string assignment crash

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1.00/5 (3 votes)

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Hi,
It is difficult to write the whole code block, because it is too long. I just want to say that it crashes in string assignment part. There is an enum, and I assign the string value to enum variables.

The backtrace is as follows ;

VB

# BACKTRACE:
0./lib/libc.so.0(kill+0x24) [2bb42730]
1./lib/libpthread.so.0(pthread_kill+0xa8) [2b9dee58]
2./lib/libpthread.so.0(raise+0x34) [2b9df42c]
3./lib/libc.so.0(abort+0xac) [2bb39b40]
4./lib/libstdc++.so.6(__gnu_cxx::__verbose_terminate_handler()++.so.6
5./lib/libstdc++.so.6(__cxxabiv1::__terminate(void (*)())++.so.6
6./lib/libstdc++.so.6(std::terminate()++.so.6
7./lib/libstdc++.so.6(__cxa_throw+0xb8) [2ba8a4bc]
8./lib/libstdc++.so.6(operator new(unsigned int)++.so.6
9./lib/libstdc++.so.6(std::string::_Rep::_S_create(unsigned int, unsigned int, std::allocator<char> const&)++.so.6
10./lib/libstdc++.so.6(std::string::_Rep::_M_clone(std::allocator<char> const&, unsigned int)++.so.6
11./lib/libstdc++.so.6(std::string::assign(std::string const&)++.so.6

Could you please help about the cause of crash ? What can be the cause ??
Thanks in advance,

[EDIT - OP code from comment]
Here is the code block. It always crashes in these two events ;

C++

void event1(){
     {
        tempValue = "";
        if(pName == ReasonTag)
            xmlParamType = ReasonForRequest;
        else if(pName == FailureMsgTag)
            xmlParamType = FailureMessage;
        else if(pName == SchemaTag)
        {
            if(pDataAtts[0] == SchemaNameTag)
                schemaName = pDataAtts[1];
        }
        else if(pName == SurnameTag)
            xmlParamType = ItemSurname;
        else if(pName == FirstnameTag)
            xmlParamType = ItemFirstname;
        else if(pName == OfficeTag)
            xmlParamType = ItemOffice;
        else if(pName == MobileTag)
            xmlParamType = ItemMobile;
        else if(pName == EmailTag)
            xmlParamType = ItemEmail;
        else if(pName == CompanyTag)
            xmlParamType = ItemCompany;
        else if(pName == AddressTag)
            xmlParamType = ItemAddress;
        else if(pName == UniqueIdTag)
            xmlParamType = UniqueId;
        else
            xmlParamType = eParamNull;
 
    }
}
 
    void event2()
    {
        switch(xmlParamType)
    {
        case ItemSurname:
             itemSurname = tempValue;
        break;
 
        case ItemFirstname:
             itemFirstname = tempValue;
        break;
 
        case ItemOffice:
             itemOffice = tempValue;
        break;
 
        case ItemMobile:
             itemMobile = tempValue;
        break;
 
        case ItemPrivate:
             itemPrivate = tempValue;
        break;
 
        case ItemEmail:
             itemEmail = tempValue;
        break;
 
        case ItemCompany:
             itemCompany = tempValue;
        break;
 
        case ItemAddress:
             itemAddress = tempValue;
        break;
 
        case UniqueId:
             uniqueId = tempValue;
        default:
            break;
    }
}

[EDIT oryginal_content = "comment"]
Here is the definitions of variables ;

C++

enum xmlParamType{ ParamNull, ReasonForRequest, SchemaName, ItemSurname, ItemFirstname, ItemOffice, ItemMobile, ItemEmail, ItemCompany, ItemAddress, ItemJobFunction, UniqueId };
OString tempValue;

And the other variables are all OString type variables, like itemSurname, itemFirstName ..

[/EDIT]

Posted 15-Jul-14 1:34am

no_-_namee

Updated 15-Jul-14 4:40am

Maciej Los

v3

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Comments

CPallini 15-Jul-14 8:02am

The cause is your code. The specific offending part I cannot locate, without seeing it.

