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Date:	Mon, 22 Feb 2010 10:33:26 +0000
From:	Andrew West <andrewwest AT gmail DOT com>
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To:	cygwin AT cygwin DOT com
Subject:	Statically initialising pthread attributes in dynamic dlls.
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Trying to initialise a pthread attribute in a static variable seems to 
cause a segfault. I've attach a simple test case compiled using;

g++ -g mutex.cpp -o mutex.dll -lpthread
g++ -g test.cpp -o test.exe -ldl

I've cropped the code down to the essential bits, so no error reporting 
if it can't find the dll, etc.

The only other bits of information I can give which might or might not 
be helpful are;

1) Calling pthread_mutexattr_init in a static variable in the executable 
works.
2) If I remove the pthread_mutexattr_init/pthread_mutexattr_destroy 
calls it works.
3) Delaying the pthread_mutexattr_init call until the first time the 
Mutex class is used works BUT then the
segfault happens when dlclose is called.

I haven't managed to track down the cause of the segfault yet, I'm 
getting a bit lost in the debugger :/

Andy

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 name="mutex.cpp"
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 filename="mutex.cpp"

#include <dlfcn.h>
#include <pthread.h>
#include <stdio.h>

struct Mutex {
  Mutex()
  {
    pthread_mutexattr_init( &_attr );
    pthread_mutexattr_settype( &_attr, PTHREAD_MUTEX_RECURSIVE );
    pthread_mutex_init( &_mutex, &_attr );
  }
  ~Mutex()
  {
    pthread_mutex_destroy( &_mutex );
    pthread_mutexattr_destroy( &_attr );
  }
protected:
  pthread_mutex_t _mutex;
  pthread_mutexattr_t _attr;
};

static Mutex mymutex;

void __EntryPoint()
{
  printf( "In mutex.dll\n" );
}

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 name="test.cpp"
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 filename="test.cpp"

#include <dlfcn.h>

int main( int argc, char** argv )
{
  void* dll = dlopen( "mutex.dll", RTLD_NOW );
  dlclose( dll );
}


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