Category Archives: Debugging

Matlab’s mxArray Internals

Posted on October 18, 2017 by Ofek Shilon

Everything in Matlab is a Matrix. The scalar 4 is a 1×1 matrix with the single value 4. The string ‘asdf’ is a 4×1 (not a typo – it is in fact a column vector) matrix, with the 4 char … Continue reading →

Posted in Debugging, Matlab, VC++ | 2 Comments

Tracking the Current Directory from the debugger: RtlpCurDirRef

Posted on July 1, 2017 by Ofek Shilon

Some rogue code was changing our current directory from under our feet, and we needed to catch it in action. I was looking for a memory location to set a data breakpoint on. (Note: for the remainder of this post … Continue reading →

Posted in Debugging, VC++, Win32 | 1 Comment

Checking Memory Corruption from the debugger in 2016

Posted on November 1, 2016 by Ofek Shilon

It used to be something like But this trick requires quite a bit of adaptation to use on modern VS versions. First, the relevant module is now ucrtbased.dll – thanks to the universal CRT the expression is no longer version-dependent. … Continue reading →

Posted in Debugging, VC++ | 2 Comments

Data Read Breakpoints – redux

Posted on March 12, 2016 by Ofek Shilon

The Problem ~5Y ago I blogged about data breakpoints. A hefty bit of the discussion was devoted to persistence of hardware breakpoints across a thread switch: all four implementations mentioned assume that HW breakpoints persist across thread boundaries, and some rough … Continue reading →

Posted in Debugging, Visual Studio | 1 Comment

Tinkering with VS2015 (CTP 6)

Posted on March 27, 2015 by Ofek Shilon

Today I downloaded the latest VS bits and played around with the native debugger. It was a brief session and so would be the records of my impressions. J Universal CRT is here! And seems like a great idea. A … Continue reading →

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Accelerating Debug Runs, Part 2: _ITERATOR_DEBUG_LEVEL

Posted on October 14, 2014 by Ofek Shilon

A previous post discussed the Windows Debug Heap – with the main motivation being how to avoid it, as it is just empty, expensive overhead, and it isn’t clear why it is on by default in the first place. Remarkably, … Continue reading →

Posted in Debugging, VC++ | 1 Comment

Accelerating Debug Runs, Part 1: _NO_DEBUG_HEAP

Posted on September 20, 2014 by Ofek Shilon

(A more appropriate but even-less-catchy title might have been ‘accelerating runs from the debugger‘. As elaborated below, these two are not strictly equal). A common notion is that debug builds can and should carry as much debugging overhead as one … Continue reading →

Posted in Debugging, Visual Studio, Win32 | Leave a comment

Debugging Memory Corruption II

Posted on August 1, 2014 by Ofek Shilon

Some years ago I shared a trick that let’s you call _CrtCheckMemory from the debugger anywhere, without re-compilation.   The updated (as of VS2013) string to type at a watch window is: {,,msvcr120d.dll}_CrtCheckMemory() Let’s expand on that today, in two steps. … Continue reading →

Posted in Debugging, VC++ | 4 Comments

Debugging Handle Leaks

Posted on July 8, 2014 by Ofek Shilon

This is all well documented stuff and I won’t go into details – it’s here mostly for self reference (3rd time I had to chase this down in google). Steps are: (1) Install WDK to integrate the WinDbg engine with … Continue reading →

Posted in Debugging, Visual Studio, Win32 | Leave a comment

Setting a Watch on Wide Registers in VS

Posted on June 3, 2014 by Ofek Shilon

General-purpose registers can be watched from the watch window pretty much as regular variables: (the ‘$’ prefix is optional, but is recommended by MS – probably as means to minimize clashes with code variables.) It is less known that you … Continue reading →

Posted in Debugging, VC++ | Leave a comment