/objs/native-activity/main.o 
[armeabi] Compile thumb  : android_native_app_glue <= android_native_app_glue.c
/home/schooten/bin/packages/android-ndk-r9d/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86_64/bin/arm-linux-androideabi-gcc -MMD -MP -MF ./obj/local/armeabi/objs/android_native_app_glue/android_native_app_glue.o.d -fpic -ffunction-sections -funwind-tables -fstack-protector -no-canonical-prefixes -march=armv5te -mtune=xscale -msoft-float -mthumb -Os -g -DNDEBUG -fomit-frame-pointer -fno-strict-aliasing -finline-limit=64 -I/home/schooten/bin/packages/android-ndk-r9d/sources/android/native_app_glue -DANDROID  -Wa,--noexecstack -Wformat -Werror=format-security    -I/home/schooten/bin/packages/android-ndk-r9d/platforms/android-9/arch-arm/usr/include -c  /home/schooten/bin/packages/android-ndk-r9d/sources/android/native_app_glue/android_native_app_glue.c -o ./obj/local/armeabi/objs/android_native_app_glue/android_native_app_glue.o 
[armeabi] StaticLibrary  : libandroid_native_app_glue.a
rm -f obj/local/armeabi/libandroid_native_app_glue.a
/home/schooten/bin/packages/android-ndk-r9d/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86_64/bin/arm-linux-androideabi-ar crsD ./obj/local/armeabi/libandroid_native_app_glue.a ./obj/local/armeabi/objs/android_native_app_glue/android_native_app_glue.o
[armeabi] StaticLibrary  : libstdc++.a
rm -f obj/local/armeabi/libstdc++.a
/home/schooten/bin/packages/android-ndk-r9d/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86_64/bin/arm-linux-androideabi-ar crsD ./obj/local/armeabi/libstdc++.a 
[armeabi] SharedLibrary  : libnative-activity.so
/home/schooten/bin/packages/android-ndk-r9d/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86_64/bin/arm-linux-androideabi-g++ -Wl,-soname,libnative-activity.so -shared --sysroot=/home/schooten/bin/packages/android-ndk-r9d/platforms/android-9/arch-arm ./obj/local/armeabi/objs/native-activity/main.o ./obj/local/armeabi/libandroid_native_app_glue.a jni/lib/libv8_libbase.arm.a jni/lib/libv8_nosnapshot.a jni/lib/libv8_base.a jni/lib/libstlport_static.a ./obj/local/armeabi/libstdc++.a -lgcc -no-canonical-prefixes  -Wl,--no-undefined -Wl,-z,noexecstack -Wl,-z,relro -Wl,-z,now  -L/home/schooten/bin/packages/android-ndk-r9d/platforms/android-9/arch-arm/usr/lib -llog -landroid -lEGL -lGLESv1_CM -llog -lstdc++ -lc -lm -o ./obj/local/armeabi/libnative-activity.so
/home/schooten/bin/packages/android-ndk-r9d/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: ./obj/local/armeabi/objs/native-activity/main.o: in function __clearColor(v8::FunctionCallbackInfo<v8::Value> const&):jni/main.cpp:88: error: undefined reference to 'v8::Value::Int32Value() const'
/home/schooten/bin/packages/android-ndk-r9d/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: ./obj/local/armeabi/objs/native-activity/main.o: in function __clearColor(v8::FunctionCallbackInfo<v8::Value> const&):jni/main.cpp:89: error: undefined reference to 'v8::Value::Int32Value() const'
/home/schooten/bin/packages/android-ndk-r9d/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: ./obj/local/armeabi/objs/native-activity/main.o: in function __clearColor(v8::FunctionCallbackInfo<v8::Value> const&):jni/main.cpp:90: error: undefined reference to 'v8::Value::Int32Value() const'
/home/schooten/bin/packages/android-ndk-r9d/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: ./obj/local/armeabi/objs/native-activity/main.o: in function __clearColor(v8::FunctionCallbackInfo<v8::Value> const&):jni/main.cpp:91: error: undefined reference to 'v8::Value::Int32Value() const'
/home/schooten/bin/packages/android-ndk-r9d/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: ./obj/local/armeabi/objs/native-activity/main.o: in function run_javascript(char*):jni/main.cpp:101: error: undefined reference to 'v8::Isolate::New()'
/home/schooten/bin/packages/android-ndk-r9d/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: ./obj/local/armeabi/objs/native-activity/main.o: in function run_javascript(char*):jni/include/v8.h:4045: error: undefined reference to 'v8::Isolate::Enter()'
/home/schooten/bin/packages/android-ndk-r9d/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: ./obj/local/armeabi/objs/native-activity/main.o: in function run_javascript(char*):jni/main.cpp:104: error: undefined reference to 'v8::HandleScope::HandleScope(v8::Isolate*)'
/home/schooten/bin/packages/android-ndk-r9d/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: ./obj/local/armeabi/objs/native-activity/main.o: in function run_javascript(char*):jni/main.cpp:108: error: undefined reference to 'v8::ObjectTemplate::New(v8::Isolate*)'
/home/schooten/bin/packages/android-ndk-r9d/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: ./obj/local/armeabi/objs/native-activity/main.o: in function run_javascript(char*):jni/main.cpp:110: error: undefined reference to 'v8::ObjectTemplate::New(v8::Isolate*)'
/home/schooten/bin/packages/android-ndk-r9d/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: ./obj/local/armeabi/objs/native-activity/main.o: in function run_javascript(char*):jni/main.cpp:112: error: undefined reference to 'v8::String::NewFromUtf8(v8::Isolate*, char const*, v8::String::NewStringType, int)'
... etc ...