WuRunZhe 15-Jul-14 8:05am

Well, without your code, anyone can find out the reason. Pls, rewrite your question with your main problem code part.

no_-_namee 15-Jul-14 8:17am

--- this comment is now the part of question ---
Maciej Los

WuRunZhe 15-Jul-14 8:20am

Could explain more clearly about each variable's type?

no_-_namee 15-Jul-14 8:29am

--- this comment is now the part of question ---
Maciej Los

Jochen Arndt 15-Jul-14 8:28am

1. You should not add code using comments. Use the green 'Improve question' link to edit your question and add additional information.

2. Don't add the above code. It will not help answer your question while the types of the variables are unknown.

3. You can't assign a string value to an enum or vive versa. An enum is of type integer. When trying to do so, the compiler should give you warnings or errors. If not, use the '-Wall' command line option with the GNU compiler to enable all warnings.

no_-_namee 15-Jul-14 9:06am

I don't assign a string valu to an enum. I assign a string value to a string variable. Would it cause crash ?

Richard MacCutchan 15-Jul-14 10:08am

Where does the crash occur, what variables are involved, and what is their type and content?

[no name] 15-Jul-14 10:16am

Previously you said that you are "assign the string value to enum variables" and now you say you are not. So which is it? How can you expect a clear answer when you don't give us factual information?

Maciej Los 15-Jul-14 10:47am

What a bad application design! Do you know what is Object Oriented programming? Do you know how to use classes?

George Jonsson 15-Jul-14 21:48pm

I think the proper question should be "How to parse an XML file in C++?"

Harley L. Pebley 16-Jul-14 0:19am

I'm not a C++ guru, but I don't recognize the OString type. Google indicates it might be part of an OpenOffice library? If so, I don't see an assignment operator for that class. With the assumption (a big one given the limited amount of information) that the exception comes from the line tempValue = "", you might try tempValue = OString(""); If that doesn't work, I'd suggest posting a single, short example method that demonstrates the problem rather than bits and pieces of the code you're working on.

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Stefan_Lang · Answer 1 · 2014-07-17T03:05:00

The assignment of a value to a variable of type std::string can only crash if the value passed is disguised as a type that it isn't and contains value that doesn't fit the expectation tied to that type.

In this case, you are passing variables of type OString directly, implying that the type OString has an implicit conversion operator to a type that can be assigned to a std::string variable. Most likely this type is const char*. Check the implementation of the following operator:

C++

OString::operator const char*() const

The actual function may be missing a const or two, but it must exist, or the assignment wouldn't even compile! In the implementation code, check what is returned.

There are at least two things that can go wrong in this code:
1. Returning an incorrect value, possibly by type-casting something to const char*
2. Returning a pointer that wasn't correctly initialized or assigned; this may also be due to an error in the code for the assignment operator.

If these hints don't help you identify the bug, show us the code of the relevant OString operators (assignment and conversion operators, mostly).

KarstenK · Answer 2 · 2014-07-16T05:18:00

Solution 2

debug the code and you will find out that assign a string to an enum is a real bad idea.

Enums are typed int.

Posted 16-Jul-14 5:18am

KarstenK

Comments

Richard MacCutchan 16-Jul-14 11:28am

He doesn't; see the comments above.

KarstenK 16-Jul-14 14:30pm

A "tuff guy" but if doesnt work the way is proofed to be wrong :-O

Richard MacCutchan 16-Jul-14 14:49pm

Since we still have no idea "what" doesn't work, it is all pure speculation. :(

no_-_namee 17-Jul-14 7:27am

I get a detailed message with GDB. It is as follows ;

#0 0x2b8b0410 in std::string::assign (this=0x7e3ff798, __s=0x2c080124 <Address 0x2c080124 out of bounds>, __n=0)
at /opt/ifx/Sources/inca/v2.5.0/toolchain/uclibc_toolchain_src/buildroot/toolchain_build_mips_nofpu/gcc-3.4.4-final/mips-linux-uclibc/libstdc++-v3/include/bits/basic_string.h:194
#1 0x2c0693f4 in ?? ()

Do you have any new idea about the cause of crash ?
Thanks,

KarstenK 17-Jul-14 7:47am

yes or maybe - if i could look on your code in which it happend.

My tip is some type mismatch: assigning a string value to a enum or vice versa.