exception problem with cygwin - terminate called recursively

[Philipp Kraus]

Hello,

I have a problem with exception. I compile my code under OSX, Linux and
Windows (Cygwin) with gcc but only in Windows I run everytime in a
exception message "terminate called recursively". My code runs into an
exception, but I catch them with try-catch. The code unter Linux and
OSX do it in the correct, catch the exception and runs down till the
end of the program, but under Windows the exception is thrown and the
program terminates.

Can anyone explain me the problem of the message, I don't understand
why Windows handels exceptions in another way than Linux or OSX

Thanks

Phil

 

[Philipp Kraus]

It seems to me that your exception either has no corresponding catch
clause or that it is thrown when another exception is active: this
causes std::terminate to be called.

on the main program the exception should be catched like:

myclass {
mymethod() {
if something
mymethod()

throw exception
}
}

main() {
myclass x;
try {
x.mymethod()
} catch (...) {}

}

In my optinion I think if I throw an exception the complete runing
process would be breaked down and the exception is send to the main
program, if there is a try-catch the exception is be handled, if not
the program terminates. I don't use any threads. I don't understand why
Windows should be handle the exception in another way than Linux and
OSX !?

Thanks for your answer

Phil

 

[Philipp Kraus]

Den torsdag den 14. juli 2011 17.48.24 UTC+2 skrev Philipp Kraus:

So you tried that program and it had the same behaviour?
yes


It does not.


If there is not a corresponding catch, std::terminate will be called.
You said that std::terminate was called recursively?

Sorry, my mistake. The exception that is thrown shoudl be called recursively.

Your problem might also be in the compiler flags used for the compiler.

I use on all systems the gcc, but I don't know any flags that are set
for exception handling
I'm a little bit confused

Thanks

Phil

 

[Philipp Kraus]

I have used gdb and debugging symbols for debugging my code. It seems
that the program crashs at

#0 0x77bf70b4 in ntdll!LdrFindResourceEx_U () from
C:\Windows\SYSTEM32\ntdll.dll

 

[Philipp Kraus]

Your problem might also be in the compiler flags used for the compiler.

Do you mean -fexceptions for the g++ command?

I'm a little bit closer on the problem context, I have mixed C and C++
code in the class that throws the exception. I have tested the code
with std exceptions and try to catch it with
catch (...), catch (myexception& e) or catch(std::runtime_error e), but
I cant catch the thrown exception. Is there any information about
exception handling with mixed code?
I have found some articles that there are problems with mixed code and
exception handling, but I haven't found a working solution for the
problem. I try to recompile my sources with the -fexceptions flag, but
that does not wort. Shoud I compile my C libraries with the flag?

Thanks a lot

Phil

 

[Philipp Kraus]

I'm a little bit closer on the problem context, I have mixed C and C++
code in the class that throws the exception. [...]
problem. I try to recompile my sources with the -fexceptions flag, but
that does not wort. Shoud I compile my C libraries with the flag?

The -fexceptions flag should not have any effect on C++ code whatsoever.
You need this for compiling any C code which is supposed to let C++
exceptions propagate through it. On Windows platform MSVC implements
exceptions at the OS level so there is no such special flag needed for C
code, but things may be different with cygwin or gcc.

I think this question is off-topic, but do you know a working solution for g++?
I have compiled all my libraries and my code with g++ / gcc, so should
I set the
-fexceptions flag on each library or only on my code?

Thanks

Phil

 

[Philipp Kraus]

@online.de:

I'm a little bit closer on the problem context, I have mixed C and
C++ code in the class that throws the exception.
[...]
problem. I try to recompile my sources with the -fexceptions flag,
but that does not wort. Shoud I compile my C libraries with the
flag?

The -fexceptions flag should not have any effect on C++ code
whatsoever. You need this for compiling any C code which is supposed
to let C++ exceptions propagate through it. On Windows platform MSVC
implements exceptions at the OS level so there is no such special
flag needed for C code, but things may be different with cygwin or
gcc.

I think this question is off-topic, but do you know a working solution
for g++? I have compiled all my libraries and my code with g++ / gcc,
so should I set the
-fexceptions flag on each library or only on my code?

I don't know if this is off-topic or not, there is too less information.
For example it is not clear what you mean exactly by "mix of C and C++ in
the class" and if "your code" is C or C++. Maybe you could post a minimal
example demonstrating the problem?

