[Boost-users] [filesystem] path::native_file_string() heap issue and

From: Brendon Costa (bcosta_at_[hidden])
Date: 2005-11-10 22:59:07

Hi all,

    I have been using the boost filesystem library for a little while 
under NetBSD and all is fine however I have just been porting our 
application over to windows and have come across a problem with the 
boost filesystem library (Boost 1.33.0). I am compiling with MinGW (g++ 
3.4.2) on a Windows XP system.

When debugging our application in gdb i get a SIGTRAP with an Invalid 
Address specified to RtlFreeHeap. This is when using the 
path::native_file_string() method. I also have another problem where a 
SEGFAULT ocurrs when using the boost::filesystem::exists() method, 
however i think that may be linked to the native_file_string() error.

I wrote a small test program as shown below to reproduce the error when 
using path::native_file_string()

#include <iostream>
#include <boost/filesystem/operations.hpp>
int main()
{
   std::string filename = "test.dat";
   boost::filesystem::path boost_filename(filename);
  
   std::cout << "Filename: " << filename << std::endl;
   std::cout << "Boost string(): " << boost_filename.string() << std::endl;
   std::cout << "Boost native_file_string(): " << 
boost_filename.native_file_string() << std::endl;
   return 0;
}

This compiles fine, and it also will run fine outside of GDB. However if 
i run it inside GDB i get errors on the line that uses 
boost_native_file_string() that are shown below:

Starting program: X:\msys\Utils_test/./a.exe

Program received signal SIGTRAP, Trace/breakpoint trap.
0x7c901231 in _libkernel32_a_iname ()
(gdb) warning: HEAP[a.exe]:
warning: Invalid Address specified to RtlFreeHeap( 003D0000, 003D5138 )

bt
#0  0x7c901231 in _libkernel32_a_iname ()
#1  0x7c96c943 in _libkernel32_a_iname ()
#2  0x7c96cd80 in _libkernel32_a_iname ()
#3  0x7c96df66 in _libkernel32_a_iname ()
#4  0x7c94a5d0 in _libkernel32_a_iname ()
#5  0x7c9268ad in _libkernel32_a_iname ()
#6  0x77c2c2de in _libkernel32_a_iname ()
#7  0x00409855 in operator delete(void*) () at boost_test.cpp:59
#8  0x0042e2dc in std::string::_Rep::_M_destroy(std::allocator<char> 
const&) ()
    at c:/Boost/include/boost-1_33/boost/filesystem/path.hpp:57
#9  0x00430d68 in std::string::~string() ()
    at c:/Boost/include/boost-1_33/boost/filesystem/path.hpp:57
#10 0x004015d6 in main () at boost_test.cpp:12
(gdb)

I also have a larger program where part of its code uses the boost 
filesystem library that looks like:

      static std::string GetUnusedFileName(const char* suggestion = 
"test_file")
      {
         int count = 0;
         std::string base = suggestion;
         std::string filename(base + ".dat");
       
         while(boost::filesystem::exists(boost::filesystem::path(filename)))
         {
            std::ostringstream stream;
            stream << base << "_" << count << ".dat";
           
            filename = stream.str();
            count++;
         }
        
         return filename;
      }

This will usually cause a seg fault when calling the 
filesystem::exists() method. I currently do not have a stack trace for 
that and was unable to reproduce one but i think the two errors may be 
linked.

Am i using the system correctly? The code works fine in NetBSD so i 
assume so.

Has this bug been identified in the past and possibly fixed for the 
1_33_1_beta release? I started compiling that but there are a few 
changes i need to make to the build system to go to 1_33_1 that may be 
time consuming for a problem that may not yet have been addressed anyway.

Thanks for any help in advance,
Brendon Costa.