特别是，这一行告诉我*.a文件包括：

/home/schooten/bin/packages/android-ndk-r9d/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86_64/bin/arm-linux-androideabi-g++ -Wl,-soname,libnative-activity.so -shared --sysroot=/home/schooten/bin/packages/android-ndk-r9d/platforms/android-9/arch-arm ./obj/local/armeabi/objs/native-activity/main.o ./obj/local/armeabi/libandroid_native_app_glue.a jni/lib/libv8_libbase.arm.a jni/lib/libv8_nosnapshot.a jni/lib/libv8_base.a jni/lib/libstlport_static.a ./obj/local/armeabi/libstdc++.a -lgcc -no-canonical-prefixes  -Wl,--no-undefined -Wl,-z,noexecstack -Wl,-z,relro -Wl,-z,now  -L/home/schooten/bin/packages/android-ndk-r9d/platforms/android-9/arch-arm/usr/lib -llog -landroid -lEGL -lGLESv1_CM -llog -lstdc++ -lc -lm -o ./obj/local/armeabi/libnative-activity.so

我的Android.mk看起来是这样的：

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)
LOCAL_MODULE          := stlport
LOCAL_MODULE_FILENAME := stlport_static
LOCAL_SRC_FILES := lib/libstlport_static.a
include $(PREBUILT_STATIC_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE          := v8_base
LOCAL_MODULE_FILENAME := v8_base_static
LOCAL_SRC_FILES := lib/libv8_base.a
include $(PREBUILT_STATIC_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE          := v8_nosnapshot
LOCAL_MODULE_FILENAME := v8_nosnapshot_static
LOCAL_SRC_FILES := lib/libv8_nosnapshot.a
include $(PREBUILT_STATIC_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE          := v8_libbase
LOCAL_MODULE_FILENAME := v8_libbase_static
LOCAL_SRC_FILES := lib/libv8_libbase.arm.a
include $(PREBUILT_STATIC_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE    := native-activity
LOCAL_SRC_FILES := main.cpp
LOCAL_LDLIBS    := -llog -landroid -lEGL -lGLESv1_CM
LOCAL_STATIC_LIBRARIES := android_native_app_glue v8_libbase v8_nosnapshot v8_base stlport
LOCAL_C_INCLUDES := $(LOCAL_PATH)/include
include $(BUILD_SHARED_LIBRARY)

$(call import-module,android/native_app_glue)

LOCAL_STATIC_LIBRARIES顺序是经验性确定的。我再摆弄几个，但都没有用。我甚至试过LOCAL_WHOLE_STATIC_LIBRARIES。我用nm检查了符号的存在：

arm-linux-gnueabi-nm jni/lib/libv8_base.a | grep Int32Value
         U _ZNK2v85Value10Int32ValueEv
00000000 T _ZNK2v85Value10Int32ValueEv
         U _ZNK2v85Value10Int32ValueEv