It's very simple. I use the libxml2 functions for parsing XML data. The library
have some error function / callback function for detecting errors
during the parsing.

eg:

my xmlclass {
public:
doxml( std::string p_xml ) {

xmlParseMemory(p_xml.c_str)
if (xmlErrorDetect()) {
xmlClear()
throw std::runtime_error("error")
}
}
}

In my main function
{
myxmlclass obj;
try {
obj.doxml("abcdef");
} catch (...) {
std::cout << "exception is caught" << std::endl;
}
}


The calls with xml prefix are the calls of the libxml2. I have checked
with gdb, the throw will be called, but not caught in the main. I can
change
the (...) to anything, but I can't catch the exception. I have tested
with std::exception, own exception, that derivated from std::exception.
Under
the Cygwin g++ I can't catch it, same code under OSX and Linux works
fine, the exception is caught and I can handle it.

All I know that with Linux and gcc, all C code which has to be able to
propagate exceptions through it must be compiled with -fexceptions.

The -fexceptions is enabled on default, so I think its correct.

I do not understand where the problem is and how I can solve it

 

[Philipp Kraus]

On 2011-07-16 18:04:37 +0200, Paavo Helde said:

@online.de:

I'm a little bit closer on the problem context, I have mixed C and
C++ code in the class that throws the exception.
[...]
problem. I try to recompile my sources with the -fexceptions flag,
but that does not wort. Shoud I compile my C libraries with the
flag?

The -fexceptions flag should not have any effect on C++ code
whatsoever. You need this for compiling any C code which is
supposed to let C++ exceptions propagate through it. On Windows
platform MSVC implements exceptions at the OS level so there is no
such special flag needed for C code, but things may be different
with cygwin or gcc.

I think this question is off-topic, but do you know a working
solution for g++? I have compiled all my libraries and my code with
g++ / gcc, so should I set the
-fexceptions flag on each library or only on my code?

I don't know if this is off-topic or not, there is too less
information. For example it is not clear what you mean exactly by
"mix of C and C++ in the class" and if "your code" is C or C++. Maybe
you could post a minimal example demonstrating the problem?

It's very simple. I use the libxml2 functions for parsing XML data.
The library have some error function / callback function for detecting
errors during the parsing.

You mention a callback function, but there is no callback function in
your example code. Do you use xmlSetGenericErrorFunc()? If yes, then this
should be included in the example.

eg:

my xmlclass {
public:
doxml( std::string p_xml ) {

xmlParseMemory(p_xml.c_str)
if (xmlErrorDetect()) {
xmlClear()
throw std::runtime_error("error")
}
}
}

In my main function
{
myxmlclass obj;
try {
obj.doxml("abcdef");
} catch (...) {
std::cout << "exception is caught" << std::endl;
}
}

This code does not compile (lots of missing semicolons and other errors),
neither does it throw exceptions through C code, so I believe it has no
relevance to your real problem. Please post a compilable example
demonstrating the problem!

The original excerpt of the method is:

xmlResetLastError();
bool l_error = false;

xmlGenericErrorFunc l_fptr = myclass::XMLErrorFunction; <=
XMLErrorFunction is a static
method of the class which is empty to supress parsing content on the CLI
initGenericErrorDefaultFunc( &l_fptr );

const char* l_xmlcontent = p_xml.c_str();
xmlDocPtr l_xml = xmlParseMemory( l_xmlcontent,
strlen(l_xmlcontent) );
if ((!l_xml) || (xmlGetLastError())) {
if (l_xml)
xmlFreeDoc( l_xml );
xmlCleanupParser();
throw std::runtime_error("XML data can not be parsed"); <=
this exception is thrown, but can not be caught /
here I have tested with std::exception, derivated exceptions...
}

AFAIK -fexceptions are not enabled by default for C code, are you sure
that the libxml2 library has been compiled with -fexceptions?

I have testet with and without compiling -fexceptions, both test are
create the same problem.

You cannot solve the problem without understanding it. Throwing
exceptions through non-C++ code is undefined behavior, but your example
does no such thing, so I'm not sure either where the problem is.

I have create a class, that uses with external C includes the libxml2
calls for parsing XML data. In this class I throw an
exception (see excerpt), which should be caught in the main. On Linux
and OSX g++ it works, exception is thrown and caught.
On Windows (g++ under Cygwin) the exception is thrown (checked with
gdb) but not caught. Windows creates the message:
terminate called after throwing an instance of <exception> terminate
called recursively
The library is compiled on all three systems with gcc and my code with
g++. All compilers are version 4.x, only the subversions
are different

Phil