Crash of mysql under cygwin with g++ 3.3.1

[Fabrice Marchal]

Hallo Gerrit,

Thanks for your help. I would like to ask you a few questions:

1) If I use your mysql-4.0.17 libraries, that is if I link my code 
against your libmysqlclient.a
then my code works OK. On the other hand, then it requires 
cygmysqlclient.dll also: what is
that library exactly? Is it the equivalent of mySQL.dll which is 
included in the mysql for windows?

2) I have now identified the bug, or at least what causes it: here is 
small example that
crashes when using cygwin-1-5-7.1, MYSQL 4.0.18 and GCC3.3.1 (G++):

#include <mysql.h>
#include <iostream>
using namespace std;

class Connection{
   MYSQL* mqlh;
public:
 Connection(){
   mqlh = mysql_init( NULL );
   cout << "OK" << endl;
 }
};

int main( int argc, char** args ){
   Connection* con = new Connection();
   // crashes here
}

As you can see, it seems that something is really wrong. It seems to be 
caused by new()
since removing the mysql_init() from the new() call seems to work.
I have to mention that I link only against -lmySQL which is provided in 
the mysql for
windows distro. Maybe that is the problem (i.e. it was build from older 
cygwin releases)

As I would like to ship a "clean" version, I don't know what to do. 
Normally, people
would install mysql-for-win, then install my code plus just the cygwin DLL.

Regards,
Fabrice



Gerrit P. Haase wrote:

>Hallo Fabrice,
>
>late reply, sorry.
>
>Your code snippet works for me with the latest Cygwin gcc-3.3.1 and
>MySQL 4.0.17 which I compiled today and which is available for testing
>here: http://anfaenger.de/cygwin-1.5/mysql/
>
>$ gcc -I/usr/include/mysql \
>    -o mysql mysql.cpp \
>    -L/usr/lib/mysql -lmysqlclient \
>    -L/usr/lib -lstdc++
>
>$ ./mysql
>
>$ g++ -I/usr/include/mysql \
>    -o mysql mysql.cpp \
>    -L/usr/lib/mysql -lmysqlclient
>
>$ ./mysql
>
>No problem here.
>
>
>Am Freitag, 28. November 2003 um 01:46 schriebst du:
>
>  
>
>>I dont know if this is a problem of mysql, g++ or
>>cygwin but the following simple code keeps crashing with g++3.3.1
>>Platform: cygwin-1.5.5, mysql 3.23 (and mysql 4.1 as well).
>>Note that the code does not crash if all the mysql_ calls are
>>made from inside the "main()" block. GDB reports that the crash occurs
>>when returning from the Connection() constructor.
>>The code was working with former g++2.95 under cygwin.
>>    
>>
>
>  
>
>>#include "mysql.h"
>>#include <iostream>
>>    
>>
>
>  
>
>>using namespace std;
>>    
>>
>
>  
>
>>class Connection{
>>  MYSQL *mysql;
>>public:
>>  Connection(){
>>    mysql = mysql_init( NULL );
>>    if( mysql == 0 ){
>>        cerr << "failed to init" << endl;
>>        exit(-1); }
>>    mysql_real_connect( mysql, "", "", "", "test", 3306, NULL, 0);
>>  }
>>};
>>    
>>
>
>  
>
>>int main( int argc, char** args ){
>>    Connection con;
>>}
>>    
>>
>
>
>
>
>HTH,
>Gerrit
>  
>


-- 
========================================================================
Fabrice Marchal           http://www.inf.ethz.ch/~marchal 
fabrice.marchal@ieee.org  marchal@inf.ethz.ch         +41-(0)1-632-56-79
ETH Zurich, CoLab Computational Laboratory        FAX:+41-(0)1-632-17-03
========================================================================



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