在Mac OS X上的-fno-rtti共享库中多态捕获异常 [英] Polymorphically catching an exception in a -fno-rtti shared library on Mac OS X
问题描述
我正在用 f-no-rtti
构建一个共享库。在内部,这个库会抛出 std:invalid_argument
并捕获 std :: exception
,但是 catch
下面的代码重现了这个问题(g ++ 4.2,Mac OS X 10.6):
// library.cpp:导出f(),用-fno-rtti编译
#include< stdexcept>
#include< iostream>
externC{
void f(){
try {
throw std :: invalid_argument(std :: exception handler);
} catch(std :: exception& e){
std :: cout<< e.what()<< \\\
;
} catch(...){
std :: cout<< ...处理程序\\;
code
$ b $ hr
// main.cpp:主要的可执行文件,动态加载库
#include< dlfcn.h>
typedef void(* fPtr)();
int main(){
void * handle = dlopen(./libexception_problem.dylib,RTLD_LAZY);
fPtr p_f = reinterpret_cast< fPtr>(dlsym(handle,f));
p_f();
输出:
MacBook-Pro:teste pfranco $#可以正常运行rtti
MacBook-Pro:teste pfranco $ g ++ -c library.cpp &安培;&安培; g ++ -shared -o libexception_problem.dylib library.o&& g ++ main.cpp -o main&& ./main
std ::异常处理程序
MacBook-Pro:teste pfranco $#中断-fno-rtti
MacBook-Pro:teste pfranco $ g ++ -c -fno-rtti库。 cpp&& g ++ -shared -o libexception_problem.dylib library.o&& g ++ -fno-rtti main.cpp -o main&& ./main
...处理程序
MacBook-Pro:teste pfranco $#-no_dead_strip_inits_and_terms不会更改任何内容
MacBook-Pro:teste pfranco $ g ++ -c -no_dead_strip_inits_and_terms -fno-rtti library.cpp&& g ++ -no_dead_strip_inits_and_terms -shared -o libexception_problem.dylib library.o&& g ++ -fno-rtti -no_dead_strip_inits_and_terms main.cpp -o main&& ./main
...处理程序
MacBook-Pro:teste pfranco $#与共享库链接,但这并不总是一个选项
MacBook-Pro:teste pfranco $ g ++ -c -fno-rtti library.cpp&& g ++ -shared -o libexception_problem.dylib library.o&& g ++ -fno-rtti main.cpp -o main -L。 -lexception_problem&& ./main
std ::异常处理程序
只有当抛出的代码位于共享库中,并且只有捕获类型是实际异常的基类时才会发生这种情况 - catch(std :: invalid_argument&)
可以正常工作, std :: logic_error&
不会。
有趣的是,即使在运行完全相同的命令时, Linux上也不会发生这种情况。
问题:
- 为什么会发生这种情况?这是一个错误,未定义的行为或设计?
$ b如何使它工作,缺乏与库的链接?
$ b 非常感谢。
解决方案结果发现这是Apple gcc的一个bug。不过,他们最近回复了我的错误报告,称它不会被修复。
I'm building a shared library with f-no-rtti
. Internally, this library throws std:invalid_argument
and catches std::exception
, but the catch
clause is never entered.
The following code reproduces the problem (g++ 4.2, Mac OS X 10.6):
// library.cpp: exports f(), compiled with -fno-rtti
#include <stdexcept>
#include <iostream>
extern "C" {
void f() {
try {
throw std::invalid_argument("std::exception handler");
} catch( std::exception& e) {
std::cout << e.what() << "\n";
} catch(...) {
std::cout << "... handler\n";
}
}
}
// main.cpp: the main executable, dynamically loads the library
#include <dlfcn.h>
typedef void(*fPtr)();
int main() {
void* handle = dlopen( "./libexception_problem.dylib", RTLD_LAZY );
fPtr p_f = reinterpret_cast<fPtr>( dlsym( handle, "f" ) );
p_f();
}
Output:
MacBook-Pro:teste pfranco$ # works fine with rtti
MacBook-Pro:teste pfranco$ g++ -c library.cpp && g++ -shared -o libexception_problem.dylib library.o && g++ main.cpp -o main && ./main
std::exception handler
MacBook-Pro:teste pfranco$ # breaks with -fno-rtti
MacBook-Pro:teste pfranco$ g++ -c -fno-rtti library.cpp && g++ -shared -o libexception_problem.dylib library.o && g++ -fno-rtti main.cpp -o main && ./main
... handler
MacBook-Pro:teste pfranco$ #-no_dead_strip_inits_and_terms doesn't change anything
MacBook-Pro:teste pfranco$ g++ -c -no_dead_strip_inits_and_terms -fno-rtti library.cpp && g++ -no_dead_strip_inits_and_terms -shared -o libexception_problem.dylib library.o && g++ -fno-rtti -no_dead_strip_inits_and_terms main.cpp -o main && ./main
... handler
MacBook-Pro:teste pfranco$ # linking against the shared library works, but this isn't always an option
MacBook-Pro:teste pfranco$ g++ -c -fno-rtti library.cpp && g++ -shared -o libexception_problem.dylib library.o && g++ -fno-rtti main.cpp -o main -L. -lexception_problem && ./main
std::exception handler
This only happens if the code that throws is in a shared library, and only if the caught type is a base class of the actual exception - catch(std::invalid_argument&)
works fine, std::logic_error&
doesn't.
Interestingly, this doesn't happen on Linux, even when running the exact same commands.
Questions:
- Why does this happen? Is this a bug, undefined behavior or by design?
- How could I make it work, short of linking against the library?
Thanks a lot.
解决方案 Turns out this a bug on Apple's gcc. They've recently replied to my bug report saying it won't be fixed, though.
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