Readelf报表程序是共享库，而不是可执行文件 [英] Readelf reports program is a shared library instead of executable
问题描述
使用独立的Android NDK r10e工具链(使用--toolchain = x86-clang3.6开关构建)，得到了这种奇怪的行为.在运行makefile之前，已设置交叉编译的环境变量 ，SYSROOT指向Android工具链位置，CXX等于i686-linux-android-clang ++.基本上，我有一堆要编译为Android可执行文件的cpp文件.可悲的是，clang ++一直在生成.so共享库(已通过readelf检查-它确实是共享库).我忘记了对编译器/链接器的特殊切换吗?
got this strange behaviour with standalone Android NDK r10e Toolchain (built with --toolchain=x86-clang3.6 switch). Environment variables for cross compilation have been set before running makefile, SYSROOT points to Android toolchain location, CXX equals i686-linux-android-clang++. Basically, I have a bunch of cpp files that I would like to compile to Android executable. Sadly, clang++ keeps producing .so shared library (checked with readelf - it is indeed shared object). Is there a special switch to compiler / linker that I have forgotten?
Makefile:(main.cpp包含main函数)
Makefile: (main.cpp contains main function)
CFLAGS=-c -Wall -std=c++11 -Wextra --sysroot=${SYSROOT} -march=i686
LDFLAGS=-lc -lc++_shared -L${SYSROOT}/usr/lib
SOURCES=main.cpp File1.cpp File2.cpp File3.cpp File4.cpp
OBJECTS=$(SOURCES:.cpp=.o)
EXECUTABLE=test
all: $(SOURCES) $(EXECUTABLE)
$(EXECUTABLE): $(OBJECTS) ${CXX} $(LDFLAGS) $(OBJECTS) -o $@
.cpp.o: ${CXX} $(CFLAGS) $< -o $@
clean: rm *.o test
推荐答案
clang ++不断产生.so共享库(已通过readelf检查-它确实是共享库).我忘记了对编译器/链接器的特殊切换吗?
clang++ keeps producing .so shared library (checked with readelf - it is indeed shared object). Is there a special switch to compiler / linker that I have forgotten?
我的 猜测 :readelf正在输出Elf file type is DYN (shared object file)，您将其解释为共享对象:)
My guess: readelf is outputting Elf file type is DYN (shared object file), and you are interpreting that to mean a shared object :)
您可能做过类似的事情:
You probably did something like:
readelf -l test | grep -i "file type"
实际上，这是位置独立可执行(PIE)和readelf报告的产物.
In reality, that's an artifact of Position Independent Executable (PIE) and readelf reporting.
重要的部分是readelf报告 DYN ，而不报告 EXE . EXE表示它缺少PIE，通常会触发与安全相关的缺陷.
The important part is readelf is reporting DYN, and not reporting EXE. EXE means it lacks PIE, and that usually triggers a security related defect.
PIE是在Android 4.1上添加的，但它是可选的. Android 5.0及更高版本需要PIE.来自 Android 5.0中的安全性增强功能:
PIE was added at Android 4.1, but it was optional. PIE is required for Android 5.0 and above. From Security Enhancements in Android 5.0:
非PIE链接器支持已删除. Android现在需要所有动态链接的可执行文件来支持PIE(与位置无关) 可执行文件).这可以改善Android的地址空间布局 随机化(ASLR)实现.
non-PIE linker support removed. Android now requires all dynamically linked executables to support PIE (position-independent executables). This enhances Android’s address space layout randomization (ASLR) implementation.
另请参见与堆栈无关的位置独立可执行文件.它讨论了PIE和Android.
Also see Position Independent Executables on Stack Overflow. It discusses PIE and Android.
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