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Search - "heap corruption"
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assignment: use winAPI to create a "virus" that put itself in autorun and does nothing.
me, a curious student: does the assignment and adds a heap corruption code just as a joke.
after sending the assignment to the teacher I realized that I have sent the real virus.
result: teacher comes next lesson without a computer and stares at me silently and viciously.
we'll see what happens next
any idea on what's going on in his head?28 -
I could bitch about XSLT again, as that was certainly painful, but that’s less about learning a skill and more about understanding someone else’s mental diarrhea, so let me pick something else.
My most painful learning experience was probably pointers, but not pointers in the usual sense of `char *ptr` in C and how they’re totally confusing at first. I mean, it was that too, but in addition it was how I had absolutely none of the background needed to understand them, not having any learning material (nor guidance), nor even a typical compiler to tell me what i was doing wrong — and on top of all of that, only being able to run code on a device that would crash/halt/freak out whenever i made a mistake. It was an absolute nightmare.
Here’s the story:
Someone gave me the game RACE for my TI-83 calculator, but it turned out to be an unlocked version, which means I could edit it and see the code. I discovered this later on by accident while trying to play it during class, and when I looked at it, all I saw was incomprehensible garbage. I closed it, and the game no longer worked. Looking back I must have changed something, but then I thought it was just magic. It took me a long time to get curious enough to look at it again.
But in the meantime, I ended up played with these “programs” a little, and made some really simple ones, and later some somewhat complex ones. So the next time I opened RACE again I kind of understood what it was doing.
Moving on, I spent a year learning TI-Basic, and eventually reached the limit of what it could do. Along the way, I learned that all of the really amazing games/utilities that were incredibly fast, had greyscale graphics, lowercase text, no runtime indicator, etc. were written in “Assembly,” so naturally I wanted to use that, too.
I had no idea what it was, but it was the obvious next step for me, so I started teaching myself. It was z80 Assembly, and there was practically no documents, resources, nothing helpful online.
I found the specs, and a few terrible docs and other sources, but with only one year of programming experience, I didn’t really understand what they were telling me. This was before stackoverflow, etc., too, so what little help I found was mostly from forum posts, IRC (mostly got ignored or made fun of), and reading other people’s source when I could find it. And usually that was less than clear.
And here’s where we dive into the specifics. Starting with so little experience, and in TI-Basic of all things, meant I had zero understanding of pointers, memory and addresses, the stack, heap, data structures, interrupts, clocks, etc. I had mastered everything TI-Basic offered, which astoundingly included arrays and matrices (six of each), but it hid everything else except basic logic and flow control. (No, there weren’t even functions; it has labels and goto.) It has 27 numeric variables (A-Z and theta, can store either float or complex numbers), 8 Lists (numeric arrays), 6 matricies (2d numeric arrays), 10 strings, and a few other things like “equations” and literal bitmap pictures.
Soo… I went from knowing only that to learning pointers. And pointer math. And data structures. And pointers to pointers, and the stack, and function calls, and all that goodness. And remember, I was learning and writing all of this in plain Assembly, in notepad (or on paper at school), not in C or C++ with a teacher, a textbook, SO, and an intelligent compiler with its incredibly helpful type checking and warnings. Just raw trial and error. I learned what I could from whatever cryptic sources I could find (and understand) online, and applied it.
But actually using what I learned? If a pointer was wrong, it resulted in unexpected behavior, memory corruption, freezes, etc. I didn’t have a debugger, an emulator, etc. I had notepad, the barebones compiler, and my calculator.
Also, iterating meant changing my code, recompiling, factory resetting my calculator (removing the battery for 30+ sec) because bugs usually froze it or corrupted something, then transferring the new program over, and finally running it. It was soo slowwwww. But I made steady progress.
Painful learning experience? Check.
Pointer hell? Absolutely.4 -
I am working on an open source game project, and the most common way to draw things is using a class named ManagedSurface. The class is otherwise awesome, but it has a method called getBasePtr(x, y), which gives you a pointer to the requested coordinates. Fair enough (this is C++ without STL by the way).
But WHY THE HELL CAN I REQUEST ANY POINTER THAT I WANT, EVEN IF IT'S OUTSIDE THE SURFACE? Other cointainers have sanity checks, asserts and such, and the surface KEEPS TRACK OF IT'S WIDTH AND HEIGHT.
WAS IT SO FUCKING HARD TO ADD assert(x <= w); assert(y <= h);???
I spent 3 days on valgrind trying to find a heap corruption that manifested at random points in the code.
FUUUUCK!
On the bright side, I learned how to use valgrind (which is awesomely awesome).4 -
Starting the Monday with a good old heap corruption in a c# project that uses only managed code.
Occurs on 2/3 PCs.
Today is going to productive :/