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Debugging a delayed-load DLL (such as a Python extension) with Eclipse/MinGW

Submitted by keath on Fri, 2009-01-30 12:28

So here's the scenario: you've built a DLL that gets dynamically-loaded at run-time by another application (possibly not yours) and now you want to debug it under Eclipse, but execution blows right past your breakpoints! What to do?

In my case, I'm debugging a Python extension, but this scenario applies to other situations as well - Apache modules, PHP extensions and plug-ins to other applications. In all of these cases the application loads you DLL at some point after it has launched - usually in response to a script or user action. Debugging the DLL in these situations can be challenging because it is not loaded in memory along with the application.

I uninstalled QuickTime today...

Submitted by keath on Sat, 2009-01-10 11:46

After being bugged for what has to be the 1000th time by Apple Update to install software I neither need or want, I'd had enough. I realized that on most of my machines, I don't need QuickTime any more and it's not worth the annoying extra nagware that Apple feels is necessary to install on my system along with it.

Most websites no longer use QuickTime video and I use my Mac for synching my Ipod with ITunes, so bye bye Apple software on my Windows machines and good riddance.

I don't think I'm alone here and I think this is a good lesson for any software make - if you make your products singularly obnoxious, people will stop using them.

MinGW/MSYS Vista Issues

Submitted by keath on Thu, 2008-12-11 22:46

The MinGW and MSYS environment has a couple of problems under Windows Vista:

First, the install, install-info and patch commands are flagged automatically by Vista as requiring Administrator privileges based simply on their names. Nice. This will cause mysterious permission denied errors during builds. The UAC dialog won't pop up in this case either.

The fix is to add ".manifest" files for each of these commands in the same directory as the command. The manifest file looks something like this:

install.exe.manifest:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
  <assemblyIdentity version="1.0.0.0"
     processorArchitecture="X86"
     name="install.exe"
     type="win32"/>

  <!-- Identify the application security requirements. -->
  <trustInfo xmlns="urn:schemas-microsoft-com:asm.v3">
    <security>
      <requestedPrivileges>
        <requestedExecutionLevel
          level="asInvoker"
          uiAccess="false"/>
        </requestedPrivileges>
       </security>
  </trustInfo>
</assembly>

Create and edit one of these for each of the commands above. If you have Cygwin, you can copy them from /cygwin/bin.

The second problem I ran into under Vista is that tar operations on gzipped or bzip2 files will frequently fail with a "child died with signal 13" error. It appears that the MSYS versions of gzip and bzip2 have issues under Vista. I can use the Cygwin versions in their place with no problems. If you're using MSYS to build packages, be careful with having cygwin in your PATH however.

Free Virtual Machines for Windows

Submitted by keath on Sun, 2008-11-30 23:12

I recently had the need for a virtualization solution for Windows to host some Linux-based embedded development tools. Not wanting to shell out big bucks for one of the commercial solutions, I decided to check out some of the free options.

Fix for VBScript Error When Installing iTunes/Quicktime on Vista

Submitted by keath on Sun, 2007-04-08 14:55

The iTunes/QuickTime installer will fail with a "VBScript not installed" error on some installations of Vista. I'm not sure exactly what leads to this situation as it does not seem to affect all Vista users, but there is a relatively simple fix:

  • Click Start, All Programs, Accessories then right click on Command Prompt and select "Run as Administrator"
  • cd to your windows\system32 directory
  • enter the following command:

    regsvr32 vbscript.dll

This will re-register VBScript and allow the iTunes installer to run.

Accessing Mac OS X Windows Sharing from Vista

Submitted by keath on Sat, 2007-03-24 15:15

Windows Vista will not work with Mac OS X Windows file sharing support by default. If you attempt to access a folder shared from Mac OS X, Vista will display a logon error repeatedly.

The problem is that Vista, by default, will only use NTLMv2 for authentication, which is not supported by Mac OS X's Windows Sharing service.

To get around this:

  1. In Vista, open the Control Panel
  2. Switch to "Classic" view
  3. Double-click Administration Tools
  4. Double-click Local Security Policy
  5. Expand "Local Policies" and select "Security Options"
  6. Locate "Network Security: LAN Manager Authentication Level" in the list and double-click it.
  7. Change the setting from "Send NTMLv2 response only" to "Send LM & NTLM - use NTLMv2 session if negotiated"
  8. Click OK

Now you should be able to access your Mac OS X shares.

You might also have this problem accessing Samba shares on Linux or Unix systems running an older version of Samba. The same fix should work in this case as well. Current versions of Samba support NTLMv2.