【发布时间】：2016-02-27 17:04:11
【问题描述】：
如果我使用 -static-libstdc++ 构建一个 C++ 应用程序，该应用程序加载一个共享库（通过 dlopen），该库也是使用 -static-libstdc++ 构建的，那么在 dlopen 期间应用程序段会出错。
但是——这只发生在某些设置中：
- GCC 4.7.4，32 位：通过
- GCC 4.8.3，32 位：通过
- GCC 4.8.4，64 位：通过
- GCC 4.9.2，64 位：通过
- GCC 4.9.3，32 位：失败（除非指定了
RTLD_DEEPBIND） - GCC 4.9.3，64 位：通过
调查结果：
- 如果在为共享库或应用程序构建时不使用
-static-libstdc++，它可以工作。 - 如果 (
RTLD_LAZY | RTLD_DEEPBIND) 被传递给 dlopen，它就可以工作。所以我怀疑这个问题与应用程序和.so之间的符号混淆/重复有关。 - 有趣的是，如果我让代码首先使用 (
RTLD_LAZY | RTLD_DEEPBIND) 加载 .so，然后关闭它并仅使用RTLD_LAZY重新加载，它也可以工作。
复制步骤
代码：
functions.cpp
extern "C"
{
int ExportedFunction1()
{
std::cout << "\n---\n" << __FUNCTION__ << "\n---\n" << std::endl;
return(0);
}
}
main.cpp
#include <iostream>
#include <dlfcn.h>
int main(int argc, char * argv[])
{
void * ph(NULL);
if(argc == 2 && argv[1][0] == '1')
{
std::cout << "Calling dlopen with flags RTLD_LAZY | RTLD_DEEPBIND..." << std::flush;
ph = dlopen("./libfunctions.so", RTLD_LAZY | RTLD_DEEPBIND);
std::cout << "done. Result: " << ph << std::endl;
if(ph)
dlclose(ph);
}
std::cout << "Calling dlopen with flags RTLD_LAZY..." << std::flush;
ph = dlopen("./libfunctions.so", RTLD_LAZY);
std::cout << "done. Result: " << ph << std::endl;
if(ph)
dlclose(ph);
return 0;
}
构建
$ g++ -m32 -g -fPIC -c functions.cpp -o functions.o
$ g++ -m32 -g -fPIC -shared -Wl,-soname,libfunctions.so -static-libgcc -static-libstdc++ functions.o -o libfunctions.so
$ g++ -m32 -g -fPIC -static-libgcc -static-libstdc++ main.cpp -l dl -o main
运行
$ ./main
Calling dlopen with flags RTLD_LAZY...Segmentation fault (core dumped)
回溯
$ gdb -c ./core ./main
GNU gdb (GDB) 7.9.1
Copyright (C) 2015 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "i686-linux".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from ./main...done.
[New LWP 19846]
warning: Could not load shared library symbols for linux-gate.so.1.
Do you need "set solib-search-path" or "set sysroot"?
Core was generated by `./main'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0 __atomic_add_single (__val=1, __mem=0x0)
at /home/test/dev/3rdParty/gcc/build/i686-pc-linux-gnu/libstdc++-v3/include/ext/atomicity.h:74
74 { *__mem += __val; }
(gdb) bt
#0 __atomic_add_single (__val=1, __mem=0x0)
at /home/test/dev/3rdParty/gcc/build/i686-pc-linux-gnu/libstdc++-v3/include/ext/atomicity.h:74
#1 __atomic_add_dispatch (__val=1, __mem=0x0)
at /home/test/dev/3rdParty/gcc/build/i686-pc-linux-gnu/libstdc++-v3/include/ext/atomicity.h:98
#2 _M_add_reference (this=0x0)
at /home/test/dev/3rdParty/gcc/build/i686-pc-linux-gnu/libstdc++-v3/include/bits/locale_classes.h:510
#3 std::locale::locale (this=0xb74f7ffc <__gnu_internal::buf_cout_sync+28>)
at /home/test/dev/3rdParty/gcc/gcc-4.9.3/libstdc++-v3/src/c++98/locale_init.cc:223
#4 0xb746f559 in basic_streambuf (this=<optimized out>)
at /home/test/dev/3rdParty/gcc/build/i686-pc-linux-gnu/libstdc++-v3/include/streambuf:466
#5 stdio_sync_filebuf (__f=0xb76a2a20 <_IO_2_1_stdout_>, this=<optimized out>)
at /home/test/dev/3rdParty/gcc/build/i686-pc-linux-gnu/libstdc++-v3/include/ext/stdio_sync_filebuf.h:77
#6 std::ios_base::Init::Init (this=0xb74f7a01 <std::__ioinit>)
at /home/test/dev/3rdParty/gcc/gcc-4.9.3/libstdc++-v3/src/c++98/ios_init.cc:85
#7 0xb7469419 in __static_initialization_and_destruction_0 (__initialize_p=1, __priority=65535)
at /home/test/dev/3rdParty/build_toolchain/include/c++/4.9.3/iostream:74
#8 0xb7469456 in _GLOBAL__sub_I_functions.cpp(void) () at functions.cpp:12
#9 0xb772c25e in ?? () from /lib/ld-linux.so.2
#10 0xb772c35a in ?? () from /lib/ld-linux.so.2
#11 0xb7730622 in ?? () from /lib/ld-linux.so.2
#12 0xb772c117 in ?? () from /lib/ld-linux.so.2
#13 0xb772fdf4 in ?? () from /lib/ld-linux.so.2
#14 0xb76edcae in ?? () from /lib/libdl.so.2
#15 0xb772c117 in ?? () from /lib/ld-linux.so.2
#16 0xb76ee3b6 in ?? () from /lib/libdl.so.2
#17 0xb76edd61 in dlopen () from /lib/libdl.so.2
#18 0x0804e102 in main (argc=1, argv=0xbfadc254) at main.cpp:18
这对我来说很奇怪，这似乎只在某些版本的 GCC 中失败，并且仅适用于 32 位。我还没有尝试过 GCC 5。
感谢您的想法/建议。
【问题讨论】：
标签： c++ linux gcc shared-libraries libstdc++