arm-linux-gnueabi-nm jni/lib/libv8_base.a | grep Utf8Value
00000000 T _ZN2v86String9Utf8ValueC1ENS_6HandleINS_5ValueEEE
00000000 T _ZN2v86String9Utf8ValueC2ENS_6HandleINS_5ValueEEE
00000000 T _ZN2v86String9Utf8ValueD1Ev
00000000 T _ZN2v86String9Utf8ValueD2Ev
         U _ZN2v86String9Utf8ValueC1ENS_6HandleINS_5ValueEEE
         U _ZN2v86String9Utf8ValueD1Ev
         U _ZN2v86String9Utf8ValueC1ENS_6HandleINS_5ValueEEE
         U _ZN2v86String9Utf8ValueD1Ev
         U _ZN2v86String9Utf8ValueC1ENS_6HandleINS_5ValueEEE
         U _ZN2v86String9Utf8ValueD1Ev
         U _ZN2v86String9Utf8ValueC1ENS_6HandleINS_5ValueEEE
         U _ZN2v86String9Utf8ValueD1Ev
         U _ZN2v86String9Utf8ValueC1ENS_6HandleINS_5ValueEEE
         U _ZN2v86String9Utf8ValueD1Ev

我不是名字咀嚼方面的专家，但他们似乎就在那里。所有的值都是零，但我相信这是正常的。

所以我想，也许链接器不理解静态库，而且它无声地失败了。

但是我该如何检查链接器为什么没能拾取符号呢？

Answer 1

在朋友的帮助下，我终于修好了。首先，我尝试了一个解决方法，尝试将V8链接为一个共享库，但结果并不好，因为我使用的NDK本机活动接口与加载其他共享对象不兼容。

我的静态库有两个不同的问题。第一个也是最重要的一点是，V8构建的静态库不适合链接。您可以通过以下方法来检查：

ar x [static_library.a]

它通常从库中提取*.o对象。在本案中，它报告说：

`x' cannot be used on thin archives

瘦归档只是对*.o文件的绝对路径的一组引用，没有实际内容。这解释了为什么我的构建在移除或删除V8构建树中的原始*.o文件时停止工作。奇怪的是，链接者对此保持沉默。

在V8中，创建静态库目前不是一个构建选项。谢天谢地，这家伙有个补丁用于在V8中创建适当的静态库。

该应用程序仍然没有链接后，我这样做，因为我复制错误的文件，第一次循环。事实证明，静态库也是为主机体系结构构建的(不要问我为什么)，我意外地复制了这些库。我知道你可以用：

file objectfile.o

看看它是什么建筑。因此，我发现我的静态库是i386而不是arm。因此，链接器跳过了这些文件，因为体系结构不匹配(您可以在静态库中混合架构)。

下面是我根据Curu的补丁为V8 3.27.28制作的V8补丁。我会尽力让这个补丁被提交。补丁1：

~/Work/javascript/Engines/v8-trunk/tools/gyp$ diff -u v8.gyp.orig  v8.gyp
--- v8.gyp.orig 2014-06-18 21:09:59.368336736 +0200
+++ v8.gyp  2014-06-18 21:12:20.264331660 +0200
@@ -108,6 +108,7 @@
     {
       'target_name': 'v8_snapshot',
       'type': 'static_library',
+      'standalone_static_library': 1,
       'conditions': [
         ['want_separate_host_toolset==1', {
           'toolsets': ['host', 'target'],
@@ -180,6 +181,7 @@
     {
       'target_name': 'v8_nosnapshot',
       'type': 'static_library',
+      'standalone_static_library': 1,
       'dependencies': [
         'v8_base',
       ],
@@ -237,6 +239,7 @@
     {
       'target_name': 'v8_base',
       'type': 'static_library',
+      'standalone_static_library': 1,
       'dependencies': [
         'v8_libbase.<(v8_target_arch)',
       ],

修补程序2：

~/Work/javascript/Engines/v8-trunk/third_party/icu$ diff -u icu.gyp.orig icu.gyp
--- icu.gyp.orig    2014-06-18 21:10:22.060335920 +0200
+++ icu.gyp 2014-06-18 21:15:06.468325674 +0200
@@ -56,6 +56,7 @@
         {
           'target_name': 'icudata',
           'type': 'static_library',
+          'standalone_static_library': 1,
           'defines': [
             'U_HIDE_DATA_SYMBOL',
           ],
@@ -141,6 +142,11 @@
         {
           'target_name': 'icui18n',
           'type': '<(component)',
+          'conditions': [
+            [ 'component!="shared_library"', {
+                'standalone_static_library': 1,
+            }],
+          ],
           'sources': [
             '<@(icui18n_sources)',
           ],
@@ -241,6 +247,11 @@
         {
           'target_name': 'icuuc',
           'type': '<(component)',
+          'conditions': [
+            [ 'component!="shared_library"', {
+                'standalone_static_library': 1,
+            }],
+          ],
           'sources': [
             '<@(icuuc_sources)',
           ],